Re: Purpose of theoretical physics - Was "What's wrong with loop [Archive]

Arnold Neumaier

Oct22-04, 12:01 PM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\n\nLubo? Motl wrote:\n\n> It\'s not just a matter of beliefs: it\'s an issue of choosing which\n> theories are more satisfying scientifically. You don\'t need QED to\n> describe chemistry: you can work with an effective theory with\n> hundreds of "elementary" particles called "atoms" which can interact\n> through millions of interactions whose coefficients you may determine\n> experimentally. Of course that at the end, you can make such theories\n> agree with whatever experimental data you have. Would you agree that\n> the Standard Model is a better theory than this "constructive physical\n> chemistry"? If you do, how would you explain what is better about it?\n>\n> There is no guarantee that the "final dream" of this reductionist\n> program - a theory with no inputs - will become true. The Nature may\n> need some parameters at the end. However, this does not change the\n> fact that among two theories able to agree with the observed\n> phenomena, the less arbitrary theory (with less parameters and\n> assumptions) is scientifically preferred. This preference is about the\n> rules of science, and it is a different question that the question\n> "how much Nature allows us to understand at the end".\n\nActually, chemists prefer the theory based on Dirac-Fock theory or even\ncruder approximations, treating the nuclei as elementary. This gives them\nall the information they need, while they can deduce nothing at all from\nthe standard model.\n\nThus what is preferred depends a lot on which use can be made of it.\n\nNothing in science is against a complicated model if it gives more ready\naccess to the quantities of interest than a formally simpler but\ncomputationally more difficult or even untractable formulation.\n\nGiven only the standard model, we\'d know very little about our world,\nand only very inaccurately. Not even the masses of the nuclei can be\npredicted at present with any confidence, let alone the properties\nof water or gold.\n\nAnd given only string theory, we\'d know essentially nothing about our\nworld.\n\n\nArnold Neumaier\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>Lubo? Motl wrote:

> It's not just a matter of beliefs: it's an issue of choosing which
> theories are more satisfying scientifically. You don't need QED to
> describe chemistry: you can work with an effective theory with
> hundreds of "elementary" particles called "atoms" which can interact
> through millions of interactions whose coefficients you may determine
> experimentally. Of course that at the end, you can make such theories
> agree with whatever experimental data you have. Would you agree that
> the Standard Model is a better theory than this "constructive physical
> chemistry"? If you do, how would you explain what is better about it?
>
> There is no guarantee that the "final dream" of this reductionist
> program - a theory with no inputs - will become true. The Nature may
> need some parameters at the end. However, this does not change the
> fact that among two theories able to agree with the observed
> phenomena, the less arbitrary theory (with less parameters and
> assumptions) is scientifically preferred. This preference is about the
> rules of science, and it is a different question that the question
> "how much Nature allows us to understand at the end".

Actually, chemists prefer the theory based on Dirac-Fock theory or even
cruder approximations, treating the nuclei as elementary. This gives them
all the information they need, while they can deduce nothing at all from
the standard model.

Thus what is preferred depends a lot on which use can be made of it.

Nothing in science is against a complicated model if it gives more ready
access to the quantities of interest than a formally simpler but
computationally more difficult or even untractable formulation.

Given only the standard model, we'd know very little about our world,
and only very inaccurately. Not even the masses of the nuclei can be
predicted at present with any confidence, let alone the properties
of water or gold.

And given only string theory, we'd know essentially nothing about our
world.

Arnold Neumaier

Lubos Motl

Oct23-04, 10:11 AM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>On Fri, 22 Oct 2004, Arnold Neumaier wrote:\n\n> Actually, chemists prefer the theory based on Dirac-Fock theory or even\n> cruder approximations, treating the nuclei as elementary. This gives them\n> all the information they need, while they can deduce nothing at all from\n> the standard model.\n>\n> Thus what is preferred depends a lot on which use can be made of it.\n\nI was describing how to decide which theories are more *true* - which of\nthem are preferred as a description of true reality - and not the question\nwhich approximations are *useful* in some contexts.\n\nIf we wouldn\'t agree that the Standard Model is more *true* than the\nDirac-Fock theory or "even cruder approximations", then it would be really\nhard to agree about anything.\n\n> Nothing in science is against a complicated model if it gives more ready\n> access to the quantities of interest than a formally simpler but\n> computationally more difficult or even untractable formulation.\n\nWhat you describe is simply not an approach of a physicist, and I can\'t\nagree with it at all. Nature does not care whether Her theories are easy\nor difficult for us, and how easy it is to calculate them. If they\'re easy\nto calculate, good for us; if they\'re hard, we must work harder and/or try\nvarious new approximations or other, equivalent approaches that may\nsimplify the situation.\n\nQCD is definitely pretty complicated - especially at long distances - but\nit is the correct theory. It is definitely more correct than a collection\nof phenomenological laws that describe the individual actual observations.\nYou can replace QCD by a set of hundreds of simpler formulae, each of them\npredicting a certain region of the parameter space of the experiments. But\nit won\'t be a theory comparable to QCD, and you will certainly never get a\nNobel prize for something like that. ;-)\n\nThe small number of parameters and arbitrariness is what distinguishes a\nrigid, powerful, predictive, deeper theory from a random collection of\nphenomenological observations that can only describe what has already been\nseen. Who does not understand the *dramatic* difference between *theories*\nand mere *descriptions* of our observations, does not understand what\ntheoretical physics means.\n\n> Given only the standard model, we\'d know very little about our world,\n> and only very inaccurately. Not even the masses of the nuclei can be\n> predicted at present with any confidence, let alone the properties\n> of water or gold.\n\nThat\'s demagogy. A true statement would be that the Lagrangian of the\nStandard Model is not the only *idea* that we need to understand all\nfeatures of reality, but it is an idea that *implies* (in combination with\nGR) all known rules about reality, including the properties of water and\ngold, and it is just a matter of mathematical difficulty that prevents us\nfrom extracting the right information directly from the SM.\n\nHaving the Standard Model certainly does not *reduce* our ability to\nunderstand the property of gold and water.\n\nA person may only be interested in drinking water and earning gold, and\nknowing their general properties is sufficient for her happy life, but it\ndoes not mean that her opinion are equally relevant or true for physics as\na physical theory!\n\n> And given only string theory, we\'d know essentially nothing about our\n> world.\n\nThat\'s ridiculous. What you say is not only untrue. If we knew string\ntheory, we could derive that the world follows general relativity and\ngauge theories with chiral fermions etc. at low energies - even if we did\nnot know immediately which groups and representations are the right ones.\nIf people had had string theory - with the current papers - in 1965, they\ncould have developed the Standard Model within a year. Well, of course,\nthis is because the papers implicitly contain virtually all important\nknowledge about GR and QFT, too - but that\'s because *string theory\nitself* contains them.\n\nWhat you say is also untrue sociogically: string *theorists* often know\nmuch more about QFT, GR, and other aspects of physics than\nnon-string-theorists specializing on these fields.\n\nCheers, Lubos\n___________________________________________ ___________________________________\nE-mail: lumo@matfyz.cz fax: +1-617/496-0110 Web: http://lumo.matfyz.cz/\neFax: +1-801/454-1858 work: +1-617/384-9488 home: +1-617/868-4487 (call)\nWebs: http://schwinger.harvard.edu/~motl/ http://motls.blogspot.com/\n^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>On Fri, 22 Oct 2004, Arnold Neumaier wrote:

> Actually, chemists prefer the theory based on Dirac-Fock theory or even
> cruder approximations, treating the nuclei as elementary. This gives them
> all the information they need, while they can deduce nothing at all from
> the standard model.
>
> Thus what is preferred depends a lot on which use can be made of it.

I was describing how to decide which theories are more *true* - which of
them are preferred as a description of true reality - and not the question
which approximations are *useful* in some contexts.

If we wouldn't agree that the Standard Model is more *true* than the
Dirac-Fock theory or "even cruder approximations", then it would be really
hard to agree about anything.

> Nothing in science is against a complicated model if it gives more ready
> access to the quantities of interest than a formally simpler but
> computationally more difficult or even untractable formulation.

What you describe is simply not an approach of a physicist, and I can't
agree with it at all. Nature does not care whether Her theories are easy
or difficult for us, and how easy it is to calculate them. If they're easy
to calculate, good for us; if they're hard, we must work harder and/or try
various new approximations or other, equivalent approaches that may
simplify the situation.

QCD is definitely pretty complicated - especially at long distances - but
it is the correct theory. It is definitely more correct than a collection
of phenomenological laws that describe the individual actual observations.
You can replace QCD by a set of hundreds of simpler formulae, each of them
predicting a certain region of the parameter space of the experiments. But
it won't be a theory comparable to QCD, and you will certainly never get a
Nobel prize for something like that. ;-)

The small number of parameters and arbitrariness is what distinguishes a
rigid, powerful, predictive, deeper theory from a random collection of
phenomenological observations that can only describe what has already been
seen. Who does not understand the *dramatic* difference between *theories*
and mere *descriptions* of our observations, does not understand what
theoretical physics means.

> Given only the standard model, we'd know very little about our world,
> and only very inaccurately. Not even the masses of the nuclei can be
> predicted at present with any confidence, let alone the properties
> of water or gold.

That's demagogy. A true statement would be that the Lagrangian of the
Standard Model is not the only *idea* that we need to understand all
features of reality, but it is an idea that *implies* (in combination with
GR) all known rules about reality, including the properties of water and
gold, and it is just a matter of mathematical difficulty that prevents us
from extracting the right information directly from the SM.

Having the Standard Model certainly does not *reduce* our ability to
understand the property of gold and water.

A person may only be interested in drinking water and earning gold, and
knowing their general properties is sufficient for her happy life, but it
does not mean that her opinion are equally relevant or true for physics as
a physical theory!

> And given only string theory, we'd know essentially nothing about our
> world.

That's ridiculous. What you say is not only untrue. If we knew string
theory, we could derive that the world follows general relativity and
gauge theories with chiral fermions etc. at low energies - even if we did
not know immediately which groups and representations are the right ones.
If people had had string theory - with the current papers - in 1965, they
could have developed the Standard Model within a year. Well, of course,
this is because the papers implicitly contain virtually all important
knowledge about GR and QFT, too - but that's because *string theory
itself* contains them.

What you say is also untrue sociogically: string *theorists* often know
much more about QFT, GR, and other aspects of physics than
non-string-theorists specializing on these fields.

Cheers, Lubos
__{_______________________________________________ _____________________________}
E-mail: lumo@matfyz.cz fax: +1-617/496-0110 Web: http://lumo.matfyz.cz/
eFax: +1-801/454-1858 work: +1-617/384-9488 home: +1-617/868-4487 (call)
Webs: http://schwinger.harvard.edu/~motl/ http://motls.blogspot.com/
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Arnold Neumaier

Oct24-04, 09:04 AM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\n\nLubos Motl wrote:\n> On Fri, 22 Oct 2004, Arnold Neumaier wrote:\n>\n>>Actually, chemists prefer the theory based on Dirac-Fock theory or even\n>>cruder approximations, treating the nuclei as elementary. This gives them\n>>all the information they need, while they can deduce nothing at all from\n>>the standard model.\n>>\n>>Thus what is preferred depends a lot on which use can be made of it.\n>\n> I was describing how to decide which theories are more *true* - which of\n> them are preferred as a description of true reality - and not the question\n> which approximations are *useful* in some contexts.\n>\n> If we wouldn\'t agree that the Standard Model is more *true* than the\n> Dirac-Fock theory or "even cruder approximations", then it would be really\n> hard to agree about anything.\n\nTrue is not something that can be put into the comparative.\nEither something is true, or it isn\'t. Dirac-Fock theory is true in\nthe sense that it produces correct predictions. (It is be even\n\'more true\' than string theory in the sense that it makes more correct\npredictions than the latter.)\n\n\n>>Nothing in science is against a complicated model if it gives more ready\n>>access to the quantities of interest than a formally simpler but\n>>computationally more difficult or even untractable formulation.\n>\n> What you describe is simply not an approach of a physicist, and I can\'t\n> agree with it at all.\n\nApparently you exclude everyone except string theorists from the\ncommunity of physicists. All textbook physics I know is of the kind\nI described. Do you want to say that thermodynamics is not physics\nbecause it is just a very useful approximation to reality?\n\n99.999% of all physics is based on approximate models.\nThe esteem physics has in society is based solely on making useful\nmodels of reality that give correct predictions.\n\n\n> Nature does not care whether Her theories are easy\n> or difficult for us, and how easy it is to calculate them.\n\nNature does not care at all. It worked wor billions of years without\nanyone but God and His hosts to ponder a theory.\n\n\n> QCD is definitely pretty complicated - especially at long distances - but\n> it is the correct theory.\n\nDirac-Fock is as correct as QCD, and much more predictive.\nIf you discard Dirac-Fock as incorrect because its accuracy is limited,\nyou\'d have to discard QCD as well, since it does not account for\nweak and electromagnetic interactions, and you\'d have to discard\neven the standard model since it does not account for gravitation.\nThis leaves no theory at all...\n\n>>Given only the standard model, we\'d know very little about our world,\n>>and only very inaccurately. Not even the masses of the nuclei can be\n>>predicted at present with any confidence, let alone the properties\n>>of water or gold.\n>\n\n> That\'s demagogy. A true statement would be that the Lagrangian of the\n> Standard Model is not the only *idea* that we need to understand all\n> features of reality, but it is an idea that *implies* (in combination with\n> GR) all known rules about reality, including the properties of water and\n> gold,\n\nPlease give references and not only words.\n\nApparently you know much more, as a citicen of \'the planet called Zetor here\'\nhttp://www.kolej.mff.cuni.cz/~lmotm275/\n\'\'Name: Lubos Motl (Who Where item), member of MOTL league,\nI am an alien.\'\'\nI\'d be happy to be educated...\n\nSo please show me a derivation of the properties of water based on the\nstandard model. Certainly it requires that one can calculate the atomic\nweight of H and O to the accuracy known to chemists, and as far as I\nknow, theorists are _very_ far from being able to do that.\n\n\n> Having the Standard Model certainly does not *reduce* our ability to\n> understand the property of gold and water.\n>\n> A person may only be interested in drinking water and earning gold, and\n> knowing their general properties is sufficient for her happy life, but it\n> does not mean that her opinion are equally relevant or true for physics as\n> a physical theory!\n>\n>>And given only string theory, we\'d know essentially nothing about our\n>>world.\n>\n>\n> That\'s ridiculous.\n\n.... but true. it just shows that it is ridiculous at present to claim\nthat string theory is the truth.\n\n\n> What you say is not only untrue. If we knew string\n> theory, we could derive that the world follows general relativity and\n> gauge theories with chiral fermions etc. at low energies -\n\nWhere is this derived? Please give references and not only words.\n\n\n> even if we did\n> not know immediately which groups and representations are the right ones.\n\n.... and which values the masses and coupling constants have, how many\nfamilies of particles there are, etc., which makes all the difference\nto our existence.\n\n\n> What you say is also untrue sociogically: string *theorists* often know\n> much more about QFT, GR, and other aspects of physics than\n> non-string-theorists specializing on these fields.\n\nShow me this \'much more\' by giving a calculation of the atomic\nweight of H and O to the accuracy known to chemists based on the\nstandard model, which you claimed above is possible.\n\nIf you can\'t, I take it as a sign that the alleged knowledge of much\nmore is only hype.\n\n\nArnold Neumaier\n\n\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>Lubos Motl wrote:
> On Fri, 22 Oct 2004, Arnold Neumaier wrote:
>
>>Actually, chemists prefer the theory based on Dirac-Fock theory or even
>>cruder approximations, treating the nuclei as elementary. This gives them
>>all the information they need, while they can deduce nothing at all from
>>the standard model.
>>
>>Thus what is preferred depends a lot on which use can be made of it.
>
> I was describing how to decide which theories are more *true* - which of
> them are preferred as a description of true reality - and not the question
> which approximations are *useful* in some contexts.
>
> If we wouldn't agree that the Standard Model is more *true* than the
> Dirac-Fock theory or "even cruder approximations", then it would be really
> hard to agree about anything.

True is not something that can be put into the comparative.
Either something is true, or it isn't. Dirac-Fock theory is true in
the sense that it produces correct predictions. (It is be even
'more true' than string theory in the sense that it makes more correct
predictions than the latter.)

>>Nothing in science is against a complicated model if it gives more ready
>>access to the quantities of interest than a formally simpler but
>>computationally more difficult or even untractable formulation.
>
> What you describe is simply not an approach of a physicist, and I can't
> agree with it at all.

Apparently you exclude everyone except string theorists from the
community of physicists. All textbook physics I know is of the kind
I described. Do you want to say that thermodynamics is not physics
because it is just a very useful approximation to reality?

99.999% of all physics is based on approximate models.
The esteem physics has in society is based solely on making useful
models of reality that give correct predictions.

> Nature does not care whether Her theories are easy
> or difficult for us, and how easy it is to calculate them.

Nature does not care at all. It worked wor billions of years without
anyone but God and His hosts to ponder a theory.

> QCD is definitely pretty complicated - especially at long distances - but
> it is the correct theory.

Dirac-Fock is as correct as QCD, and much more predictive.
If you discard Dirac-Fock as incorrect because its accuracy is limited,
you'd have to discard QCD as well, since it does not account for
weak and electromagnetic interactions, and you'd have to discard
even the standard model since it does not account for gravitation.
This leaves no theory at all...

>>Given only the standard model, we'd know very little about our world,
>>and only very inaccurately. Not even the masses of the nuclei can be
>>predicted at present with any confidence, let alone the properties
>>of water or gold.
>

> That's demagogy. A true statement would be that the Lagrangian of the
> Standard Model is not the only *idea* that we need to understand all
> features of reality, but it is an idea that *implies* (in combination with
> GR) all known rules about reality, including the properties of water and
> gold,

Please give references and not only words.

Apparently you know much more, as a citicen of 'the planet called Zetor here'
http://www.kolej.mff.cuni.cz/~lmotm275/
''Name: Lubos Motl (Who Where item), member of MOTL league,
I am an alien.''
I'd be happy to be educated...

So please show me a derivation of the properties of water based on the
standard model. Certainly it requires that one can calculate the atomic
weight of H and O to the accuracy known to chemists, and as far as I
know, theorists are _very_ far from being able to do that.

> Having the Standard Model certainly does not *reduce* our ability to
> understand the property of gold and water.
>
> A person may only be interested in drinking water and earning gold, and
> knowing their general properties is sufficient for her happy life, but it
> does not mean that her opinion are equally relevant or true for physics as
> a physical theory!
>
>>And given only string theory, we'd know essentially nothing about our
>>world.
>
>
> That's ridiculous.

.... but true. it just shows that it is ridiculous at present to claim
that string theory is the truth.

> What you say is not only untrue. If we knew string
> theory, we could derive that the world follows general relativity and
> gauge theories with chiral fermions etc. at low energies -

Where is this derived? Please give references and not only words.

> even if we did
> not know immediately which groups and representations are the right ones.

.... and which values the masses and coupling constants have, how many
families of particles there are, etc., which makes all the difference
to our existence.

> What you say is also untrue sociogically: string *theorists* often know
> much more about QFT, GR, and other aspects of physics than
> non-string-theorists specializing on these fields.

Show me this 'much more' by giving a calculation of the atomic
weight of H and O to the accuracy known to chemists based on the
standard model, which you claimed above is possible.

If you can't, I take it as a sign that the alleged knowledge of much
more is only hype.

Arnold Neumaier

backdoorstudent

Oct24-04, 09:04 AM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\n\nLubos Motl <motl@feynman.harvard.edu> wrote in message news:<Pine.LNX.4.31.0410231050480.2703-100000@feynman.harvard.edu>...\n> On Fri, 22 Oct 2004, Arnold Neumaier wrote:\n> > Given only the standard model, we\'d know very little about our world,\n> > and only very inaccurately. Not even the masses of the nuclei can be\n> > predicted at present with any confidence, let alone the properties\n> > of water or gold.\n>\n> That\'s demagogy. A true statement would be that the Lagrangian of the\n> Standard Model is not the only *idea* that we need to understand all\n> features of reality, but it is an idea that *implies* (in combination with\n> GR) all known rules about reality, including the properties of water and\n> gold, and it is just a matter of mathematical difficulty that prevents us\n> from extracting the right information directly from the SM.\n\nProve it!\n\nHow do you know it is just a matter of mathematical difficulty? How do\nyou know it is not something that is actually NOT derived? Did you\never think it conceivable that phenomena emerge with little bearing on\nthe nature of their components?\n\nA "true statement" is that nobody knows if chemistry even in principle\ncould be derived from the standard model.\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>Lubos Motl <motl@feynman.harvard.edu> wrote in message news:<Pine.LNX.4.31.0410231050480.2703-100000@feynman.harvard.edu>...
> On Fri, 22 Oct 2004, Arnold Neumaier wrote:
> > Given only the standard model, we'd know very little about our world,
> > and only very inaccurately. Not even the masses of the nuclei can be
> > predicted at present with any confidence, let alone the properties
> > of water or gold.
>
> That's demagogy. A true statement would be that the Lagrangian of the
> Standard Model is not the only *idea* that we need to understand all
> features of reality, but it is an idea that *implies* (in combination with
> GR) all known rules about reality, including the properties of water and
> gold, and it is just a matter of mathematical difficulty that prevents us
> from extracting the right information directly from the SM.

Prove it!

How do you know it is just a matter of mathematical difficulty? How do
you know it is not something that is actually NOT derived? Did you
ever think it conceivable that phenomena emerge with little bearing on
the nature of their components?

A "true statement" is that nobody knows if chemistry even in principle
could be derived from the standard model.

Lubos Motl

Oct24-04, 04:11 PM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>On Sun, 24 Oct 2004, Arnold Neumaier wrote:\n\n> True is not something that can be put into the comparative.\n\nThe whole history of developments in theoretical physics is about the\nsearch for "more true" theories. The progress in theory is the march from\nless true, approximate theories, to deeper and more true theories. Your\nstatement is in contradiction with the very meaning of research in theory,\nthe very meaning of pure science. Your opinion is in contradiction with\nthe whole history of human thinking.\n\n> Either something is true, or it isn\'t. Dirac-Fock theory is true in\n> the sense that it produces correct predictions. (It is be even\n> \'more true\' than string theory in the sense that it makes more correct\n> predictions than the latter.)\n\nThe Dirac-Fock theory could only be more true if string theory turned out\nto be completely wrong. If it does not happen, then string theory is, of\ncourse, more complete, more accurate, and more true that any other idea in\nthis Universe.\n\n> Apparently you exclude everyone except string theorists from the\n> community of physicists. All textbook physics I know is of the kind\n> I described.\n\nThen, you have obviously not seen a single physics textbook, perhaps\nexcept for some very bad ones. Or maybe, you completely misunderstood\nthem. Do you really want to claim that there exists a good physics\ntextbook that presents any doubts about my point that theoretical physics\nis a search for more complete, more general theories that can describe and\npredict larger classes of phenomena more accurately, using less\nindependent assumptions and less parameters? I don\'t want to believe that\nyou\'re serious.\n\nMy viewpoint is shared by virtually all good physicists in the history of\nthis planet. Let me just enumerate a couple of examples whom I mean.\nEinstein, Dirac, Heisenberg, Feynman, Landau, Weinberg. What you say is\nplain nonsense. If a high school textbook as bad as you suggest existed,\nit should be removed from schools within one year, I believe.\n\n> Do you want to say that thermodynamics is not physics\n> because it is just a very useful approximation to reality?\n\nThermodynamics is not a complete theory of any phenomenon in the world.\nThermodynamics is a collection of interrelated principles that other\ntheories must satisfy in a certain limit. In some sense it is an axiomatic\nsystem, and it is a set of useful tools to approach a certain important\nclass of problems that appear in most physical contexts.\n\nYou can read Einstein\'s essay. Einstein would explain you that relativity\nand thermodynamics are examples of principial theories (relativity is not\na complete theory of a particular phenomenon either; it is again a set\nof restrictions that other theories must satisfy). Principial theories\nstart with certain assumptions - principles - and try to derive\nconsequences. The other class of theories is, according to Einstein,\nthe class of constructive theories.\n\n> 99.999% of all physics is based on approximate models.\n\nThat\'s one of my points.\n\n> The esteem physics has in society is based solely on making useful\n> models of reality that give correct predictions.\n\nWhether or not this cliche is correct depends on the meaning of the words.\n\nWe would probably disagree what a "correct prediction" means. We would\nalso disagree what "esteem" is and whether it is the primary and the most\nimportant thing. Your confused interpretation of all these important\npoints makes your last sentence above meaningless.\n\nAt any rate, the key developments in theoretical physics are breakthroughs\nin which the old theories are labeled as approximations that are replaced\nby a more complete picture. These are not only the key developments for\nphysics as such, but incidentally also the main source of "esteem" that\nphysics has in the society, and the source of theoretical Nobel prizes.\n\nIf you care about "esteem" so much: Einstein is the most famous physicist\nin the society, and he certainly fits everything I say. He was the first\nreal person who was looking for the "theory of everything". He made very\nimportant steps towards this goal, but the last 30 years of his life just\ncould not lead to a success in his case.\n\n> Nature does not care at all. It worked wor billions of years without\n> anyone but God and His hosts to ponder a theory.\n\nRight. I am happy to see you retract your previous statement that true\ntheories in physics must be easy for us to use them.\n\n> > QCD is definitely pretty complicated - especially at long distances - but\n> > it is the correct theory.\n>\n> Dirac-Fock is as correct as QCD, and much more predictive.\n\nThis is an unverifiable statement because it compares two theories that\nstudy different phenomena. If we want to talk about these questions\nseriously, we must consider theories that try to address the same\nphenomena. OK, let\'s do it. QCD is a part of the Standard Model, and the\nStandard Model is certainly more predictive than any approximation such as\nthe Dirac-Fock scheme - simply because it contains all of them, and it is\na much more complete and accurate approximation.\n\n> If you discard Dirac-Fock as incorrect because its accuracy is limited,\n> you\'d have to discard QCD as well, since it does not account for\n\nI am not discarding them. I am ordering them according to their accuracy,\naccording to the amount how much true and deep they are. QCD is obviously\nmore true than Dirac-Fock.\n\n> weak and electromagnetic interactions, and you\'d have to discard\n> even the standard model since it does not account for gravitation.\n> This leaves no theory at all...\n\nThe future physicists will be able to be as strict as you suggest, and it\nleaves them with string theory. The full string theory is either wrong,\nor it is the *exact* theory of Nature that does not admit any more\n"refinements".\n\n> > That\'s demagogy. A true statement would be that the Lagrangian of the\n> > Standard Model is not the only *idea* that we need to understand all\n> > features of reality, but it is an idea that *implies* (in combination with\n> > GR) all known rules about reality, including the properties of water and\n> > gold,\n>\n> Please give references and not only words.\n\nWhat references? I don\'t argue that someone has *calculated* the\nproperties of gold from the Standard Model. I am saying that these\nproperties are included in the Standard Model. It is a matter of beliefs\nat this moment whether the gold is correctly described by the Standard\nModel, but one belief is a belief of a physicist, and the other is a\nbelief of a person who does not trust physics.\n\n> Apparently you know much more, as a citicen of \'the planet called Zetor here\'\n> \'\'Name: Lubos Motl (Who Where item), member of MOTL league,\n> I am an alien.\'\'\n\nI don\'t know what you find wrong with my being an alien. ;-) Some new form\nof nationalism?\n\n> I\'d be happy to be educated...\n\nIt does not look so.\n\n> > That\'s ridiculous.\n>\n> ... but true. it just shows that it is ridiculous at present to claim\n> that string theory is the truth.\n\nIf it is ridiculous, then it cannot be true. Your original statement -\nmany of them - was ridiculous, and of course it was not true. By the way:\nI am not claiming that we have definitively proved that string theory is\nthe true description of reality. I am saying that if it works, and there\nare all good reasons to believe that it does, then it is a more true\ntheory than any other theory we have ever had in physics. Sorry, but I\nalso believe that one does not have to have a PhD in physics to understand\nthis simple statement.\n\n> > If we knew string theory, we could derive that the world follows\n> > general relativity and gauge theories with chiral fermions etc. at low\n> > energies ...\n>\n> Where is this derived? Please give references and not only words.\n\nChapter 3 of basic textbooks of string theory, such as\nGreen-Schwarz-Witten or Polchinski (volume 1, page 114, for example). At\nHarvard and MIT, even many undergrad students don\'t have any problems with\nthis material. I understand that Vienna is not quite Harvard or MIT, but\nat any rate, I believe that you should at least try to learn the basics of\nmodern theoretical physics if you really intend to participate in\ndiscussions about it.\n\n> ... and which values the masses and coupling constants have, how many\n> families of particles there are, etc., which makes all the difference\n> to our existence.\n\nYes, we have not derived this theoretically yet, but string theory is the\nonly known theoretical structure that offers mechanisms behind all these\nquestions, and the capacity to explain them.\n\n> > What you say is also untrue sociogically: string *theorists* often know\n> > much more about QFT, GR, and other aspects of physics than\n> > non-string-theorists specializing on these fields.\n>\n> Show me this \'much more\' by giving a calculation of the atomic\n> weight of H and O to the accuracy known to chemists based on the\n> standard model, which you claimed above is possible.\n\nI was talking about QFT and GR, not about the weight of oxygen.\nNevertheless, it\'s great that you also mentioned Hydrogen because we can\ncalculate the atomic weight of the hydrogen much more accurately than what\nyou want, from the masses of electron, proton, and QED applied to the atom\n(including loops that are measurable, but far too small for chemists.)\n\n> If you can\'t, I take it as a sign that the alleged knowledge of much\n> more is only hype.\n\nIt\'s not hype. It is called "physics". It\'s just a too difficult problem\nto calculate the exact properties of Oxygen from the Standard Model, and\nit is just not interesting enough for anyone to really work on it because\nall physicists are convinced that the Standard Model gives the right\nproperties of the Oxygen. The confidence in this statement follow\nhierarchical relations between the Standard Model and its increasingly\ninaccurate approximations, that are still enough to describe the atoms and\nnuclei well enough. Anyone is free to believe that the Oxygen contradicts\nthe Standard Model, but no one can expect me to think that the people who\nbelieve in the Oxygen-SM contradictions understand how physics works. They\ndon\'t, and you\'re an example.\n\nBest\nLubos\n_________________________ __________________________________________________ ___\nE-mail: lumo@matfyz.cz fax: +1-617/496-0110 Web: http://lumo.matfyz.cz/\neFax: +1-801/454-1858 work: +1-617/384-9488 home: +1-617/868-4487 (call)\nWebs: http://schwinger.harvard.edu/~motl/ http://motls.blogspot.com/\n^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>On Sun, 24 Oct 2004, Arnold Neumaier wrote:

> True is not something that can be put into the comparative.

The whole history of developments in theoretical physics is about the
search for "more true" theories. The progress in theory is the march from
less true, approximate theories, to deeper and more true theories. Your
statement is in contradiction with the very meaning of research in theory,
the very meaning of pure science. Your opinion is in contradiction with
the whole history of human thinking.

> Either something is true, or it isn't. Dirac-Fock theory is true in
> the sense that it produces correct predictions. (It is be even
> 'more true' than string theory in the sense that it makes more correct
> predictions than the latter.)

The Dirac-Fock theory could only be more true if string theory turned out
to be completely wrong. If it does not happen, then string theory is, of
course, more complete, more accurate, and more true that any other idea in
this Universe.

> Apparently you exclude everyone except string theorists from the
> community of physicists. All textbook physics I know is of the kind
> I described.

Then, you have obviously not seen a single physics textbook, perhaps
except for some very bad ones. Or maybe, you completely misunderstood
them. Do you really want to claim that there exists a good physics
textbook that presents any doubts about my point that theoretical physics
is a search for more complete, more general theories that can describe and
predict larger classes of phenomena more accurately, using less
independent assumptions and less parameters? I don't want to believe that
you're serious.

My viewpoint is shared by virtually all good physicists in the history of
this planet. Let me just enumerate a couple of examples whom I mean.
Einstein, Dirac, Heisenberg, Feynman, Landau, Weinberg. What you say is
plain nonsense. If a high school textbook as bad as you suggest existed,
it should be removed from schools within one year, I believe.

> Do you want to say that thermodynamics is not physics
> because it is just a very useful approximation to reality?

Thermodynamics is not a complete theory of any phenomenon in the world.
Thermodynamics is a collection of interrelated principles that other
theories must satisfy in a certain limit. In some sense it is an axiomatic
system, and it is a set of useful tools to approach a certain important
class of problems that appear in most physical contexts.

You can read Einstein's essay. Einstein would explain you that relativity
and thermodynamics are examples of principial theories (relativity is not
a complete theory of a particular phenomenon either; it is again a set
of restrictions that other theories must satisfy). Principial theories
start with certain assumptions - principles - and try to derive
consequences. The other class of theories is, according to Einstein,
the class of constructive theories.

> 99.999% of all physics is based on approximate models.

That's one of my points.

> The esteem physics has in society is based solely on making useful
> models of reality that give correct predictions.

Whether or not this cliche is correct depends on the meaning of the words.

We would probably disagree what a "correct prediction" means. We would
also disagree what "esteem" is and whether it is the primary and the most
important thing. Your confused interpretation of all these important
points makes your last sentence above meaningless.

At any rate, the key developments in theoretical physics are breakthroughs
in which the old theories are labeled as approximations that are replaced
by a more complete picture. These are not only the key developments for
physics as such, but incidentally also the main source of "esteem" that
physics has in the society, and the source of theoretical Nobel prizes.

If you care about "esteem" so much: Einstein is the most famous physicist
in the society, and he certainly fits everything I say. He was the first
real person who was looking for the "theory of everything". He made very
important steps towards this goal, but the last 30 years of his life just
could not lead to a success in his case.

> Nature does not care at all. It worked wor billions of years without
> anyone but God and His hosts to ponder a theory.

Right. I am happy to see you retract your previous statement that true
theories in physics must be easy for us to use them.

> > QCD is definitely pretty complicated - especially at long distances - but
> > it is the correct theory.
>
> Dirac-Fock is as correct as QCD, and much more predictive.

This is an unverifiable statement because it compares two theories that
study different phenomena. If we want to talk about these questions
seriously, we must consider theories that try to address the same
phenomena. OK, let's do it. QCD is a part of the Standard Model, and the
Standard Model is certainly more predictive than any approximation such as
the Dirac-Fock scheme - simply because it contains all of them, and it is
a much more complete and accurate approximation.

> If you discard Dirac-Fock as incorrect because its accuracy is limited,
> you'd have to discard QCD as well, since it does not account for

I am not discarding them. I am ordering them according to their accuracy,
according to the amount how much true and deep they are. QCD is obviously
more true than Dirac-Fock.

> weak and electromagnetic interactions, and you'd have to discard
> even the standard model since it does not account for gravitation.
> This leaves no theory at all...

The future physicists will be able to be as strict as you suggest, and it
leaves them with string theory. The full string theory is either wrong,
or it is the *exact* theory of Nature that does not admit any more
"refinements".

> > That's demagogy. A true statement would be that the Lagrangian of the
> > Standard Model is not the only *idea* that we need to understand all
> > features of reality, but it is an idea that *implies* (in combination with
> > GR) all known rules about reality, including the properties of water and
> > gold,
>
> Please give references and not only words.

What references? I don't argue that someone has *calculated* the
properties of gold from the Standard Model. I am saying that these
properties are included in the Standard Model. It is a matter of beliefs
at this moment whether the gold is correctly described by the Standard
Model, but one belief is a belief of a physicist, and the other is a
belief of a person who does not trust physics.

> Apparently you know much more, as a citicen of 'the planet called Zetor here'
> ''Name: Lubos Motl (Who Where item), member of MOTL league,
> I am an alien.''

I don't know what you find wrong with my being an alien. ;-) Some new form
of nationalism?

> I'd be happy to be educated...

It does not look so.

> > That's ridiculous.
>
> ... but true. it just shows that it is ridiculous at present to claim
> that string theory is the truth.

If it is ridiculous, then it cannot be true. Your original statement -
many of them - was ridiculous, and of course it was not true. By the way:
I am not claiming that we have definitively proved that string theory is
the true description of reality. I am saying that if it works, and there
are all good reasons to believe that it does, then it is a more true
theory than any other theory we have ever had in physics. Sorry, but I
also believe that one does not have to have a PhD in physics to understand
this simple statement.

> > If we knew string theory, we could derive that the world follows
> > general relativity and gauge theories with chiral fermions etc. at low
> > energies ...
>
> Where is this derived? Please give references and not only words.

Chapter 3 of basic textbooks of string theory, such as
Green-Schwarz-Witten or Polchinski (volume 1, page 114, for example). At
Harvard and MIT, even many undergrad students don't have any problems with
this material. I understand that Vienna is not quite Harvard or MIT, but
at any rate, I believe that you should at least try to learn the basics of
modern theoretical physics if you really intend to participate in
discussions about it.

> ... and which values the masses and coupling constants have, how many
> families of particles there are, etc., which makes all the difference
> to our existence.

Yes, we have not derived this theoretically yet, but string theory is the
only known theoretical structure that offers mechanisms behind all these
questions, and the capacity to explain them.

> > What you say is also untrue sociogically: string *theorists* often know
> > much more about QFT, GR, and other aspects of physics than
> > non-string-theorists specializing on these fields.
>
> Show me this 'much more' by giving a calculation of the atomic
> weight of H and O to the accuracy known to chemists based on the
> standard model, which you claimed above is possible.

I was talking about QFT and GR, not about the weight of oxygen.
Nevertheless, it's great that you also mentioned Hydrogen because we can
calculate the atomic weight of the hydrogen much more accurately than what
you want, from the masses of electron, proton, and QED applied to the atom
(including loops that are measurable, but far too small for chemists.)

> If you can't, I take it as a sign that the alleged knowledge of much
> more is only hype.

It's not hype. It is called "physics". It's just a too difficult problem
to calculate the exact properties of Oxygen from the Standard Model, and
it is just not interesting enough for anyone to really work on it because
all physicists are convinced that the Standard Model gives the right
properties of the Oxygen. The confidence in this statement follow
hierarchical relations between the Standard Model and its increasingly
inaccurate approximations, that are still enough to describe the atoms and
nuclei well enough. Anyone is free to believe that the Oxygen contradicts
the Standard Model, but no one can expect me to think that the people who
believe in the Oxygen-SM contradictions understand how physics works. They
don't, and you're an example.

Best
Lubos
__{_______________________________________________ _____________________________}
E-mail: lumo@matfyz.cz fax: +1-617/496-0110 Web: http://lumo.matfyz.cz/
eFax: +1-801/454-1858 work: +1-617/384-9488 home: +1-617/868-4487 (call)
Webs: http://schwinger.harvard.edu/~motl/ http://motls.blogspot.com/
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Lubos Motl

Oct24-04, 04:46 PM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>On Sun, 24 Oct 2004, backdoorstudent wrote:\n\n> > gold, and it is just a matter of mathematical difficulty that prevents us\n> > from extracting the right information directly from the SM.\n>\n> Prove it!\n\nDo you want chemistry from the Standard Model? I would have to cite\nthousands of papers ;-).\n\nWe have actually extracted most of these chemical properties, using a\nsophisticated chain of increasingly simplified approximations; some of\nthese approximations have been found before the more complete theory was\nfound.\n\nLet me be more specific about the atoms and chemistry.\n\nWe can show that QCD (a sector of the Standard Model) implies the\nexistence of baryons such as proton and neutron with the right masses, to\nsome degree of accuracy. There are hundreds of papers about it, and\nlattice QCD people try to become increasingly better in all these\nquestions.\n\nThere are many ways for me to continue, but one can use the approximation\nbased on these protons and neutrons, derived in the previous sentence, and\nthe effective forces between them.\n\nThis brings us into nuclear physics. One can then show that the effective\ndynamics of protons and neutrons is gonna satisfy certain rules, and the\nenergy of a nucleus can be calculated pretty well from the combined\ndroplet/shell model. We understand the structure of nuclei, in agreement\nwith the Standard Model.\n\nOne can easily show that at atomic distances from the nucleus, the\nStandard Model can be approximated to Schrodinger\'s equation for electrons\n(QED-dominated phenomena), supplemented by loop diagrams - if we need\nthem. In fact, the details of the nuclei become pretty irrelevant for\natomic physics and chemistry, and one can easily show why they\'re not\nimportant.\n\nWe can then solve all these Schrodinger\'s equations exactly for the\nnon-relativistic Hydrogen, and compute the corrections (relativistic and\nspin-orbit interactions; magnetic moment interactions; loops of QED; other\nloops of the Standard Model) of virtually any reasonable order from\nperturbation theory. It agrees with the experimental measurement of the\nHydrogen atom.\n\nWe can also use numerical and other methods to calculate the energy levels\nof more complicated atoms, and we can derive the approximate validity of\nvarious other approximations that others did - e.g. Mendeleev. We\nunderstand why Mendeleev\'s table works it does - from QED, if you wish.\n\nThen we go to the molecules, and use some other approximations to study\nthese ever more complex systems.\n\nAs the system grows, we are using an increasingly approximate description,\nbut one that is still pretty well connected to the lower, more fundamental\nlayer of explanation below it.\n\n> How do you know it is just a matter of mathematical difficulty?\n\nIn physics, we really never know everything quite for *sure*, but it is\njust *extremely* unreasonable to assume that there is some big problem\nwaiting underneath these steps that seem to work very well. If you make 70\ncm long steps, there may have been a squirrel in between your feet, but it\nis very unlikely that you missed an elephant.\n\n> How do you know it is not something that is actually NOT derived?\n\nThe most important part of the answer is to actually know something about\nphysics. Of course, before one knows how the known physics works and how\nit explains the relations between different phenomena, she may believe in\nall possible crazy ideas that the world is undescribable, problematic,\nmathematics must fail, Gods are controlling us (and other material\nobjects) despite any laws of Nature, and so on.\n\nSome people prefer to believe such things over learning any physics.\n\nBut the person who knows something about QCD; nuclear physics; atomic\nphysics; chemistry - simply knows that it is quite irrational to expect a\nbig problem of the Standard Model in its explanation of oxygen or gold,\nand anyone who has learned enough will agree that my statement that the\nStandard Model implies the right properties of gold and water is most\nlikely correct.\n\n> Did you ever think it conceivable that phenomena emerge with little\n> bearing on the nature of their components?\n\nNot really. What you say would simply be an extraordinary claim, and\nextraordinary claims require extraordinary evidence.\n\nWe are focusing on particle physics, but it does not mean that we ignore\nthe rest of science. If there were something that would seem to have the\npotential to contradict the description in terms of quantum theory applied\nto a large number of particles, we would notice.\n\nI just don\'t see any room for some supernatural phenomena that would have\nto be added to the Standard Model and modify it drastically. There is also\nno known mathematically acceptable (or even natural) way to modify the\nlaws of physics so that they would suddenly change completely for larger\nsystems, without destroying the agreement with reality.\n\nNonrelativistic and classical physics *may* have been modified to get\nrelativity and quantum physics. Quantum field theory *may* be generalized\ninto string theory. But there just does not seem to be a way to make the\nStandard Model fail completely for macroscopic, but still reasonably\nsmall, objects (where gravity is irrelevant). Moreover, there seems to be\nabsolutely no experimental motivation to do so. There may be religious\nmotivation - or motivation of people who hate the idea of reductionism -\nbut these motivations do not have any consequences in science.\n\nNothing is for sure, but the more one knows about physics, the more\nunlikely she finds these modifications.\n\nYour question may sound reasonable to you as long as you keep it as vague\nas you do. But try to invent any particular, concrete scenario how\ncompletely new effects suddenly change the laws of elementary particles,\nas soon as you apply them to slightly bigger systems. Try to invent a\npossible loophole in my sketch of the proof above. If you analyze it\ncarefully, you will be able to see that virtually any such conjecture can\nmore or less be ruled out.\n\n> A "true statement" is that nobody knows if chemistry even in principle\n> could be derived from the standard model.\n\nI would not subscribe to this statement. We know - with the careful,\nlimited, scientific meaning of the word "know" - that chemistry is\ncontained in the Standard Model. In fact, we know a huge amount of details\nabout the question why is it so and what it exactly means. Your "true\nstatement" sounds like one of those misunderstandings of people who really\ndon\'t want science to work, and who will always prefer superstitions,\ndespite any success that appears in science.\n\nIt\'s your life. You can believe whatever you want, and you can choose a\ncareer of the search for ghosts. I am just telling you that most\nscientists expect that no ghosts exist, and if you just confirm the\nStandard Model, we won\'t be too thrilled.\n_______________________________________ _______________________________________\nE-mail: lumo@matfyz.cz fax: +1-617/496-0110 Web: http://lumo.matfyz.cz/\neFax: +1-801/454-1858 work: +1-617/384-9488 home: +1-617/868-4487 (call)\nWebs: http://schwinger.harvard.edu/~motl/ http://motls.blogspot.com/\n^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>On Sun, 24 Oct 2004, backdoorstudent wrote:

> > gold, and it is just a matter of mathematical difficulty that prevents us
> > from extracting the right information directly from the SM.
>
> Prove it!

Do you want chemistry from the Standard Model? I would have to cite
thousands of papers ;-).

We have actually extracted most of these chemical properties, using a
sophisticated chain of increasingly simplified approximations; some of
these approximations have been found before the more complete theory was
found.

Let me be more specific about the atoms and chemistry.

We can show that QCD (a sector of the Standard Model) implies the
existence of baryons such as proton and neutron with the right masses, to
some degree of accuracy. There are hundreds of papers about it, and
lattice QCD people try to become increasingly better in all these
questions.

There are many ways for me to continue, but one can use the approximation
based on these protons and neutrons, derived in the previous sentence, and
the effective forces between them.

This brings us into nuclear physics. One can then show that the effective
dynamics of protons and neutrons is gonna satisfy certain rules, and the
energy of a nucleus can be calculated pretty well from the combined
droplet/shell model. We understand the structure of nuclei, in agreement
with the Standard Model.

One can easily show that at atomic distances from the nucleus, the
Standard Model can be approximated to Schrodinger's equation for electrons
(QED-dominated phenomena), supplemented by loop diagrams - if we need
them. In fact, the details of the nuclei become pretty irrelevant for
atomic physics and chemistry, and one can easily show why they're not
important.

We can then solve all these Schrodinger's equations exactly for the
non-relativistic Hydrogen, and compute the corrections (relativistic and
spin-orbit interactions; magnetic moment interactions; loops of QED; other
loops of the Standard Model) of virtually any reasonable order from
perturbation theory. It agrees with the experimental measurement of the
Hydrogen atom.

We can also use numerical and other methods to calculate the energy levels
of more complicated atoms, and we can derive the approximate validity of
various other approximations that others did - e.g. Mendeleev. We
understand why Mendeleev's table works it does - from QED, if you wish.

Then we go to the molecules, and use some other approximations to study
these ever more complex systems.

As the system grows, we are using an increasingly approximate description,
but one that is still pretty well connected to the lower, more fundamental
layer of explanation below it.

> How do you know it is just a matter of mathematical difficulty?

In physics, we really never know everything quite for *sure*, but it is
just *extremely* unreasonable to assume that there is some big problem
waiting underneath these steps that seem to work very well. If you make 70
cm long steps, there may have been a squirrel in between your feet, but it
is very unlikely that you missed an elephant.

> How do you know it is not something that is actually NOT derived?

The most important part of the answer is to actually know something about
physics. Of course, before one knows how the known physics works and how
it explains the relations between different phenomena, she may believe in
all possible crazy ideas that the world is undescribable, problematic,
mathematics must fail, Gods are controlling us (and other material
objects) despite any laws of Nature, and so on.

Some people prefer to believe such things over learning any physics.

But the person who knows something about QCD; nuclear physics; atomic
physics; chemistry - simply knows that it is quite irrational to expect a
big problem of the Standard Model in its explanation of oxygen or gold,
and anyone who has learned enough will agree that my statement that the
Standard Model implies the right properties of gold and water is most
likely correct.

> Did you ever think it conceivable that phenomena emerge with little
> bearing on the nature of their components?

Not really. What you say would simply be an extraordinary claim, and
extraordinary claims require extraordinary evidence.

We are focusing on particle physics, but it does not mean that we ignore
the rest of science. If there were something that would seem to have the
potential to contradict the description in terms of quantum theory applied
to a large number of particles, we would notice.

I just don't see any room for some supernatural phenomena that would have
to be added to the Standard Model and modify it drastically. There is also
no known mathematically acceptable (or even natural) way to modify the
laws of physics so that they would suddenly change completely for larger
systems, without destroying the agreement with reality.

Nonrelativistic and classical physics *may* have been modified to get
relativity and quantum physics. Quantum field theory *may* be generalized
into string theory. But there just does not seem to be a way to make the
Standard Model fail completely for macroscopic, but still reasonably
small, objects (where gravity is irrelevant). Moreover, there seems to be
absolutely no experimental motivation to do so. There may be religious
motivation - or motivation of people who hate the idea of reductionism -
but these motivations do not have any consequences in science.

Nothing is for sure, but the more one knows about physics, the more
unlikely she finds these modifications.

Your question may sound reasonable to you as long as you keep it as vague
as you do. But try to invent any particular, concrete scenario how
completely new effects suddenly change the laws of elementary particles,
as soon as you apply them to slightly bigger systems. Try to invent a
possible loophole in my sketch of the proof above. If you analyze it
carefully, you will be able to see that virtually any such conjecture can
more or less be ruled out.

> A "true statement" is that nobody knows if chemistry even in principle
> could be derived from the standard model.

I would not subscribe to this statement. We know - with the careful,
limited, scientific meaning of the word "know" - that chemistry is
contained in the Standard Model. In fact, we know a huge amount of details
about the question why is it so and what it exactly means. Your "true
statement" sounds like one of those misunderstandings of people who really
don't want science to work, and who will always prefer superstitions,
despite any success that appears in science.

It's your life. You can believe whatever you want, and you can choose a
career of the search for ghosts. I am just telling you that most
scientists expect that no ghosts exist, and if you just confirm the
Standard Model, we won't be too thrilled.
__{_______________________________________________ _____________________________}
E-mail: lumo@matfyz.cz fax: +1-617/496-0110 Web: http://lumo.matfyz.cz/
eFax: +1-801/454-1858 work: +1-617/384-9488 home: +1-617/868-4487 (call)
Webs: http://schwinger.harvard.edu/~motl/ http://motls.blogspot.com/
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Arnold Neumaier

Oct25-04, 08:09 AM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\n\n\n\nLubos Motl wrote:\n>\n> At any rate, the key developments in theoretical physics are breakthroughs\n> in which the old theories are labeled as approximations that are replaced\n> by a more complete picture.\n\nThe picture is that clear only if the new theories explain things that\nwere at conflict with the old theories.\n\n\n>>Nature does not care at all. It worked wor billions of years without\n>>anyone but God and His hosts to ponder a theory.\n>\n> Right. I am happy to see you retract your previous statement that true\n> theories in physics must be easy for us to use them.\n\nBut the ones we know to be true are. Because if they aren\'t we cannot\nknow that they are true.\n\n\n>>>QCD is definitely pretty complicated - especially at long distances - but\n>>>it is the correct theory.\n>>\n>>Dirac-Fock is as correct as QCD, and much more predictive.\n>\n> This is an unverifiable statement because it compares two theories that\n> study different phenomena. If we want to talk about these questions\n> seriously, we must consider theories that try to address the same\n> phenomena. OK, let\'s do it. QCD is a part of the Standard Model, and the\n> Standard Model is certainly more predictive than any approximation such as\n> the Dirac-Fock scheme - simply because it contains all of them, and it is\n> a much more complete and accurate approximation.\n\nIt is _supposed_ to contain all of them, but this is at present wishful\nthinking. The Dirac-Fock equations as used by the chemical physicists\nhave with them numerical constants that no one has been able to derive\nfrom the standard model, not even approximately.\n\n\n\n>>>That\'s demagogy. A true statement would be that the Lagrangian of the\n>>>Standard Model is not the only *idea* that we need to understand all\n>>>features of reality, but it is an idea that *implies* (in combination with\n>>>GR) all known rules about reality, including the properties of water and\n>>>gold,\n>>\n>>Please give references and not only words.\n>\n> What references? I don\'t argue that someone has *calculated* the\n> properties of gold from the Standard Model. I am saying that these\n> properties are included in the Standard Model. It is a matter of beliefs\n> at this moment whether the gold is correctly described by the Standard\n> Model, but one belief is a belief of a physicist, and the other is a\n> belief of a person who does not trust physics.\n\nBeliefs are not psrt of a theory.\n\nFor chemical phenomena, Dirac-Fock is a better theory than the standard\nmodel since it works without further belief.\n\n\n>>Apparently you know much more, as a citicen of \'the planet called Zetor here\'\n>> \'\'Name: Lubos Motl (Who Where item), member of MOTL league,\n>> I am an alien.\'\'\n>\n> I don\'t know what you find wrong with my being an alien. ;-) Some new form\n> of nationalism?\n\nNothing wrong, but your civilisation seems so superior, and I alluded\nto that...\n\n\n>>... and which values the masses and coupling constants have, how many\n>>families of particles there are, etc., which makes all the difference\n>>to our existence.\n>\n> Yes, we have not derived this theoretically yet,\n\nThis is what I mean. Your position is based on belief, not on facts.\nWhat you state as facts are dreams that might or might not become true\none day. Why don\'t you give us proof from the advanced insight of your\nhome planet\'s civilization?\n\n\n> but string theory is the\n> only known theoretical structure that offers mechanisms behind all these\n> questions, and the capacity to explain them.\n\n_possibly_ explain them, subject to your dream becoming true...\n\n\n>> > What you say is also untrue sociogically: string *theorists* often know\n>> > much more about QFT, GR, and other aspects of physics than\n>> > non-string-theorists specializing on these fields.\n>>\n>>Show me this \'much more\' by giving a calculation of the atomic\n>>weight of H and O to the accuracy known to chemists based on the\n>>standard model, which you claimed above is possible.\n>\n> I was talking about QFT and GR, not about the weight of oxygen.\n\nCertainly, oxygen is an object that should be describable by the standard\nmodel which, it is claimed, govern all phenomena on earth at accessible\nenergies. Moreover, it is part of the \'other aspects of physics\'\nthat you bragged string *theorists* often know much more about.\n\n\n> Nevertheless, it\'s great that you also mentioned Hydrogen because we can\n> calculate the atomic weight of the hydrogen much more accurately than what\n> you want, from the masses of electron, proton, and QED applied to the atom\n> (including loops that are measurable, but far too small for chemists.)\n\nBut the proton mass is not one of the parameters of the standard model,\nand can at present not be accurately predicted from the standard model\nor from string theory. The latter can predict not a single number in the\nstandard model, except perhaps the dimension of space.\n\n\n> It\'s just a too difficult problem\n> to calculate the exact properties of Oxygen from the Standard Model, and\n> it is just not interesting enough for anyone to really work on it because\n> all physicists are convinced that the Standard Model gives the right\n> properties of the Oxygen.\n\nSome people are working _very_hard_ at calculating the proton mass,\nand the 5% accuracy they get is far from being close to the accuracy of\nexperiments. There is plenty of scope for being slightly wrong...\n\n\nArnold Neumaier\n\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>Lubos Motl wrote:
>
> At any rate, the key developments in theoretical physics are breakthroughs
> in which the old theories are labeled as approximations that are replaced
> by a more complete picture.

The picture is that clear only if the new theories explain things that
were at conflict with the old theories.

>>Nature does not care at all. It worked wor billions of years without
>>anyone but God and His hosts to ponder a theory.
>
> Right. I am happy to see you retract your previous statement that true
> theories in physics must be easy for us to use them.

But the ones we know to be true are. Because if they aren't we cannot
know that they are true.

>>>QCD is definitely pretty complicated - especially at long distances - but
>>>it is the correct theory.
>>
>>Dirac-Fock is as correct as QCD, and much more predictive.
>
> This is an unverifiable statement because it compares two theories that
> study different phenomena. If we want to talk about these questions
> seriously, we must consider theories that try to address the same
> phenomena. OK, let's do it. QCD is a part of the Standard Model, and the
> Standard Model is certainly more predictive than any approximation such as
> the Dirac-Fock scheme - simply because it contains all of them, and it is
> a much more complete and accurate approximation.

It is _supposed_ to contain all of them, but this is at present wishful
thinking. The Dirac-Fock equations as used by the chemical physicists
have with them numerical constants that no one has been able to derive
from the standard model, not even approximately.

>>>That's demagogy. A true statement would be that the Lagrangian of the
>>>Standard Model is not the only *idea* that we need to understand all
>>>features of reality, but it is an idea that *implies* (in combination with
>>>GR) all known rules about reality, including the properties of water and
>>>gold,
>>
>>Please give references and not only words.
>
> What references? I don't argue that someone has *calculated* the
> properties of gold from the Standard Model. I am saying that these
> properties are included in the Standard Model. It is a matter of beliefs
> at this moment whether the gold is correctly described by the Standard
> Model, but one belief is a belief of a physicist, and the other is a
> belief of a person who does not trust physics.

Beliefs are not psrt of a theory.

For chemical phenomena, Dirac-Fock is a better theory than the standard
model since it works without further belief.

>>Apparently you know much more, as a citicen of 'the planet called Zetor here'
>> ''Name: Lubos Motl (Who Where item), member of MOTL league,
>> I am an alien.''
>
> I don't know what you find wrong with my being an alien. ;-) Some new form
> of nationalism?

Nothing wrong, but your civilisation seems so superior, and I alluded
to that...

>>... and which values the masses and coupling constants have, how many
>>families of particles there are, etc., which makes all the difference
>>to our existence.
>
> Yes, we have not derived this theoretically yet,

This is what I mean. Your position is based on belief, not on facts.
What you state as facts are dreams that might or might not become true
one day. Why don't you give us proof from the advanced insight of your
home planet's civilization?

> but string theory is the
> only known theoretical structure that offers mechanisms behind all these
> questions, and the capacity to explain them.

_possibly_ explain them, subject to your dream becoming true...

>> > What you say is also untrue sociogically: string *theorists* often know
>> > much more about QFT, GR, and other aspects of physics than
>> > non-string-theorists specializing on these fields.
>>
>>Show me this 'much more' by giving a calculation of the atomic
>>weight of H and O to the accuracy known to chemists based on the
>>standard model, which you claimed above is possible.
>
> I was talking about QFT and GR, not about the weight of oxygen.

Certainly, oxygen is an object that should be describable by the standard
model which, it is claimed, govern all phenomena on earth at accessible
energies. Moreover, it is part of the 'other aspects of physics'
that you bragged string *theorists* often know much more about.

> Nevertheless, it's great that you also mentioned Hydrogen because we can
> calculate the atomic weight of the hydrogen much more accurately than what
> you want, from the masses of electron, proton, and QED applied to the atom
> (including loops that are measurable, but far too small for chemists.)

But the proton mass is not one of the parameters of the standard model,
and can at present not be accurately predicted from the standard model
or from string theory. The latter can predict not a single number in the
standard model, except perhaps the dimension of space.

> It's just a too difficult problem
> to calculate the exact properties of Oxygen from the Standard Model, and
> it is just not interesting enough for anyone to really work on it because
> all physicists are convinced that the Standard Model gives the right
> properties of the Oxygen.

Some people are working _very_hard_ at calculating the proton mass,
and the 5% accuracy they get is far from being close to the accuracy of
experiments. There is plenty of scope for being slightly wrong...

Arnold Neumaier

Arnold Neumaier

Oct27-04, 10:56 AM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\n\n\n\nLubos Motl wrote:\n>\n> Do you want chemistry from the Standard Model? I would have to cite\n> thousands of papers ;-).\n>\n> We have actually extracted most of these chemical properties, using a\n> sophisticated chain of increasingly simplified approximations; some of\n> these approximations have been found before the more complete theory was\n> found.\n>\n> Let me be more specific about the atoms and chemistry.\n>\n> We can show that QCD (a sector of the Standard Model) implies the\n> existence of baryons such as proton and neutron with the right masses, to\n> some degree of accuracy. There are hundreds of papers about it, and\n> lattice QCD people try to become increasingly better in all these\n> questions.\n\nThe degree of accuracy obtained is about 5%, far too low to be of use in\nchemistry or even in nuclear physics. The accuracy of the effective\nforces between them is even poorer.\n\nWe have very little control over confinement, which is essential to\nget useful forces at the energies relevant for nuclear physics.\nThus predictivity of the standard model for nuclear information\nis almost nil.\n\nAnd indeed, nuclear physicists do not use the standard model\n(except for paying religious lip service to it), but work with\ntheir own phenomenological models. They just borrow some of the symmetries\n(which were of course known long before the standard model was born).\n\n\n> There are many ways for me to continue, but one can use the approximation\n> based on these protons and neutrons, derived in the previous sentence, and\n> the effective forces between them.\n\nIf we had only the standard model and the numerical estimates computed from it,\nthis would give _very_ poor predictions of most chemical properties of\neverything including the hydrogen spectrum.\n\n\n> This brings us into nuclear physics. One can then show that the effective\n> dynamics of protons and neutrons is gonna satisfy certain rules, and the\n> energy of a nucleus can be calculated pretty well from the combined\n> droplet/shell model. We understand the structure of nuclei, in agreement\n> with the Standard Model.\n\nOnly assuming _measured_ data about form factors of proton and neutron,\nwhich have _not_ been calculated from the standard model but must be put in\nas additional information.\n\n\n> One can easily show that at atomic distances from the nucleus, the\n> Standard Model can be approximated to Schrodinger\'s equation for electrons\n> (QED-dominated phenomena), supplemented by loop diagrams - if we need\n> them. In fact, the details of the nuclei become pretty irrelevant for\n> atomic physics and chemistry, and one can easily show why they\'re not\n> important.\n\nYes, but one cannot calculate the atomic weights, and again must\nsupplement the qualitative results from the standard model by\nadditional experimental information.\n\n\n> We can then solve all these Schrodinger\'s equations exactly for the\n> non-relativistic Hydrogen, and compute the corrections (relativistic and\n> spin-orbit interactions; magnetic moment interactions; loops of QED; other\n> loops of the Standard Model) of virtually any reasonable order from\n> perturbation theory. It agrees with the experimental measurement of the\n> Hydrogen atom.\n\nYes. From this level on upwards, one has enough experimental data to\ncalculate chemical information for small molecules that is predictive\nin the sense that it may give quantitative information that is reasonably\naccurate and not put in by hand.\n\n> We can also use numerical and other methods to calculate the energy levels\n> of more complicated atoms, and we can derive the approximate validity of\n> various other approximations that others did - e.g. Mendeleev. We\n> understand why Mendeleev\'s table works it does - from QED, if you wish.\n\nAlready for proteins, one again needs to complement the theoretical\ninput by measurements to get predictions of reasonable accuracy.\n\nThus the standard model is a very inaccurate tool for chemistry.\nIt is useful only for elementary particle scattering experiments.\n\n\n> But the person who knows something about QCD; nuclear physics; atomic\n> physics; chemistry - simply knows that it is quite irrational to expect a\n> big problem of the Standard Model in its explanation of oxygen or gold,\n> and anyone who has learned enough will agree that my statement that the\n> Standard Model implies the right properties of gold and water is most\n> likely correct.\n\nOnly that some variant of the standard model may do it.\nThe current accuracy of computations is too poor to make more definite\nstatements.\n\n\n>>A "true statement" is that nobody knows if chemistry even in principle\n>>could be derived from the standard model.\n>\n> I would not subscribe to this statement. We know - with the careful,\n> limited, scientific meaning of the word "know" - that chemistry is\n> contained in the Standard Model.\n\nWhat you call \'know\' is commonly called \'expect\'.\nSome of our expectations turn out to be true, others meed\nmodification after learning more, and it is difficult to tell\nin advance which is which.\n\nPart of scientific culture entails to be modest in one\'s claims\nand to distinguish in one\'s statements between what is known,\nwhat is expected to be true, and what is hoped for but unproven.\n\nYou allow yourself liberties that go far beyond that.\n\n\nArnold Neumaier\n\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>Lubos Motl wrote:
>
> Do you want chemistry from the Standard Model? I would have to cite
> thousands of papers ;-).
>
> We have actually extracted most of these chemical properties, using a
> sophisticated chain of increasingly simplified approximations; some of
> these approximations have been found before the more complete theory was
> found.
>
> Let me be more specific about the atoms and chemistry.
>
> We can show that QCD (a sector of the Standard Model) implies the
> existence of baryons such as proton and neutron with the right masses, to
> some degree of accuracy. There are hundreds of papers about it, and
> lattice QCD people try to become increasingly better in all these
> questions.

The degree of accuracy obtained is about 5%, far too low to be of use in
chemistry or even in nuclear physics. The accuracy of the effective
forces between them is even poorer.

We have very little control over confinement, which is essential to
get useful forces at the energies relevant for nuclear physics.
Thus predictivity of the standard model for nuclear information
is almost nil.

And indeed, nuclear physicists do not use the standard model
(except for paying religious lip service to it), but work with
their own phenomenological models. They just borrow some of the symmetries
(which were of course known long before the standard model was born).

> There are many ways for me to continue, but one can use the approximation
> based on these protons and neutrons, derived in the previous sentence, and
> the effective forces between them.

If we had only the standard model and the numerical estimates computed from it,
this would give _very_ poor predictions of most chemical properties of
everything including the hydrogen spectrum.

> This brings us into nuclear physics. One can then show that the effective
> dynamics of protons and neutrons is gonna satisfy certain rules, and the
> energy of a nucleus can be calculated pretty well from the combined
> droplet/shell model. We understand the structure of nuclei, in agreement
> with the Standard Model.

Only assuming _measured_ data about form factors of proton and neutron,
which have _not_ been calculated from the standard model but must be put in
as additional information.

> One can easily show that at atomic distances from the nucleus, the
> Standard Model can be approximated to Schrodinger's equation for electrons
> (QED-dominated phenomena), supplemented by loop diagrams - if we need
> them. In fact, the details of the nuclei become pretty irrelevant for
> atomic physics and chemistry, and one can easily show why they're not
> important.

Yes, but one cannot calculate the atomic weights, and again must
supplement the qualitative results from the standard model by
additional experimental information.

> We can then solve all these Schrodinger's equations exactly for the
> non-relativistic Hydrogen, and compute the corrections (relativistic and
> spin-orbit interactions; magnetic moment interactions; loops of QED; other
> loops of the Standard Model) of virtually any reasonable order from
> perturbation theory. It agrees with the experimental measurement of the
> Hydrogen atom.

Yes. From this level on upwards, one has enough experimental data to
calculate chemical information for small molecules that is predictive
in the sense that it may give quantitative information that is reasonably
accurate and not put in by hand.

> We can also use numerical and other methods to calculate the energy levels
> of more complicated atoms, and we can derive the approximate validity of
> various other approximations that others did - e.g. Mendeleev. We
> understand why Mendeleev's table works it does - from QED, if you wish.

Already for proteins, one again needs to complement the theoretical
input by measurements to get predictions of reasonable accuracy.

Thus the standard model is a very inaccurate tool for chemistry.
It is useful only for elementary particle scattering experiments.

> But the person who knows something about QCD; nuclear physics; atomic
> physics; chemistry - simply knows that it is quite irrational to expect a
> big problem of the Standard Model in its explanation of oxygen or gold,
> and anyone who has learned enough will agree that my statement that the
> Standard Model implies the right properties of gold and water is most
> likely correct.

Only that some variant of the standard model may do it.
The current accuracy of computations is too poor to make more definite
statements.

>>A "true statement" is that nobody knows if chemistry even in principle
>>could be derived from the standard model.
>
> I would not subscribe to this statement. We know - with the careful,
> limited, scientific meaning of the word "know" - that chemistry is
> contained in the Standard Model.

What you call 'know' is commonly called 'expect'.
Some of our expectations turn out to be true, others meed
modification after learning more, and it is difficult to tell
in advance which is which.

Part of scientific culture entails to be modest in one's claims
and to distinguish in one's statements between what is known,
what is expected to be true, and what is hoped for but unproven.

You allow yourself liberties that go far beyond that.

Arnold Neumaier

Lubos Motl

Oct29-04, 09:59 AM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>On Wed, 27 Oct 2004, Arnold Neumaier wrote:\n\n> The degree of accuracy obtained is about 5%, far too low to be of use in\n> chemistry or even in nuclear physics.\n\nRight, and this verified 5% precision is enough for us to know that the\nmodel (the Standard Model) is most likely correct. This match just makes\nit virtually impossible that there is some new bug or "big correction"\nthat must be added to the Standard Model in order to describe the nuclei.\n\nYou know, in theoretical physics we work with quantities that a priori may\ndiffer by many orders of magnitude - for example by 122 orders of\nmagnitude for the cosmological constant. ;-) An agreement of a nice theory\nwith a lot of data with 1%-5% precision - in the context where the theory\nis just too "nonlinear" to calculate better - is just an impressive\nargument that the theory has to be correct, especially if it is more\ndirectly tested at high energies where the quarks are weakly interacting\n(with a better precision, near 1% or better) and especially if we see no\nway how new physics may be added to the theory without spoiling its\nsuccess completely.\n\nIt would be great if someone calculated these quantities from the Standard\nModel exactly - which sounds unlikely. On the other hand, if someone\nimproves the calculation of one quantity from a 5% accuracy to a 0.5%\naccuracy, we won\'t be terribly impressed. It\'s just not the most\ninteresting part of physics to improve the accuracy how we calculate a\nrandom - and pretty irrelevant - observable in nuclear physics, unless\nthis calculation brings new powerful methods that can be used universally.\nThe gauge/gravity duality is a shining example of such a method, but\nthat\'s not the type of insights that YOU are looking for.\n\n> The accuracy of the effective forces between them is even poorer.\n\nBecause it\'s just a difficult system to calculate. We don\'t need to do it\nexactly in order to decide whether the theory is correct. We\'ve done\nenough to assume that it is correct.\n\n> We have very little control over confinement, which is essential to\n> get useful forces at the energies relevant for nuclear physics.\n> Thus predictivity of the standard model for nuclear information\n> is almost nil.\n\nYou can also say the same thing backwards: most of the detailed data from\nnuclear physics is pretty irrelevant and useless for our understanding of\nthe important ideas contained in the underlying theory of matter. Well,\nthis is the formulation we would choose in high-energy physics. ;-)\n\n> And indeed, nuclear physicists do not use the standard model\n> (except for paying religious lip service to it), but work with\n> their own phenomenological models.\n\nMost of the high-energy physicists do not care about the particular energy\nlevels of different nuclei (except for respecting nuclear physics verbally\nas a piece of solid science), but they work with more fundamental\ntheories.\n\n> They just borrow some of the symmetries\n> (which were of course known long before the standard model was born).\n\nThe high-energy physicists sometimes borrow a number or an idea, too. ;-)\n\n> If we had only the standard model and the numerical estimates computed\n> from it, this would give _very_ poor predictions of most chemical\n> properties of everything including the hydrogen spectrum.\n\nYou seem to misunderstand what\'s the goal of the search for deeper\ntheories. We want to know the deeper theories simply because it is\nimportant for human curiosity to know the truth. If we already know some\nnumbers about the complicated systems from the experiment, that\'s fine,\nbut it\'s not the really satisfying experience.\n\nWe want to know that we have a theory that contains all these data. I\napologize, but we sort of know, with the careful physicist\'s understanding\nof the word "know", that the Standard Model contains them. Nevertheless,\nit is still easier to compute the energy levels of a carbon nucleus than\nto compute them from the Standard Model. It\'s not the most interesting and\nmost rewarding task to try to apply the strongly interacting theories of\nquarks to such complicated systems - simply because the result is more or\nless guaranteed to work, and it will impress no one - the improvement over\nthings that have already been done will be purely quantitative. And if\nthis calculation does not work, everyone will probably think that the\nperson had to make an error anyway - it\'s not hard to make errors in such\ncomplicated calculations.\n\nIn physics, if we look for the *really* important things - and once again,\nI apologize, but one energy level of one nucleus is *not* a really\nimportant insight - we must master the art to look for the right problems,\nthose that give us the maximal amount of information for the minimal\namount of assumptions (and work) that we must invest. And the excited\nenergy levels of a carbon nucleus are *not* the best systems to learn\nabout the structure of the proton.\n\n> Only assuming _measured_ data about form factors of proton and neutron,\n> which have _not_ been calculated from the standard model but must be put in\n> as additional information.\n\nThat\'s a very broad question whether the form factors can be\njustified/calculated from the first principles. It\'s certainly not true\nthat they can\'t be justified at all, and various asymptotic behaviors of\nthese form factors etc. can be calculated from QCD.\n\n> Yes, but one cannot calculate the atomic weights, and again must\n> supplement the qualitative results from the standard model by\n> additional experimental information.\n\nIt does not really matter whether we can do it in practice. The important\nthing is that we have a theory that pretty obviously contains all these\nnumbers, and the mystery is just gone. A primary motivation for pure\nscience is to uncover rational justifications behind the mysteries, and\nthis *has* basically been done for the data surrounding all of chemistry\nand nuclear physics.\n\n> Yes. From this level on upwards, one has enough experimental data to\n> calculate chemical information for small molecules that is predictive\n> in the sense that it may give quantitative information that is reasonably\n> accurate and not put in by hand.\n\nThese things are easier to calculate in practice because QED has a small\ncoupling, unlike QCD at the proton scale. But it does not mean that QCD is\na "worse" theory. It is just a theory of a system that objectively is\nstrongly interacting.\n\n> Already for proteins, one again needs to complement the theoretical\n> input by measurements to get predictions of reasonable accuracy.\n\nProteins are damned complicated systems. People like you will always\ncomplain because there will always exist complex enough systems that have\nnot been calculated directly from the first principles. But it will be\nbecoming increasingly harder to argue that there is some totally new\nphysics that must be "supplemented" for the fundamental theory to contain\neverything we see. Already today, your position is virtually undefendable.\n\n> Thus the standard model is a very inaccurate tool for chemistry.\n\nThe Standard Model is a theory that trivially contains all of chemistry,\nand it is just a matter of calculational difficulty whether someone finds\nit useful (and interesting) to use the SM directly.\n\n> It is useful only for elementary particle scattering experiments.\n\nBeing useful is a totally different question than being true. Being\n"useful" depends on our laziness, abilities to compute, power of our\ncomputers and so forth - usefulness is not a characteristic property\nassociated with the very laws of a given theory. Usefulness is more about\nour abilities and our personal desires, and as a pure scientist, I am not\ninterested in it too much.\n\n> Only that some variant of the standard model may do it.\n\nThere is one Standard Model only. Well, today we talk about the\nnu-Standard-Model that contains neutrino masses. ;-)\n\n> The current accuracy of computations is too poor to make more definite\n> statements.\n\nThat\'s your belief that is extremely hard to justify by any rational\nargument. If you found a convincing bug with the Standard Model that makes\nit unable to describe chemistry or nuclear physics correctly, that would\nbe an A* class Nobel prize discovery. But now it\'s just your wishful\nthinking, and the conclusion of everything we know is that the Standard\nModel contains all these things.\n\n> > I would not subscribe to this statement. We know - with the careful,\n> > limited, scientific meaning of the word "know" - that chemistry is\n> > contained in the Standard Model.\n>\n> What you call \'know\' is commonly called \'expect\'.\n\nI only said "know" because we\'re not really expecting anything specific. I\nmay say that "We don\'t expect discoveries that will invalidate the\nStandard Model as a theory behind chemistry and nuclear physics". I don\'t\nknow what it really means to say "We expect the Standard Model to be\ncorrect". It already *is* sort of proved correct, and I don\'t expect any\nrevolution that will suddenly eliminate all skeptics. "Expecting" means to\nassume that something will happen. The skeptics will just die away\ncontinuously even more than so far, as the Standard Model is increasingly\nmore well-established as a theory of all these phenomena.\n\n> Some of our expectations turn out to be true, others meed\n> modification after learning more, and it is difficult to tell\n> in advance which is which.\n\nThis is the whole purpose of science that we *want* to say such things and\nother things in advance - and to make predictions. Thousands of people\nhave worked on it for decades, and they found the Standard Model to be the\ntheory behind these phenomena. Therefore they can say, in advance, (or\npredict, if you wish) that they think that the Standard Model will be a\ncorrect theory for all these "regular" phenomena below the electroweak\nscale. It\'s sexy to say that the SM may be seriously wrong for some of the\nordinary contexts, but it is certainly an extraordinary claim that\nrequires extraordinary evidence - because it would contradict thousands of\npapers that support the statement that the SM works.\n\n> Part of scientific culture entails to be modest in one\'s claims\n> and to distinguish in one\'s statements between what is known,\n> what is expected to be true, and what is hoped for but unproven.\n\nAnother part of scientific culture is to distinguish realistic\npossibilities from unrealistic, wild speculations, whose probability is\nvery tiny. Yours are wild speculations.\n\nBest wishes\nLubos\n___________________________________ ___________________________________________\nE-mail: lumo@matfyz.cz fax: +1-617/496-0110 Web: http://lumo.matfyz.cz/\neFax: +1-801/454-1858 work: +1-617/384-9488 home: +1-617/868-4487 (call)\nWebs: http://schwinger.harvard.edu/~motl/ http://motls.blogspot.com/\n^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>On Wed, 27 Oct 2004, Arnold Neumaier wrote:

> The degree of accuracy obtained is about 5%, far too low to be of use in
> chemistry or even in nuclear physics.

Right, and this verified 5% precision is enough for us to know that the
model (the Standard Model) is most likely correct. This match just makes
it virtually impossible that there is some new bug or "big correction"
that must be added to the Standard Model in order to describe the nuclei.

You know, in theoretical physics we work with quantities that a priori may
differ by many orders of magnitude - for example by 122 orders of
magnitude for the cosmological constant. ;-) An agreement of a nice theory
with a lot of data with 1%-5% precision - in the context where the theory
is just too "nonlinear" to calculate better - is just an impressive
argument that the theory has to be correct, especially if it is more
directly tested at high energies where the quarks are weakly interacting
(with a better precision, near 1% or better) and especially if we see no
way how new physics may be added to the theory without spoiling its
success completely.

It would be great if someone calculated these quantities from the Standard
Model exactly - which sounds unlikely. On the other hand, if someone
improves the calculation of one quantity from a 5% accuracy to a .5%
accuracy, we won't be terribly impressed. It's just not the most
interesting part of physics to improve the accuracy how we calculate a
random - and pretty irrelevant - observable in nuclear physics, unless
this calculation brings new powerful methods that can be used universally.
The gauge/gravity duality is a shining example of such a method, but
that's not the type of insights that YOU are looking for.

> The accuracy of the effective forces between them is even poorer.

Because it's just a difficult system to calculate. We don't need to do it
exactly in order to decide whether the theory is correct. We've done
enough to assume that it is correct.

> We have very little control over confinement, which is essential to
> get useful forces at the energies relevant for nuclear physics.
> Thus predictivity of the standard model for nuclear information
> is almost nil.

You can also say the same thing backwards: most of the detailed data from
nuclear physics is pretty irrelevant and useless for our understanding of
the important ideas contained in the underlying theory of matter. Well,
this is the formulation we would choose in high-energy physics. ;-)

> And indeed, nuclear physicists do not use the standard model
> (except for paying religious lip service to it), but work with
> their own phenomenological models.

Most of the high-energy physicists do not care about the particular energy
levels of different nuclei (except for respecting nuclear physics verbally
as a piece of solid science), but they work with more fundamental
theories.

> They just borrow some of the symmetries
> (which were of course known long before the standard model was born).

The high-energy physicists sometimes borrow a number or an idea, too. ;-)

> If we had only the standard model and the numerical estimates computed
> from it, this would give _very_ poor predictions of most chemical
> properties of everything including the hydrogen spectrum.

You seem to misunderstand what's the goal of the search for deeper
theories. We want to know the deeper theories simply because it is
important for human curiosity to know the truth. If we already know some
numbers about the complicated systems from the experiment, that's fine,
but it's not the really satisfying experience.

We want to know that we have a theory that contains all these data. I
apologize, but we sort of know, with the careful physicist's understanding
of the word "know", that the Standard Model contains them. Nevertheless,
it is still easier to compute the energy levels of a carbon nucleus than
to compute them from the Standard Model. It's not the most interesting and
most rewarding task to try to apply the strongly interacting theories of
quarks to such complicated systems - simply because the result is more or
less guaranteed to work, and it will impress no one - the improvement over
things that have already been done will be purely quantitative. And if
this calculation does not work, everyone will probably think that the
person had to make an error anyway - it's not hard to make errors in such
complicated calculations.

In physics, if we look for the *really* important things - and once again,
I apologize, but one energy level of one nucleus is *not* a really
important insight - we must master the art to look for the right problems,
those that give us the maximal amount of information for the minimal
amount of assumptions (and work) that we must invest. And the excited
energy levels of a carbon nucleus are *not* the best systems to learn
about the structure of the proton.

> Only assuming _measured_ data about form factors of proton and neutron,
> which have _not_ been calculated from the standard model but must be put in
> as additional information.

That's a very broad question whether the form factors can be
justified/calculated from the first principles. It's certainly not true
that they can't be justified at all, and various asymptotic behaviors of
these form factors etc. can be calculated from QCD.

> Yes, but one cannot calculate the atomic weights, and again must
> supplement the qualitative results from the standard model by
> additional experimental information.

It does not really matter whether we can do it in practice. The important
thing is that we have a theory that pretty obviously contains all these
numbers, and the mystery is just gone. A primary motivation for pure
science is to uncover rational justifications behind the mysteries, and
this *has* basically been done for the data surrounding all of chemistry
and nuclear physics.

> Yes. From this level on upwards, one has enough experimental data to
> calculate chemical information for small molecules that is predictive
> in the sense that it may give quantitative information that is reasonably
> accurate and not put in by hand.

These things are easier to calculate in practice because QED has a small
coupling, unlike QCD at the proton scale. But it does not mean that QCD is
a "worse" theory. It is just a theory of a system that objectively is
strongly interacting.

> Already for proteins, one again needs to complement the theoretical
> input by measurements to get predictions of reasonable accuracy.

Proteins are damned complicated systems. People like you will always
complain because there will always exist complex enough systems that have
not been calculated directly from the first principles. But it will be
becoming increasingly harder to argue that there is some totally new
physics that must be "supplemented" for the fundamental theory to contain
everything we see. Already today, your position is virtually undefendable.

> Thus the standard model is a very inaccurate tool for chemistry.

The Standard Model is a theory that trivially contains all of chemistry,
and it is just a matter of calculational difficulty whether someone finds
it useful (and interesting) to use the SM directly.

> It is useful only for elementary particle scattering experiments.

Being useful is a totally different question than being true. Being
"useful" depends on our laziness, abilities to compute, power of our
computers and so forth - usefulness is not a characteristic property
associated with the very laws of a given theory. Usefulness is more about
our abilities and our personal desires, and as a pure scientist, I am not
interested in it too much.

> Only that some variant of the standard model may do it.

There is one Standard Model only. Well, today we talk about the
\nu-Standard-Model that contains neutrino masses. ;-)

> The current accuracy of computations is too poor to make more definite
> statements.

That's your belief that is extremely hard to justify by any rational
argument. If you found a convincing bug with the Standard Model that makes
it unable to describe chemistry or nuclear physics correctly, that would
be an A* class Nobel prize discovery. But now it's just your wishful
thinking, and the conclusion of everything we know is that the Standard
Model contains all these things.

> > I would not subscribe to this statement. We know - with the careful,
> > limited, scientific meaning of the word "know" - that chemistry is
> > contained in the Standard Model.
>
> What you call 'know' is commonly called 'expect'.

I only said "know" because we're not really expecting anything specific. I
may say that "We don't expect discoveries that will invalidate the
Standard Model as a theory behind chemistry and nuclear physics". I don't
know what it really means to say "We expect the Standard Model to be
correct". It already *is* sort of proved correct, and I don't expect any
revolution that will suddenly eliminate all skeptics. "Expecting" means to
assume that something will happen. The skeptics will just die away
continuously even more than so far, as the Standard Model is increasingly
more well-established as a theory of all these phenomena.

> Some of our expectations turn out to be true, others meed
> modification after learning more, and it is difficult to tell
> in advance which is which.

This is the whole purpose of science that we *want* to say such things and
other things in advance - and to make predictions. Thousands of people
have worked on it for decades, and they found the Standard Model to be the
theory behind these phenomena. Therefore they can say, in advance, (or
predict, if you wish) that they think that the Standard Model will be a
correct theory for all these "regular" phenomena below the electroweak
scale. It's sexy to say that the SM may be seriously wrong for some of the
ordinary contexts, but it is certainly an extraordinary claim that
requires extraordinary evidence - because it would contradict thousands of
papers that support the statement that the SM works.

> Part of scientific culture entails to be modest in one's claims
> and to distinguish in one's statements between what is known,
> what is expected to be true, and what is hoped for but unproven.

Another part of scientific culture is to distinguish realistic
possibilities from unrealistic, wild speculations, whose probability is
very tiny. Yours are wild speculations.

Best wishes
Lubos
__{_______________________________________________ _____________________________}
E-mail: lumo@matfyz.cz fax: +1-617/496-0110 Web: http://lumo.matfyz.cz/
eFax: +1-801/454-1858 work: +1-617/384-9488 home: +1-617/868-4487 (call)
Webs: http://schwinger.harvard.edu/~motl/ http://motls.blogspot.com/
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Dirk Bruere at Neopax

Oct29-04, 02:07 PM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\n\n\nLubo? Motl wrote:\n\n\n>\n> There is no guarantee that the "final dream" of this reductionist\n> program - a theory with no inputs - will become true. The Nature may\n> need some parameters at the end. However, this does not change the\n\nActually, unless you are a theist or a fan of Strong Anthropological theory , I\nsuggest that Nature does not need any input parameters.\n\n--\nDirk\n\nThe Consensus:-\nThe political party for the new millenium\nhttp://www.theconsensus.org\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>Lubo? Motl wrote:

>
> There is no guarantee that the "final dream" of this reductionist
> program - a theory with no inputs - will become true. The Nature may
> need some parameters at the end. However, this does not change the

Actually, unless you are a theist or a fan of Strong Anthropological theory , I
suggest that Nature does not need any input parameters.

--
Dirk

The Consensus:-
The political party for the new millenium
http://www.theconsensus.org

Dirk Bruere at Neopax

Oct29-04, 02:07 PM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\n\n\nbackdoorstudent wrote:\n>\n> Don\'t you guys think that the purpose of theoretical physics is about\n> much more than making predictions; it\'s about understanding them as\n> well? Shouldn\'t your theory tell you exactly how a result comes out\n> rather than just be a recipe for their quantities?\n>\n> Isn\'t a physical theory (a good one, anyway) more than a black box\n> with mysterious knobs that, via tweaking, gives various outputs for\n> various inputs? If a theory is only about prediction, i.e., knowing\n> the outcome but not understanding exactly why (or even how) the\n> outcome exists, then it is not much more than accounting. Is it not\n> more engineering than science?\n\nIt\'s a data compression algorithm.\n\n--\nDirk\n\nThe Consensus:-\nThe political party for the new millenium\nhttp://www.theconsensus.org\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>backdoorstudent wrote:
>
> Don't you guys think that the purpose of theoretical physics is about
> much more than making predictions; it's about understanding them as
> well? Shouldn't your theory tell you exactly how a result comes out
> rather than just be a recipe for their quantities?
>
> Isn't a physical theory (a good one, anyway) more than a black box
> with mysterious knobs that, via tweaking, gives various outputs for
> various inputs? If a theory is only about prediction, i.e., knowing
> the outcome but not understanding exactly why (or even how) the
> outcome exists, then it is not much more than accounting. Is it not
> more engineering than science?

It's a data compression algorithm.

--
Dirk

The Consensus:-
The political party for the new millenium
http://www.theconsensus.org

Ed Fredkin

Oct30-04, 08:10 AM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\nDirk Bruere at Neopax <dirk@neopax.com> wrote in message news:<2uffo2F292iu8U1@uni-berlin.de>...\n> backdoorstudent wrote:\n> >\n> > Don\'t you guys think that the purpose of theoretical physics is about\n> > much more than making predictions; it\'s about understanding them as\n> > well? Shouldn\'t your theory tell you exactly how a result comes out\n> > rather than just be a recipe for their quantities?\n> >\n> > Isn\'t a physical theory (a good one, anyway) more than a black box\n> > with mysterious knobs that, via tweaking, gives various outputs for\n> > various inputs? If a theory is only about prediction, i.e., knowing\n> > the outcome but not understanding exactly why (or even how) the\n> > outcome exists, then it is not much more than accounting. Is it not\n> > more engineering than science?\n>\n> It\'s a data compression algorithm.\n\nIt\'s a lossy data compression algorithm.\nEd F\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>Dirk Bruere at Neopax <dirk@neopax.com> wrote in message news:<2uffo2F292iu8U1@uni-berlin.de>...
> backdoorstudent wrote:
> >
> > Don't you guys think that the purpose of theoretical physics is about
> > much more than making predictions; it's about understanding them as
> > well? Shouldn't your theory tell you exactly how a result comes out
> > rather than just be a recipe for their quantities?
> >
> > Isn't a physical theory (a good one, anyway) more than a black box
> > with mysterious knobs that, via tweaking, gives various outputs for
> > various inputs? If a theory is only about prediction, i.e., knowing
> > the outcome but not understanding exactly why (or even how) the
> > outcome exists, then it is not much more than accounting. Is it not
> > more engineering than science?
>
> It's a data compression algorithm.

It's a lossy data compression algorithm.
Ed F

robert j. kolker

Oct30-04, 08:10 AM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\n\nDirk Bruere at Neopax wrote:\n\n>\n> It\'s a data compression algorithm.\n\nA physical theory is an intellectual artifact which encapsulates our\nbest guesses about how the world works. It is a quantitiative testable\nprediction cranker-outer.\n\nOnly two things count in a phyical theory.\n\n1. Internal consistency\n\n2. Empirical correctness. Everything else is hee-haw.\n\nBob Kolker\n\n>\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>Dirk Bruere at Neopax wrote:

>
> It's a data compression algorithm.

A physical theory is an intellectual artifact which encapsulates our
best guesses about how the world works. It is a quantitiative testable
prediction cranker-outer.

Only two things count in a phyical theory.

1. Internal consistency

2. Empirical correctness. Everything else is hee-haw.

Bob Kolker

>

robert j. kolker

Oct30-04, 08:10 AM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\n\nDirk Bruere at Neopax wrote:\n\n>\n> Actually, unless you are a theist or a fan of Strong Anthropological theory , I\n> suggest that Nature does not need any input parameters.\n\nBut our theories about nature do.\n\nBob Kolker\n\n>\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>Dirk Bruere at Neopax wrote:

>
> Actually, unless you are a theist or a fan of Strong Anthropological theory , I
> suggest that Nature does not need any input parameters.

But our theories about nature do.

Bob Kolker

>

Dirk Bruere at Neopax

Nov2-04, 12:38 PM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\n\nEd Fredkin wrote:\n\n> Dirk Bruere at Neopax <dirk@neopax.com> wrote in message news:<2uffo2F292iu8U1@uni-berlin.de>...\n>\n>>backdoorstudent wrote:\n>>\n>>>Don\'t you guys think that the purpose of theoretical physics is about\n>>>much more than making predictions; it\'s about understanding them as\n>>>well? Shouldn\'t your theory tell you exactly how a result comes out\n>>>rather than just be a recipe for their quantities?\n>>>\n>>>Isn\'t a physical theory (a good one, anyway) more than a black box\n>>>with mysterious knobs that, via tweaking, gives various outputs for\n>>>various inputs? If a theory is only about prediction, i.e., knowing\n>>>the outcome but not understanding exactly why (or even how) the\n>>>outcome exists, then it is not much more than accounting. Is it not\n>>>more engineering than science?\n>>\n>>It\'s a data compression algorithm.\n>\n>\n> It\'s a lossy data compression algorithm.\n\nProbably not inevitably.\nObviously that is true at present because we have to use multiple incompatible\ntheories to cover the known ground.\n\n--\nDirk\n\nThe Consensus:-\nThe political party for the new millenium\nhttp://www.theconsensus.org\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>Ed Fredkin wrote:

> Dirk Bruere at Neopax <dirk@neopax.com> wrote in message news:<2uffo2F292iu8U1@uni-berlin.de>...
>
>>backdoorstudent wrote:
>>
>>>Don't you guys think that the purpose of theoretical physics is about
>>>much more than making predictions; it's about understanding them as
>>>well? Shouldn't your theory tell you exactly how a result comes out
>>>rather than just be a recipe for their quantities?
>>>
>>>Isn't a physical theory (a good one, anyway) more than a black box
>>>with mysterious knobs that, via tweaking, gives various outputs for
>>>various inputs? If a theory is only about prediction, i.e., knowing
>>>the outcome but not understanding exactly why (or even how) the
>>>outcome exists, then it is not much more than accounting. Is it not
>>>more engineering than science?
>>
>>It's a data compression algorithm.
>
>
> It's a lossy data compression algorithm.

Probably not inevitably.
Obviously that is true at present because we have to use multiple incompatible
theories to cover the known ground.

--
Dirk

The Consensus:-
The political party for the new millenium
http://www.theconsensus.org

Dirk Bruere at Neopax

Nov3-04, 10:04 AM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>robert j. kolker wrote:\n\n> Dirk Bruere at Neopax wrote:\n>\n>\n>>It\'s a data compression algorithm.\n>\n>\n> A physical theory is an intellectual artifact which encapsulates our\n> best guesses about how the world works. It is a quantitiative testable\n> prediction cranker-outer.\n>\n> Only two things count in a phyical theory.\n>\n> 1. Internal consistency\n>\n> 2. Empirical correctness. Everything else is hee-haw.\n\nYou could throw away (1) as long as it still provided the correct predictions.\nAlthough I\'m not entirely sure what that would mean in practice. A\nnon-computable theory?\n\n--\nDirk\n\nThe Consensus:-\nThe political party for the new millenium\nhttp://www.theconsensus.org\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>robert j. kolker wrote:

> Dirk Bruere at Neopax wrote:
>
>
>>It's a data compression algorithm.
>
>
> A physical theory is an intellectual artifact which encapsulates our
> best guesses about how the world works. It is a quantitiative testable
> prediction cranker-outer.
>
> Only two things count in a phyical theory.
>
> 1. Internal consistency
>
> 2. Empirical correctness. Everything else is hee-haw.

You could throw away (1) as long as it still provided the correct predictions.
Although I'm not entirely sure what that would mean in practice. A
non-computable theory?

--
Dirk

The Consensus:-
The political party for the new millenium
http://www.theconsensus.org

Arnold Neumaier

Nov3-04, 10:06 AM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>Lubos Motl wrote:\n> On Wed, 27 Oct 2004, Arnold Neumaier wrote:\n>\n>>The degree of accuracy obtained is about 5%, far too low to be of use in\n>>chemistry or even in nuclear physics.\n>\n> Right, and this verified 5% precision is enough for us to know that the\n> model (the Standard Model) is most likely correct.\n\nNo. It only says that it is consistent with our macroscopic knowledge.\nIf this were the main experimental prediction we would be far from\ndeclaring the standard model correct. We believe it is correct because\nit gives much better predictions for scattering at high energies.\n\n\n> This match just makes\n> it virtually impossible that there is some new bug or "big correction"\n> that must be added to the Standard Model in order to describe the nuclei.\n\nThe accuracy is much poorer than that of Newton\'s celestial mechanics,\nwhich, after all, is known to have needed corrections.\n\n\n> It would be great if someone calculated these quantities from the Standard\n> Model exactly - which sounds unlikely. On the other hand, if someone\n> improves the calculation of one quantity from a 5% accuracy to a 0.5%\n> accuracy, we won\'t be terribly impressed.\n\nBut we would be if the result were _not_ in agreement with experiment.\n\n\n>>The accuracy of the effective forces between them is even poorer.\n>\n> Because it\'s just a difficult system to calculate. We don\'t need to do it\n> exactly in order to decide whether the theory is correct. We\'ve done\n> enough to assume that it is correct.\n\nNo, but to expect it is consistent with current experiemnts.\nTo know that it is correct within current experimental accuracy\nwe\'d need to show that it is able to predict things to this accuracy.\n\n\n\n>>We have very little control over confinement, which is essential to\n>>get useful forces at the energies relevant for nuclear physics.\n>>Thus predictivity of the standard model for nuclear information\n>>is almost nil.\n>\n> You can also say the same thing backwards: most of the detailed data from\n> nuclear physics is pretty irrelevant and useless for our understanding of\n> the important ideas contained in the underlying theory of matter. Well,\n> this is the formulation we would choose in high-energy physics. ;-)\n\nOf course, but this does not contradict my statement. I never claimed\nthat nuclear physics explains or predicts elementary particles, but you\nclaimed that elementary particle theory explains and predicts all of\nphysics. I was only arguing against the latter!\n\n\n>>And indeed, nuclear physicists do not use the standard model\n>>(except for paying religious lip service to it), but work with\n>>their own phenomenological models.\n>\n> Most of the high-energy physicists do not care about the particular energy\n> levels of different nuclei (except for respecting nuclear physics verbally\n> as a piece of solid science), but they work with more fundamental\n> theories.\n\nBut not with the standard model, which for them is completely useless.\n\n\n>>If we had only the standard model and the numerical estimates computed\n>>from it, this would give _very_ poor predictions of most chemical\n>>properties of everything including the hydrogen spectrum.\n>\n> You seem to misunderstand what\'s the goal of the search for deeper\n> theories. We want to know the deeper theories simply because it is\n> important for human curiosity to know the truth. If we already know some\n> numbers about the complicated systems from the experiment, that\'s fine,\n> but it\'s not the really satisfying experience.\n\nI don\'t dispute that string theory is a candidate for a deeper theory\nof physics, but only your exaggerated claims that it _is_ the _truth_\nand _predicts_ all other levels. So far it predicted nothing verifiable\nwe did not know already, in stark contrast to all other theories which\nhave contributed to physics.\n\n\n> We want to know that we have a theory that contains all these data. I\n> apologize, but we sort of know, with the careful physicist\'s understanding\n> of the word "know", that the Standard Model contains them.\n\nYour usage of "know" is not the standard usage; others use "expect" for\nyour assumed knowledge.\n\n\n> It\'s not the most interesting and\n> most rewarding task to try to apply the strongly interacting theories of\n> quarks to such complicated systems\n\nWhat is rewarding depends one one\'s goals. Surely there are other\nvalue systems than yours. Most physicists do not care much about the\ndeepest level which for you is the only worthwhile challenge and the only\nreally important thing. They, including Nobel committees, find instead\nmany other things really important.\n\n\n> In physics, if we look for the *really* important things - and once again,\n> I apologize, but one energy level of one nucleus is *not* a really\n> important insight - we must master the art to look for the right problems,\n\n> That\'s a very broad question whether the form factors can be\n> justified/calculated from the first principles. It\'s certainly not true\n> that they can\'t be justified at all, and various asymptotic behaviors of\n> these form factors etc. can be calculated from QCD.\n\nOf proton form factors?? Please give a reference.\n\n\n>>Yes, but one cannot calculate the atomic weights, and again must\n>>supplement the qualitative results from the standard model by\n>>additional experimental information.\n>\n> It does not really matter whether we can do it in practice.\n\nIf we can\'t do it in practice we cannot know whether it would work.\n\n\n> These things are easier to calculate in practice because QED has a small\n> coupling, unlike QCD at the proton scale. But it does not mean that QCD is\n> a "worse" theory. It is just a theory of a system that objectively is\n> strongly interacting.\n\nFeynman had a different view of that...\n\n\n>>Thus the standard model is a very inaccurate tool for chemistry.\n>\n> The Standard Model is a theory that trivially contains all of chemistry,\n\nThis is one of your "truths" that cannot be substantiated.\nIt contains all of chemistry at best in the trivial sense as one could\nsay that language contains all great works of literature.\nTo extract the latter from the former is the achievement, however...\n\n\n>>>I would not subscribe to this statement. We know - with the careful,\n>>>limited, scientific meaning of the word "know" - that chemistry is\n>>>contained in the Standard Model.\n>>\n>>What you call \'know\' is commonly called \'expect\'.\n>\n> I only said "know" because we\'re not really expecting anything specific. I\n> may say that "We don\'t expect discoveries that will invalidate the\n> Standard Model as a theory behind chemistry and nuclear physics".\n\nThis is a much more moderate statement which I would not criticise.\n\n\n\n>>Some of our expectations turn out to be true, others meed\n>>modification after learning more, and it is difficult to tell\n>>in advance which is which.\n>\n> This is the whole purpose of science that we *want* to say such things and\n> other things in advance - and to make predictions.\n\nScience has many purposes, different ones for different people.\nMost people do science because it is useful for society or for their\npurse. A few only do it for the sake of "truth" in your sense.\n\n\nArnold Neumaier\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>Lubos Motl wrote:
> On Wed, 27 Oct 2004, Arnold Neumaier wrote:
>
>>The degree of accuracy obtained is about 5%, far too low to be of use in
>>chemistry or even in nuclear physics.
>
> Right, and this verified 5% precision is enough for us to know that the
> model (the Standard Model) is most likely correct.

No. It only says that it is consistent with our macroscopic knowledge.
If this were the main experimental prediction we would be far from
declaring the standard model correct. We believe it is correct because
it gives much better predictions for scattering at high energies.

> This match just makes
> it virtually impossible that there is some new bug or "big correction"
> that must be added to the Standard Model in order to describe the nuclei.

The accuracy is much poorer than that of Newton's celestial mechanics,
which, after all, is known to have needed corrections.

> It would be great if someone calculated these quantities from the Standard
> Model exactly - which sounds unlikely. On the other hand, if someone
> improves the calculation of one quantity from a 5% accuracy to a .5%
> accuracy, we won't be terribly impressed.

But we would be if the result were _not_ in agreement with experiment.

>>The accuracy of the effective forces between them is even poorer.
>
> Because it's just a difficult system to calculate. We don't need to do it
> exactly in order to decide whether the theory is correct. We've done
> enough to assume that it is correct.

No, but to expect it is consistent with current experiemnts.
To know that it is correct within current experimental accuracy
we'd need to show that it is able to predict things to this accuracy.

>>We have very little control over confinement, which is essential to
>>get useful forces at the energies relevant for nuclear physics.
>>Thus predictivity of the standard model for nuclear information
>>is almost nil.
>
> You can also say the same thing backwards: most of the detailed data from
> nuclear physics is pretty irrelevant and useless for our understanding of
> the important ideas contained in the underlying theory of matter. Well,
> this is the formulation we would choose in high-energy physics. ;-)

Of course, but this does not contradict my statement. I never claimed
that nuclear physics explains or predicts elementary particles, but you
claimed that elementary particle theory explains and predicts all of
physics. I was only arguing against the latter!

>>And indeed, nuclear physicists do not use the standard model
>>(except for paying religious lip service to it), but work with
>>their own phenomenological models.
>
> Most of the high-energy physicists do not care about the particular energy
> levels of different nuclei (except for respecting nuclear physics verbally
> as a piece of solid science), but they work with more fundamental
> theories.

But not with the standard model, which for them is completely useless.

>>If we had only the standard model and the numerical estimates computed
>>from it, this would give _very_ poor predictions of most chemical
>>properties of everything including the hydrogen spectrum.
>
> You seem to misunderstand what's the goal of the search for deeper
> theories. We want to know the deeper theories simply because it is
> important for human curiosity to know the truth. If we already know some
> numbers about the complicated systems from the experiment, that's fine,
> but it's not the really satisfying experience.

I don't dispute that string theory is a candidate for a deeper theory
of physics, but only your exaggerated claims that it _is_ the _truth_
and _predicts_ all other levels. So far it predicted nothing verifiable
we did not know already, in stark contrast to all other theories which
have contributed to physics.

> We want to know that we have a theory that contains all these data. I
> apologize, but we sort of know, with the careful physicist's understanding
> of the word "know", that the Standard Model contains them.

Your usage of "know" is not the standard usage; others use "expect" for
your assumed knowledge.

> It's not the most interesting and
> most rewarding task to try to apply the strongly interacting theories of
> quarks to such complicated systems

What is rewarding depends one one's goals. Surely there are other
value systems than yours. Most physicists do not care much about the
deepest level which for you is the only worthwhile challenge and the only
really important thing. They, including Nobel committees, find instead
many other things really important.

> In physics, if we look for the *really* important things - and once again,
> I apologize, but one energy level of one nucleus is *not* a really
> important insight - we must master the art to look for the right problems,

> That's a very broad question whether the form factors can be
> justified/calculated from the first principles. It's certainly not true
> that they can't be justified at all, and various asymptotic behaviors of
> these form factors etc. can be calculated from QCD.

Of proton form factors?? Please give a reference.

>>Yes, but one cannot calculate the atomic weights, and again must
>>supplement the qualitative results from the standard model by
>>additional experimental information.
>
> It does not really matter whether we can do it in practice.

If we can't do it in practice we cannot know whether it would work.

> These things are easier to calculate in practice because QED has a small
> coupling, unlike QCD at the proton scale. But it does not mean that QCD is
> a "worse" theory. It is just a theory of a system that objectively is
> strongly interacting.

Feynman had a different view of that...

>>Thus the standard model is a very inaccurate tool for chemistry.
>
> The Standard Model is a theory that trivially contains all of chemistry,

This is one of your "truths" that cannot be substantiated.
It contains all of chemistry at best in the trivial sense as one could
say that language contains all great works of literature.
To extract the latter from the former is the achievement, however...

>>>I would not subscribe to this statement. We know - with the careful,
>>>limited, scientific meaning of the word "know" - that chemistry is
>>>contained in the Standard Model.
>>
>>What you call 'know' is commonly called 'expect'.
>
> I only said "know" because we're not really expecting anything specific. I
> may say that "We don't expect discoveries that will invalidate the
> Standard Model as a theory behind chemistry and nuclear physics".

This is a much more moderate statement which I would not criticise.

>>Some of our expectations turn out to be true, others meed
>>modification after learning more, and it is difficult to tell
>>in advance which is which.
>
> This is the whole purpose of science that we *want* to say such things and
> other things in advance - and to make predictions.

Science has many purposes, different ones for different people.
Most people do science because it is useful for society or for their
purse. A few only do it for the sake of "truth" in your sense.

Arnold Neumaier