<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>In this month\'s edition of the "New Scientist" magazine (July 2004),\nthere is an article which says that the fine structure constant alpha\nwas smaller\nin the past ( alpha = e^2/ hbar c), and the speed of light was\ngreater.\nSince the speed of light can be given by the ratio of E/B (electric\nfield/ magnetic field) does this mean that the electric and magnetic\nfields of photons could have been different in the past?\nEnergy in a photon is distributed between the electric and magnetic\nfields, and if E and B had changed in the past then energy must have\nleft the photon with some E and B associated with it - perhaps another\nphoton with a smaller wavelength.If a photon from a distant galaxy\noriginally had a wavelength of\n10^ - 7 metres (and therefore a frequency of 10^15),since, according\nto the article in the magazine,there is evidence that the constant has\nchanged\nby about 4 parts in 10^8 over 2 x 10^9 years,this would mean that the\nenergy of any photons created from a photon of wavelength 10^ - 7\nmetres,coming from a galaxy at a distance of 2 x 10^9 years,would be:\n\n(10^15 / 10^8 x 4 = 2.5 x 10^6\nso the created photon would have a maximum frequency of 7.5 x 10^6 and\nsince the speed of light is about 3 x 10^8 m/s it would have a\nwavelength of about\n3 x 10^8 / 2.5 x 10^6 = 120 metres.\n\nSo, one possible way to test whether or not the fine structure\nconstant has changed with time, would be to look for photons in space\nwith this wavelength\nand to see if they are as abundant as photons from galaxies with\nwavelengths corresponding to 10^ -7 metres ( 10^-7 metres at the time\nthey were emitted from the galaxies).\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>In this month's edition of the "New Scientist" magazine (July 2004),
there is an article which says that the fine structure constant \alpha
was smaller
in the past ( \alpha = e^2/ \hbar c), and the speed of light was
greater.
Since the speed of light can be given by the ratio of E/B (electric
field/ magnetic field) does this mean that the electric and magnetic
fields of photons could have been different in the past?
Energy in a photon is distributed between the electric and magnetic
fields, and if E and B had changed in the past then energy must have
left the photon with some E and B associated with it - perhaps another
photon with a smaller wavelength.If a photon from a distant galaxy
originally had a wavelength of
10^ - 7 metres (and therefore a frequency of 10^15),since, according
to the article in the magazine,there is evidence that the constant has
changed
by about 4 parts in 10^8 over 2 x 10^9 years,this would mean that the
energy of any photons created from a photon of wavelength 10^ - 7
metres,coming from a galaxy at a distance of 2 x 10^9 years,would be:
(10^15 / 10^8 x 4 = 2.5 x 10^6
so the created photon would have a maximum frequency of 7.5 x 10^6 and
since the speed of light is about 3 x 10^8 m/s it would have a
wavelength of about
3 x 10^8 / 2.5 x 10^6 = 120 metres.
So, one possible way to test whether or not the fine structure
constant has changed with time, would be to look for photons in space
with this wavelength
and to see if they are as abundant as photons from galaxies with
wavelengths corresponding to 10^ -7 metres ( 10^-7 metres at the time
they were emitted from the galaxies).
Thomas Dent
Jul4-04, 11:12 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>\nalistair@goforit64.fsnet.co.uk (alistair) wrote\n\n> In this month\'s edition of the "New Scientist" magazine (July 2004),\n> there is an article which says that the fine structure constant alpha\n> was smaller\n> in the past ( alpha = e^2/ hbar c), and the speed of light was\n> greater.\n\nWRONGGG! The speed of light is *defined* to be a constant number of\nmetres per second, under the current system of units. If you are using\nSI units correctly, the speed of light will never change. And you can\nalways define units such that c is constant. Please, Alistair, *read*\nwhat people said in the previous thread about fundamental constants\nand suchlike.\n\nHow did this drivel get into New Scientist? See below.\n\n\n> Since the speed of light can be given by the ratio of E/B (electric\n> field/ magnetic field)\n\nUh? It\'s the product of the permittivity and permeability of free\nspace. Under the SI system of units, these are defined such that their\nproduct is a constant.\n\n\n> does this mean that the electric and magnetic\n> fields of photons could have been different in the past?\n\nEvery photon has different electric and magnetic fields anyway.\n\n> Energy in a photon is distributed between the electric and magnetic\n> fields, and if E and B had changed in the past then energy must have\n> left the photon with some E and B associated with it - perhaps another\n> photon with a smaller wavelength.If a photon from a distant galaxy\n> originally had a wavelength of\n> 10^ - 7 metres (and therefore a frequency of 10^15),since, according\n> to the article in the magazine,there is evidence that the constant has\n> changed\n> by about 4 parts in 10^8 over 2 x 10^9 years,this would mean that the\n> energy of any photons created from a photon of wavelength 10^ - 7\n> metres,coming from a galaxy at a distance of 2 x 10^9 years,would be:\n>\n> (10^15 / 10^8 x 4 = 2.5 x 10^6\n> so the created photon would have a maximum frequency of 7.5 x 10^6 and\n> since the speed of light is about 3 x 10^8 m/s it would have a\n> wavelength of about\n> 3 x 10^8 / 2.5 x 10^6 = 120 metres.\n>\n> So, one possible way to test whether or not the fine structure\n> constant has changed with time, would be to look for photons in space\n> with this wavelength\n> and to see if they are as abundant as photons from galaxies with\n> wavelengths corresponding to 10^ -7 metres ( 10^-7 metres at the time\n> they were emitted from the galaxies).\n\nNote, there is this thing called COSMOLOGICAL REDSHIFT by which\nphotons emitted a long way away in the past have a different frequency\nthan photons from the same atomic transition emitted in the lab since\nthey have travelled across the expanding Universe. This happens even\nthough c is constant. So before thinking about any of this stuff you\nhave to correct for redshift. After that, what is left only affects\nthe *relative* frequencies of spectral lines from any given source,\nwhich can be expressed in terms of *dimensionless* ratios and related\nto alpha.\n\nWhat you read in New Scientist isn\'t necessarily true. The reporter in\nthis case (Eugenie Samuel) has little or no scientific training, at\nleast not enough to tell the difference between meaningless/fringe\nspeculation and science. New Scientist contains about 50% outright\nmisinformation in physics.\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>alistair@goforit64.fsnet.co.uk (alistair) wrote
> In this month's edition of the "New Scientist" magazine (July 2004),
> there is an article which says that the fine structure constant \alpha
> was smaller
> in the past ( \alpha = e^2/ \hbar c), and the speed of light was
> greater.
WRONGGG! The speed of light is *defined* to be a constant number of
metres per second, under the current system of units. If you are using
SI units correctly, the speed of light will never change. And you can
always define units such that c is constant. Please, Alistair, *read*
what people said in the previous thread about fundamental constants
and suchlike.
How did this drivel get into New Scientist? See below.
> Since the speed of light can be given by the ratio of E/B (electric
> field/ magnetic field)
Uh? It's the product of the permittivity and permeability of free
space. Under the SI system of units, these are defined such that their
product is a constant.
> does this mean that the electric and magnetic
> fields of photons could have been different in the past?
Every photon has different electric and magnetic fields anyway.
> Energy in a photon is distributed between the electric and magnetic
> fields, and if E and B had changed in the past then energy must have
> left the photon with some E and B associated with it - perhaps another
> photon with a smaller wavelength.If a photon from a distant galaxy
> originally had a wavelength of
> 10^ - 7 metres (and therefore a frequency of 10^15),since, according
> to the article in the magazine,there is evidence that the constant has
> changed
> by about 4 parts in 10^8 over 2 x 10^9 years,this would mean that the
> energy of any photons created from a photon of wavelength 10^ - 7
> metres,coming from a galaxy at a distance of 2 x 10^9 years,would be:
>
> (10^15 / 10^8 x 4 = 2.5 x 10^6
> so the created photon would have a maximum frequency of 7.5 x 10^6 and
> since the speed of light is about 3 x 10^8 m/s it would have a
> wavelength of about
> 3 x 10^8 / 2.5 x 10^6 = 120 metres.
>
> So, one possible way to test whether or not the fine structure
> constant has changed with time, would be to look for photons in space
> with this wavelength
> and to see if they are as abundant as photons from galaxies with
> wavelengths corresponding to 10^ -7 metres ( 10^-7 metres at the time
> they were emitted from the galaxies).
Note, there is this thing called COSMOLOGICAL REDSHIFT by which
photons emitted a long way away in the past have a different frequency
than photons from the same atomic transition emitted in the lab since
they have travelled across the expanding Universe. This happens even
though c is constant. So before thinking about any of this stuff you
have to correct for redshift. After that, what is left only affects
the *relative* frequencies of spectral lines from any given source,
which can be expressed in terms of *dimensionless* ratios and related
to \alpha.
What you read in New Scientist isn't necessarily true. The reporter in
this case (Eugenie Samuel) has little or no scientific training, at
least not enough to tell the difference between meaningless/fringe
speculation and science. New Scientist contains about 50% outright
misinformation in physics.
carlip@no-physics-spam.ucdavis.edu
Jul6-04, 02:47 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>\nThomas Dent <tdent@auth.gr> wrote:\n\n> alistair@goforit64.fsnet.co.uk (alistair) wrote\n\n> > In this month\'s edition of the "New Scientist" magazine (July 2004),\n> > there is an article which says that the fine structure constant alpha\n> > was smaller in the past ( alpha = e^2/ hbar c), and the speed of light\n> > was greater.\n\n> WRONGGG! The speed of light is *defined* to be a constant number of\n> metres per second, under the current system of units. If you are using\n> SI units correctly, the speed of light will never change.\n\nWell, this is a little tricky. There\'s certainly a defined quantity\ncalled ``the speed of light\'\' that can never change. But whether this\nis the same as ``the speed at which light actually travels\'\' is not\n*solely* a matter of definition. For example, the current limit on\nthe mass of the photon is about 10^-16 eV. But if, say, the photon\nreally has a mass of 10^-18 eV, then not all photons will travel at\nthe same speed.\n\nWe probably agree that dimensionless constants can, in principle, change\nin time, and that all measurements are really measurements of dimensionless\nquantities. But many of the fundamental constants are defined in terms\nof dimensionful quantities that include c, and if it turns out that they\nall change consistently in a way that can be simply described as a change\nin the factor of c in each of them, it\'s not so horrible to call this a\nchange in the speed of light. (This is, of course, ambiguous -- any such\nchange can be replaced by a change in other dimensionful quantities --\nbut ``ambiguous\'\' isn\'t necessarily ``wrong.\'\')\n\nOn the other hand, for the case in question (a simplistic article in\nNew Scientist), there\'s certainly no way at all to defend the claim\nthat the purported variation in alpha should be interpreted as varying\nlight speed.\n\n> What you read in New Scientist isn\'t necessarily true. The reporter in\n> this case (Eugenie Samuel) has little or no scientific training, at\n> least not enough to tell the difference between meaningless/fringe\n> speculation and science. New Scientist contains about 50% outright\n> misinformation in physics.\n\nThis is sadly true -- New Scientist seems to have decided to be a science\ntabloid, attracting readers with sensationalist claims that quickly\ndisappear. (Wouldn\'t it be nice to see a lead story that said, ``By the\nway, the following twenty stories in our last year\'s issues turned out to\nbe wrong\'\'?)\n\nSteve Carlip\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>Thomas Dent <tdent@auth.gr> wrote:
> alistair@goforit64.fsnet.co.uk (alistair) wrote
> > In this month's edition of the "New Scientist" magazine (July 2004),
> > there is an article which says that the fine structure constant \alpha
> > was smaller in the past ( \alpha = e^2/ \hbar c), and the speed of light
> > was greater.
> WRONGGG! The speed of light is *defined* to be a constant number of
> metres per second, under the current system of units. If you are using
> SI units correctly, the speed of light will never change.
Well, this is a little tricky. There's certainly a defined quantity
called ``the speed of light'' that can never change. But whether this
is the same as ``the speed at which light actually travels'' is not
*solely* a matter of definition. For example, the current limit on
the mass of the photon is about 10^-16 eV. But if, say, the photon
really has a mass of 10^-18 eV, then not all photons will travel at
the same speed.
We probably agree that dimensionless constants can, in principle, change
in time, and that all measurements are really measurements of dimensionless
quantities. But many of the fundamental constants are defined in terms
of dimensionful quantities that include c, and if it turns out that they
all change consistently in a way that can be simply described as a change
in the factor of c in each of them, it's not so horrible to call this a
change in the speed of light. (This is, of course, ambiguous -- any such
change can be replaced by a change in other dimensionful quantities --
but ``ambiguous'' isn't necessarily ``wrong.'')
On the other hand, for the case in question (a simplistic article in
New Scientist), there's certainly no way at all to defend the claim
that the purported variation in \alpha should be interpreted as varying
light speed.
> What you read in New Scientist isn't necessarily true. The reporter in
> this case (Eugenie Samuel) has little or no scientific training, at
> least not enough to tell the difference between meaningless/fringe
> speculation and science. New Scientist contains about 50% outright
> misinformation in physics.
This is sadly true -- New Scientist seems to have decided to be a science
tabloid, attracting readers with sensationalist claims that quickly
disappear. (Wouldn't it be nice to see a lead story that said, ``By the
way, the following twenty stories in our last year's issues turned out to
be wrong''?)
Steve Carlip
Thomas Dent
Jul9-04, 04:49 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\ncarlip@no-physics-spam.ucdavis.edu wrote\n\n> Thomas Dent wrote:\n>\n> > (alistair) wrote\n>\n> > > In this month\'s edition of the "New Scientist" magazine (July 2004),\n> > > there is an article which says (...) the speed of light\n> > > was greater.\n>\n> (...) If you are using\n> > SI units correctly, the speed of light will never change.\n>\n> There\'s certainly a defined quantity\n> called ``the speed of light\'\' that can never change. But whether this\n> is the same as ``the speed at which light actually travels\'\' is not\n> *solely* a matter of definition. For example, the current limit on\n> the mass of the photon is about 10^-16 eV. But if, say, the photon\n> really has a mass of 10^-18 eV, then not all photons will travel at\n> the same speed.\n\nIsn\'t this a big old red herring? What New Sci meant, and what\nAlistair meant, and what I meant by "speed of light", was "c", the\nspeed of massless excitations in Minkowski space in vacuo. We know\nthat Scharnhorst photons travel faster than c, that photons in a\nmedium travel slower than c, that massive photons (if such there be)\ntravel slower than c, etc. etc. - none of which is at all relevant. It\ngums up the discussion if we have to say "the speed of massless\nphotons in flat space in vacuo" every time to avoid these quibbles.\n\n\n> (...) But many of the fundamental constants are defined in terms\n> of dimensionful quantities that include c, and if it turns out that they\n> all change consistently in a way that can be simply described as a change\n> in the factor of c in each of them, it\'s not so horrible to call this a\n> change in the speed of light.\n\nUnfortunately for such attempts, the number of powers of c that we\ninclude in these formulae is itself only a matter of convention. Take\n\nalpha = e^2/4 pi hbar c\n\nwhich appears to "vary inversely" with c, if we hold that e and hbar\nare "constant". But let us write another equation:\n\nalpha = e^2/4 pi gbar\n\nwhere gbar is the "reduced Plunck\'s constant" which is defined to be\nhbar c. If we hold e and gbar "constant" then alpha *does not* vary\nwith c at all!\n\nNow, why is hbar any more "fundamental" than gbar? Why shouldn\'t we\nuse the system\n\nc, gbar, G -> Plunck units\n\nrather than\n\nc, hbar, G -> Planck units?\n\nIn fact gbar seems a rather more natural choice than hbar, since it\nalso makes the Plunck mass M_Plunck = sqrt(gbar / G) simpler. Adopting\nPlunck units would also make the formulae for the Plunck length, time,\nand temperature simpler since they would have c^3 rather than c^(5/2)\nas they do for Planck units. And the value of Plunck\'s constant is a\nvery memorable\n\ngbar = 197 MeV fm (for particle physicists) = 197 eV nm (for quantum\noptics and semiconductor physicists)\n\nrather than the messy hbar = 1.05 * 10^-34 J s or 6.58 * 10^-22 MeV s.\n\nIn conclusion, since we can use (hbar c^m) and (G c^n) instead of hbar\nand G in our system of fundamental quantities, the supposed power-law\n"dependence of any dimensionless quantity on c" is undetermined up to\nthe two arbitrary integers m and n, and is a function of human\nconvention rather than of physics.\n\nThomas\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>carlip@no-physics-spam.ucdavis.edu wrote
> Thomas Dent wrote:
>
> > (alistair) wrote
>
> > > In this month's edition of the "New Scientist" magazine (July 2004),
> > > there is an article which says (...) the speed of light
> > > was greater.
>
> (...) If you are using
> > SI units correctly, the speed of light will never change.
>
> There's certainly a defined quantity
> called ``the speed of light'' that can never change. But whether this
> is the same as ``the speed at which light actually travels'' is not
> *solely* a matter of definition. For example, the current limit on
> the mass of the photon is about 10^-16 eV. But if, say, the photon
> really has a mass of 10^-18 eV, then not all photons will travel at
> the same speed.
Isn't this a big old red herring? What New Sci meant, and what
Alistair meant, and what I meant by "speed of light", was "c", the
speed of massless excitations in Minkowski space in vacuo. We know
that Scharnhorst photons travel faster than c, that photons in a
medium travel slower than c, that massive photons (if such there be)
travel slower than c, etc. etc. - none of which is at all relevant. It
gums up the discussion if we have to say "the speed of massless
photons in flat space in vacuo" every time to avoid these quibbles.
> (...) But many of the fundamental constants are defined in terms
> of dimensionful quantities that include c, and if it turns out that they
> all change consistently in a way that can be simply described as a change
> in the factor of c in each of them, it's not so horrible to call this a
> change in the speed of light.
Unfortunately for such attempts, the number of powers of c that we
include in these formulae is itself only a matter of convention. Take
\alpha = e^2/4 \pi \hbar c
which appears to "vary inversely" with c, if we hold that e and \hbar
are "constant". But let us write another equation:
\alpha = e^2/4 \pi gbar
where gbar is the "reduced Plunck's constant" which is defined to be
\hbar c. If we hold e and gbar "constant" then \alpha *does not* vary
with c at all!
Now, why is \hbar any more "fundamental" than gbar? Why shouldn't we
use the system
c, gbar, G -> Plunck units
rather than
c, \hbar, G -> Planck units?
In fact gbar seems a rather more natural choice than \hbar, since it
also makes the Plunck mass M_{Plunck} = \sqrt(gbar / G) simpler. Adopting
Plunck units would also make the formulae for the Plunck length, time,
and temperature simpler since they would have c^3 rather than c^(5/2)
as they do for Planck units. And the value of Plunck's constant is a
very memorable
gbar = 197 MeV fm (for particle physicists) = 197 eV nm (for quantum
optics and semiconductor physicists)
rather than the messy \hbar = 1.05 * 10^-34 J s or 6.58 * 10^-22 MeV s.
In conclusion, since we can use (\hbar c^m) and (G c^n) instead of \hbar
and G in our system of fundamental quantities, the supposed power-law
"dependence of any dimensionless quantity on c" is undetermined up to
the two arbitrary integers m and n, and is a function of human
convention rather than of physics.
Thomas
Peter Shor
Jul9-04, 04:49 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\ncarlip@no-physics-spam.ucdavis.edu wrote in message news:<40eaf3ac\\$1@news.sentex.net>...\n> Thomas Dent <tdent@auth.gr> wrote:\n>\n> > alistair@goforit64.fsnet.co.uk (alistair) wrote\n>\n> > > In this month\'s edition of the "New Scientist" magazine (July 2004),\n> > > there is an article which says that the fine structure constant alpha\n> > > was smaller in the past ( alpha = e^2/ hbar c), and the speed of light\n> > > was greater.\n>\n> > WRONGGG! The speed of light is *defined* to be a constant number of\n> > metres per second, under the current system of units. If you are using\n> > SI units correctly, the speed of light will never change.\n>\n> Well, this is a little tricky. There\'s certainly a defined quantity\n> called ``the speed of light\'\' that can never change. But whether this\n> is the same as ``the speed at which light actually travels\'\' is not\n> *solely* a matter of definition. For example, the current limit on\n> the mass of the photon is about 10^-16 eV. But if, say, the photon\n> really has a mass of 10^-18 eV, then not all photons will travel at\n> the same speed.\n\nNo, the New Scientist article is talking about a change in the\ndimensionless fine structure constant (no units, SI or otherwise). If\nthe fine structure constant changes, how can you tell whether the\nspeed of light or Planck\'s constant or the charge of the electron was\nwhat changed? I may have seen an answer to this somewhere, but I\ncan\'t remember what it was, and it may have been incorrect. The\narticle does say "assuming that the other constants remained the same\n...." and I\'m sure they chose the speed of light as the constant they\nassume changed to get more reader interest.\n\nThe New Scientist article is available online.\nhttp://www.newscientist.com/news/news.jsp?id=ns99996092\nIt says that there\'s a reasonable amount of controversy about the\nresults. (But if you work it out, there\'s no inconsistency between the\nreported German experiments that show alpha has changed less than one\npart in 10^15 over 4 years, and the possibility that alpha changed by\n4 parts in 10^8 over 2 billion years ... the German experiments would\nneed to be an order of magnitude or so more precise to catch this\nchange if you assume it\'s happening at a steady pace).\n\nThe other funny thing is that of the two groups that claim that alpha\nhas changed, one says the alpha has increased and the other says it\nhas decreased. Since these statements are made several paragraphs\naway from each other, it\'s easy to read the article and not notice\nthis discrepancy. I would suspect that at least one of these two\ngroups is wrong (although since one is the value four billion years\nago, and the other is the value two billion years ago, there isn\'t a\nlogical contradiction).\n\nPeter Shor\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>carlip@no-physics-spam.ucdavis.edu wrote in message news:<40eaf3ac$1@news.sentex.net>...
> Thomas Dent <tdent@auth.gr> wrote:
>
> > alistair@goforit64.fsnet.co.uk (alistair) wrote
>
> > > In this month's edition of the "New Scientist" magazine (July 2004),
> > > there is an article which says that the fine structure constant \alpha
> > > was smaller in the past ( \alpha = e^2/ \hbar c), and the speed of light
> > > was greater.
>
> > WRONGGG! The speed of light is *defined* to be a constant number of
> > metres per second, under the current system of units. If you are using
> > SI units correctly, the speed of light will never change.
>
> Well, this is a little tricky. There's certainly a defined quantity
> called ``the speed of light'' that can never change. But whether this
> is the same as ``the speed at which light actually travels'' is not
> *solely* a matter of definition. For example, the current limit on
> the mass of the photon is about 10^-16 eV. But if, say, the photon
> really has a mass of 10^-18 eV, then not all photons will travel at
> the same speed.
No, the New Scientist article is talking about a change in the
dimensionless fine structure constant (no units, SI or otherwise). If
the fine structure constant changes, how can you tell whether the
speed of light or Planck's constant or the charge of the electron was
what changed? I may have seen an answer to this somewhere, but I
can't remember what it was, and it may have been incorrect. The
article does say "assuming that the other constants remained the same
...." and I'm sure they chose the speed of light as the constant they
assume changed to get more reader interest.
The New Scientist article is available online.
http://www.newscientist.com/news/news.jsp?id=ns99996092
It says that there's a reasonable amount of controversy about the
results. (But if you work it out, there's no inconsistency between the
reported German experiments that show \alpha has changed less than one
part in 10^15 over 4 years, and the possibility that \alpha changed by
4 parts in 10^8 over 2 billion years ... the German experiments would
need to be an order of magnitude or so more precise to catch this
change if you assume it's happening at a steady pace).
The other funny thing is that of the two groups that claim that \alpha
has changed, one says the \alpha has increased and the other says it
has decreased. Since these statements are made several paragraphs
away from each other, it's easy to read the article and not notice
this discrepancy. I would suspect that at least one of these two
groups is wrong (although since one is the value four billion years
ago, and the other is the value two billion years ago, there isn't a
logical contradiction).
Peter Shor
Oz
Jul12-04, 04:44 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\nThomas Dent <tdent@auth.gr> writes\n>Isn\'t this a big old red herring? What New Sci meant, and what\n>Alistair meant, and what I meant by "speed of light", was "c", the\n>speed of massless excitations in Minkowski space in vacuo. We know\n>that Scharnhorst photons travel faster than c, that photons in a\n>medium travel slower than c, that massive photons (if such there be)\n>travel slower than c, etc. etc. - none of which is at all relevant.\n\nHmm. Maybe, but perhaps what you _said_ *is* relevant.\n\nNaively c is determined by u_o and e_o of the vacuum.\nNobody has ever really explained why the vacuum should have these\nparticular values. However we are now filling the vacuum with dark\nenergy (let alone quantum effects). Now I presume that the current\nassumption is that Em doesn\'t couple at all with dark energy, but what\nif it did, just a teeny bit? I would imagine that any coupling would\nslow a photon (from infinite speed) to something just a little less (for\nsome value of little).\n\nNow, as far as I can tell from gleanings of various posts here, dark\nenergy may not have been constant throughout the life of the universe.\nI\'m not at all clear if it has a constant base level (per unit volume)\nand so was relatively less important in a small early universe, or\nwhether the amount of dark energy per unit volume actually changed in\nthe early universe. If (and I speculate here, bad news moderator-wise)\nthere was actually less dark energy per unit volume, then c would be\nhigher, given the proposal above. A higher value for c, particularly a\nmuch higher value, might be quite helpful in dealing with the horizon\nproblem.\n\nThis leads me on a further step. If dark energy was indeed less per unit\nvolume in the very early (and more curved - timewise) universe, then\nshouldn\'t we expect some correlation between curvature and amount of\ndark energy? That might imply that balck holes have less dark energy\n(although in what co-ordinate system might be problematical) than flat\nspacetime.\n\nEr... I think I had better stop there ...\n\n--\nOz\nThis post is worth absolutely nothing and is probably fallacious.\n\nBTOPENWORLD address about to cease. DEMON address no longer in use.\n>>Use oz@farmeroz.port995.com<<\nozacoohdb@despammed.com still functions.\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>Thomas Dent <tdent@auth.gr> writes
>Isn't this a big old red herring? What New Sci meant, and what
>Alistair meant, and what I meant by "speed of light", was "c", the
>speed of massless excitations in Minkowski space in vacuo. We know
>that Scharnhorst photons travel faster than c, that photons in a
>medium travel slower than c, that massive photons (if such there be)
>travel slower than c, etc. etc. - none of which is at all relevant.
Hmm. Maybe, but perhaps what you _said_ *is* relevant.
Naively c is determined by u_o and e_o of the vacuum.
Nobody has ever really explained why the vacuum should have these
particular values. However we are now filling the vacuum with dark
energy (let alone quantum effects). Now I presume that the current
assumption is that Em doesn't couple at all with dark energy, but what
if it did, just a teeny bit? I would imagine that any coupling would
slow a photon (from infinite speed) to something just a little less (for
some value of little).
Now, as far as I can tell from gleanings of various posts here, dark
energy may not have been constant throughout the life of the universe.
I'm not at all clear if it has a constant base level (per unit volume)
and so was relatively less important in a small early universe, or
whether the amount of dark energy per unit volume actually changed in
the early universe. If (and I speculate here, bad news moderator-wise)
there was actually less dark energy per unit volume, then c would be
higher, given the proposal above. A higher value for c, particularly a
much higher value, might be quite helpful in dealing with the horizon
problem.
This leads me on a further step. If dark energy was indeed less per unit
volume in the very early (and more curved - timewise) universe, then
shouldn't we expect some correlation between curvature and amount of
dark energy? That might imply that balck holes have less dark energy
(although in what co-ordinate system might be problematical) than flat
spacetime.
Er... I think I had better stop there ...
--
Oz
This post is worth absolutely nothing and is probably fallacious.
BTOPENWORLD address about to cease. DEMON address no longer in use.
>>Use oz@farmeroz.port995.com<<
ozacoohdb@despammed.com still functions.
Thomas Dent
Jul13-04, 07:25 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>\nOz <oz@farmeroz.port995.com> wrote\n\n> Thomas Dent <tdent@auth.gr> writes\n> >Isn\'t this a big old red herring? What New Sci meant, and what\n> >Alistair meant, and what I meant by "speed of light", was "c", the\n> >speed of massless excitations in Minkowski space in vacuo. We know\n> >that Scharnhorst photons travel faster than c, that photons in a\n> >medium travel slower than c, that massive photons (if such there be)\n> >travel slower than c, etc. etc. - none of which is at all relevant.\n\n>(...)\n> Naively c is determined by u_o and e_o of the vacuum.\n> Nobody has ever really explained why the vacuum should have these\n> particular values.\n\nThe numerical values of these constants are a matter of conventional\ndefinition and have no physics content. See\n\nhttp://scienceworld.wolfram.com/physics/PermeabilityofFreeSpace.html\nhttp://scienceworld.wolfram.com/physics/PermittivityofFreeSpace.html\n\nThey have these values as a result of historical accidents which led\nto the current definition of SI units.\n\n> However we are now filling the vacuum with dark\n> energy (let alone quantum effects). Now I presume that the current\n> assumption is that Em doesn\'t couple at all with dark energy, but what\n> if it did, just a teeny bit? I would imagine that any coupling would\n> slow a photon (from infinite speed)\n\nPhotons don\'t travel at infinite speed. Plus, one can couple\nelectromagnetism to \'dark energy\' (in the form of a scalar field) in a\nLorentz-invariant way that also respects gauge invariance, so that\nboth c and the speed of photons are unaffected.\n\n> to something just a little less (for some value of little).\n\nInfinity minus something little is infinity.\n\n> Now, as far as I can tell from gleanings of various posts here, dark\n> energy may not have been constant throughout the life of the universe.\n> (...) If (and I speculate here, bad news moderator-wise)\n> there was actually less dark energy per unit volume, then c would be\n> higher, given the proposal above. A higher value for c, particularly a\n> much higher value, might be quite helpful in dealing with the horizon\n> problem.\n\nNo, as I keep saying, you can *always* define units such that c=1, or\nc=300,000, or any number you like, at all points in spacetime. The\nhorizon problem can be stated in terms of dimensionless numbers,\nnamely, the size of the particle horizon at decoupling relative to the\nsize of the currently observable Universe. Any solution to it can be\ncast in terms of dimensionless ratios which are not affected by choice\nof units. For example the number of e-foldings of inflation.\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>Oz <oz@farmeroz.port995.com> wrote
> Thomas Dent <tdent@auth.gr> writes
> >Isn't this a big old red herring? What New Sci meant, and what
> >Alistair meant, and what I meant by "speed of light", was "c", the
> >speed of massless excitations in Minkowski space in vacuo. We know
> >that Scharnhorst photons travel faster than c, that photons in a
> >medium travel slower than c, that massive photons (if such there be)
> >travel slower than c, etc. etc. - none of which is at all relevant.
>(...)
> Naively c is determined by u_o and e_o of the vacuum.
> Nobody has ever really explained why the vacuum should have these
> particular values.
The numerical values of these constants are a matter of conventional
definition and have no physics content. See
They have these values as a result of historical accidents which led
to the current definition of SI units.
> However we are now filling the vacuum with dark
> energy (let alone quantum effects). Now I presume that the current
> assumption is that Em doesn't couple at all with dark energy, but what
> if it did, just a teeny bit? I would imagine that any coupling would
> slow a photon (from infinite speed)
Photons don't travel at infinite speed. Plus, one can couple
electromagnetism to 'dark energy' (in the form of a scalar field) in a
Lorentz-invariant way that also respects gauge invariance, so that
both c and the speed of photons are unaffected.
> to something just a little less (for some value of little).
Infinity minus something little is infinity.
> Now, as far as I can tell from gleanings of various posts here, dark
> energy may not have been constant throughout the life of the universe.
> (...) If (and I speculate here, bad news moderator-wise)
> there was actually less dark energy per unit volume, then c would be
> higher, given the proposal above. A higher value for c, particularly a
> much higher value, might be quite helpful in dealing with the horizon
> problem.
No, as I keep saying, you can *always* define units such that c=1, or
c=300,000, or any number you like, at all points in spacetime. The
horizon problem can be stated in terms of dimensionless numbers,
namely, the size of the particle horizon at decoupling relative to the
size of the currently observable Universe. Any solution to it can be
cast in terms of dimensionless ratios which are not affected by choice
of units. For example the number of e-foldings of inflation.
greywolf42
Jul13-04, 10:17 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>\nOz <oz@farmeroz.port995.com> wrote in message\nnews:pSxl8\\$N+0i8AFw\\$d@farmeroz.port995.com...\n>\n>\n> Thomas Dent <tdent@auth.gr> writes\n> >Isn\'t this a big old red herring? What New Sci meant, and what\n> >Alistair meant, and what I meant by "speed of light", was "c", the\n> >speed of massless excitations in Minkowski space in vacuo. We know\n> >that Scharnhorst photons travel faster than c, that photons in a\n> >medium travel slower than c, that massive photons (if such there be)\n> >travel slower than c, etc. etc. - none of which is at all relevant.\n>\n> Hmm. Maybe, but perhaps what you _said_ *is* relevant.\n>\n> Naively c is determined by u_o and e_o of the vacuum.\n> Nobody has ever really explained why the vacuum should have these\n> particular values.\n\nA correction to your statement of history:\n\nContrary to your statement, Maxwell very explicitly explained the\nrelationship between the speed of light and the magnetic and electric\nproperties of the vacuum. And he did this when he first developed\n"Maxwell\'s equations." Back in 1861, in "On Physical Lines of Force,"\nproposition XVI. He calculated the speed of transverse waves in his aether\nfluid, based on the electric and magnetic experiments of Kohlrausch and\nWeber. The speed matched the speed of light as previously determined by\nFizeau. This was the reason that light was identified as transverse\nelectric and magnetic waves.\n\nOf course, modern theorists do not bother with Maxwell\'s derivations.\nIndeed, one of the reasons for the creation of the arbitrary constants u_0\nand e_0 in the 1920\'s was to remove the last traces of Maxwell\'s physical\nmodel from \'modern\' electromagnetic formalism.\n\n{snip the rest}\n\n--\ngreywolf42\nubi dubium ibi libertas\n{remove planet for return e-mail}\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>Oz <oz@farmeroz.port995.com> wrote in message
news:pSxl8$N+0i8AFw$d@farmeroz.port995.com...
>
>
> Thomas Dent <tdent@auth.gr> writes
> >Isn't this a big old red herring? What New Sci meant, and what
> >Alistair meant, and what I meant by "speed of light", was "c", the
> >speed of massless excitations in Minkowski space in vacuo. We know
> >that Scharnhorst photons travel faster than c, that photons in a
> >medium travel slower than c, that massive photons (if such there be)
> >travel slower than c, etc. etc. - none of which is at all relevant.
>
> Hmm. Maybe, but perhaps what you _said_ *is* relevant.
>
> Naively c is determined by u_o and e_o of the vacuum.
> Nobody has ever really explained why the vacuum should have these
> particular values.
A correction to your statement of history:
Contrary to your statement, Maxwell very explicitly explained the
relationship between the speed of light and the magnetic and electric
properties of the vacuum. And he did this when he first developed
"Maxwell's equations." Back in 1861, in "On Physical Lines of Force,"
proposition XVI. He calculated the speed of transverse waves in his aether
fluid, based on the electric and magnetic experiments of Kohlrausch and
Weber. The speed matched the speed of light as previously determined by
Fizeau. This was the reason that light was identified as transverse
electric and magnetic waves.
Of course, modern theorists do not bother with Maxwell's derivations.
Indeed, one of the reasons for the creation of the arbitrary constants u_0
and e_0 in the 1920's was to remove the last traces of Maxwell's physical
model from 'modern' electromagnetic formalism.
{snip the rest}
--
greywolf42
ubi dubium ibi libertas
{remove planet for return e-mail}
carlip@no-physics-spam.ucdavis.edu
Jul13-04, 12:41 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>Thomas Dent <tdent@auth.gr> wrote:\n\n> carlip@no-physics-spam.ucdavis.edu wrote\n\n> > (...) But many of the fundamental constants are defined in terms\n> > of dimensionful quantities that include c, and if it turns out that they\n> > all change consistently in a way that can be simply described as a change\n> > in the factor of c in each of them, it\'s not so horrible to call this a\n> > change in the speed of light.\n\n> Unfortunately for such attempts, the number of powers of c that we\n> include in these formulae is itself only a matter of convention. Take\n\n> alpha = e^2/4 pi hbar c\n\n> which appears to "vary inversely" with c, if we hold that e and hbar\n> are "constant". But let us write another equation:\n\n> alpha = e^2/4 pi gbar\n\n> where gbar is the "reduced Plunck\'s constant" which is defined to be\n> hbar c. If we hold e and gbar "constant" then alpha *does not* vary\n> with c at all!\n\nAgreed. Any statement that ``the speed of light is changing\'\' (or that\nany other dimensionful quantity is) is a statement about convention,\nand not about nature. All I meant was that *if* people agree on a set\nof conventions, then it\'s a useful abbreviation for a statement about\nreal physics.\n\nMaybe a little more...if some set of dimensionless quantities were found\nto all change in concert, it might be helpful to define conventions in a\nway that let us describe the changes as a single change of a dimensionful\nquantity. For example, if we found that alpha ``varied inversely with c\'\'\n*and* that rest energies of elementary particles all ``varied as c^2\'\'\n*and* that the dimensionless quantity Gm^2/hc (where m is, say, the electron\nmass) ``varied inversely with c,\'\' then the abbreviation ``c is changing\'\'\nwould be genuinely useful, as a mnemonic if nothing else. It would still\nbe conventional -- one could, as you say, absorb factors of c in various\nplaces in a way that would make such a description invalid. But there\'s\nnothing *wrong* with a statement based on a choice of conventions, as long\nas one doesn\'t overestimate what it means.\n\nSteve Carlip\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>Thomas Dent <tdent@auth.gr> wrote:
> carlip@no-physics-spam.ucdavis.edu wrote
> > (...) But many of the fundamental constants are defined in terms
> > of dimensionful quantities that include c, and if it turns out that they
> > all change consistently in a way that can be simply described as a change
> > in the factor of c in each of them, it's not so horrible to call this a
> > change in the speed of light.
> Unfortunately for such attempts, the number of powers of c that we
> include in these formulae is itself only a matter of convention. Take
> \alpha = e^2/4 \pi \hbar c
> which appears to "vary inversely" with c, if we hold that e and \hbar
> are "constant". But let us write another equation:
> \alpha = e^2/4 \pi gbar
> where gbar is the "reduced Plunck's constant" which is defined to be
> \hbar c. If we hold e and gbar "constant" then \alpha *does not* vary
> with c at all!
Agreed. Any statement that ``the speed of light is changing'' (or that
any other dimensionful quantity is) is a statement about convention,
and not about nature. All I meant was that *if* people agree on a set
of conventions, then it's a useful abbreviation for a statement about
real physics.
Maybe a little more...if some set of dimensionless quantities were found
to all change in concert, it might be helpful to define conventions in a
way that let us describe the changes as a single change of a dimensionful
quantity. For example, if we found that \alpha ``varied inversely with c''
*and* that rest energies of elementary particles all ``varied as c^2''
*and* that the dimensionless quantity Gm^2/hc (where m is, say, the electron
mass) ``varied inversely with c,'' then the abbreviation ``c is changing''
would be genuinely useful, as a mnemonic if nothing else. It would still
be conventional -- one could, as you say, absorb factors of c in various
places in a way that would make such a description invalid. But there's
nothing *wrong* with a statement based on a choice of conventions, as long
as one doesn't overestimate what it means.
Steve Carlip
Oz
Jul13-04, 12:52 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>Thomas Dent <tdent@auth.gr> writes\n>\n>Oz <oz@farmeroz.port995.com> wrote\n>\n>> Thomas Dent <tdent@auth.gr> writes\n>> >Isn\'t this a big old red herring? What New Sci meant, and what\n>> >Alistair meant, and what I meant by "speed of light", was "c", the\n>> >speed of massless excitations in Minkowski space in vacuo. We know\n>> >that Scharnhorst photons travel faster than c, that photons in a\n>> >medium travel slower than c, that massive photons (if such there be)\n>> >travel slower than c, etc. etc. - none of which is at all relevant.\n>\n>>(...)\n>> Naively c is determined by u_o and e_o of the vacuum.\n>> Nobody has ever really explained why the vacuum should have these\n>> particular values.\n>\n>The numerical values of these constants are a matter of conventional\n>definition and have no physics content.\n\nI wasn\'t talking about their numerical values, but the value they have\n(in whatever units you might choose).\n\n>They have these values as a result of historical accidents which led\n>to the current definition of SI units.\n\nc = 1/sqrt(e_0 u_0),\n\nso their values are of some interest, whatever units you choose.\n\n>> However we are now filling the vacuum with dark\n>> energy (let alone quantum effects). Now I presume that the current\n>> assumption is that Em doesn\'t couple at all with dark energy, but what\n>> if it did, just a teeny bit? I would imagine that any coupling would\n>> slow a photon (from infinite speed)\n>\n>Photons don\'t travel at infinite speed.\n\nPrecisely. But why should they travel at c? One possibility is that the\nvacuum is behaving as a medium, with some interaction which affects c,\nbecause it is filled with (quite a lot of) dark energy.\n\n>Plus, one can couple\n>electromagnetism to \'dark energy\' (in the form of a scalar field) in a\n>Lorentz-invariant way that also respects gauge invariance, so that\n>both c and the speed of photons are unaffected.\n\nVery probably, but is that the only way to couple it?\n\n>> Now, as far as I can tell from gleanings of various posts here, dark\n>> energy may not have been constant throughout the life of the universe.\n>> (...) If (and I speculate here, bad news moderator-wise)\n>> there was actually less dark energy per unit volume, then c would be\n>> higher, given the proposal above. A higher value for c, particularly a\n>> much higher value, might be quite helpful in dealing with the horizon\n>> problem.\n>\n>No, as I keep saying, you can *always* define units such that c=1, or\n>c=300,000, or any number you like, at all points in spacetime.\n\nI am well aware of that.\n\n>The\n>horizon problem can be stated in terms of dimensionless numbers,\n>namely, the size of the particle horizon at decoupling relative to the\n>size of the currently observable Universe.\n\nThat is surely model-dependent. A model that had c very much larger than\nits is today then the horizon problem would vanish.\n\n--\nOz\nThis post is worth absolutely nothing and is probably fallacious.\n\nBTOPENWORLD address about to cease. DEMON address no longer in use.\n>>Use oz@farmeroz.port995.com<<\nozacoohdb@despammed.com still functions.\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>Thomas Dent <tdent@auth.gr> writes
>
>Oz <oz@farmeroz.port995.com> wrote
>
>> Thomas Dent <tdent@auth.gr> writes
>> >Isn't this a big old red herring? What New Sci meant, and what
>> >Alistair meant, and what I meant by "speed of light", was "c", the
>> >speed of massless excitations in Minkowski space in vacuo. We know
>> >that Scharnhorst photons travel faster than c, that photons in a
>> >medium travel slower than c, that massive photons (if such there be)
>> >travel slower than c, etc. etc. - none of which is at all relevant.
>
>>(...)
>> Naively c is determined by u_o and e_o of the vacuum.
>> Nobody has ever really explained why the vacuum should have these
>> particular values.
>
>The numerical values of these constants are a matter of conventional
>definition and have no physics content.
I wasn't talking about their numerical values, but the value they have
(in whatever units you might choose).
>They have these values as a result of historical accidents which led
>to the current definition of SI units.
c = 1/\sqrt(e_0 u_0),
so their values are of some interest, whatever units you choose.
>> However we are now filling the vacuum with dark
>> energy (let alone quantum effects). Now I presume that the current
>> assumption is that Em doesn't couple at all with dark energy, but what
>> if it did, just a teeny bit? I would imagine that any coupling would
>> slow a photon (from infinite speed)
>
>Photons don't travel at infinite speed.
Precisely. But why should they travel at c? One possibility is that the
vacuum is behaving as a medium, with some interaction which affects c,
because it is filled with (quite a lot of) dark energy.
>Plus, one can couple
>electromagnetism to 'dark energy' (in the form of a scalar field) in a
>Lorentz-invariant way that also respects gauge invariance, so that
>both c and the speed of photons are unaffected.
Very probably, but is that the only way to couple it?
>> Now, as far as I can tell from gleanings of various posts here, dark
>> energy may not have been constant throughout the life of the universe.
>> (...) If (and I speculate here, bad news moderator-wise)
>> there was actually less dark energy per unit volume, then c would be
>> higher, given the proposal above. A higher value for c, particularly a
>> much higher value, might be quite helpful in dealing with the horizon
>> problem.
>
>No, as I keep saying, you can *always* define units such that c=1, or
>c=300,000, or any number you like, at all points in spacetime.
I am well aware of that.
>The
>horizon problem can be stated in terms of dimensionless numbers,
>namely, the size of the particle horizon at decoupling relative to the
>size of the currently observable Universe.
That is surely model-dependent. A model that had c very much larger than
its is today then the horizon problem would vanish.
--
Oz
This post is worth absolutely nothing and is probably fallacious.
BTOPENWORLD address about to cease. DEMON address no longer in use.
>>Use oz@farmeroz.port995.com<<
ozacoohdb@despammed.com still functions.
FrediFizzx
Jul14-04, 03:52 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"Oz" <oz@farmeroz.port995.com> wrote in message\nnews:7Sdh8gDIBB9AFwkZ@farmeroz.port995.com...\n| Thomas Dent <tdent@auth.gr> writes\n| >\n| >Oz <oz@farmeroz.port995.com> wrote\n[snip]\n| >> Naively c is determined by u_o and e_o of the vacuum.\n| >> Nobody has ever really explained why the vacuum should have these\n| >> particular values.\n| >\n| >The numerical values of these constants are a matter of conventional\n| >definition and have no physics content.\n\nNot exactly. Mu0 and eps0 automatically "fallout" from the arbitrary\ndefinition of the ampere so that SI and/or MKS follow experimental results\nand are consistent with other systems of units.\n\n| I wasn\'t talking about their numerical values, but the value they have\n| (in whatever units you might choose).\n|\n| >They have these values as a result of historical accidents which led\n| >to the current definition of SI units.\n|\n| c = 1/sqrt(e_0 u_0),\n|\n| so their values are of some interest, whatever units you choose.\n\nYou are absolutely correct. This is a constant debate on the other groups\nand no one that I have seen so far has resolved it other than myself. It\nrequires only one postulate to reconcile mu0 and eps0 with other systems of\nunits. Vacuum charge = +,- sqrt(hbar*c) in cgs or +,- sqrt(4pi*eps0*hbar*c)\nin SI. If this is true, then vacuum capacitance and inductance can and does\nexist. The following expressions are true in all systems of units.\n\nw = 1/sqrt(L*C) and c = lambda*w/2pi with w being angular frequency. So,\n\nc = (lambda/2pi)(1/sqrt(Lvac*Cvac).\n\nWhich would also be true in all systems of units. Now in SI,\n\nLvac = mu0*lambda/8pi^2 and Cvac = 2*eps0*lambda.\n\nMake the replacements and we are left with,\n\nc = 1/sqrt(eps0*mu0) in SI. So it is easy to see that this expression is\nsimply "shorthand" for\n\nc = (lambda/2pi)(1/sqrt(Lvac*Cvac) which is always true in all systems of\nunits if our single postulate is correct and is the expression that\ncertainly would have much physical content.\n\n| >> However we are now filling the vacuum with dark\n| >> energy (let alone quantum effects). Now I presume that the current\n| >> assumption is that Em doesn\'t couple at all with dark energy, but what\n| >> if it did, just a teeny bit? I would imagine that any coupling would\n| >> slow a photon (from infinite speed)\n| >\n| >Photons don\'t travel at infinite speed.\n|\n| Precisely. But why should they travel at c? One possibility is that the\n| vacuum is behaving as a medium, with some interaction which affects c,\n| because it is filled with (quite a lot of) dark energy.\n\nYou bet it is if +,- sqrt(hbar*c) is vacuum charge. A system of coupled\noscillators that is all bound throughout the entire Universe.\n\nFrediFizzx\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>"Oz" <oz@farmeroz.port995.com> wrote in message
news:7Sdh8gDIBB9AFwkZ@farmeroz.port995.com...
| Thomas Dent <tdent@auth.gr> writes
| >
| >Oz <oz@farmeroz.port995.com> wrote
[snip]
| >> Naively c is determined by u_o and e_o of the vacuum.
| >> Nobody has ever really explained why the vacuum should have these
| >> particular values.
| >
| >The numerical values of these constants are a matter of conventional
| >definition and have no physics content.
Not exactly. Mu0 and eps0 automatically "fallout" from the arbitrary
definition of the ampere so that SI and/or MKS follow experimental results
and are consistent with other systems of units.
| I wasn't talking about their numerical values, but the value they have
| (in whatever units you might choose).
|
| >They have these values as a result of historical accidents which led
| >to the current definition of SI units.
|
| c = 1/\sqrt(e_0 u_0),
|
| so their values are of some interest, whatever units you choose.
You are absolutely correct. This is a constant debate on the other groups
and no one that I have seen so far has resolved it other than myself. It
requires only one postulate to reconcile mu0 and eps0 with other systems of
units. Vacuum charge = +,- \sqrt(\hbar*c) in cgs or +,- \sqrt(4pi*eps0*\hbar*c)
in SI. If this is true, then vacuum capacitance and inductance can and does
exist. The following expressions are true in all systems of units.
w = 1/\sqrt(L*C) and c = \lambda*w/2pi with w being angular frequency. So,
c = (\lambda/2pi)(1/\sqrt(Lvac*Cvac).
Which would also be true in all systems of units. Now in SI,
Lvac = mu0*\lambda/8pi^2 and Cvac = 2*eps0*\lambda.
Make the replacements and we are left with,
c = 1/\sqrt(eps0*mu0) in SI. So it is easy to see that this expression is
simply "shorthand" for
c = (\lambda/2pi)(1/\sqrt(Lvac*Cvac) which is always true in all systems of
units if our single postulate is correct and is the expression that
certainly would have much physical content.
| >> However we are now filling the vacuum with dark
| >> energy (let alone quantum effects). Now I presume that the current
| >> assumption is that Em doesn't couple at all with dark energy, but what
| >> if it did, just a teeny bit? I would imagine that any coupling would
| >> slow a photon (from infinite speed)
| >
| >Photons don't travel at infinite speed.
|
| Precisely. But why should they travel at c? One possibility is that the
| vacuum is behaving as a medium, with some interaction which affects c,
| because it is filled with (quite a lot of) dark energy.
You bet it is if +,- \sqrt(\hbar*c) is vacuum charge. A system of coupled
oscillators that is all bound throughout the entire Universe.
FrediFizzx
Thomas Dent
Jul14-04, 11:49 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>\nOz <oz@farmeroz.port995.com> wrote\n\n> >> Naively c is determined by u_o and e_o of the vacuum. (...)\n> >\n> >The numerical values of these constants are a matter of conventional\n> >definition and have no physics content.\n>\n> I wasn\'t talking about their numerical values, but the value they have\n> (in whatever units you might choose).\n\nHow can they have values that are not numerical? The numerical values\nof u_0 and e_0 are simply a reflection of the choice of units for\nlength, time, electric charge etc. What other values can one talk\nabout?\n\n> >They have these values as a result of historical accidents (...)\n>\n> c = 1/sqrt(e_0 u_0),\n>\n> so their values are of some interest, whatever units you choose.\n\nWell, if you somehow define units which do not depend on the speed of\nlight then it is possible to measure (at least some combinations of)\ne_0 and u_0 and c, which is indeed what Maxwell pointed out. However,\nI can choose units such that c = 1 and e_0 = 1/4 pi and u_0 = 4 pi, or\neven e_0 = 1 and u_0 = 1, and I don\'t think these values are very\ninteresting.\n\n> >> (...) Now I presume that the current\n> >> assumption is that Em doesn\'t couple at all with dark energy, but what\n> >> if it did, just a teeny bit? I would imagine that any coupling would\n> >> slow a photon (from infinite speed)\n> >\n> >Photons don\'t travel at infinite speed.\n>\n> Precisely. But why should they travel at c?\n\nBecause the local structure of spacetime is (so far as we know)\ndescribed by the Lorentz group, for which c is the invariant speed,\nand massless particles in such a spacetime automatically travel at c.\nYou simply impose that particles should be in a representation of the\nLorentz group. Conversely, if they travel at some speed other than c,\ntheir mass^2 is different from zero.\n\nEven if there were no dark energy at all, you could still have a\nlocally Lorentz invariant spacetime in which massless particles travel\nat c (and not at infinite speed, which would require the Galilean\ninvariance).\n\n> One possibility is that the\n> vacuum is behaving as a medium, with some interaction which affects c,\n> because it is filled with (quite a lot of) dark energy.\n\nI don\'t know where the idea comes from that there is "quite a lot of"\ndark energy. The energy density of dark matter is of the order of 1\nhydrogen atom per cubic metre (the critical density). Plus, I don\'t\nknow what is meant by c being "affected". You can if you like think of\nspacetime itself as a "medium" in which light propagates. Because of\nthe local Lorentz symmetry of the "medium", light (being massless)\ngoes at c.\n\n> >Plus, one can couple\n> >electromagnetism to \'dark energy\' (in the form of a scalar field) in a\n> >Lorentz-invariant way that also respects gauge invariance, so that\n> >both c and the speed of photons are unaffected.\n>\n> Very probably, but is that the only way to couple it?\n\nWell, of course not, you can write down all sorts of nasty-looking\nterms which violate any symmetry you like. You will find out that most\nof these are ruled out by experiment, I think. Even if some of them\nsurvive, why do something complicated like explicitly breaking Lorentz\nsymmetry or gauge symmetry when there is no experimental reason for\nit?\n\n> > you can *always* define units such that c=1, or\n> > c=300,000, or any number you like, at all points in spacetime.\n>\n> I am well aware of that.\n\nThen take account of it!\n\n> >The horizon problem can be stated in terms of dimensionless numbers,\n> >namely, the size of the particle horizon at decoupling relative to the\n> >size of the currently observable Universe.\n>\n> That is surely model-dependent. A model that had c very much larger than\n> it is today then the horizon problem would vanish.\n\nYour second sentence is contradicted by your first sentence. "Varying\nc" on its own does not solve anything. It *completely* depends on on\nwhat else happens in the model, which you have not specified. What\nhappens to particle masses, energy density, etc. etc.? You need to say\nthat c changes *relative to some other speed*. I can redefine units\nright now so that the speed of light becomes 10,000 times smaller:\n\nI set c = 0.0001. There! I did it!\n\nNow, have any cosmological problems been solved? Of course not.\n\nSo you need to show explicitly that whatever you propose cannot be\nabsorbed by a redefinition of units. This is what "varying c" people\nhave not (to my knowledge) done.\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>Oz <oz@farmeroz.port995.com> wrote
> >> Naively c is determined by u_o and e_o of the vacuum. (...)
> >
> >The numerical values of these constants are a matter of conventional
> >definition and have no physics content.
>
> I wasn't talking about their numerical values, but the value they have
> (in whatever units you might choose).
How can they have values that are not numerical? The numerical values
of u_0 and e_0 are simply a reflection of the choice of units for
length, time, electric charge etc. What other values can one talk
about?
> >They have these values as a result of historical accidents (...)
>
> c = 1/\sqrt(e_0 u_0),
>
> so their values are of some interest, whatever units you choose.
Well, if you somehow define units which do not depend on the speed of
light then it is possible to measure (at least some combinations of)
e_0 and u_0 and c, which is indeed what Maxwell pointed out. However,
I can choose units such that c = 1 and e_0 = 1/4 \pi and u_0 = 4 \pi, or
even e_0 = 1 and u_0 = 1, and I don't think these values are very
interesting.
> >> (...) Now I presume that the current
> >> assumption is that Em doesn't couple at all with dark energy, but what
> >> if it did, just a teeny bit? I would imagine that any coupling would
> >> slow a photon (from infinite speed)
> >
> >Photons don't travel at infinite speed.
>
> Precisely. But why should they travel at c?
Because the local structure of spacetime is (so far as we know)
described by the Lorentz group, for which c is the invariant speed,
and massless particles in such a spacetime automatically travel at c.
You simply impose that particles should be in a representation of the
Lorentz group. Conversely, if they travel at some speed other than c,
their mass^2 is different from zero.
Even if there were no dark energy at all, you could still have a
locally Lorentz invariant spacetime in which massless particles travel
at c (and not at infinite speed, which would require the Galilean
invariance).
> One possibility is that the
> vacuum is behaving as a medium, with some interaction which affects c,
> because it is filled with (quite a lot of) dark energy.
I don't know where the idea comes from that there is "quite a lot of"
dark energy. The energy density of dark matter is of the order of 1
hydrogen atom per cubic metre (the critical density). Plus, I don't
know what is meant by c being "affected". You can if you like think of
spacetime itself as a "medium" in which light propagates. Because of
the local Lorentz symmetry of the "medium", light (being massless)
goes at c.
> >Plus, one can couple
> >electromagnetism to 'dark energy' (in the form of a scalar field) in a
> >Lorentz-invariant way that also respects gauge invariance, so that
> >both c and the speed of photons are unaffected.
>
> Very probably, but is that the only way to couple it?
Well, of course not, you can write down all sorts of nasty-looking
terms which violate any symmetry you like. You will find out that most
of these are ruled out by experiment, I think. Even if some of them
survive, why do something complicated like explicitly breaking Lorentz
symmetry or gauge symmetry when there is no experimental reason for
it?
> > you can *always* define units such that c=1, or
> > c=300,000, or any number you like, at all points in spacetime.
>
> I am well aware of that.
Then take account of it!
> >The horizon problem can be stated in terms of dimensionless numbers,
> >namely, the size of the particle horizon at decoupling relative to the
> >size of the currently observable Universe.
>
> That is surely model-dependent. A model that had c very much larger than
> it is today then the horizon problem would vanish.
Your second sentence is contradicted by your first sentence. "Varying
c" on its own does not solve anything. It *completely* depends on on
what else happens in the model, which you have not specified. What
happens to particle masses, energy density, etc. etc.? You need to say
that c changes *relative to some other speed*. I can redefine units
right now so that the speed of light becomes 10,000 times smaller:
I set c = .0001. There! I did it!
Now, have any cosmological problems been solved? Of course not.
So you need to show explicitly that whatever you propose cannot be
absorbed by a redefinition of units. This is what "varying c" people
have not (to my knowledge) done.
Oz
Jul15-04, 04:57 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>FrediFizzx <fredifizzx@hotmail.com> writes\n>\n>>Oz:\n>| c = 1/sqrt(e_0 u_0),\n>|\n>| so their values are of some interest, whatever units you choose.\n>\n>You are absolutely correct. This is a constant debate on the other groups\n>and no one that I have seen so far has resolved it other than myself.\n\nI trust you are aware of the crank index?\n\n>It\n>requires only one postulate to reconcile mu0 and eps0 with other systems of\n>units.\n\nThat\'s interesting, but whatever value in whatever units you chose,\nthere must be an equivalent value for these, even if you set both equal\nto one. [ am agreeing with you]\n\n>Make the replacements and we are left with,\n>\n>c = 1/sqrt(eps0*mu0) in SI. So it is easy to see that this expression is\n>simply "shorthand" for\n>\n>c = (lambda/2pi)(1/sqrt(Lvac*Cvac) which is always true in all systems of\n>units if our single postulate is correct and is the expression that\n>certainly would have much physical content.\n\nOK.\n\n>| Precisely. But why should they travel at c? One possibility is that the\n>| vacuum is behaving as a medium, with some interaction which affects c,\n>| because it is filled with (quite a lot of) dark energy.\n>\n>You bet it is if +,- sqrt(hbar*c) is vacuum charge.\n\nUnnggthh!\n\nHang on, what *is* \'vacuum charge\'?\nThere are far too many units for me to reliably sort this one out,\nbut are you saying that the vacuum could be modelled to look like a gas\nof charges?\n\nIf this is so then it would have to be a very special sort of gas. For\none thing it would have to look the same in all frames. That would put\nextreme conditions on its distribution that I am not sure can be made\nlorentz invariant. Of course one could invoke a magic wand and just make\nit so, but that\'s a bit <ahem> \'unscientific\'. Mind you I am pretty\nunclear about the properties of dark energy, I rather suspect these\nmight have been set up so as to be mathemagically lorentz invariant too.\n\n>A system of coupled\n>oscillators that is all bound throughout the entire Universe.\n\nEr, what, you mean like dark energy?\n\nUm, shouldn\'t one be able to calculate a figure for this?\n\n--\nOz\nThis post is worth absolutely nothing and is probably fallacious.\n\nBTOPENWORLD address about to cease. DEMON address no longer in use.\n>>Use oz@farmeroz.port995.com<<\nozacoohdb@despammed.com still functions.\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>FrediFizzx <fredifizzx@hotmail.com> writes
>
>>Oz:
>| c = 1/\sqrt(e_0 u_0),
>|
>| so their values are of some interest, whatever units you choose.
>
>You are absolutely correct. This is a constant debate on the other groups
>and no one that I have seen so far has resolved it other than myself.
I trust you are aware of the crank index?
>It
>requires only one postulate to reconcile mu0 and eps0 with other systems of
>units.
That's interesting, but whatever value in whatever units you chose,
there must be an equivalent value for these, even if you set both equal
to one. [ am agreeing with you]
>Make the replacements and we are left with,
>
>c = 1/\sqrt(eps0*mu0) in SI. So it is easy to see that this expression is
>simply "shorthand" for
>
>c = (\lambda/2pi)(1/\sqrt(Lvac*Cvac) which is always true in all systems of
>units if our single postulate is correct and is the expression that
>certainly would have much physical content.
OK.
>| Precisely. But why should they travel at c? One possibility is that the
>| vacuum is behaving as a medium, with some interaction which affects c,
>| because it is filled with (quite a lot of) dark energy.
>
>You bet it is if +,- \sqrt(\hbar*c) is vacuum charge.
Unnggthh!
Hang on, what *is* 'vacuum charge'?
There are far too many units for me to reliably sort this one out,
but are you saying that the vacuum could be modelled to look like a gas
of charges?
If this is so then it would have to be a very special sort of gas. For
one thing it would have to look the same in all frames. That would put
extreme conditions on its distribution that I am not sure can be made
lorentz invariant. Of course one could invoke a magic wand and just make
it so, but that's a bit <ahem> 'unscientific'. Mind you I am pretty
unclear about the properties of dark energy, I rather suspect these
might have been set up so as to be mathemagically lorentz invariant too.
>A system of coupled
>oscillators that is all bound throughout the entire Universe.
Er, what, you mean like dark energy?
Um, shouldn't one be able to calculate a figure for this?
--
Oz
This post is worth absolutely nothing and is probably fallacious.
BTOPENWORLD address about to cease. DEMON address no longer in use.
>>Use oz@farmeroz.port995.com<<
ozacoohdb@despammed.com still functions.
FrediFizzx
Jul15-04, 03:23 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"Oz" <oz@farmeroz.port995.com> wrote in message\nnews:KSJt8tJaTj9AFwCq@farmeroz.port995.com...\n| FrediFizzx <fredifizzx@hotmail.com> writes\n| >\n| >>Oz:\n| >| c = 1/sqrt(e_0 u_0),\n| >|\n| >| so their values are of some interest, whatever units you choose.\n| >\n| >You are absolutely correct. This is a constant debate on the other\ngroups\n| >and no one that I have seen so far has resolved it other than myself.\n|\n| I trust you are aware of the crank index?\n\nSure. ;-) But I assure you that my resolution of this debate is\nmathematically consistent throughout.\n\n| >It\n| >requires only one postulate to reconcile mu0 and eps0 with other systems\nof\n| >units.\n|\n| That\'s interesting, but whatever value in whatever units you chose,\n| there must be an equivalent value for these, even if you set both equal\n| to one. [ am agreeing with you]\n|\n| >Make the replacements and we are left with,\n| >\n| >c = 1/sqrt(eps0*mu0) in SI. So it is easy to see that this expression is\n| >simply "shorthand" for\n| >\n| >c = (lambda/2pi)(1/sqrt(Lvac*Cvac) which is always true in all systems of\n| >units if our single postulate is correct and is the expression that\n| >certainly would have much physical content.\n|\n| OK.\n\nTo add to this; both in cgs and hbar = c = 1 units the expression reduces\nto,\n\nc = sqrt(Cvac/Lvac). and Cvac = lambda/2pi in both systems.\n\n| >| Precisely. But why should they travel at c? One possibility is that the\n| >| vacuum is behaving as a medium, with some interaction which affects c,\n| >| because it is filled with (quite a lot of) dark energy.\n| >\n| >You bet it is if +,- sqrt(hbar*c) is vacuum charge.\n|\n| Unnggthh!\n|\n| Hang on, what *is* \'vacuum charge\'?\n\nSee Volovik\'s "The Universe in a Helium Droplet" for some really good\nconcepts about vacuum fermionic charge. I have my own ideas and concepts\nbut they are not fully worked out yet so go to the crank factor you mention\nabove until then. My concepts do seem to be "aligning" very well with\nVolovik\'s. However, I am still learning more and more about it everyday. I\nam really just a naive student with an idea that seems like it could be\ncorrect the more I learn about it. So at least I am staying "encouraged".\n\n| There are far too many units for me to reliably sort this one out,\n| but are you saying that the vacuum could be modelled to look like a gas\n| of charges?\n\nThis is somewhat cranky but I would think it would have to be more like a\nsupersolid. On average. We still have the quantum fluctuations. Yes, this\ndoes present problems with Lorentz invariance as the structure of the\nsupersolid might be a preferred frame. Unless this frame is the same\n"undefined frame" as that for a photon. IOW, the "bottom" produces the top.\n\n| If this is so then it would have to be a very special sort of gas. For\n| one thing it would have to look the same in all frames. That would put\n| extreme conditions on its distribution that I am not sure can be made\n| lorentz invariant. Of course one could invoke a magic wand and just make\n| it so, but that\'s a bit <ahem> \'unscientific\'. Mind you I am pretty\n| unclear about the properties of dark energy, I rather suspect these\n| might have been set up so as to be mathemagically lorentz invariant too.\n\nWe know that +,- sqrt(hbar*c) is invariant, so the question I think would\nbe; is or can hbar*c/(4D volume) be invariant?\n\n| >A system of coupled\n| >oscillators that is all bound throughout the entire Universe.\n|\n| Er, what, you mean like dark energy?\n\nYes.\n\n| Um, shouldn\'t one be able to calculate a figure for this?\n\nThe proposed geometrical configuration of the quantum vacuum gets to be very\ncomplex fast when trying to work it out. I think we might be missing some\nvacuum quantum "entities" in order to be able to do the calculations. If\nthe top quark is the last fermion, why? If the Higgs mass is around 250\nGeV/c^2, why? Seems like we are missing a fourth limit to the Universe in\naddition to hbar, c and G. My naive model is showing a lot of Goldstone\ntype bosons also.\n\nFrediFizzx\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>"Oz" <oz@farmeroz.port995.com> wrote in message
news:KSJt8tJaTj9AFwCq@farmeroz.port995.com...
| FrediFizzx <fredifizzx@hotmail.com> writes
| >
| >>Oz:
| >| c = 1/\sqrt(e_0 u_0),| >|| >| so their values are of some interest, whatever units you choose.
| >
| >You are absolutely correct. This is a constant debate on the other
groups
| >and no one that I have seen so far has resolved it other than myself.
|
| I trust you are aware of the crank index?
Sure. ;-) But I assure you that my resolution of this debate is
mathematically consistent throughout.
| >It
| >requires only one postulate to reconcile mu0 and eps0 with other systems
of
| >units.
|
| That's interesting, but whatever value in whatever units you chose,
| there must be an equivalent value for these, even if you set both equal
| to one. [ am agreeing with you]
|
| >Make the replacements and we are left with,
| >
| >c = 1/\sqrt(eps0*mu0) in SI. So it is easy to see that this expression is
| >simply "shorthand" for
| >
| >c = (\lambda/2pi)(1/\sqrt(Lvac*Cvac) which is always true in all systems of
| >units if our single postulate is correct and is the expression that
| >certainly would have much physical content.
|
| OK.
To add to this; both in cgs and \hbar = c = 1 units the expression reduces
to,
c = \sqrt(Cvac/Lvac). and Cvac = \lambda/2pi in both systems.
| >| Precisely. But why should they travel at c? One possibility is that the
| >| vacuum is behaving as a medium, with some interaction which affects c,
| >| because it is filled with (quite a lot of) dark energy.
| >
| >You bet it is if +,- \sqrt(\hbar*c) is vacuum charge.
|
| Unnggthh!
|
| Hang on, what *is* 'vacuum charge'?
See Volovik's "The Universe in a Helium Droplet" for some really good
concepts about vacuum fermionic charge. I have my own ideas and concepts
but they are not fully worked out yet so go to the crank factor you mention
above until then. My concepts do seem to be "aligning" very well with
Volovik's. However, I am still learning more and more about it everyday. I
am really just a naive student with an idea that seems like it could be
correct the more I learn about it. So at least I am staying "encouraged".
| There are far too many units for me to reliably sort this one out,
| but are you saying that the vacuum could be modelled to look like a gas
| of charges?
This is somewhat cranky but I would think it would have to be more like a
supersolid. On average. We still have the quantum fluctuations. Yes, this
does present problems with Lorentz invariance as the structure of the
supersolid might be a preferred frame. Unless this frame is the same
"undefined frame" as that for a photon. IOW, the "bottom" produces the top.
| If this is so then it would have to be a very special sort of gas. For
| one thing it would have to look the same in all frames. That would put
| extreme conditions on its distribution that I am not sure can be made
| lorentz invariant. Of course one could invoke a magic wand and just make
| it so, but that's a bit <ahem> 'unscientific'. Mind you I am pretty
| unclear about the properties of dark energy, I rather suspect these
| might have been set up so as to be mathemagically lorentz invariant too.
We know that +,- \sqrt(\hbar*c) is invariant, so the question I think would
be; is or can \hbar*c/(4D volume) be invariant?
| >A system of coupled
| >oscillators that is all bound throughout the entire Universe.
|
| Er, what, you mean like dark energy?
Yes.
| Um, shouldn't one be able to calculate a figure for this?
The proposed geometrical configuration of the quantum vacuum gets to be very
complex fast when trying to work it out. I think we might be missing some
vacuum quantum "entities" in order to be able to do the calculations. If
the top quark is the last fermion, why? If the Higgs mass is around 250
GeV/c^2, why? Seems like we are missing a fourth limit to the Universe in
addition to \hbar, c and G. My naive model is showing a lot of Goldstone
type bosons also.
FrediFizzx
Serenus Zeitblom
Jul16-04, 09:19 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\ncarlip@no-physics-spam.ucdavis.edu wrote in message\n> Maybe a little more...if some set of dimensionless quantities were found\n> to all change in concert, it might be helpful to define conventions in a\n> way that let us describe the changes as a single change of a dimensionful\n> quantity. For example, if we found that alpha ``varied inversely with c\'\'\n> *and* that rest energies of elementary particles all ``varied as c^2\'\'\n> *and* that the dimensionless quantity Gm^2/hc (where m is, say, the electron\n> mass) ``varied inversely with c,\'\' then the abbreviation ``c is changing\'\'\n> would be genuinely useful, as a mnemonic if nothing else.\n\nExcellent! And in a related vein:\n\n\nAt present the speed of light\nis N times the maximum speed of my trusty old car.\nOne day I get up in the morning and find that this\ndimensionless ratio has halved. I declare that the speed\nof light has halved. According to the real die-hards, who claim that\nit is *meaningless* to speak of a varying speed of light,\nthis scenario is *impossible*, indeed unthinkable. I assume\nthat by this they mean that "changing" the speed\nof light will produce changes in the fuel in my car and its\nstructure, in just precisely the right way that the two effects\ncancel. That is, halving the speed of light halves\nthe speed of my car.\n\nThis may be true. My question is: how do they\n*know* that it is true? Could it be that we simply *don\'t know*\nwhether a "changing" speed of light makes sense?\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>carlip@no-physics-spam.ucdavis.edu wrote in message
> Maybe a little more...if some set of dimensionless quantities were found
> to all change in concert, it might be helpful to define conventions in a
> way that let us describe the changes as a single change of a dimensionful
> quantity. For example, if we found that \alpha ``varied inversely with c''
> *and* that rest energies of elementary particles all ``varied as c^2''
> *and* that the dimensionless quantity Gm^2/hc (where m is, say, the electron
> mass) ``varied inversely with c,'' then the abbreviation ``c is changing''
> would be genuinely useful, as a mnemonic if nothing else.
Excellent! And in a related vein:
At present the speed of light
is N times the maximum speed of my trusty old car.
One day I get up in the morning and find that this
dimensionless ratio has halved. I declare that the speed
of light has halved. According to the real die-hards, who claim that
it is *meaningless* to speak of a varying speed of light,
this scenario is *impossible*, indeed unthinkable. I assume
that by this they mean that "changing" the speed
of light will produce changes in the fuel in my car and its
structure, in just precisely the right way that the two effects
cancel. That is, halving the speed of light halves
the speed of my car.
This may be true. My question is: how do they
*know* that it is true? Could it be that we simply *don't know*
whether a "changing" speed of light makes sense?
Creighton Hogg
Jul16-04, 09:19 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\nOn 15 Jul 2004, FrediFizzx wrote:\n\n>\n>\n> "Oz" <oz@farmeroz.port995.com> wrote in message\n> news:KSJt8tJaTj9AFwCq@farmeroz.port995.com...\n>\n> | Um, shouldn\'t one be able to calculate a figure for this?\n>\n> The proposed geometrical configuration of the quantum vacuum gets to be very\n> complex fast when trying to work it out. I think we might be missing some\n> vacuum quantum "entities" in order to be able to do the calculations. If\n> the top quark is the last fermion, why? If the Higgs mass is around 250\n> GeV/c^2, why? Seems like we are missing a fourth limit to the Universe in\n> addition to hbar, c and G. My naive model is showing a lot of Goldstone\n> type bosons also.\n\nWhere are you getting the Goldstone bosons? What\'s the symmetry that\nyou\'re spontaneously breaking and what is it being broken down to?\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 15 Jul 2004, FrediFizzx wrote:
>
>
> "Oz" <oz@farmeroz.port995.com> wrote in message
> news:KSJt8tJaTj9AFwCq@farmeroz.port995.com...
>
> | Um, shouldn't one be able to calculate a figure for this?
>
> The proposed geometrical configuration of the quantum vacuum gets to be very
> complex fast when trying to work it out. I think we might be missing some
> vacuum quantum "entities" in order to be able to do the calculations. If
> the top quark is the last fermion, why? If the Higgs mass is around 250
> GeV/c^2, why? Seems like we are missing a fourth limit to the Universe in
> addition to \hbar, c and G. My naive model is showing a lot of Goldstone
> type bosons also.
Where are you getting the Goldstone bosons? What's the symmetry that
you're spontaneously breaking and what is it being broken down to?
greywolf42
Jul19-04, 04:09 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\nSerenus Zeitblom <serenuszeitblomphd@yahoo.com> wrote in message\nnews:c7fd6c7a.0407152147.6f26e5da@posting.google.com...\n>\n>\n> carlip@no-physics-spam.ucdavis.edu wrote in message\n> > Maybe a little more...if some set of dimensionless quantities were found\n> > to all change in concert, it might be helpful to define conventions in a\n> > way that let us describe the changes as a single change of a\ndimensionful\n> > quantity. For example, if we found that alpha ``varied inversely with\nc\'\'\n> > *and* that rest energies of elementary particles all ``varied as c^2\'\'\n> > *and* that the dimensionless quantity Gm^2/hc (where m is, say, the\nelectron\n> > mass) ``varied inversely with c,\'\' then the abbreviation ``c is\nchanging\'\'\n> > would be genuinely useful, as a mnemonic if nothing else.\n>\n> Excellent! And in a related vein:\n>\n>\n> At present the speed of light\n> is N times the maximum speed of my trusty old car.\n> One day I get up in the morning and find that this\n> dimensionless ratio has halved. I declare that the speed\n> of light has halved. According to the real die-hards, who claim that\n> it is *meaningless* to speak of a varying speed of light,\n> this scenario is *impossible*, indeed unthinkable. I assume\n> that by this they mean that "changing" the speed\n> of light will produce changes in the fuel in my car and its\n> structure, in just precisely the right way that the two effects\n> cancel. That is, halving the speed of light halves\n> the speed of my car.\n>\n> This may be true. My question is: how do they\n> *know* that it is true? Could it be that we simply *don\'t know*\n> whether a "changing" speed of light makes sense?\n\nIt is \'known\' by the simple redefinition of simultenaity within special\nrelativity, (Einstein, 1905). The requirement of e-synching makes the\nlight-speed measurement attempt always provide the \'accepted\' value.\n\nAs Tom Roberts nicely put it:\n\n"If one uses light to synchronize clocks then it is quite clear that\nmeasuring the one-way speed of light in an inertial frame to be c is is a\ntautology (because the method of synchronization essentially puts it in by\nhand)."\n\nhttp://www.google.com/groups?selm=10e0s80c4bbg949%40corp.supernews.com\n\n--\ngreywolf42\nubi dubium ibi libertas\n{remove planet for return e-mail}\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>Serenus Zeitblom <serenuszeitblomphd@yahoo.com> wrote in message
news:c7fd6c7a.0407152147.6f26e5da@posting.google.com...
>
>
> carlip@no-physics-spam.ucdavis.edu wrote in message
> > Maybe a little more...if some set of dimensionless quantities were found
> > to all change in concert, it might be helpful to define conventions in a
> > way that let us describe the changes as a single change of a
dimensionful
> > quantity. For example, if we found that \alpha ``varied inversely with
c''
> > *and* that rest energies of elementary particles all ``varied as c^2''
> > *and* that the dimensionless quantity Gm^2/hc (where m is, say, the
electron
> > mass) ``varied inversely with c,'' then the abbreviation ``c is
changing''
> > would be genuinely useful, as a mnemonic if nothing else.
>
> Excellent! And in a related vein:
>
>
> At present the speed of light
> is N times the maximum speed of my trusty old car.
> One day I get up in the morning and find that this
> dimensionless ratio has halved. I declare that the speed
> of light has halved. According to the real die-hards, who claim that
> it is *meaningless* to speak of a varying speed of light,
> this scenario is *impossible*, indeed unthinkable. I assume
> that by this they mean that "changing" the speed
> of light will produce changes in the fuel in my car and its
> structure, in just precisely the right way that the two effects
> cancel. That is, halving the speed of light halves
> the speed of my car.
>
> This may be true. My question is: how do they
> *know* that it is true? Could it be that we simply *don't know*
> whether a "changing" speed of light makes sense?
It is 'known' by the simple redefinition of simultenaity within special
relativity, (Einstein, 1905). The requirement of e-synching makes the
light-speed measurement attempt always provide the 'accepted' value.
As Tom Roberts nicely put it:
"If one uses light to synchronize clocks then it is quite clear that
measuring the one-way speed of light in an inertial frame to be c is is a
tautology (because the method of synchronization essentially puts it in by
hand)."
--
greywolf42
ubi dubium ibi libertas
{remove planet for return e-mail}
Thomas Dent
Jul22-04, 01:07 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\n\nserenuszeitblomphd@yahoo.com (Serenus Zeitblom) wrote\n\n> carlip@no-physics-spam.ucdavis.edu wrote in message\n> > Maybe a little more...if some set of dimensionless quantities were found\n> > to all change in concert, it might be helpful to define conventions in a\n> > way that let us describe the changes as a single change of a dimensionful\n> > quantity. For example, if we found that alpha ``varied inversely with c\'\'\n> > *and* that rest energies of elementary particles all ``varied as c^2\'\'\n> > *and* that the dimensionless quantity Gm^2/hc (where m is, say, the electron\n> > mass) ``varied inversely with c,\'\' then the abbreviation ``c is changing\'\'\n> > would be genuinely useful, as a mnemonic if nothing else.\n>\n\nThe likelihood that any fundamental theory would give such a neat set\nof exact power laws is probably extremely close to zero. And when you\ndon\'t know the fundamental theory, you can\'t make assumptions about\nhow it might behave when considering observables. The most general\nbehaviour cannot be summarized as "varying c". For example, if nuclear\nbinding energy changes relative to the electron mass. You can write\nnuclear energy as E, or as m_N c^2 where N is the nucleus. So how does\nit "vary"? If you write the electron mass as m_e c^2, you cannot carry\non if m_N c^2 changes relative to m_e c^2. And suppose the muon mass\nchanges with respect to the electron mass. "Varying c" is really a\nvery restrictive formulation, in addition to being ambiguous, since it\ncannot accommodate any variation in ratios of two quantities of the\nsame dimension.\n\n\n> At present the speed of light is N times the maximum speed of\n> my trusty old car.\n> One day I get up in the morning and find that this\n> dimensionless ratio has halved. I declare that the speed\n> of light has halved. According to the real die-hards, who claim that\n> it is *meaningless* to speak of a varying speed of light,\n> this scenario is *impossible*,\n\nNo. The ratio of your car\'s speed to that of light can meaningfully\nvary; you can declare anything you like to declare; nothing in the\nscenario is "impossible", according to anyone, die-hard or -soft. If\nyou want to say things that make no sense, no-one can stop you.\n\n> indeed unthinkable.\n\nIt is perfectly thinkable that the ratio of your car\'s speed to that\nof light will change, and also that you will make some curious and\nnonsensical statement about it, in a situation where a normal person\nwould visit the garage.\n\n\n> I assume that by this they mean\n\nYour argument becomes (more) confused here. Not content with putting\nwords in other people\'s mouths, you are not clear about what words you\nare talking about. What is "this"?\n\n> that "changing" the speed\n> of light will produce changes in the fuel in my car and its\n> structure, in just precisely the right way that the two effects\n> cancel. That is, halving the speed of light halves\n> the speed of my car.\n\nI have no idea what this paragraph means. If the speed of your car\nchanges relative to c, there is no question of "cancellation", since\nthere is a real physical effect. (Such an effect may well be easily\nexplicable by some variation in the structure or fuel of the car, such\nas the failure of half of the spark-plugs, but this can always be\nexpressed in terms of dimensionless variables.)\n\n\n> This may be true. My question is: how do they\n> *know* that it is true? Could it be that we simply *don\'t know*\n> whether a "changing" speed of light makes sense?\n\nBy simple application of logic and the well-known freedom to transform\nthe system of units into one where c is constant.\n\nNow, knowledge is justified true belief, so if you don\'t believe that\n"varying c" is (on its own) a scientifically meaningless formulation,\nyou don\'t know it. But I do!\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>serenuszeitblomphd@yahoo.com (Serenus Zeitblom) wrote
> carlip@no-physics-spam.ucdavis.edu wrote in message
> > Maybe a little more...if some set of dimensionless quantities were found
> > to all change in concert, it might be helpful to define conventions in a
> > way that let us describe the changes as a single change of a dimensionful
> > quantity. For example, if we found that \alpha ``varied inversely with c''
> > *and* that rest energies of elementary particles all ``varied as c^2''
> > *and* that the dimensionless quantity Gm^2/hc (where m is, say, the electron
> > mass) ``varied inversely with c,'' then the abbreviation ``c is changing''
> > would be genuinely useful, as a mnemonic if nothing else.
>
The likelihood that any fundamental theory would give such a neat set
of exact power laws is probably extremely close to zero. And when you
don't know the fundamental theory, you can't make assumptions about
how it might behave when considering observables. The most general
behaviour cannot be summarized as "varying c". For example, if nuclear
binding energy changes relative to the electron mass. You can write
nuclear energy as E, or as m_N c^2 where N is the nucleus. So how does
it "vary"? If you write the electron mass as m_e c^2, you cannot carry
on if m_N c^2 changes relative to m_e c^2. And suppose the muon mass
changes with respect to the electron mass. "Varying c" is really a
very restrictive formulation, in addition to being ambiguous, since it
cannot accommodate any variation in ratios of two quantities of the
same dimension.
> At present the speed of light is N times the maximum speed of
> my trusty old car.
> One day I get up in the morning and find that this
> dimensionless ratio has halved. I declare that the speed
> of light has halved. According to the real die-hards, who claim that
> it is *meaningless* to speak of a varying speed of light,
> this scenario is *impossible*,
No. The ratio of your car's speed to that of light can meaningfully
vary; you can declare anything you like to declare; nothing in the
scenario is "impossible", according to anyone, die-hard or -soft. If
you want to say things that make no sense, no-one can stop you.