View Full Version : Discussion with Nima Arkani-Hamed on SPS
Lubos Motl
Apr19-04, 01:48 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>Hello!\n\nProf. Nima Arkani-Hamed has kindly agreed to be the first person to be\n"interviewed" on SPS.\n\nPlease use this week to ask him questions, and he will answer them\nsometime next week. The optimal way to ask the question is to reply *this*\nmessage. Please don\'t copy the body of this message. Thank you!\n\nOK, so let me start.\n\n# Prof. Arkani-Hamed: imagine that you are a bookmaker, and you task is to\nestimate the probability of the following events (of course, if you\nwrite a more detailed answer, it will be appreciated):\n\n1. The LHC will find convincing evidence of supersymmetry by 2010.\n2. A collider or another experiment will see evidence of large extra\ndimensions or warped extra dimensions by 2015.\n3. An investigation of CMB nongaussianities will support the idea of the\nghost condensate by 2015.\n4. String theorists will only be a small group in the math departments\nin 2015.\n5. The cultural barrier between the phenomenologists and the string\ntheorists will significantly diminish by 2010.\n6. It will be possible for string theory to give a successful and\ncompletely new prediction about physics, even without knowing anything\nabout the "right vacuum" within the landscape.\n7. A nontrivial relation between the parameters of the Standard Model\nwill be calculated theoretically by 2030.\n\nAll the best\nLubos\n_____________________________________ _________________________________________\nE-mail: lumo@matfyz.cz fax: +1-617/496-0110 Web: http://lumo.matfyz.cz/\neFax: +1-801/454-1858 work: +1-617/496-8199 home: +1-617/868-4487 (call)\n^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>Hello!
Prof. Nima Arkani-Hamed has kindly agreed to be the first person to be
"interviewed" on SPS.
Please use this week to ask him questions, and he will answer them
sometime next week. The optimal way to ask the question is to reply *this*
message. Please don't copy the body of this message. Thank you!
OK, so let me start.
# Prof. Arkani-Hamed: imagine that you are a bookmaker, and you task is to
estimate the probability of the following events (of course, if you
write a more detailed answer, it will be appreciated):
1. The LHC will find convincing evidence of supersymmetry by 2010.
2. A collider or another experiment will see evidence of large extra
dimensions or warped extra dimensions by 2015.
3. An investigation of CMB nongaussianities will support the idea of the
ghost condensate by 2015.
4. String theorists will only be a small group in the math departments
in 2015.
5. The cultural barrier between the phenomenologists and the string
theorists will significantly diminish by 2010.
6. It will be possible for string theory to give a successful and
completely new prediction about physics, even without knowing anything
about the "right vacuum" within the landscape.
7. A nontrivial relation between the parameters of the Standard Model
will be calculated theoretically by 2030.
All the best
Lubos
__{_______________________________________________ _____________________________}
E-mail: lumo@matfyz.cz fax: +1-617/496-0110 Web: http://lumo.matfyz.cz/
eFax: +1-801/454-1858 work: +1-617/496-8199 home: +1-617/868-4487 (call)
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Lubos Motl
Apr19-04, 04:54 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>I forgot to say that Nima Arkani-Hamed, a full professor at Harvard,\n\nhttp://schwinger.harvard.edu/~motl/PeoplePixWeb/\n\nis a leading particle phenomenologist, a co-author of the popular and\nhighly-cited stringy-inspired scenario in which our Universe has large\nextra dimensions (with Gia Dvali and Savas Dimopoulos), but also a\nco-author of deconstruction; discrete gravitational dimensions and little\nHiggs; ghost condensation; various models of inflation, symmetry\nbreaking, neutrino masses and many others. See\n\nhttp://www.slac.stanford.edu/spires/find/hep/www?rawcmd=find+a+arkani-hamed\n___________________________________________ ___________________________________\nE-mail: lumo@matfyz.cz fax: +1-617/496-0110 Web: http://lumo.matfyz.cz/\neFax: +1-801/454-1858 work: +1-617/496-8199 home: +1-617/868-4487 (call)\n^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>I forgot to say that Nima Arkani-Hamed, a full professor at Harvard,
http://schwinger.harvard.edu/~motl/PeoplePixWeb/
is a leading particle phenomenologist, a co-author of the popular and
highly-cited stringy-inspired scenario in which our Universe has large
extra dimensions (with Gia Dvali and Savas Dimopoulos), but also a
co-author of deconstruction; discrete gravitational dimensions and little
Higgs; ghost condensation; various models of inflation, symmetry
breaking, neutrino masses and many others. See
http://www.slac.stanford.edu/spires/find/hep/www?rawcmd=find+a+arkani-hamed
__{_______________________________________________ _____________________________}
E-mail: lumo@matfyz.cz fax: +1-617/496-0110 Web: http://lumo.matfyz.cz/
eFax: +1-801/454-1858 work: +1-617/496-8199 home: +1-617/868-4487 (call)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Moorglade
Apr20-04, 06:42 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>[Prof. Arkani-Hamed,]\n\nI think a number of your papers are quite interesting, but I would\nlike to probe into the proposed Cosmic?.. Bose-Einstein-Condensate?\n\n1)Is there any chance of this being a Quark Condensate?..sort of like\na Promordial Fluid that all Matter evolves from?..and still be\nghost-condensate to our detectors.\n\n2)In the accelerated Expansion currently being detected, the expansion\nwould tear the fabric of space apart (under certain conditions), how\nwould a string worldline be continueous along the fabric of space, say\nfrom our Galaxy to an area of immense expansion, and remain a bonafide\nunbroken worldline?\n\nMany thanks for taken some of your valuable time to read, and\nhopefully shed a little light on the nature of things, Paul Valletta\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>[Prof. Arkani-Hamed,]
I think a number of your papers are quite interesting, but I would
like to probe into the proposed Cosmic?.. Bose-Einstein-Condensate?
1)Is there any chance of this being a Quark Condensate?..sort of like
a Promordial Fluid that all Matter evolves from?..and still be
ghost-condensate to our detectors.
2)In the accelerated Expansion currently being detected, the expansion
would tear the fabric of space apart (under certain conditions), how
would a string worldline be continueous along the fabric of space, say
from our Galaxy to an area of immense expansion, and remain a bonafide
unbroken worldline?
Many thanks for taken some of your valuable time to read, and
hopefully shed a little light on the nature of things, Paul Valletta
<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>Prof. Nima Arkani-Hamed,\n\nWhen one endeavors through life in the areas of interest I have found\nyou engaged in, there are certain fundamentals laws aside from the\nknown proofs, that become the basis of ones perceptions.\n\nIn all fairness, I would show you this link:\n\nhttp://www.edge.org/q2004/index.html#randall\n\n.....to help you see what I am saying and then ask, what Law might\nbecome Prof. Nima Arkani-Hamed\'s Law?\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>Prof. Nima Arkani-Hamed,
When one endeavors through life in the areas of interest I have found
you engaged in, there are certain fundamentals laws aside from the
known proofs, that become the basis of ones perceptions.
In all fairness, I would show you this link:
http://www.edge.org/q2004/index.html#randall
.....to help you see what I am saying and then ask, what Law might
become Prof. Nima Arkani-Hamed's Law?
Urs Schreiber
Apr22-04, 08:01 AM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>On Mon, 19 Apr 2004, Lubos Motl wrote:\n\n> Prof. Nima Arkani-Hamed has kindly agreed to be the first person to be\n> "interviewed" on SPS.\n>\n> Please use this week to ask him questions, and he will answer them\n> sometime next week. The optimal way to ask the question is to reply *this*\n> message. Please don\'t copy the body of this message. Thank you!\n\nI\'d like to understand roughly what the concepts of "Ghost Inflation" are.\n\nWhat is the nature of the ghost field appearing here. Is ghost\ninflation dealing with BRST ghosts (I guess not) or with \'phantom matter\'?\n\nWhere would such a ghost field come from, physically? What is the\nrelation to string theory?\n\n\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>On Mon, 19 Apr 2004, Lubos Motl wrote:
> Prof. Nima Arkani-Hamed has kindly agreed to be the first person to be
> "interviewed" on SPS.
>
> Please use this week to ask him questions, and he will answer them
> sometime next week. The optimal way to ask the question is to reply *this*
> message. Please don't copy the body of this message. Thank you!
I'd like to understand roughly what the concepts of "Ghost Inflation" are.
What is the nature of the ghost field appearing here. Is ghost
inflation dealing with BRST ghosts (I guess not) or with 'phantom matter'?
Where would such a ghost field come from, physically? What is the
relation to string theory?
jgraber
Apr23-04, 10:45 PM
First, I would like to thank Nima Arkani-Hamed for sharing his opinions and spending his valuable time explaining string theory to us.
Here are my questions. Feel free to edit them to make more sense or be more generally applicable:
String Theory and Axions At the American Physical Society meeting in Philadelphia not too long ago, Ed Witten said “Supersymmetry is compatible with the axion, but String Theory requires it”
Do you agree? How deep must we look for the axion before we begin to think that supersymmetry is discredited if we fail to find the axion?
Black holes and Horizons. Classical GR black holes have event horizons and singularities. It seems to be generally accepted that string theory black holes do not have singularities.
What about Horizons? Mathur at least seems to say that individual string configurations do not have true event horizons. What is your take on horizons and string theory based black holes?
Black holes and metrics. It seems to be accepted that string theory leads either to a scalar tensor theory of gravitation or higher derivative terms or perhaps both. Which (or what else) is your preference. Are these extra terms likely to be big enough to be measured by Ligo or Lisa.?
Black holes and the Schwarzschild metric. Until recently one heard that String theory calculations were based on extreme or near extreme black holes, not Schwarzschild ones.
Now recently at least two string representations of Schwarzschild are published. I am trying to read these papers, but it is not clear to me how close the String “Schwarzschild” representation is to the classical GR one.
Black hole Information Loss: Well known issue, your comments?
Finally, an issue that has already been beaten almost to death on s.p.r: the Landscape and all that:
how predictive is String Theory? Or is it like Cartesian Geometry: A very useful tool which predicts nothing?
Once again, TIA to N.A-H for sharing his wisdom with us. Jim Graber
Lubos Motl
Apr26-04, 08:12 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>The deadline for the questions for Nima Arkani-Hamed is tonight. Harry up.\nHe might answer them sometime tomorrow, or a couple of days later.\n\nAll the best\nLubos\n_____________________________________ _________________________________________\nE-mail: lumo@matfyz.cz fax: +1-617/496-0110 Web: http://lumo.matfyz.cz/\neFax: +1-801/454-1858 work: +1-617/496-8199 home: +1-617/868-4487 (call)\n^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>The deadline for the questions for Nima Arkani-Hamed is tonight. Harry up.
He might answer them sometime tomorrow, or a couple of days later.
All the best
Lubos
__{_______________________________________________ _____________________________}
E-mail: lumo@matfyz.cz fax: +1-617/496-0110 Web: http://lumo.matfyz.cz/
eFax: +1-801/454-1858 work: +1-617/496-8199 home: +1-617/868-4487 (call)
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Mikael Djurfeldt
Apr26-04, 05:47 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>Even though I\'m eagerly trying to learn string theory, I should begin by\nwarning you that I\'m still a total novice.\n\nI\'ve noticed that there has been questions regarding *specific*\npredictions in the string theory field. There has also been suggested\nthe very generic (but good) question of how predictive string theory is.\n\nI\'d like to know any kind of answers to a kind of in-between question:\n\nWhich of currently planned experiments could give useful constraints for\nstring theory, guiding it in some direction, or perhaps pruning it?\n\nThe trivial answer is of course that many, many, experiments have the\npotential to have later implications for the theory, depending on\ntheoretical developments, but I\'d like to know if there are some\nparticularly interesting experiments on the horizon, and interesting\nways to use the theory to make constraints out of the results.\n\nThanks,\nM\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>Even though I'm eagerly trying to learn string theory, I should begin by
warning you that I'm still a total novice.
I've noticed that there has been questions regarding *specific*
predictions in the string theory field. There has also been suggested
the very generic (but good) question of how predictive string theory is.
I'd like to know any kind of answers to a kind of in-between question:
Which of currently planned experiments could give useful constraints for
string theory, guiding it in some direction, or perhaps pruning it?
The trivial answer is of course that many, many, experiments have the
potential to have later implications for the theory, depending on
theoretical developments, but I'd like to know if there are some
particularly interesting experiments on the horizon, and interesting
ways to use the theory to make constraints out of the results.
Thanks,
M
Dear Professor Nima Arkani-Hamed,
Thank you for participating in this news group.
I am also a newcomer to string theory, but I have a decent understanding of the underlying elementary differential geometry. I've been struggling with some basic motivations before letting myself get too deeply into the formalism.
For example, I've been trying to teach myself something about bosonic string theory and I am already stuck on some philosphical issues. In particular, I think it is pretty neat how the Nambu-Goto action provides for the equations of motion of a classical string. I also can understand why the Nambu-Goto action may be difficult to quantize directly and why this motivates the use of the Polyakov action. Here is where I get stuck. Is there something that is somehow fundamental about the Polyakov action? Do people spend much time considering its "meaning"? This might sound like a silly question, but it is the kind of thing I get hung up on.
When I first asked myself this question, i.e. "Why Polyakov?", I started trying to come up with alternatives. It didn't take me long to draw an analogy between (part of) the Polyakov action and something else I had seen called BF-Yang-Mills theory. I discussed this at length in another thread here so I won't bore you with the details. The point is, there seems to be many ways to construct Polyakov-like actions that reduce to Nambu-Goto classically.
Why is Polyakov special?
Lubos has made a strong case that it is special because it is conformally invariant. However, I can't help but feel that this connection between string theory and conformal field theory seems somewhat artificial. To me, the fact that the Polyakov action is conformally invariant allowing for the use of the powerful methods of CFT is not something the doctor ordered. Why should nature be like that?
I know that Maxwell's equations are conformally invariant, which seems highly suggestive. But general relativity is not conformally invariant. The connection between string theory and general relativity is still hazy to me.
If no one feels like addressing my more philosophical questions, how about a more concrete one? :)
Right now, I've heard that spin-2 particles in string theory must inevitably lead to general relativity. In outline form, it looks to me like
spin-2 --> general relativity.
Without getting too much into details, would it be possible to give a quick outline with a little more bullets how the road from string theory to general relativity plays out?
Best wishes and thanks again,
Eric
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