Urs Schreiber
Jul19-04, 04:51 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>Today I have heard a very intersting talk by Gerard t\'Hooft and I have taken\nthe time to write a little report about it\n(http://golem.ph.utexas.edu/string/archives/000400.html):\n\n\nToday Prof. Gerard t\'Hooft gave a talk at University Duisburg-Essen on Black\nHoles in Elementary Particle Physics. Maybe due to the media hype about\nHawking\'s announcement of his new idea about the black hole information\n\'paradox\', t\'Hooft decided to throw his TV set away, and not only his but\nlots of them, in fact enough that they would form a spherical shell\ncollapsing to a black hole.\n\nUsing this picture to emphasize the process in which \'known physics\',\nrepresented by well understood TV sets, passes the horizon and hence a\nborder beyond which all kinds of apparent paradoxes lurk, he talked about\nsome standard facts of high energy physics and then briefly mentioned some\nof his intriguing observations and speculations concerning physics of the\nstretched horizon, the collision of infalling particles with outgoing\nHawking radiation as well as the possibility of a deterministic hidden\nvariable model of quantum theory, which, as he says, he develops as a hobby.\n\nAfter the talk we went to a nearby Biergarten and I had the chance to ask\nsome more detailed questions.\n\nI have to admit that I haven\'t read any of t\'Hooft\'s papers concerning the\nabove mentioned issues, so I learned for the first time about his\ncalculation which indicates that, somehow, the scattering of Hawking\nradiation at infalling matter (one form - even though not the only one\nrelevant I\'d think - of back reaction which is not usually taken into\naccount in related discussions, but which certainly should be) has some\nsurprising resemblance to string scattering amplitudes - well, except for\nthe curious fact that the analogy requires a imaginary string tension.\n\nVery interesting are also his ideas about the foundations of quantum\nmechanics, holography and string theory.\n\nHe says that he expects that there is a deterministic and local (yes, local)\nhidden variable theory behind it all, which would be apparent if only we\nknew the correct degrees of freedom of nature. Since we don\'t, we only see a\nstatistical average of this deterministic process, and this translates in a\nnon-local way to the quantum mechanical wavefunction, roughly.\n\nTo me this philosophy sounded a lot like approaches by Lee Smolin to get\nquantum mechanical dynamics from the classical statistics of ensembles of\nlarge matrices that encode the deterministic interrelation of all particles\n(well, probably, if at all, of all D0 branes) in the universe. But when I\nasked Prof. t\'Hooft about this he said he wasn\'t fully familiar with\nSmolin\'s approach.\n\nAnyway, t\'Hooft\'s idea now is that the full deterministic theory has no\ninformation loss, but that on the \'coarse grained\' level of familiar quantum\ntheory information is lost all the time in virtual black holes that are\nabundant in vacuum fluctuations. The point is that, he says, this way\ninformation about degrees of freedom in the bulk diasappears. The only\ninformation left is that at some holographic boundary! This way, I think, he\ntries to give a \'dynamical\' explanation of holography.\n\nI asked if and how he sees string theory fit into this picture, and he said\nthat he thinks that since in string theory essentially only the S-matrix is\na well defined observable, and since this means that only on-shell\ninformation at the \'boundary\' is available while local physics in the bulk\nis fundamentally out of reach of present day string theory, this fits in\nperfectly with the above picture, where ordinary quantum mechanics is kind\nof an \'effective theory\' on the boundary while the true bulk theory is a\ndeterministic hidden-variable thingy.\n\nI have to say that when first confronted with speculations like this some\nalarm bells go off - but then I realize that when t\'Hooft discovered\nholography a while back this idea must have sounded - before Maldacena came\nalong and gave an explicit relization - just as weird, and now it is widely\naccepted and even standard lore.\n\nSo maybe in this little chat over a glass of beer I was actually shown a\nglimpse of the big physics picture of the future, without my poor mind being\nable to fully grasp it.\n\nOn the other hand, when asked what he thinks about how his ideas about\nstring/gauge duality and holography have come to life in string theory, he\nanswered, humbly and jokingly, that he almost fails to recognize his\noriginal ideas.\n\nThere was much more discussion, but that\'s all I am going to report here. It\nwas a big pleasure to talk to such an outstanding person as t\'Hooft is, and\nI have some things to think about now. First of all, I\'ll toss away my TV\nset...\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>Today I have heard a very intersting talk by Gerard t'Hooft and I have taken
the time to write a little report about it
(http://golem.ph.utexas.edu/string/archives/000400.html):
Today Prof. Gerard t'Hooft gave a talk at University Duisburg-Essen on Black
Holes in Elementary Particle Physics. Maybe due to the media hype about
Hawking's announcement of his new idea about the black hole information
'paradox', t'Hooft decided to throw his TV set away, and not only his but
lots of them, in fact enough that they would form a spherical shell
collapsing to a black hole.
Using this picture to emphasize the process in which 'known physics',
represented by well understood TV sets, passes the horizon and hence a
border beyond which all kinds of apparent paradoxes lurk, he talked about
some standard facts of high energy physics and then briefly mentioned some
of his intriguing observations and speculations concerning physics of the
stretched horizon, the collision of infalling particles with outgoing
Hawking radiation as well as the possibility of a deterministic hidden
variable model of quantum theory, which, as he says, he develops as a hobby.
After the talk we went to a nearby Biergarten and I had the chance to ask
some more detailed questions.
I have to admit that I haven't read any of t'Hooft's papers concerning the
above mentioned issues, so I learned for the first time about his
calculation which indicates that, somehow, the scattering of Hawking
radiation at infalling matter (one form - even though not the only one
relevant I'd think - of back reaction which is not usually taken into
account in related discussions, but which certainly should be) has some
surprising resemblance to string scattering amplitudes - well, except for
the curious fact that the analogy requires a imaginary string tension.
Very interesting are also his ideas about the foundations of quantum
mechanics, holography and string theory.
He says that he expects that there is a deterministic and local (yes, local)
hidden variable theory behind it all, which would be apparent if only we
knew the correct degrees of freedom of nature. Since we don't, we only see a
statistical average of this deterministic process, and this translates in a
non-local way to the quantum mechanical wavefunction, roughly.
To me this philosophy sounded a lot like approaches by Lee Smolin to get
quantum mechanical dynamics from the classical statistics of ensembles of
large matrices that encode the deterministic interrelation of all particles
(well, probably, if at all, of all D0 branes) in the universe. But when I
asked Prof. t'Hooft about this he said he wasn't fully familiar with
Smolin's approach.
Anyway, t'Hooft's idea now is that the full deterministic theory has no
information loss, but that on the 'coarse grained' level of familiar quantum
theory information is lost all the time in virtual black holes that are
abundant in vacuum fluctuations. The point is that, he says, this way
information about degrees of freedom in the bulk diasappears. The only
information left is that at some holographic boundary! This way, I think, he
tries to give a 'dynamical' explanation of holography.
I asked if and how he sees string theory fit into this picture, and he said
that he thinks that since in string theory essentially only the S-matrix is
a well defined observable, and since this means that only on-shell
information at the 'boundary' is available while local physics in the bulk
is fundamentally out of reach of present day string theory, this fits in
perfectly with the above picture, where ordinary quantum mechanics is kind
of an 'effective theory' on the boundary while the true bulk theory is a
deterministic hidden-variable thingy.
I have to say that when first confronted with speculations like this some
alarm bells go off - but then I realize that when t'Hooft discovered
holography a while back this idea must have sounded - before Maldacena came
along and gave an explicit relization - just as weird, and now it is widely
accepted and even standard lore.
So maybe in this little chat over a glass of beer I was actually shown a
glimpse of the big physics picture of the future, without my poor mind being
able to fully grasp it.
On the other hand, when asked what he thinks about how his ideas about
string/gauge duality and holography have come to life in string theory, he
answered, humbly and jokingly, that he almost fails to recognize his
original ideas.
There was much more discussion, but that's all I am going to report here. It
was a big pleasure to talk to such an outstanding person as t'Hooft is, and
I have some things to think about now. First of all, I'll toss away my TV
set...
the time to write a little report about it
(http://golem.ph.utexas.edu/string/archives/000400.html):
Today Prof. Gerard t'Hooft gave a talk at University Duisburg-Essen on Black
Holes in Elementary Particle Physics. Maybe due to the media hype about
Hawking's announcement of his new idea about the black hole information
'paradox', t'Hooft decided to throw his TV set away, and not only his but
lots of them, in fact enough that they would form a spherical shell
collapsing to a black hole.
Using this picture to emphasize the process in which 'known physics',
represented by well understood TV sets, passes the horizon and hence a
border beyond which all kinds of apparent paradoxes lurk, he talked about
some standard facts of high energy physics and then briefly mentioned some
of his intriguing observations and speculations concerning physics of the
stretched horizon, the collision of infalling particles with outgoing
Hawking radiation as well as the possibility of a deterministic hidden
variable model of quantum theory, which, as he says, he develops as a hobby.
After the talk we went to a nearby Biergarten and I had the chance to ask
some more detailed questions.
I have to admit that I haven't read any of t'Hooft's papers concerning the
above mentioned issues, so I learned for the first time about his
calculation which indicates that, somehow, the scattering of Hawking
radiation at infalling matter (one form - even though not the only one
relevant I'd think - of back reaction which is not usually taken into
account in related discussions, but which certainly should be) has some
surprising resemblance to string scattering amplitudes - well, except for
the curious fact that the analogy requires a imaginary string tension.
Very interesting are also his ideas about the foundations of quantum
mechanics, holography and string theory.
He says that he expects that there is a deterministic and local (yes, local)
hidden variable theory behind it all, which would be apparent if only we
knew the correct degrees of freedom of nature. Since we don't, we only see a
statistical average of this deterministic process, and this translates in a
non-local way to the quantum mechanical wavefunction, roughly.
To me this philosophy sounded a lot like approaches by Lee Smolin to get
quantum mechanical dynamics from the classical statistics of ensembles of
large matrices that encode the deterministic interrelation of all particles
(well, probably, if at all, of all D0 branes) in the universe. But when I
asked Prof. t'Hooft about this he said he wasn't fully familiar with
Smolin's approach.
Anyway, t'Hooft's idea now is that the full deterministic theory has no
information loss, but that on the 'coarse grained' level of familiar quantum
theory information is lost all the time in virtual black holes that are
abundant in vacuum fluctuations. The point is that, he says, this way
information about degrees of freedom in the bulk diasappears. The only
information left is that at some holographic boundary! This way, I think, he
tries to give a 'dynamical' explanation of holography.
I asked if and how he sees string theory fit into this picture, and he said
that he thinks that since in string theory essentially only the S-matrix is
a well defined observable, and since this means that only on-shell
information at the 'boundary' is available while local physics in the bulk
is fundamentally out of reach of present day string theory, this fits in
perfectly with the above picture, where ordinary quantum mechanics is kind
of an 'effective theory' on the boundary while the true bulk theory is a
deterministic hidden-variable thingy.
I have to say that when first confronted with speculations like this some
alarm bells go off - but then I realize that when t'Hooft discovered
holography a while back this idea must have sounded - before Maldacena came
along and gave an explicit relization - just as weird, and now it is widely
accepted and even standard lore.
So maybe in this little chat over a glass of beer I was actually shown a
glimpse of the big physics picture of the future, without my poor mind being
able to fully grasp it.
On the other hand, when asked what he thinks about how his ideas about
string/gauge duality and holography have come to life in string theory, he
answered, humbly and jokingly, that he almost fails to recognize his
original ideas.
There was much more discussion, but that's all I am going to report here. It
was a big pleasure to talk to such an outstanding person as t'Hooft is, and
I have some things to think about now. First of all, I'll toss away my TV
set...