Re: Multiverse concepts in string theory

2006-02-15 Thread Wei Dai



To clarify,that quotecomes 
fromJohn Peacock, the reviewer of The Cosmic Landscape for 
American Scientist.

What he's saying is that physics, like art,is 
partly a function of the human aesthetic response, because empirical evidence 
only constrainstheories allowed in physics, but does not determine it. 
I would agree with him only partly, because a 
large part of what Peacock includes under "aesthetics" is a common preference 
for simplicity, which can be formalized in various ways (e.g. Kolmogorov 
complexity). 

But even taking into account the formalizable 
common preference for simplicity, I think there is still a role for aesthetics 
to play in physics. I can think of two arguments for this. One is to say that 
the general preference for simplicity in our aesthetic response is a result of 
the limited complexity of our minds. In other words, everything weconsider 
beautifulmust be relatively simple, but not everything simple has to be 
considered beautiful. Thus the most beautiful theory is not necessarily the 
simplest one.

The other argument is that all of the 
formalizations of complexity leave a free parameter, for example the choice of 
universal Turing machine in algorithmic information theory. Our aesthetic 
choices can therefore be encoded into this free parameter.

  - Original Message - 
  From: 
  Kim 
  Jones 
  To: Wei Dai 
  Cc: everything-list@eskimo.com 
  Sent: Tuesday, February 14, 2006 10:40 
  PM
  Subject: Re: Multiverse concepts in 
  string theory
  Thankyou.
  
  So it used to be "science and religion."
  
  In fact it should have been all along "science and religion and 
  art".
  
  Is it possible that we've been missing an important part of the 
  discussion here?
  
  Art (painting, music - whatever) is the revelation of 1st person 
  experience; the 'word of the creator'.
  
  Take it from there
  
  
  Kim Jones
  
  
  
  On 14/02/2006, at 11:06 AM, Wei Dai wrote:
  In short, 
physics is a human creative art on the same level as painting and music, and 
that is reason enough to be proud of what the subject has 
achieved.


Re: Multiverse concepts in string theory

2006-02-15 Thread Saibal Mitra



Hi Stephen,

Yes I agree. But once you have many scientists 
believing in a certain paradigm, it takes radical new discoveries to overturn 
it. The lack of confirmation is usually not enough.

Saibal




- Original Message - 

  From: 
  Stephen 
  Paul King 
  To: everything-list@eskimo.com 
  Sent: Wednesday, February 15, 2006 1:45 
  AM
  Subject: Re: Multiverse concepts in 
  string theory
  
  Hi Saibal,
  
   Does this not lead one to suspect that 
  they secretly believe SUSY to be "not even wrong" and yet seek to save face? 
  My problem is that any scientific theory must be highly falsifiable, otherwise 
  we are just going back to the days of Scholastic debates...
  
  http://clublet.com/why?AngelsOnTheHeadsOfPins
  
  Onward!
  
  Stephen
  
  
- Original Message - 
From: 
Saibal Mitra 

To: Stephen Paul King ; everything-list@eskimo.com 

Sent: Tuesday, February 14, 2006 6:20 
PM
    Subject: Re: Multiverse concepts in 
    string theory

Stephen,

Theorists are always a bit ahead and they have 
already foundways to save SUSY from negative results from the LHC. 


Saibal


- Original Message - 

  From: 
  Stephen 
  Paul King 
  To: everything-list@eskimo.com 
  
  Sent: Tuesday, February 14, 2006 1:04 
  PM
  Subject: Re: Multiverse concepts in 
      string theory
  
  Hi Norman,
  
   It will be a wonderful thing to get a 
  confirmation by next year but I am afraid that the usual behavior of 
  theorist will occur: the theory will be re-tinkered so that the particle 
  masses are too massive to be created by humans. It has been happening 
  already in astrophysics...
  
   Btw, have you any familiarity with 
  modeling the dynamics of scalar fields in relativistic situations? I need 
  some help. ;-)
  
  Onward!
  
  Stephen
  
  
  - Original Message - 
  
From: 
Norman 
Samish 
To: Everything-list 
Sent: Tuesday, February 14, 2006 
1:36 AM
    Subject: Re: Multiverse concepts in 
    string theory

Stephen,

As you say, the version of string theorywith an 
infinity of universes isan elegant concept. However, when 
you say". . . its most fundamental assumption,the existence 
of a supersymmerty relation between bosons and fermions, has never even 
come close to matching experimental observation,"one could infer 
that there is little likelihood that SUSY will ever be shown to 
bea good theory.

Thismay change soon.Wikipedia says 
"Experimentalists have not yet found any superpartners for known 
particles, either because they are too massive to be created in our 
current particle accelerators, or because they may not exist at 
all. By the year 2007, the Large Hadron Collider at CERN 
should be ready for use, producing collisions at sufficiently high 
energies to detect the superpartners many theorists hope to 
see."

So maybe, in a couple of years, there WILL be 
experimental observation supporting SUSY.

I agree that the posts by Hal Finney and Wei Dai are 
well said and inspirational. Thanks,

Norman


Re: Multiverse concepts in string theory

2006-02-14 Thread Saibal Mitra



Stephen,

Theorists are always a bit ahead and they have 
already foundways to save SUSY from negative results from the LHC. 


Saibal


- Original Message - 

  From: 
  Stephen 
  Paul King 
  To: everything-list@eskimo.com 
  Sent: Tuesday, February 14, 2006 1:04 
  PM
  Subject: Re: Multiverse concepts in 
  string theory
  
  Hi Norman,
  
   It will be a wonderful thing to get a 
  confirmation by next year but I am afraid that the usual behavior of theorist 
  will occur: the theory will be re-tinkered so that the particle masses are too 
  massive to be created by humans. It has been happening already in 
  astrophysics...
  
   Btw, have you any familiarity with 
  modeling the dynamics of scalar fields in relativistic situations? I need some 
  help. ;-)
  
  Onward!
  
  Stephen
  
  
  - Original Message - 
  
From: 
Norman 
Samish 
To: Everything-list 
Sent: Tuesday, February 14, 2006 1:36 
AM
Subject: Re: Multiverse concepts in 
string theory

Stephen,

As you say, the version of string theorywith an 
infinity of universes isan elegant concept. However, when you 
say". . . its most fundamental assumption,the existence of a 
supersymmerty relation between bosons and fermions, has never even come 
close to matching experimental observation,"one could infer that there 
is little likelihood that SUSY will ever be shown to bea good 
theory.

Thismay change soon.Wikipedia says 
"Experimentalists have not yet found any superpartners for known particles, 
either because they are too massive to be created in our current particle 
accelerators, or because they may not exist at all. By the year 
2007, the Large Hadron Collider at CERN should be ready for use, producing 
collisions at sufficiently high energies to detect the superpartners many 
theorists hope to see."

So maybe, in a couple of years, there WILL be experimental 
observation supporting SUSY.

I agree that the posts by Hal Finney and Wei Dai are well 
said and inspirational. Thanks,

Norman


Re: Multiverse concepts in string theory

2006-02-14 Thread Stephen Paul King



Hi Saibal,

 Does this not lead one to suspect that they 
secretly believe SUSY to be "not even wrong" and yet seek to save face? My 
problem is that any scientific theory must be highly falsifiable, otherwise we 
are just going back to the days of Scholastic debates...

http://clublet.com/why?AngelsOnTheHeadsOfPins

Onward!

Stephen


  - Original Message - 
  From: 
  Saibal Mitra 
  
  To: Stephen Paul King ; everything-list@eskimo.com 
  Sent: Tuesday, February 14, 2006 6:20 
  PM
  Subject: Re: Multiverse concepts in 
  string theory
  
  Stephen,
  
  Theorists are always a bit ahead and they have 
  already foundways to save SUSY from negative results from the LHC. 
  
  
  Saibal
  
  
  - Original Message - 
  
From: 
Stephen 
Paul King 
To: everything-list@eskimo.com 

Sent: Tuesday, February 14, 2006 1:04 
PM
    Subject: Re: Multiverse concepts in 
    string theory

Hi Norman,

 It will be a wonderful thing to get a 
confirmation by next year but I am afraid that the usual behavior of 
theorist will occur: the theory will be re-tinkered so that the particle 
masses are too massive to be created by humans. It has been happening 
already in astrophysics...

 Btw, have you any familiarity with 
modeling the dynamics of scalar fields in relativistic situations? I need 
some help. ;-)

Onward!

Stephen


- Original Message - 

  From: 
  Norman 
  Samish 
  To: Everything-list 
  Sent: Tuesday, February 14, 2006 1:36 
  AM
  Subject: Re: Multiverse concepts in 
      string theory
  
  Stephen,
  
  As you say, the version of string theorywith an 
  infinity of universes isan elegant concept. However, when you 
  say". . . its most fundamental assumption,the existence of a 
  supersymmerty relation between bosons and fermions, has never even come 
  close to matching experimental observation,"one could infer that 
  there is little likelihood that SUSY will ever be shown to bea good 
  theory.
  
  Thismay change soon.Wikipedia says 
  "Experimentalists have not yet found any superpartners for known 
  particles, either because they are too massive to be created in our 
  current particle accelerators, or because they may not exist at all. 
  By the year 2007, the Large Hadron Collider at CERN should be ready 
  for use, producing collisions at sufficiently high energies to detect the 
  superpartners many theorists hope to see."
  
  So maybe, in a couple of years, there WILL be 
  experimental observation supporting SUSY.
  
  I agree that the posts by Hal Finney and Wei Dai are 
  well said and inspirational. Thanks,
  
  Norman


Re: Multiverse concepts in string theory

2006-02-14 Thread Kim Jones
Thankyou.So it used to be "science and religion."In fact it should have been all along "science and religion and art".Is it possible that we've been missing an important part of the discussion here?Art (painting, music - whatever) is the revelation of 1st person experience; the 'word of the creator'.Take it from thereKim JonesOn 14/02/2006, at 11:06 AM, Wei Dai wrote:In short, physics is a human creative art on the same level as painting and music, and that is reason enough to be proud of what the subject has achieved.

RE: Multiverse concepts in string theory

2006-02-13 Thread Jonathan Colvin
Hal wrote:

 I also get the impression that Susskind's attempts to bring disreputable
 multiverse models into holy string theory is more likely to kill
 string theory than to rehabilitate multiverses.  Perhaps I am getting a
 biased view by only reading this one blog, which opposes string theory,
 but it seems that more and more people are saying that the emperor has
 no clothes.  If string theory needs a multiverse then it is even less
 likely to ever be able to make physical predictions, and its prospects
 are even worse than had been thought.  A lot of people seem to be piling
 on and saying that it is time for physics to explore alternative ideas.
 The hostile NY Times book review is just one example.

Two words: Continental drift.

Ok, continental drift is observable, whereas multiverses aren't, but it is
worth remembering the ridicule heaped (up until not so very long ago) on
those who dared to suggest what is now known as plate techtonics.

Jonathan Colvin



Re: Multiverse concepts in string theory

2006-02-13 Thread Bruno Marchal


Le 13-févr.-06, à 09:44, Hal Finney wrote (in part):




In many of our discussions of multiverse models, we have explicitly or
implicitly included the notion of measure, that some universes would be
more common or more prominent than others.  This is often linked to
extensions of Occam's Razor, so that universes with relatively simple
models would have higher measure than those that are more complex.



The necessity of simplicity could perhaps be a consequence of comp, 
but this remains to be shown. But even if that is the case, I don't see 
how simplicity would make the model having a higher measure, unless 
you attach consciousness to particular individuals in particular 
universe, but this can be done only by identifying the first person and 
some arbitrary particular third person description. And the UDA shows 
this cannot be done (with comp).




Physics is a science, and that means it needs to work with theories 
that

can be tested and disproven.  We are a long way from being able to come
up with any experiment that a working physicist in his lab could run
to see whether multiverse models are correct.  (And no, quantum suicide
doesn't count!)



The day physicists will understand the logician's sense of model and 
theories, things will be pretty much clear. If we agree that physicists 
obey the same laws as the particles they describe, then, even just the 
two slits experiment entails mutiverses, and confirms QM which is 
literally a mutiverse theory (even with the collapse,  which is just an 
invention for cutting on the typical quantum contagion of the 
superpositions).
Also, note that the 0-universe, 1-universe, infinity-of-universes are 
all on the same par. Nobody has ever tested the existence of a 
primitive physical universe nor of the existence of Aristotelian Prime 
Matter, and other common sense idea  on which those physicalist ideas 
derive.
Note also that the theory of Matter given by the loebian 
(introspective) machine is 100% testable.






I also get the impression that Susskind's attempts to bring 
disreputable

multiverse models into holy string theory is more likely to kill
string theory than to rehabilitate multiverses.



String theory relies entirely on QM and so inherits all its 
interpretation problems.
Except that in String Theory, like Quantum Cosmology,  the wave 
collapse is still more unintelligible. Witten makes the points in a 
conference some years ago. According to him String Theory is still very 
fuzzy on the whole wave aspect of strings, above its  traditional role 
as computation tool.






 Perhaps I am getting a
biased view by only reading this one blog, which opposes string theory,
but it seems that more and more people are saying that the emperor has
no clothes.  If string theory needs a multiverse then it is even less
likely to ever be able to make physical predictions, and its prospects
are even worse than had been thought.  A lot of people seem to be 
piling

on and saying that it is time for physics to explore alternative ideas.
The hostile NY Times book review is just one example.



To be sure I disagree that string theory is not testable, and I think 
the multiverse idea is testable and already indirectly tested and that 
it is the most certain consequence of QM.
Now, as a theory of everything, string theories, like QM and actually 
the whole physics enterprise, are flawed at the start, because those 
approach relies (consciously or not) on a hardly clear or coherent 
theology inherited mainly from Aristotle, and which tends to put the 
mind-body problem under the rug.


Bruno

http://iridia.ulb.ac.be/~marchal/




Re: Multiverse concepts in string theory

2006-02-13 Thread Wei Dai



Hal wrote:
 I also get the impression that Susskind's 
attempts to bring "disreputable" multiverse models into "holy" string 
theory is more likely to kill string theory than to rehabilitate 
multiverses. Perhaps I am getting a biased view by only reading 
this one blog, which opposes string theory, but it seems that more and 
more people are saying that the emperor has no clothes. If string 
theory needs a multiverse then it is even less likely to ever be able to 
make physical predictions, and its prospects are even worse than had 
been thought. A lot of people seem to be piling on and saying that 
it is time for physics to explore alternative ideas. The hostile NY 
Times book review is just one example.
String theory isn't going to be killed until 
there's a replacement available, and any replacement is likely to face the same 
issue of describing a large collection of universes of which only a small subset 
can support life.So Iwouldn't beconcerned about more effort 
being devoted to looking for alternatives to string theory. In the mean time, 
the multiverse meme continues to spread. Take the review of Susskind's 
bookin American Scientist (http://www.americanscientist.org/template/BookReviewTypeDetail/assetid/49558)for 
example:

In the end, however, good though this book is, I 
was left feeling that the argument was not carried to its logical conclusion. 
Despite his justified scorn for intelligent design, Susskind retains a hint of 
this worldview in his own attitude. It was Galileo who said that the book of 
Nature is written in mathematics, and almost all physicists subscribe to this 
view. When we contemplate the power and simplicity of constructions like general 
relativity, there is a temptation to carry intelligent design to an extreme in 
which God wrote the equations, from which all else follows. Frequently this 
perspective is quite explicit, as with Einstein (recall Bohr's admonition, "Stop 
telling God what to do!"). The landscape picture derails this thinking to some 
extent, but Susskind just transfers the quasi-religious awe to string theory, 
whose mathematical results he repeatedly describes as "miraculous."

But if life on Earth is a random accident in a universe where only chance 
yielded laws of physics suitable for life, why stop there? Perhaps string theory 
itself is nothing special and only part of a wider spectrum of possible 
prescriptions for reality. If the search for a unique and inevitable explanation 
of Nature has proved illusory at every step, is it really plausible that 
suddenly string theory can make everything right at the last? Reading Susskind's 
book should make you doubt that possibility, in which case we may have reached 
the end of the search for underlying simplicity that has driven physics since 
the beginning. A comment made by Steven Weinberg in his 1977 book The First 
Three Minutes sums things up well: "The more the universe seems 
comprehensible, the more it also seems pointless." Pointless to look for meaning 
in our existence in the universe, and also (according to Susskind) pointless to 
look for meaning in physics. To a physicist, this is a pretty depressing 
conclusion, but there is some consolation: The beauty we perceive in the laws of 
physics perhaps tells us as much about the human aesthetic response as it does 
about any fundamental design of the universe. In short, physics is a human 
creative art on the same level as painting and music, and that is reason enough 
to be proud of what the subject has achieved.


Re: Multiverse concepts in string theory

2006-02-13 Thread Stephen Paul King



Dear Wei and Friends,

 I have been 
following this thread with some interest (Hal initial post was wonderful, 
BTW!)and echo the comments of Wei here, but I would offer a note of 
caution: we must be very careful that the elevation of string theory (SUSY) to 
almost dogmatic "Sacred Cow" status does not bode well for many of us, 
particularly those that have found that its most fundamental assumption, the 
existence of a supersymmerty relation between bosons and fermions, has never 
even come close to matching experimental observation. 
 Maybe, just 
maybe, SUSY is a good theory or maybe it is just a very elegant bit of pure 
mathematics. Remember, just because a mathematical theory can be shown to be 
self-consistent and elegant, there is no requirement that that theory have 
anything to do with the physical world we experience.
 I find that the 
choices presented by Weinberg and the Intelligent Design advocates are not the 
only possibilities. Consider that we still do not have a consistent and faithful 
model of observers within our physics and thus can not even start to coherently 
consider what the notion of "comprehensibility" means in the context of physics. 
;-)

Onward!

Stephen


  - Original Message - 
  From: 
  Wei Dai 
  To: everything-list@eskimo.com 
  Sent: Monday, February 13, 2006 7:06 
  PM
  Subject: Re: Multiverse concepts in 
  string theory
  
  Hal wrote:
   I also get the impression that Susskind's 
  attempts to bring "disreputable" multiverse models into "holy" string 
  theory is more likely to kill string theory than to rehabilitate 
  multiverses. Perhaps I am getting a biased view by only reading 
  this one blog, which opposes string theory, but it seems that more and 
  more people are saying that the emperor has no clothes. If 
  string theory needs a multiverse then it is even less likely to ever 
  be able to make physical predictions, and its prospects are even worse 
  than had been thought. A lot of people seem to be piling on and 
  saying that it is time for physics to explore alternative ideas. The 
  hostile NY Times book review is just one example.
  String theory isn't going to be killed until 
  there's a replacement available, and any replacement is likely to face the 
  same issue of describing a large collection of universes of which only a small 
  subset can support life.So Iwouldn't beconcerned about more 
  effort being devoted to looking for alternatives to string theory. In the mean 
  time, the multiverse meme continues to spread. Take the review of Susskind's 
  bookin American Scientist (http://www.americanscientist.org/template/BookReviewTypeDetail/assetid/49558)for 
  example:
  
  In the end, however, good though this book is, I 
  was left feeling that the argument was not carried to its logical conclusion. 
  Despite his justified scorn for intelligent design, Susskind retains a hint of 
  this worldview in his own attitude. It was Galileo who said that the book of 
  Nature is written in mathematics, and almost all physicists subscribe to this 
  view. When we contemplate the power and simplicity of constructions like 
  general relativity, there is a temptation to carry intelligent design to an 
  extreme in which God wrote the equations, from which all else follows. 
  Frequently this perspective is quite explicit, as with Einstein (recall Bohr's 
  admonition, "Stop telling God what to do!"). The landscape picture derails 
  this thinking to some extent, but Susskind just transfers the quasi-religious 
  awe to string theory, whose mathematical results he repeatedly describes as 
  "miraculous."
  
  But if life on Earth is a random accident in a universe where only chance 
  yielded laws of physics suitable for life, why stop there? Perhaps string 
  theory itself is nothing special and only part of a wider spectrum of possible 
  prescriptions for reality. If the search for a unique and inevitable 
  explanation of Nature has proved illusory at every step, is it really 
  plausible that suddenly string theory can make everything right at the last? 
  Reading Susskind's book should make you doubt that possibility, in which case 
  we may have reached the end of the search for underlying simplicity that has 
  driven physics since the beginning. A comment made by Steven Weinberg in his 
  1977 book The First Three Minutes sums things up well: "The more the 
  universe seems comprehensible, the more it also seems pointless." Pointless to 
  look for meaning in our existence in the universe, and also (according to 
  Susskind) pointless to look for meaning in physics. To a physicist, this is a 
  pretty depressing conclusion, but there is some consolation: The beauty we 
  perceive in the laws of physics perhaps tells us as much about the human 
  aesthetic response as it does about any fundamental design of the universe. In 
  short, physics is a human creat

Re: Multiverse concepts in string theory

2006-02-13 Thread Norman Samish



Stephen,

As you say, the version of string theorywith an infinity 
of universes isan elegant concept. However, when you say". . . 
its most fundamental assumption,the existence of a supersymmerty relation 
between bosons and fermions, has never even come close to matching experimental 
observation,"one could infer that there is little likelihood that SUSY 
will ever be shown to bea good theory.

Thismay change soon.Wikipedia says 
"Experimentalists have not yet found any superpartners for known particles, 
either because they are too massive to be created in our current particle 
accelerators, or because they may not exist at all. By the year 
2007, the Large Hadron Collider at CERN should be ready for use, producing 
collisions at sufficiently high energies to detect the superpartners many 
theorists hope to see."

So maybe, in a couple of years, there WILL be experimental 
observation supporting SUSY.

I agree that the posts by Hal Finney and Wei Dai are well said 
and inspirational. Thanks,

Norman
~~
- Original Message - From: Stephen Paul King 
To: everything-list@eskimo.com Sent: Monday, February 13, 2006 7:29 
PMSubject: Re: Multiverse concepts in string theoryDear Wei and 
Friends, I have been following this thread with some 
interest (Hal initial post was wonderful, BTW!) and echo the comments of Wei 
here, but I would offer a note of caution: we must be very careful that the 
elevation of string theory (SUSY) to almost dogmatic "Sacred Cow" status does 
not bode well for many of us, particularly those that have found that its most 
fundamental assumption, the existence of a supersymmerty relation between bosons 
and fermions, has never even come close to matching experimental observation. 
 Maybe, just maybe, SUSY is a good theory or maybe it is 
just a very elegant bit of pure mathematics. Remember, just because a 
mathematical theory can be shown to be self-consistent and elegant, there is no 
requirement that that theory have anything to do with the physical world we 
experience. I find that the choices presented by Weinberg 
and the Intelligent Design advocates are not the only possibilities. Consider 
that we still do not have a consistent and faithful model of observers within 
our physics and thus can not even start to coherently consider what the notion 
of "comprehensibility" means in the context of physics. 
;-)Onward!Stephen
~`- Original Message - 
From: Wei Dai To: everything-list@eskimo.com Sent: Monday, February 
13, 2006 7:06 PMSubject: Re: Multiverse concepts in string 
theoryHal wrote: I also get the impression that Susskind's 
attempts to bring "disreputable" multiverse models into "holy" string 
theory is more likely to kill string theory than to rehabilitate 
multiverses. Perhaps I am getting a biased view by only reading 
this one blog, which opposes string theory, but it seems that more and 
more people are saying that the emperor has no clothes. If string 
theory needs a multiverse then it is even less likely to ever be able to 
make physical predictions, and its prospects are even worse than had 
been thought. A lot of people seem to be piling on and saying that 
it is time for physics to explore alternative ideas. The hostile NY 
Times book review is just one example.String theory isn't going to be 
killed until there's a replacement available, and any replacement is likely to 
face the same issue of describing a large collection of universes of which only 
a small subset can support life. So I wouldn't be concerned about more effort 
being devoted to looking for alternatives to string theory. In the mean time, 
the multiverse meme continues to spread. Take the review of Susskind's book in 
American Scientist 
(http://www.americanscientist.org/template/BookReviewTypeDetail/assetid/49558) 
for example:In the end, however, good though this book is, I was left 
feeling that the argument was not carried to its logical conclusion. Despite his 
justified scorn for intelligent design, Susskind retains a hint of this 
worldview in his own attitude. It was Galileo who said that the book of Nature 
is written in mathematics, and almost all physicists subscribe to this view. 
When we contemplate the power and simplicity of constructions like general 
relativity, there is a temptation to carry intelligent design to an extreme in 
which God wrote the equations, from which all else follows. Frequently this 
perspective is quite explicit, as with Einstein (recall Bohr's admonition, "Stop 
telling God what to do!"). The landscape picture derails this thinking to some 
extent, but Susskind just transfers the quasi-religious awe to string theory, 
whose mathematical results he repeatedly describes as "miraculous."
But if life on Earth is a random accident in a universe 
where only chance yielded laws of physics suitable for life, why stop there? 
Perhaps string theory itself is nothing special and only part of a wider