Dialog with the Bogdanovs (Part 2)

John Baez

From: baez@galaxy.ucr.edu (John Baez)
Newsgroups: sci.physics.research,sci.physics
Subject: Re: Physics bitten by reverse Alan Sokal hoax?
Date: Sun, 3 Nov 2002 21:41:20 +0000 (UTC)
Organization: UCR
Message-ID: (aq1uoo$sr2$1@glue.ucr.edu)


In article (aptbm5$rp6$1@panther.uwo.ca),
igor.bogdanov (igor.bogdanov@free.fr) wrote:

>On his webpage, Dr John Baez relates some aspects of the "Bogdanov
>affair". We are very greatful regarding his effort to keep his page up
>to date.

You're welcome!

In what follows I will focus on the physics of your papers.
The other issues surrounding this case are also fascinating,
but I'd like to treat them separately, and perhaps in some 
other forum, since sci.physics.research is mainly about physics.

>John Baez's text: 

>>For example, here's the beginning of their paper "Topological Origin
>>of Inertia:

>>>We draw from the above that whatever the orientation, the plane of 
>>>oscillation of Foucault's pendulum is necessarily aligned with the 
>>>initial singularity marking the origin of physical space S^3, 
>>>that of Euclidean space E^4 (described by the family of instantons
>>>I_beta of whatever radius beta), and, finally, that of Lorentzian 
>>>space-time M^4. 

>Comment : It is not "their" paper but Igor's paper.

Thanks; I've fixed this on my webpage:

http://math.ucr.edu/home/baez/bogdanov.html

>We simply suggest that at 0 scale, the
>observables must be replaced by the homology cycles in the moduli space
>of gravitational instantons.  We then get a deep correspondence  -a
>symmetry of duality- between physical theory and topological field
>theory. 

Yes, you say this in your paper.  However, you need to be 
much more specific for there to be any substance to such a claim.
Now is a good chance for you to do this.  For example:

1) Could you please define "at 0 scale"?  

2) You mention "the observables".  Observables in which 
theory?

3) You say "must be replaced".  Why must they be replaced?  
And how?  

Presumably you are hinting at some correspondence between 
observables in some theory and homology cycles in the moduli 
space of gravitational instantons.  Please describe this 
correspondence as precisely as possible.  Merely stating
that it exists is not enough to convince us that it does.

4) You speak of a "deep correspondence" between some
unspecified physical theory and some unspecified topological
field theory.  Which theories are you talking about here?
How does the correspondence go?

5) What does any of this have to do with Foucault's 
pendulum or the origin of inertia?  Again, please describe
the connection as precisely as possible.

>>I appreciate the fact that to someone not expert in physics,
>>this stuff may seem no weirder than any other paper in a physics
>>journal. They are indeed using actual physics jargon - but I assure 
>>you, it makes no sense.

>Comment : OK.  However, we would prefer "not clearly understandable."
>Perhaps for two reasons : 1) first it is a secondary paper written long
>time after the "key paper"  (Classical&Quantum Grav.) where all our
>ideas are exposed and developed in more details. 2) second : once more
>it is conjectural paper. 
 
Regarding these points:

1) I was not able to find explanations of any of the relevant 
concepts in your Classical and Quantum Gravity paper, either.

2) It's okay to make conjectures, but there is little point
in publishing conjectures that cannot be understood.  

>John Baez text : How in the world could the plane of oscillation of a
>pendulum be "aligned with the initial singularity", i.e. the big bang?
>The big bang did not occur anywhere in particular; it happened
>everywhere. 

>Comment : Well, it is exactly what we wrote :  of course, there is no
>"priviledged" point and the initial singularity is  -as you said-
>everywhere. 

Given this, what does it mean to say a given plane in 
space is "aligned with the initial singularity"?  At best
it is a vacuous statement.

>It is precisely our view : in conjecture 4.9  (nothing more
>that an conjecture, by the way) we have considered that the
>2-dimensional plane of oscillation of the pendulum conserves the initial
>singularity S for inertial reference, whatever the orientation of this
>plane in physical space R3."

I don't what it means for a plane to "conserve the initial
singularity S for inertial reference".  You are using words
in a rather strange way!

I know what it means for a process to conserve some quantity,
e.g.: "nuclear fusion conserves charge".  It means that the 
quantity doesn't change as the process happens.  I don't 
know what it means for a plane to conserve something.  And 
I don't know what it means for something to conserve the
initial singularity.  I also don't know what the extra
phrase "for inertial reference" is supposed to modify, and
how it could modify anything in this sentence in a sensible
way.  

So, could you please explain much more clearly what you mean
here?

>It is explicitly written  in conjecture 4.9
>John Baez text : Indeed, nothing in the paper suggests that they really
>understand N = 2 supergravity, Donaldson theory, or KMS states. For all
>I can tell, they merely stuck together a patchwork of plausible-sounding
>sentences on these subjects.  

>Comment : One more, one should refer to the PRINTED VERSION (not the
>PDF's) of CQG paper (and also to the 2 thesis) to get a clearer view of
>what we say (and know) about N = 2 supergravity, Donaldson theory, KMS
>states, etc.We have passed many years working on these topics and became
>rather familiar with all these subjects.

Okay, I'll look at the printed version.  Exactly how does this
differ from the version in the PDF file of your thesis?

Anyway, it would be very reassuring to hear you say something 
that demonstrates understanding of N = 2 supergravity, Donaldson 
theory, KMS states, von Neumann algebras, or the other subjects 
on which you write.  
 
>In our view,  the fact to
>consider a topological field theory independent of the Hamiltonian is
>just equivalent to consider the same theory as independent of the
>metric. 

This is clearly false, as explained below.

>A theory independent of H is topological because it is - by
>construction -  independent of any physical field.

A theory with zero Lagrangian is independent of the fields
appearing in that theory.  Such a theory has zero Hamiltonian:
H = 0.  This is completely different from being "independent of H".
If something is "independent of H", it doesn't matter what H
is.  Here it matters a lot that H = 0.

>Comment : We indeed would be very happy to discuss our work, thesis and
>papers (prefer the printed versions to the PDF ones because of the
>misprints) on scientific basis. 

Good!  Let's start!

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