Re: Path integrals and statistical mechanics

2003-06-23 Thread George Levy
Hi Doriano,

Welcome to the list.

You raise an interesting problem and. I don't know the answer to your 
question. However, I just want to point out that an observer in relative 
motion observes the rotation in the complex plane of space-time 
geodesics. Could there be a connection between quantum and relativistic 
rotations?

George

Doriano Brogioli wrote:

Hi to everybody. I subscribed to this mailing list yesterday, but I'd 
like to pose a question since I think it _must_ be the right place.

Quantum mechanics can be formulated in terms of path integrals 
(Feinmann integrals). By substituting the time t with an (Euclidean) 
immaginary time i s, that is, a real value s times the imaginary root 
mean square of -1, the path integral changes to the Boltzmann 
distribution, where the energy is the (classical) energy of a 
continuum (classical) mechanical system, at temperature 1/h.

From this fact, someone claims that quantum world is simply a 
classical world, but rotated by pi/2 in the complex plane of t: the 
real world is classical, but we see it at the wrong angle. In 
particular, something similar happens near the event horizon of a 
black hole, and it should be the ultimate origin of Hawking radiation.

I tried to derive this relation, or some kind of this, and I concluded 
that it holds only at a formal level. Has anyone any idea about this 
topic?

Doriano Brogioli







Re: Path integrals and statistical mechanics

2003-06-23 Thread Joao Leao
The so-called Wick rotation which is often employed to turn the
unruly measure of path integrals into a regular summable measure
and is represented as

t --- -it

has no direct relation with the so-called Weyl unitarity trick
which is used to turn the bilinear anti-symmetric non-positive definite
Lorentz metric dt^2 - dx^2- dy^2 - dz^2  to a unitary one:
-dt^2-dx^2 - etc...

though they have the same flavor as mathematical expedients
without physical (empirical) meaning. The formal analogy
between Quantum Field Theory and Stat Mech depends indeed on
the first of these tricks.  Unless, of course, if you believe
in imaginary time it will be hard for you to know what
you are talking about when you speak of a rotation in the
complex plane of t. We would most likely need 4-dimensional
wrist watches to display the current iTime ( though Apple is
probably at work on an iClock as we speak !).

-Joao Leao



George Levy wrote:

 Hi Doriano,

 Welcome to the list.

 You raise an interesting problem and. I don't know the answer to your
 question. However, I just want to point out that an observer in relative
 motion observes the rotation in the complex plane of space-time
 geodesics. Could there be a connection between quantum and relativistic
 rotations?

 George

 Doriano Brogioli wrote:

  Hi to everybody. I subscribed to this mailing list yesterday, but I'd
  like to pose a question since I think it _must_ be the right place.
 
  Quantum mechanics can be formulated in terms of path integrals
  (Feinmann integrals). By substituting the time t with an (Euclidean)
  immaginary time i s, that is, a real value s times the imaginary root
  mean square of -1, the path integral changes to the Boltzmann
  distribution, where the energy is the (classical) energy of a
  continuum (classical) mechanical system, at temperature 1/h.
 
  From this fact, someone claims that quantum world is simply a
  classical world, but rotated by pi/2 in the complex plane of t: the
  real world is classical, but we see it at the wrong angle. In
  particular, something similar happens near the event horizon of a
  black hole, and it should be the ultimate origin of Hawking radiation.
 
  I tried to derive this relation, or some kind of this, and I concluded
  that it holds only at a formal level. Has anyone any idea about this
  topic?
 
  Doriano Brogioli
 
 

--

Joao Pedro Leao  :::  [EMAIL PROTECTED]
Harvard-Smithsonian Center for Astrophysics
1815 Massachussetts Av. , Cambridge MA 02140
Work Phone: (617)-496-7990 extension 124
VoIP Phone: (617)=384-6679
Cell-Phone: (617)-817-1800
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All generalizations are abusive (specially this one!)
---





Path integrals and statistical mechanics

2003-06-20 Thread Doriano Brogioli
Hi to everybody. I subscribed to this mailing list yesterday, but I'd 
like to pose a question since I think it _must_ be the right place.

Quantum mechanics can be formulated in terms of path integrals (Feinmann 
integrals). By substituting the time t with an (Euclidean) immaginary 
time i s, that is, a real value s times the imaginary root mean square 
of -1, the path integral changes to the Boltzmann distribution, where 
the energy is the (classical) energy of a continuum (classical) 
mechanical system, at temperature 1/h.

From this fact, someone claims that quantum world is simply a classical 
world, but rotated by pi/2 in the complex plane of t: the real world is 
classical, but we see it at the wrong angle. In particular, something 
similar happens near the event horizon of a black hole, and it should be 
the ultimate origin of Hawking radiation.

I tried to derive this relation, or some kind of this, and I concluded 
that it holds only at a formal level. Has anyone any idea about this topic?

Doriano Brogioli