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seen Mar 17 '13 at 20:46

May
4
awarded  Yearling
May
4
awarded  Student
May
4
awarded  Nice Question
Oct
14
comment Other processes than formal power series expansions in quantum field theory calculations
Thanks a lot! To understand and learn to use cluster expansions, would Glimm-Jaffe's Quantum physics: a functional integral point of view be a reasonable starting point? I am a mathematician with background in PDE and wavelets, and with an undergraduate degree in physics.
Oct
8
comment Other processes than formal power series expansions in quantum field theory calculations
Thanks for the answer! I am afraid I cannot get much out of the book. Are you essentially saying that since lattice has so many problems, other possible approaches must have even more problems?
Oct
6
comment Other processes than formal power series expansions in quantum field theory calculations
Thanks for the answer. The question was more in the spirit of when there are so many approaches to approximate the exact solution of, say nonlinear wave (and Klein-Gordon, Yang-Mills-Higgs-Dirac etc) equations on the classical level, why do we choose, when we quantize, only a couple of approaches, such as power series, and lattice regularization (the latter essentially a finite difference method)?
Oct
6
comment Other processes than formal power series expansions in quantum field theory calculations
@Yuji: Yes, as you said, it is only an asymptotic series, which means that initially it may get close to the "exact value", but after some point it will diverge. A related question is if there is anything known in terms of how many terms we should calculate in order to get the most accurate result.
Oct
6
asked Other processes than formal power series expansions in quantum field theory calculations
Oct
1
comment Why is moonlight less colourful than yellow light?
@Vineet the blackbody radiation does not correspond to yellow. It has all wavelengths, but it has slightly more yellowish content than other visible colours. A white surface scatters all incoming lights. Since the Sun has been the dominant light source on Earth, what we see in white colour is Sun's spectrum. So if you want to design a lamp that looks perfectly white, it must be indistinguishable to your eyes from sunlight.
Apr
30
comment Does a particle annihilate only with its antiparticle? If yes, why?
If Wheeler's conjecture was true, wouldn't this imply that the number of electrons must be equal to the number of positrons?
Apr
28
comment Formalizing Quantum Field Theory
Can you please give some references, especially to the construction of Yang-Mills on torus and 2d Maxwell-Higgs?
Apr
28
comment General relativity (gravitation) in time and one spatial dimension
Even 2+1 is almost trivial.
Apr
28
comment What is physical in the principle of local gauge invariance?
At any given time in history the collection of all measurements done by mankind will be finite. So in principle, there can be infinitely many theories that fit those measurements (think of interpolation). But we don't even have one yet. We have many theories each fitting a particular subset of the data.
Apr
28
comment Is a periodic force capable of transporting a particle to large distances?
Velocity = integral of force. So if the periodic force gets above and below 0 "evenly" as in the sine example, and if initially the force is positive, then the velocity never gets negative.
Apr
27
comment Did Einstein prove $E=mc^2$ correctly?
Quote Hilbert: Every boy in the streets of Gottingen understands more about four dimensional geometry than Einstein. Yet, in spite of that, Einstein did the work and not the mathematicians.
Apr
25
comment “The Schwarzschild Proton” paper - Is the science valid?
I would not be so strict as Mr X, as there are exceptions, but he has some point. This maybe interesting: math.ucr.edu/home/baez/crackpot.html
Apr
20
awarded  Editor
Apr
20
revised Can a non-euclidean space be descripted through an euclidean of higher dimension? so why use non-euclidean?
link to the book changed from amazon to google
Apr
20
answered Can a non-euclidean space be descripted through an euclidean of higher dimension? so why use non-euclidean?
Apr
20
awarded  Commentator