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Physics Stack Exchange users whose comments are worth studying include Lubos Motl and Ron Maimon (now at http://www.quora.com/Ron-Maimon and http://www.physicsoverflow.org/user/Ron+Maimon). Also see http://arxiv.org/abs/hep-ph/0207124 for a review of physics since the standard model.


18h
comment Physical meaning of quantum interpretations
Apparently based on this Physics Overflow question physicsoverflow.org/29793/…
1d
comment Are atoms bad and good?
Some atoms, like carbon, are better at making life. So you might call them good if you think that is good. But almost all types of atom have a use somewhere in life. Toxicity is contextual. And even death is used by life (e.g. apoptosis).
Apr
20
comment Where is all the Dark Matter? Theoretical Question
Dark matter is usually thought to form a big sphere around a galaxy, called a halo. The DM particles are everywhere inside the sphere, all the way through. They aren't hiding, but they don't interact much with visible matter, except via gravity.
Apr
9
comment why does string theory require holography?
OK! Holography does help with calculations. Sometimes the alternative description it offers is the only known way. I'll think about what to say about this.
Apr
9
awarded  Revival
Apr
9
comment why does string theory require holography?
That's like saying "why does arithmetic need prime numbers?" The existence of prime numbers is not a starting point, but it follows logically from the definitions of counting, multiplication, etc. The point is that string theory was not designed with holography in mind, it was built step by step according to other criteria, but the resulting theory turned out to have the holographic property.
Apr
8
comment why does string theory require holography?
@John Peterson - Sorry, I don't follow... Holography is not a choice in string theory. You can't have string theory and then decide to add holography, they believe holography is already implied. But it took several decades before this was discovered to be an implication of the theory.
Apr
7
answered why does string theory require holography?
Apr
6
comment Form of the S matrix for interacting scalar field
@Amara, if you ever see this- try asking at Physics Overflow.
Mar
31
comment Form of the S matrix for interacting scalar field
Why are people voting to close?
Mar
30
comment 2 + 1 dimensional gravity as an exactly soluble system
P.S. I just saw Arnold Neumaier's link above - it will help.
Mar
30
comment 2 + 1 dimensional gravity as an exactly soluble system
The last step should explain why the cosmological constant in the geometry becomes the structure constant in the algebra.
Mar
30
comment 2 + 1 dimensional gravity as an exactly soluble system
3) Understand how infinitesimal translations, rotations and boosts, act on the new matrix variable.
Mar
30
comment 2 + 1 dimensional gravity as an exactly soluble system
2) Understand the change of variables, first to spin connection and frame field, then their recombination into the new matrix.
Mar
30
comment 2 + 1 dimensional gravity as an exactly soluble system
1) Understand general relativity in 2+1 dimensions, in a vacuum spacetime, for the three cases.
Mar
30
comment 2 + 1 dimensional gravity as an exactly soluble system
@Ali rezaie I don't have a single reference, that understanding came from many different sources. But you can do it yourself, step by step:
Mar
29
answered Are The Quantum Assumptions of MBT Theory Correct?
Mar
29
answered 2 + 1 dimensional gravity as an exactly soluble system
Mar
29
comment 2 + 1 dimensional gravity as an exactly soluble system
I will try to answer it, and maybe I will suggest a rewrite of the question too, but I can't do it right away.
Mar
29
comment 2 + 1 dimensional gravity as an exactly soluble system
DON'T CLOSE THIS QUESTION! Rewrite it if necessary. There is a topic of real substance here, namely gauge theories corresponding to 2+1 gravity with various values of cosmological constant (that's the lambda).