String Theory and The Empirical Existens of Consciousness

[jimmy85]

“Despite various claims, loop quantum gravity is not able to calculate the
black hole entropy, unlike string theory. The fact that the entropy is
proportional to the area does not follow from loop quantum gravity. It is
rather an assumption of the calculation. The calculation assumes that the
black hole interior can be neglected and the entropy comes from a new kind
of dynamics attached to the surface area - there is no justification of
this assumption. Not surprisingly, one is led to an area/entropy
proportionality law. The only non-trivial check could be the coefficient,
but it comes out incorrectly (see the Immirzi discrepancy).

The Immirzi discrepancy was believed to be proportional to the logarithm
of two or three, and a speculative explanation in terms of quasinormal
modes was proposed. However it only worked for one type of the black hole

• a clear example of a numerical coincidence - and moreover it was
  realized in July 2004 that the original calculation of the Immirzi
  parameter was incorrect, and the correct value (described by Meissner) is
  not proportional to the logarithm of an integer. The value of the Immirzi
  parameter - even according to the optimists - remains unexplained. Another
  description of the situation goes as follows: Because the Immirzi
  parameter represents the renormalization of Newton’s constant and there is
  no renormalization in a finite theory - and loop quantum gravity claims to
  be one - the Immirzi parameter should be equal to one which leads to a
  wrong value of the black hole entropy.”
  Please see:
  What’s wrong with loop quantum gravity:
  physicsforums.com/showthread.php?t=43682
  1 Too many assumptions
  2 Commentary from the renormalization group aspect
  3 As a predictive theory
  4 Self-consistency
  5 Gap to high-energy physics
  6 Smooth space as limiting case
  7 Clash with special relativity
  8 Global justification of variables
  9 Testability of the discrete area spectrum
  10 The S-matrix
  11 Ultraviolet divergences
  12 Black hole entropy
  13 Foundational lacks
  14 Prejudices claimed
  15 Background independence
  16 Claims on non-principled approach

Thanks a lot, I ll try to read it

 

[bobzills]

Thanks a lot, I ll try to read it

I don’t say that it is the last word, and there still are defenders of LQG as you noted. But it looks like LQG has pretty severe problems which will prevent it from being taken seriously in the end.
I am interested if you disagree with the article referred to above.
Thanks.

 

[jimmy85]

I don’t say that it is the last word, and there still are defenders of LQG as you noted. But it looks like LQG has pretty severe problems which will prevent it from being taken seriously in the end.
I am interested if you disagree with the article referred to above.
Thanks.

hey

yes, I agree that LQG have alot of problems, but I dont totaly agree with all that was said there though I think that they were comparing LQG to a Theory of evyerthing, in that context it is extremly easy to say that the theory is an utter mess. but personately I think that LQG is solely another approach to learn more about the universe and it shouldnt be interpretated as a mean to unify everything like the particle physics, and all the other branches of physics that must be predicted and unified.
If im not mistaken LQG predicts and infinite number of families of particles in the standar model and therefore not an acurate prediction of particles physics at all. and yes LQG is also being constructed rather than being discovered, in a way that is a consequence of tha fact that LQG is starting to be developed now while string theory was started to be developed in the 70s
I beleive LQG is more just about just studying spacetime

Loop quantum gravity proponents often and explicitly state that they think
that general relativity does not have to respect the Lorentz symmetry in
any way - which displays a misunderstanding of the symmetry structure of
special and general relativity (the symmetries in general relativity
extend those in special relativity), as well as of the overwhelming
experimental support for the postulates of special relativity.

I dunno much but recently I have read that not just physicists from LQG but even indepentend physicist are looking for the breaking of Lorentz Symmetry, many phsycists think it might shed some light about the theory of everything and that indeed a symmetry breaking could exists. they are trying to do more experiements to learn more about it. I think the gravity probe B is trying to test that as well.

I also like the fact that LQG uses gauge field theory.
I honestly think that on that article they were asking to much to LQG and to the dozen phycisits that have recently made the theory , they are comparing it to string theory as if it was a theory of everything. although im sure LQG has “a lot” of problems, perhaps it might also work to learn more about reality and about spacetime which is a topic that seems to be very diferent an unique.

LQG is almost like wishful thinking but if it turns to have something right it would contribute a lot to physics. especialy in a topic that phycicist seem to have left behind that is spacetime. like dunno I beleive it deserves to be studied, nobody really knows much about the structure of spacetime. we just have special relativity that tells us that space and time are one thing and that it cause gravity, but it dosent make clear the nature and the structure of it as a physical concept. For example if a huge star explotes, it would left a hole or a singulatiry in spacetime, spacetime is a physical concept, and though it could teach us a lot about the universe itself. that is why I really like the idea of a quantization of spacetime, it seems very logical since it is a physical concept.

LQG it is not a well defined theory but it makes some prediction that could be tested soon, I think it had to do with the measurement of the speed of gama rays that happened on the early universe. LQG predicts that high energy photons travel slighly faster than low energy photons, I think that string theory differs with that prediction. We will have to wait and see which one was right on this.

 

[jimmy85]

I don’t say that it is the last word, and there still are defenders of LQG as you noted. But it looks like LQG has pretty severe problems which will prevent it from being taken seriously in the end.
I am interested if you disagree with the article referred to above.
Thanks.

btw here there is a dialouge by Carlo Rovelli debating about the diferences of string theory and LQG and about why he choose LQG.

arxiv.org/PS_cache/hep-th/pdf/0310/0310077v2.pdf