String Vs Loop Theory?

[Marshalscienceguy]

Which do you agree with?

Please state why.

[Mordred]

not detailed enough, are you referring to Loop quantum cosmology? Loop quantum gravity?

 

IN string are you referring to M theory or ADS/CFT correspondance? also which do we agree with most in lines of what? Cosmology?

[Marshalscienceguy]

not detailed enough, are you referring to Loop quantum cosmology? Loop quantum gravity?

 

IN string are you referring to M theory or ADS/CFT correspondance? also which do we agree with most in lines of what? Cosmology?

Sorry Loop Quantum gravity.

[Mordred]

ah gotcha well both models have their successes, and their problems so comparing the two is a matter of personal opinion. so rather than state my opinion seeing as I follow neither lol, I prefer QFT even though it also has its own problems. I'll simply supply a review of each. I'm also not versed enough in either models yet to formulate an opinion on either. Even though I have numerous articles and textbooks covering each, I haven't completed my studies of these two models.

 

Loop quantum gravity review

http://arxiv.org/pdf/1001.4188.pdf

 

string theory review

http://arxiv.org/pdf/hep--th/9905111.pdf

 

If your interested in learning either ADS/CFT or LQC let me know and I can supply some good articles designed to teach each. (hope your differential geometry is up to par though) that includes QFT articles

 

mind you I also follow the policy of study everything, you always learn something

 

in light of that policy you might find this 885 page article handy as it covers all 3 and others

http://arxiv.org/abs/hepth/9912205 : "Fields" - A free lengthy technical training manual on classical and quantum fields

Edited May 19, 2014 by Mordred

[ajb]

I would say that string theory has more going for it right now that loop quantum gravity despite string theory not yet living up to its promises as a TOE. String theory has has a much larger impact on physics and mathematics than loop quantum gravity has. Moreover, as a candidate TOE string theory hopes to be much more than loop quantum gravity.

 

There was also a hope at one time, similar to how the perturbative string theories and an 11d supergravity can been seen as a limit of M-theory, that maybe loop quantum gravity is also some limiting theory related to strings. This has never been realised and I don't hear such hope expressed today.

 

From a quantum gravity point of view string theory gives a consistent perturbative theory and it is known how general relativity (+ small corrections) is a limit. It is not known if the equations of loop quantum gravity really give general relativity in some limits. Until this is really shown I cannot see loop quantum gravity making a huge impact on physics.

[Mordred]

After reading "Roads to reality" by Penrose, just completed reading the 1200+ pages I would have to agree, however Penrose doesn't hold much hope in any existing model from what I can tell lol. Even his Twistor model he has his doubts though he supports it over others. At least that's the impression I got from it. Seemed to me he is holding out for some new radical take.I have to respect one thing though. He encourages others to think outside the box but in order to do that you need to understand whats in the box.

 

edit I should also give him credit his coverage of the geometry aspects of all the dominant theories was well done. As such I highly recommend anyone reading it, its a real eye opener, his viewpoints aside

Edited May 19, 2014 by Mordred