Not even wrong: a summary of criticism of string theory

[bananan]

lubos motl has published is objections to loop quantum gravity which lee smolin responded to.

what are some common objections to string theory, esp in NEW, what do string theorists think of these objections? lubos motl calls peter's book crap, gives it 1 star on amazon. (then it got deleted).

 

[marcus]

what good does animosity and vituperation do?

I don't think it does much good.

It is quite common for LQG people to speak of string research with appreciation, and to object rather to the effective string monopoly on fundamental research in the US

that is, to struggle against a flawed SOCIOLOGY.

Fact number one is that ONLY ONE physics department in the US has a non-string QG research group (with more than one faculty member). That is at Penn State.

Note that POSTDOC funding is normally assigned only to groups where there is more than one faculty. So a single faculty like J.B. may have graduate students, but wouldn't ordinarily have postdocs to work with.

Groups, with junior and senior faculty, and postdocs, and grad students, develop synergy.

rather than criticize string theory, what is much more urgent is to break the monopoly. Get a more diversified strategy in fundmental research programs and funding.

Places outside the US where they have non-string QG GROUPS (with several faculty and with postdocs) are for example

Canada's U Waterloo-Perimeter, U Western Ontario; UK: Cambridge, London Imperial, Nottingham; Netherlands: Utrecht; France: Marseille;
Mexico City...

 

[bananan]

incidentally,

if loop quantum gravity is unable to reproduce GR in the semiclassical regime, then how do we know it is a theory of gravity of any sort?

what good does animosity and vituperation do?

I don't think it does much good.

It is quite common for LQG people to speak of string research with appreciation, and to object rather to the effective string monopoly on fundamental research in the US

that is, to struggle against a flawed SOCIOLOGY.

Fact number one is that ONLY ONE physics department in the US has a non-string QG research group (with more than one faculty member). That is at Penn State.

Note that POSTDOC funding is normally assigned only to groups where there is more than one faculty. So a single faculty like J.B. may have graduate students, but wouldn't ordinarily have postdocs to work with.

Groups, with junior and senior faculty, and postdocs, and grad students, develop synergy.

rather than criticize string theory, what is much more urgent is to break the monopoly. Get a more diversified strategy in fundmental research programs and funding.

Places outside the US where they have non-string QG GROUPS (with several faculty and with postdocs) are for example

Canada's U Waterloo-Perimeter, U Western Ontario; UK: Cambridge, London Imperial, Nottingham; Netherlands: Utrecht; France: Marseille;
Mexico City...

 

[marcus]

incidentally,

if loop quantum gravity is unable to reproduce GR in the semiclassical regime, then how do we know it is a theory of gravity of any sort?

http://arxiv.org/abs/gr-qc/0604044
Graviton propagator in loop quantum gravity
Eugenio Bianchi, Leonardo Modesto, Carlo Rovelli, Simone Speziale
41 pages, 6 figures

"We compute some components of the graviton propagator in loop quantum gravity, using the spinfoam formalism, up to some second order terms in the expansion parameter."Bananan , it does not matter what you want to call LQG.
You can call it an approach to a quantum theory of gravity, or you can call it an already arrived quantum theory of gravity, or you can call it NOT a quantum theory of gravity.
You are free to imagine it any way you want. Welcome to!

I don't know what you want to do with this thread. the title suggested you want a "summary of criticism of string theory".

now it sounds like you want a "summary of criticism of LQG"

Maybe you should start a new thread to criticism LQG!

I am not so interested in this thread, the way it is going, so I may not be paying attention in future. But I wish you good luck with it and hope you get some other people interested in discussing whatever you want to discuss!

 

[bananan]

hi marcus

lubos already has that covered

when smolin says the kodama state has a good semiclassical description, does this mean that LQG can reproduce the physics of GR, in the kodama state, with desitter spacetime? Can it predict or calculate the cc? I'm surprised it's not used as the building block for futher research? if witten's objections to kodama state do not hold, wouldn't this mean LQG and the kodama state is as much a theory of quantum gravity as string theory? can you reproduce BH entropy from the kodama state, or does the kodama state require an imirizi parameter that is incompatible with BH calculation?

http://arxiv.org/abs/gr-qc/0604044
Graviton propagator in loop quantum gravity
Eugenio Bianchi, Leonardo Modesto, Carlo Rovelli, Simone Speziale
41 pages, 6 figures

"We compute some components of the graviton propagator in loop quantum gravity, using the spinfoam formalism, up to some second order terms in the expansion parameter."


Bananan , it does not matter what you want to call LQG.
You can call it an approach to a quantum theory of gravity, or you can call it an already arrived quantum theory of gravity, or you can call it NOT a quantum theory of gravity.
You are free to imagine it any way you want. Welcome to!

I don't know what you want to do with this thread. the title suggested you want a "summary of criticism of string theory".

now it sounds like you want a "summary of criticism of LQG"

Maybe you should start a new thread to criticism LQG!

I am not so interested in this thread, the way it is going, so I may not be paying attention in future. But I wish you good luck with it and hope you get some other people interested in discussing whatever you want to discuss!