Compare and Contrast LQG and ST

[PRodQuanta]

Hey everybody. I'm doing an essay on this very subject, the comparisons and contrast between LQG and ST. I've heard things, such as: ST seems to define particles and forces, where LQG seems to discribe strings themselves and They both descibe a fundimental element of nature, but it's I don't feel I have enough information for the essay.

I'm doing the essay because I am very interested in both of the subjects. So this thread is not just for the essay, but to help me learn, understand, and comprehend the subjects more clearly. The better I understand, the easier I can relay my knowledge on the subject.

I am very interested and looking forward to seeing some knowledgeable people post on this subject.

Thank you,
Paden Roder

 

[marcus]

Hey everybody. I'm doing an essay on this very subject, the comparisons and contrast between LQG and ST. I've heard things, such as: ST seems to define particles and forces, where LQG seems to discribe strings themselves and They both descibe a fundimental element of nature, but it's I don't feel I have enough information for the essay.

I'm doing the essay because I am very interested in both of the subjects. So this thread is not just for the essay, but to help me learn, understand, and comprehend the subjects more clearly. The better I understand, the easier I can relay my knowledge on the subject.

I am very interested and looking forward to seeing some knowledgeable people post on this subject.

Thank you,
Paden Roder

try to find balanced surveys by people who do not have a vested interest in one or the other and can afford to make an unbiased comparison (as much as possible, no one is perfect)

look at the Wikipedia article on LQG---it is written partly by Lubos Motl, who is an extreme string partisan (and often I think unfair if not misleading) but also by Miguel Alvarez a student of John Baez working on his PhD in Loop or related non-stringy quantum gravity (no relation AFAIK between the young Miguel A and the senior authority Enrique A, just have same last name)

Because the article is written by this odd mixture of L.M on one hand and J.B.'s grad student on other, and by several other people, it has a kind of strange, perhaps unstable, lack of bias. It is actually very interesting...

Look also at the survey articles by the prominent Spanish theoretical physicist Enrique Alvarez----invited talks he gave to conferences in 2003 and 2004----one is called "Loops versus Strings" and he makes a comparison. the important thing about Alvarez is that much of his research has been stringy. He has not been in LQG research.

But he is a rare String-researcher because he can make the comparison without getting defensive: he makes a clear impartial comparison, describing the main successes and failures of each, and the main advantages and disadvantages.

His 2003 survey "Loops versus Strings" was even the plenary talk at a conference of particle physicists about what comes after the standard model. In other words it was a purely HEP conference-----no GR people.
Overwhelmingly string-minded, in other words, with no LQG people.
Nevertheless he gave a fair description of both approaches.

Also see how you find this paper by Lee Smolin, which also makes a side by side comparison of theories and evaluates their progress systematically in many departments

"How far are we from the quantum theory of gravity"

Also look at this conversation between Leonard Susskind and Lee Smolin which was published by Edge, the online magazine

Neither is impartial, it is a passionate head-to-head clash----this too can be a way of achieving balance (at least it can be exciting) you realize that both L.S. and L.S. are "founding fathers" in respective areas and both brilliant men. Paul Steinhardt was also there and I forget who else.

Perhaps i can help by finding some links

Wikipedia
http://en.wikipedia.org/wiki/Loop_quantum_gravity

Edge magazine Susskind interview, discussion Susskind w. Smolin, Steinhardt etc.
http://www.edge.org/discourse/landscape.html

Enrique Alvarez "Loops versus Strings"
http://arxiv.org/abs/gr-qc/0307090

Enrique Alvarez 2004 survey same topic: Quantum Gravity approaches
http://arxiv.org/abs/gr-qc/0405107

Lee Smolin "How far are we from the quantum theory of gravity?" 2003 essay
http://arxiv.org/abs/hep-th/0303185

It is good to try to keep to recent (2003 and 2004) sources because the
situation and relative position is changing

 

[PRodQuanta]

Thanks a lot marcus, this helps a whole lot. Although, to everybody else, I'm still open to forum discussion.
Paden Roder

P.S.- I'll let you know what I think of the articles.