Questions on LQG and LQC

[tholan]

But IN CONTEMPORARY WORK the approach to quantize Gen Rel is not timeless.

I guess I have a lot to learn about it. Thanks.

[Martin]

BTW Tholan, don't hesitate to disagree. I will try to look at it from your perspective. Here is a sense in which I am wrong and you are right!

Look at this recent Bojowald paper

http://arxiv.org/astro-ph/0511557

Universe Scenarios from Loop Quantum Cosmology

 

Bojowald is the founder of LQC and in this talk (aimed at cosmologists, or some wider audience) he presents LQC, the field he established, as an OFFSHOOT OF CANONICAL LQG

 

the original canonical formalism provides a historical justification for LQC, and we are constantly being reminded of this!

 

Paradoxically, I am telling you that I see LQC as a separate model that must be tested and must stand or fall on its own merits. The historical origin does not provide a logical or mathematical justification, even if Bojowald seems to suggest this.

 

In effect LQC has a discrete time-evolution operator given by a difference equation, and it has only a few degrees of freedom (like two:-) ) and is very amenable to calculation.

 

This paper I mentioned discusses predictions about astronomical observation that may be feasible for testing LQC. This is why I say it should be justified (or refuted) empirically on its own merits. It does not make sense to justify it by relating to the original mother theory because canonical LQG is itself not completed and confirmed!

 

But if you, tholan, are reading articles like this you can easily get the impression that the canonical LQG is like a foundation for LQC. I wish people would not talk like that, especially these days when very few people are working on the canonical formalism and the full QG theory is being developed in other directions.

 

It might be a good research project for someone to see if LQC can make contact with some other non-canonical formulation of QG.

 

I hope this makes sense and if there is something wrong with this view you will point it out. you could also give me some links to your sources, if you want

 

Now I am reading Bojo's paper "Universe scenarios from LQC". It just appeared today. I think it is a good paper and will be useful to a lot of people. I will try to read it also with your point of view and question in mind. Perhaps you will take a look too.