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Bojowald's What happened before the Big Bang? article in the August 2007 issue of NATURE PHYSICS is available to non-subscribers
To get the article directly in HTML
http://npg.nature.com/nphys/journal/v3/n8/full/nphys654.html
Or you can go thru the Table of Contents and see the other articles in the journal.
http://npg.nature.com/nphys/journal/v3/n8/index.html
During August it was accessible only if you paid, but they just made it free.
The link gives the TOC for the August issue.
Scroll halfway down the page to where it says LETTERS and click on the PDF for the Bojo piece.
In this piece Bojowald derives (in the context of his quantum cosmology model) some definite limitations on what can be known about the universe prior to the beginning of expansion. Even though the singularity is no longer there, in the Loop Cosmology model, a Heisenberg-like principle of indeterminacy limits knowledge in some (but not all) respects.
Bojowald was just awarded the Xanthopoulos prize for his work in quantum cosmology. This was presented at the international conference of General Relativity and Gravitation (GRG) people that is held every three years.
In past years (1993 and 2001) famous string theorists have been awarded the prize. I think it is nice to see Bojowald (and Thiemann who was honored along with him) get the recognition----they do nonstring quantum gravity.
I suppose part of the news about the Nature Physics article is that it is prominent among peer-reviewed journals specializing in physics. Has the highest IPI impact rating--a measure of citations per article. (It's a subsidiary of the weekly NATURE.) It's a good place to publish---prestige and visibility-wise. Bojowald normally publishes in Physical Review Letters (PRL) and in Physical Review series D (PRD). These are good solid journals but his piece in Nature Physics caused a bigger splash.
===commentary on the Bojo article===
Carlo Rovelli is one of the founders of Loop Quantum Gravity and the author of the book Quantum Gravity published in 2004 by Cambridge University Press.
He had some comments on Martin Bojowald's article in the August issue of NP.
Here is Rovelli's commentary, just over one page
http://npg.nature.com/nphys/journal/v3/n8/full/nphys690.html
Here is a sample:
Science has frontiers; sometimes these frontiers move. One of the most impressive of science's frontiers is the Big Bang, and now a quantum theory of gravity — loop quantum gravity — is providing equations with which to explore it. Although these equations are still tentative, and rely on drastic approximations, they introduce a definite method of exploration, and are capable of describing the Universe not only close to the Big Bang but also beyond it. It is in this context that Martin Bojowald reports, in this issue, on the possibility of a peculiar limitation to our ability to observe fully the 'other side' of the Big Bang — whatever that expression might mean (Nature Phys. 3, 523–525; 2007).
To get the article directly in HTML
http://npg.nature.com/nphys/journal/v3/n8/full/nphys654.html
Or you can go thru the Table of Contents and see the other articles in the journal.
http://npg.nature.com/nphys/journal/v3/n8/index.html
During August it was accessible only if you paid, but they just made it free.
The link gives the TOC for the August issue.
Scroll halfway down the page to where it says LETTERS and click on the PDF for the Bojo piece.
In this piece Bojowald derives (in the context of his quantum cosmology model) some definite limitations on what can be known about the universe prior to the beginning of expansion. Even though the singularity is no longer there, in the Loop Cosmology model, a Heisenberg-like principle of indeterminacy limits knowledge in some (but not all) respects.
Bojowald was just awarded the Xanthopoulos prize for his work in quantum cosmology. This was presented at the international conference of General Relativity and Gravitation (GRG) people that is held every three years.
In past years (1993 and 2001) famous string theorists have been awarded the prize. I think it is nice to see Bojowald (and Thiemann who was honored along with him) get the recognition----they do nonstring quantum gravity.
I suppose part of the news about the Nature Physics article is that it is prominent among peer-reviewed journals specializing in physics. Has the highest IPI impact rating--a measure of citations per article. (It's a subsidiary of the weekly NATURE.) It's a good place to publish---prestige and visibility-wise. Bojowald normally publishes in Physical Review Letters (PRL) and in Physical Review series D (PRD). These are good solid journals but his piece in Nature Physics caused a bigger splash.
===commentary on the Bojo article===
Carlo Rovelli is one of the founders of Loop Quantum Gravity and the author of the book Quantum Gravity published in 2004 by Cambridge University Press.
He had some comments on Martin Bojowald's article in the August issue of NP.
Here is Rovelli's commentary, just over one page
http://npg.nature.com/nphys/journal/v3/n8/full/nphys690.html
Here is a sample:
Science has frontiers; sometimes these frontiers move. One of the most impressive of science's frontiers is the Big Bang, and now a quantum theory of gravity — loop quantum gravity — is providing equations with which to explore it. Although these equations are still tentative, and rely on drastic approximations, they introduce a definite method of exploration, and are capable of describing the Universe not only close to the Big Bang but also beyond it. It is in this context that Martin Bojowald reports, in this issue, on the possibility of a peculiar limitation to our ability to observe fully the 'other side' of the Big Bang — whatever that expression might mean (Nature Phys. 3, 523–525; 2007).
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