Loop Quantum Gravity/Cosmology ~ for the layman?

In summary: It is a decent book. Honestly, I like them because they did not go to in depth with any math. I've read other misc papers that have been posted here at PF, but some of those equations make my head hurt. :shy:Yes, your assumption about "loops" as opposed to "strings" is correct. Loop Quantum Cosmology is the theory that is coming from the assumption of loops, while Loop Quantum Gravity is the potential theory of gravity. Loop Quantum Cosmology resolves the big bang into a big bounce, implying a repeating or bouncing universe.
  • #1
g33kski11z
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I've read Brian Greene's "Elegant Universe" and most of Lee Smolin's "The trouble with Physics". I found them both to be decent books. Honestly, I like them because they did not go to in depth with any math. I've read other misc papers that have been posted here at PF, but some of those equations make my head hurt. :shy: I really like how Greene explained the basics of string theory but, I haven't seen anything that was a LQG/C book/article for the layperson.

Is there anything that is available? free or not..
 
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  • #2
No there isn't! It is a big gap. Someone needs to write that kind of nonmathematical book.

You can always check at Abhay Ashtekar's personal website. He is currently the main leader in Loop Quantum Cosmology.
At his website he has links to popularizations (illustrated magazine articles) and what he calls "semipopular" writing.

some of the stuff at Ashtekar's website is about LQG (the full theory) and some is about LQC (the specialized application to cosmology, resolving the big bang into a big bounce).
We should sift thru it. Some is likely to be several years old. I don't know of anything that is perfect.

I just looked at Ashtekar's site
http://cgpg.gravity.psu.edu/people/Ashtekar/articles.html
and didn't see anything I especially liked in the "semipopular" articles list
He is probably too busy to update the collection of links.
 
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  • #3
marcus said:
Someone needs to write that kind of non mathematical book.
So, what are you doing over the next 6 months..:rofl:
But seriously, thanks for the link, I'll check it out. I also saw your thread with Singh's video.
I guess I'll be starting there..
marcus said:
..some of the stuff at Ashtekar's website is about LQG (the full theory) and some is about LQC (the specialized application to cosmology, resolving the big bang into a big bounce)...
Ok, I'm sure this is totally basic to you but, what is the difference between LQG & LQC. I'm assuming these are not about strings, but "loops" of some type? Working from that assumption, how does this make the big bang a bounce? Does that imply a "repeating or bouncing" universe of some sort? Is this the leading TOE candidate? .. sorry for my noobishness.
 
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g33kski11z said:
Ok, I'm sure this is totally basic to you but, what is the difference between LQG & LQC.

Loop Quantum Gravity is a potential theory of gravity, whereas Loop Quantum Cosmology is the cosmology coming from such a theory (in the same way that string/braneworld cosmology has its foundations in string theory).

I'm moving this to Beyond the Standard Model, since it is better suited there.
 
  • #5
cristo said:
Loop Quantum Gravity is a potential theory of gravity, whereas Loop Quantum Cosmology is the cosmology coming from such a theory.
Thank you for clearing that up for me. So, is my assumption about "loops" as opposed to "strings" correct?
 
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  • #6
Actually there is a book that talks about LQG at a popular level: "Three Roads to Quantum Gravity" by Lee Smolin.
 

1. What is Loop Quantum Gravity/Cosmology?

Loop Quantum Gravity/Cosmology is a theoretical framework that attempts to merge the theories of general relativity and quantum mechanics to explain the behavior of space and time at a very small scale, such as that of subatomic particles. It is a branch of theoretical physics that aims to provide a deeper understanding of the fundamental laws of the universe.

2. How does Loop Quantum Gravity/Cosmology differ from other theories of gravity?

Unlike other theories of gravity, such as Einstein's general theory of relativity, Loop Quantum Gravity/Cosmology takes into account the principles of quantum mechanics. This means that it describes the behavior of space and time at a microscopic level, where the effects of quantum mechanics are significant. It also suggests that space and time are made up of discrete, indivisible units called quanta, rather than being continuous.

3. What does Loop Quantum Gravity/Cosmology say about the origin of the universe?

Loop Quantum Gravity/Cosmology offers a different perspective on the origin of the universe compared to other theories. It suggests that the universe has always existed in some form, and that the Big Bang was not a singular event, but rather a cyclical process of expansion and contraction. This theory also predicts that there may be other universes beyond our own.

4. Can Loop Quantum Gravity/Cosmology be tested or proven?

At this point, Loop Quantum Gravity/Cosmology is still a theoretical framework and has not been fully tested or proven. However, there are ongoing experiments and observations that could potentially provide evidence for this theory. For example, the study of cosmic microwave background radiation and gravitational waves could reveal insights into the behavior of space and time at a microscopic level.

5. How does Loop Quantum Gravity/Cosmology impact our understanding of the universe?

Loop Quantum Gravity/Cosmology offers a new perspective on the fundamental laws of the universe and has the potential to bridge the gap between general relativity and quantum mechanics. If proven to be correct, it could greatly enhance our understanding of the behavior of space and time at a microscopic level and provide a deeper understanding of the origins and evolution of the universe.

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