Underlying papers are: J. W. Barrett, “Holonomy and path structures in general relativity and Yang-Mills theory”. Int. J. Theor. Phys., 30(9):1171–1215, 1991 & arxiv.org/0705.0452
Details of the LQG quantization: http://www.hbni.ac.in/phdthesis/phys/PHYS10200904004.pdf
The difference with canonical quantization is discussed at https://arxiv.org/pdf/gr-qc/0211012.pdf and does not seem (of course earlier paper) to address the issue raised above.
Any known update on this?
Im just curious...
hi
can someone please help me to understand the loop quantum gravity
in particular :
1- why the loop ?
2- what does mean a loop ?
3- why the space time is discrete ?
(especially) 4- how a loop can give us general relativity i.e. the metric tensor/riemann tensor ? (how to reconstruct classical general relativity from these loops?)
and Thank you in advance
(I saw a lot of books but I did not understand this theory and these questions
I have some knowledge in general relativity, quantum mechanics, quantum field theory)
As my first post on this subreddit, i’d just like to mention that i’m not a physics student. I discovered my interest in the field a little late so unfortunately I don’t have the correct foundation to grasp the knowledge, but I can’t help it, its so intriguing!
As for the question, I recently learned about loop quantum gravity and that certain schools believe it better unites quantum mechanics with GE than does string theory. Is there proof of this, or is it merely a matter of subjectivity? And also, by extension, to what degree have both theories (string theory and LQG) been proven?
Thanks in advance!
I'm not qualified to give an opinion about this, but quantum loop gravity sounds cooler ngl
Hi r/AskPhysics!
I've read that spacetime intervals are discrete in loop quantum gravity. Before posting, I used this NOVA article to refresh my memory.
I know that a function must be continuous in order to be differentiable and/or integrable. Which leaves me wondering: how is calculus used in LQG? Can you take derivatives and integrals with respect to space and time?
In my sequences and series course, we use the workaround of defining a new continuous function (say, f(x) ) that behaves identically to the original ( f(n) ) for discrete values (x = n). Is something analogous or similar used in LQG?
My experience in discrete math is limited to the aforementioned calculus course and statistics (from OpenStax^(TM) Introductory Statistics).
Thanks in advance for your responses!
There’s a lot of debate in the scientific community, especially between the validity of string theory and if there’s a better theory that can compete with it.
There’s also the fact that universities and colleges have gotten a lot worse recently and that new theories get “disproved” too quickly.
Nowadays the only thing left in science specifically physics/quantum physics is a theory of everything, basically explaining what the particles are “made of” and explaining dark matter and energy. If we understood dark energy and matter we would know how the universe would end and most likely how it started.
This could be the theory of everything, however, I think the deeper question would be what’s beyond “this universe”.
I think the most logical assumption would be simulation theory. The most fundamental particles we have discovered for example a photon are just blip of “energy” with information on how it interacts with spacetime.
Assuming simulation theory is true the only thing I can visualize above us is another universe possibly with different laws of physics simulating us on a machine that can solve problems. Then above that is another simulation, think of the simulation episode from rick and morty.
I’d like to believe multiverse theory is correct, however, the laws of physics don’t allow us to leave this universe.
https://en.wikipedia.org/wiki/Loop_quantum_gravity
Very basically (it's of course more complicated than that) it would mean that the big bang is not created from "nothing" but it is a "bounce" from a previous universe that was ended.
I think it could fit with the sim theory (rebooting the universe every XX B years)
What do you think ?
Been reading some of Smolin's books from a layman position, and he seemed to think that this would be a productive step in describing Quantum Gravity.
Curious is anything has happened here in the last few years.
What do you guys think about scientific theories such as Loop Quantum Gravity (https://www.youtube.com/watch?v=QMpkFde3euA&list=PLCfRa7MXBEsq5JoO2gU3yWhxTr06SY2De), a theory that tries to unify General Relativity with Quantum Mechanics, and the simulation hypothesis? Wouldn't the need of a quantized space and time be a strong argument supporting the simulation hypothesis? I mean, a minimum possible "quantity" of space and time (10^-35 meters and 10^-43 seconds, for instance) would be very logical if we live in a simulated universe.
I hope the idea also resonates with you as well as it does with me.
I'm only in my sophomore year in high school, and they don't teach particle physics here at my school. I've read some books on String Theory, but recently I came across "loop quantum gravity" and I don't really understand what it is.
hi
can someone please help me to understand the loop quantum gravity
in particular :
1- why the loop ?
2- what does mean a loop ?
3- why the space time is discrete ?
(especially) 4- how a loop can give us general relativity i.e. the metric tensor/riemann tensor ? (how to reconstruct classical general relativity from these loops?)
and Thank you in advance
(I saw a lot of books but I did not understand this theory and these questions
I have some knowledge in general relativity, quantum mechanics, quantum field theory)
where does loop quantum gravity comes from ?
