Understanding Entropy and Gravity in Quantum Field Theory: A Beginner's Guide

In summary: But based on the information given, in summary, the author is discussing the relationship between a spherical volume in a quantized space and the maximum entropy of the system. They mention that in a local quantum field theory with a UV cut-off, the entropy would scale with the volume. However, once gravity is taken into account, this scaling would no longer hold true and would instead be influenced by dimensional reduction. This means that the entropy would be proportional to the surface area rather than the volume.
  • #1
M. next
382
0
I read a sentence that says if a spherical volume in placed in a quantized space then the maximum entropy of the system can be calculated and it after simple steps found to be:
S~V where V is the volume of the spherical volume.

"Then the author said: Each local quantum field theory(with UV cut-off, in this case the grid) will give rise to an entropy that scales in that way. But, once gravity comes into play, this will no longer be so. Gravity gives rise to so-called dimensional reduction."

Can someone explain to me (because I know nothing about quantum field theory what was meant by the quoted 2 sentences above)? Thank you in advance
 
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  • #2
I would take it to mean that it becomes proportional to the surface area rather than the volume.
 
  • #3
Which sentence are you talking about? I guess the second one. If so, what does this one mean "Each local quantum field theory(with UV cut-off, in this case the grid) will give rise to an entropy that scales in that way."

What UV cut off? "In that way"? What way?
 
  • #4
@M. next, please give the exact reference (author, title, journal, issue, page number, year published, and link to free version if possible) of the paper you are citing. At the moment, I think hardly anyone can understand your question because it is so bereft of context.

Incidentally, I believe the rule in all subforums of Physics Forums, except for "Beyond the Standard Model" is that papers discussed must have been published in peer reviewed journals, or come from sources of similar repute. Reputation does not imply correctness, and plenty of good stuff appears elsewhere, but because there is so much rubbish out there, I believe this is the rule that is used at PF.
 
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  • #5
I agree with atyy, it would be helpful to see the full context.
 

FAQ: Understanding Entropy and Gravity in Quantum Field Theory: A Beginner's Guide

1. What is entropy in quantum field theory and why is it important?

Entropy is a measure of the disorder or randomness of a system. In quantum field theory, it is a fundamental concept that helps us understand the behavior of particles and their interactions. It plays a crucial role in understanding the thermodynamic properties of a system and can provide insights into the evolution of the universe.

2. How is gravity incorporated into quantum field theory?

Gravity is one of the four fundamental forces in nature, and it is described by the theory of general relativity. In quantum field theory, gravity is incorporated by treating it as a quantum field, known as the graviton. However, the exact nature of this graviton and its interactions with other particles is still a topic of ongoing research.

3. Can quantum field theory explain the origin of the universe?

Quantum field theory provides a framework for understanding the behavior of particles and their interactions, but it does not address the origin of the universe itself. The theory of inflation, which is based on quantum field theory, offers a potential explanation for the rapid expansion of the universe in its early stages, but the ultimate origin of the universe is still a subject of speculation and ongoing research.

4. What are the challenges in understanding entropy and gravity in quantum field theory?

One of the main challenges in understanding entropy and gravity in quantum field theory is the lack of a unified theory that can fully explain these phenomena. The theories of general relativity and quantum mechanics are both highly successful in their respective domains, but they are fundamentally incompatible and cannot be used together to describe certain phenomena, such as black holes or the early universe.

5. How can a beginner approach learning about entropy and gravity in quantum field theory?

A beginner can approach learning about entropy and gravity in quantum field theory by first gaining a strong understanding of the basic principles of quantum mechanics and general relativity. They can then delve into the specific concepts of entropy and gravity in the context of quantum field theory, either through self-study or by taking a course or workshop on the subject. It is also helpful to stay updated on current research and developments in the field.

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