Simple question on quantum gravity

In summary, the purpose of quantum gravity is to reconcile general relativity and quantum mechanics into a unified theory and potentially predict new phenomena. This is a challenging task due to the different foundations of the two theories, but various approaches have been taken by physicists. A key obstacle is how to handle renormalization in the combined theories.
  • #1
professor
124
0
here is a fairly simple question... is the purpose of quantum gravity to relate gravitation/relativity to our understanding of quantum machanics as is? I am not entirely sure on this, could someone explain
 
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  • #2
and yes i know it has only been theorized...
 
  • #3
Heh, I think the purpose of the search for quantum gravity is not as easy a question as you suggest. I, too, would like to know what current experiment's result cannot be found in current theory that quantum gravity will solve. Maybe someone will answer both our questions.
 
  • #4
professor said:
here is a fairly simple question... is the purpose of quantum gravity to relate gravitation/relativity to our understanding of quantum machanics as is? I am not entirely sure on this, could someone explain


The various quantum gravity programs are aimed at a consistent method of quantizing gravity that reduces to general relativity in the h -> 0 limit. Techniques of quantization used are the ones that have been developed for other quantum theories, especially quantum field theory.

Whether this quantization, if it is achieved will support "quantum mechanics as it is", by which I suppose you mean the Standard Model of particle physics, will be a matter of experiment. A theory of quantum gravity that wound up flatly denying what theory and experiment have shown us would be regarded as a failure.
 
  • #5
alright thanks that gives me somehing to consider ...if anyone feels they have something elste to add on the subject, let me know
 
  • #6
From what I view gravity, quantum gravity should include the uncertianty principle and it's relations to electromagnetism.
 
  • #7
Because the Standard Model doesn't include gravity and has dynamic parameters, a theory of quantum gravity is definitely needed. I believe it would bring us one step (actually many steps!) closer to a more "complete" unified theory of everything. We need a theory of quantum gravity to study the components of black holes and also for physics right after the Big Bang.
 
  • #8
professor said:
here is a fairly simple question... is the purpose of quantum gravity to relate gravitation/relativity to our understanding of quantum machanics as is? I am not entirely sure on this, could someone explain

The purpose of quantum gravity is to create a unified and consistent theory that reconciles quantum mechanics with general relativity, i.e., explains all the phenomena of both theories, and perhaps to predict new phenomena.

The most obvious obstacle is that quantum mechanics has been developed on a background of Newtonian space and time, i.e., flat space-time without curvature, while general relativity views gravitation not as a force, but as curvature of space-time induced by mass. One approach that has been taken is to modify quantum mechanics to work with curved space-time. An alternative approach is to construct a theory of gravity largely equivalent to GR but in flat space-time and then to integrate the two theories. Both approaches have been used by eminent physicists. I believe, but am not sure, that a more serious problem is how to handle renormalization in the combined theories. (In quantum field theory, many divergent series arise, whose values are computed using a variety of rules of thumb for ordering terms. This "dippy" process, as Feynman called it, is "renormalization".)
 
  • #9
perfect...exaxtly what i was looking for
 

1. What is quantum gravity?

Quantum gravity is a theoretical framework that aims to unify the principles of quantum mechanics and general relativity, the two main theories of physics that describe different aspects of the universe at a fundamental level.

2. Why is quantum gravity important?

Quantum gravity is important because it seeks to solve some of the biggest mysteries in physics, such as the nature of space and time, the origin of the universe, and the behavior of matter at the smallest scales. It also has potential implications for technology and our understanding of the universe.

3. How does quantum gravity differ from classical gravity?

Classical gravity, or general relativity, describes the force of gravity as a curvature of space and time caused by massive objects. Quantum gravity, on the other hand, incorporates the principles of quantum mechanics to explain the behavior of gravity at the smallest scales, where classical physics breaks down.

4. What is the current status of quantum gravity research?

Quantum gravity is still an active area of research, and there is currently no widely accepted theory. Several different approaches, such as string theory and loop quantum gravity, are being explored, but it is a challenging problem that has yet to be fully solved.

5. How does quantum gravity relate to the search for a unified theory of physics?

Quantum gravity is considered a key component in the search for a unified theory of physics, also known as the theory of everything. This theory aims to explain all physical phenomena in the universe using a single set of principles. If successful, it would revolutionize our understanding of the universe and our place within it.

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