How Does Quantum Gravity Connect Relativity and Quantum Mechanics?

[professor]

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

 

[professor]

and yes i know it has only been theorized...

 

[Locrian]

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.

 

[selfAdjoint]

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.

 

[professor]

alright thanks that gives me somehing to consider ...if anyone feels they have something elste to add on the subject, let me know

 

[Enos]

From what I view gravity, quantum gravity should include the uncertianty principle and it's relations to electromagnetism.

 

[dwilkerson]

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.

 

[heimdall0]

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".)

 

[professor]

perfect...exaxtly what i was looking for