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Usefulness of a QG or a TOE?

  1. Dec 18, 2007 #1
    Can you tell me possible applications or uses of a theory of quantum gravity or a TOE?
     
  2. jcsd
  3. Dec 18, 2007 #2

    marcus

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    Well General Relativity is a theory of spacetime----the dynamics of it's geometry.
    A quantum theory of GR should reveal the fundamental degrees of freedom from which space and time arise---explain how matter interacts with geometry---and say why space is 3-dimensional, or why it is whatever dimensional it is.

    that is, a quantum GR should show us the microscopic mechanism from which matter and large scale geometry emerge, and the microscopic context in which matter and geometry interact.

    so the primary USE of quantized General Relativity is to answer certain questions like what is space, how does geometric distance interact with matter, what is matter (presumably some wrinkle or kink in geometry.)

    the SECOND USEfulness I would say is that quantum GR should stimulate a rebirth of the rest of fundamental physics----by getting particle field theory off of a static artificial minkowski space and getting it reformulated on a dynamic space with quantum geometry.

    So whatever particle physics is good for, has been good for in the past---quantum GR should rejuvenate particle physics and make it deeper and more useful---by forcing it to rebuild on a more realistic spacetime (more interactive with matter, less predictable).

    So whatever fundamental physics is good for. quantum GR is good for that. It's basic.

    However there is a THIRD USEfulness, which is simply to discover how to make small black holes. Small black holes would be a good source of energy, if one could make them out of stuff you didn't especially need. there might be other applications. Louis Crane (University of Kansas physics department) got a grant last year to look into that.

    Crane was also going to look into quantumgravity applications to rocket propulsion. Sounds pretty wacky but the point is that you never know what the applications of fundamental science are going to be whenever they finally impact the economic essentials ( energy, communication, transportation, materials,...whatever). It might take a thousand years to get to the really good applications---which is why it seems like a good idea to get busy with the theory.
     
  4. Dec 18, 2007 #3
    thank you marcus
     
  5. Dec 18, 2007 #4

    robphy

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    I would hope that a theory of QG or a TOE will clarify
    the roles of the various interpretations of quantum mechanics.
    Which interpretation, if any, is most fundamental?
     
  6. Dec 19, 2007 #5

    Fra

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    information approach

    I think it may depend also a little bit on who you ask, but I originally interpreted what the "TOE" would mean beyond traditional physics? My personal thinking, based on the information theoretic approach, is that I see a connection to artificial intelligence as a possible remote application. My own thinking has mostly circled around the connection to the scientific method and exactly how physical interactions relate to revision of predictions in a gaming bayesian sense. Once that program is worked out to a larger extent I see many solid applications that go way beyond traditional physics. This possible gain IMO, further increases the incentive for investing in this. Because it will not just lead to new "paper", I'm sure it will lead to rocking applications eventually.

    Congratulations to Marcus for his award!!

    /Fredrik
     
  7. Dec 19, 2007 #6

    marcus

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    thanks Fredrik, it's a source of real pleasure because we have a bunch of very good people in astro/cosmo and I respect the people who were voting.
     
  8. Dec 19, 2007 #7
    Another aspect where, maybe, a QG could help is in analizing the possibility of toplogial change in classical general relativity.

    Closely related to this is the possibility of existencence of wormholes (euclidean or even transversable ones).

    As a curiosity (almost CF fashioned) I shoulp point that beyond interstellar traveling a wormhole could have a more inmediate practical aplication. If one of the mouths of the wormhole would be nearby the sun and another nearby the eart the amount of solar energy that would arrive from the mounth of the wormhole could easily be greater than the amounth of energy that arrives in a natural way. And with an apropiate energy vector it could solve the energy problems of the industrial countries for their whole existence in a better way that eve nuclear fussion would do. As I say it is kind of CF, but in the end it could be easier than nuclear fussion, or black holes, well, maybe.
     
  9. Dec 19, 2007 #8

    Fra

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    While I see it from another angle I definitely share similar expectations. I expect the topology to be emergent, and from a gaming and learning analogy there would be in a given environment be expected a stable topology that should dynamically emerge. If the initial topology is not in equilibrium with the environment, it should eventually (taking some time due to inertia) adjust/learn/equilibrate to the optimum topology.

    Just like one would expect that an intelligent observer would even with incorrect or incompletely prior information, eventually from the interaction feedback. An observer, constructed as to NOT learn, would simply not survive, but it may well exist transiently.

    I think once we eventually understand this beyond this physics-only scale and combine it with powerful processing power it will probably revolutionize science in general, not just a part of the physics community.

    I think maybe this perspective is important from a social perspective to make non-physicists also understand the benefits. Most people will probably never face a black hole, and could think of a few other better ways to spend tax money. But if there are more spinoffs that may boost research in general, not to mention analysis of complex systems that is needed in medicin I think it gets more hands on. Ultimately I think this may help understand the "ultimate" (ie most scientific) way of processing information, for whatever benefit.

    /Fredrik
     
  10. Dec 19, 2007 #9
    Concerning quantum gravity:
    Applications -- mini black holes.
    Conceptually -- an understanding of the microscopic origin of inertia. What is mass, space and time. But I may be too optimistic here.
     
  11. Dec 19, 2007 #10
    This "geneticist" still insists:
     
  12. Dec 20, 2007 #11

    Fra

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    I figure that was what you were fishing for. Maybe the geneticists is refering to stuff like string theory :eek: :wink:

    /Fredrik
     
  13. Dec 20, 2007 #12

    robphy

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    Do you have the same feeling towards, say, the quantum theory of electromagnetism? ...whose success was inspiration for attempts to create a quantum theory of gravity.

    (In some sense, the classical theory of electromagnetism [the Maxwell Equations] could be regarded as the unified field theory of the 19th century... unifying electricity, magnetism, and optics. Near the end of that century, many thought that the "end of physics" was in sight and that all that was left was to measure some parameters and work out the implications.)
     
  14. Dec 20, 2007 #13
    Indeed. In my opinion, the quest for quantum gravity raises the most fundamental questions in physics. I thought that the complete understanding of nature and its laws was the primary (and ultimate) goal for physics, rather than the various technological achievements. Isn't it?
     
    Last edited by a moderator: Dec 20, 2007
  15. Dec 20, 2007 #14
    science that really makes a difference

    All scientific activities are supposed to "make a difference": each on their discipline. Science is the human endeavor to understand nature. This is the "difference": to understand or not to understand.

    Best,
    Christine
     
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