TrappedLight Posted September 16, 2013 Share Posted September 16, 2013 I think gravity is actually a pseudoforce Link to comment Share on other sites More sharing options...
ajb Posted September 16, 2013 Share Posted September 16, 2013 I think gravity is actually a pseudoforce You can think of it that way as you can think of gravity as described by general relativity as an inability to pick true inertial frames of reference for macroscopic objects. You can also see this at the level of test particles and their geodesics, they have acceleration even though the "force term" is zero. Though I am not sure how useful the distinction between force and pseudoforce is in this context. We have accelerations of test particles and so a force, that maybe enough and the right way to think of it. Maybe not. Link to comment Share on other sites More sharing options...
TrappedLight Posted September 16, 2013 Author Share Posted September 16, 2013 Well, I do know one important difference and that is gravity does not have a physical mediator. If it did have one, it wouldn't be a pseudo force. Link to comment Share on other sites More sharing options...
ajb Posted September 17, 2013 Share Posted September 17, 2013 Well, I do know one important difference and that is gravity does not have a physical mediator. If it did have one, it wouldn't be a pseudo force. I guess it depends on what we mean by a physical mediator. You can certainly describe gravity as space-time curvature and so "space-time geometry" is the mediator. There are various standard ways of describing the gravitational field, or better put the gravitational degrees of freedom in general relativity such as the metric itself or the Christoffel symbols and so on. Link to comment Share on other sites More sharing options...
TrappedLight Posted September 17, 2013 Author Share Posted September 17, 2013 Well, physical mediator, the graviton for example. If a graviton is found, then gravity is not a pseudo force. Link to comment Share on other sites More sharing options...
ajb Posted September 18, 2013 Share Posted September 18, 2013 Well, physical mediator, the graviton for example. If a graviton is found, then gravity is not a pseudo force. By mediator you mean "exchange particle". Right, quantisation of gravity is, as you know, very difficult and no satisfactory theory exists today. So one has to take care when discussing gravitons, but you can discuss them in terms of quantum general relativity as an effective theory and so any discussion of gravitons should be done there. You should also be aware of the idea that gravity maybe asymptotically safe, that is it is a quantum field theory, just not a purturbative one. There maybe no gravitons in this theory! Link to comment Share on other sites More sharing options...
swansont Posted September 18, 2013 Share Posted September 18, 2013 Well, physical mediator, the graviton for example. If a graviton is found, then gravity is not a pseudo force. Wait. That means E&M was a pseudoforce before an exchange particle was found? No, I disagree. Link to comment Share on other sites More sharing options...
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