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Talk:Counterexamples to Relativity (view source)
Revision as of 18:57, April 6, 2010
, 18:57, April 6, 2010→Reversion explained
::::Gravitons were historically proposed in trying to reconcile GR with QM. Other theories of gravity may not require gravitons at all. Does string theory? Gravitons are thereby attributable to GR, not to the more developed and better verified QM. ''Simply look at the name "gravitons" itself''.--[[User:Aschlafly|Andy Schlafly]] 00:23, 6 April 2010 (EDT)
::::Gravitons were historically proposed in trying to reconcile GR with QM. Other theories of gravity may not require gravitons at all. Does string theory? Gravitons are thereby attributable to GR, not to the more developed and better verified QM. ''Simply look at the name "gravitons" itself''.--[[User:Aschlafly|Andy Schlafly]] 00:23, 6 April 2010 (EDT)
:::::Actually, any quantum theory of gravity, whether it reduces to GR at large scales or not, requires gravitons ''by definition''. Do you even understand what a graviton ''is''? ''The quantum of a gravitational field.'' Just as any quantum theory of electromagnetism ''must'' include the photon in its particle spectrum, any quantum theory of gravity ''must'' include the graviton in its particle spectrum. And yes, string theory requires them; the entire reason string theory started being developed as a theory of everything is that gravitons (i.e. massless spin-2 bosons) naturally appear as part of its particle spectrum! [[User:Yill|Yill]] 14:57, 6 April 2010 (EDT)
::The "flatness problem" refers primarily to curvature expected from inflation, not GR itself. It is misleading to call the counterexample the "flatness problem," and then pretend it has a solution. The counterexample described is not resolved.--[[User:Aschlafly|Andy Schlafly]] 21:12, 5 April 2010 (EDT)
::The "flatness problem" refers primarily to curvature expected from inflation, not GR itself. It is misleading to call the counterexample the "flatness problem," and then pretend it has a solution. The counterexample described is not resolved.--[[User:Aschlafly|Andy Schlafly]] 21:12, 5 April 2010 (EDT)
::::A ''type'' of inflation is proposed to try to explain the unexpected flatness. But there's no way around the basic problem: GR says that space is curved by matter, and an overall flatness is impossible under such a model. Yet an overall flatness is what is observed.--[[User:Aschlafly|Andy Schlafly]] 00:23, 6 April 2010 (EDT)
::::A ''type'' of inflation is proposed to try to explain the unexpected flatness. But there's no way around the basic problem: GR says that space is curved by matter, and an overall flatness is impossible under such a model. Yet an overall flatness is what is observed.--[[User:Aschlafly|Andy Schlafly]] 00:23, 6 April 2010 (EDT)
:::::I still don't understand what you're saying. The ''overall'' visible universe ''is'' flat, at scales large enough that it can accurately be modeled as homogeneous and isotropic. (These scales are beyond the sizes of galactic clusters.) But on much smaller scales, where these assumptions obviously break down, matter does indeed curve spacetime; the phenomenon of gravitational lensing is precisely such an example. If you are at all confused by these different notions, I would recommend taking a look at a modern textbook on the subject; Barbara Ryden's ''Introduction to Cosmology'' is a good place to start. [[User:Yill|Yill]] 14:57, 6 April 2010 (EDT)