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Talk:Counterexamples to Relativity (view source)

Revision as of 17:43, August 14, 2010

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Reverted edits by NotesTH (Talk) to last revision by Aschlafly

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::: (From [[Talk:Global Positioning System]])

::: [[User:RonLar|RonLar]] 12:44, 3 August 2010 (EDT)

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I think that the following article: [http://relativity.livingreviews.org/Articles/lrr-2003-1/ | Relativity in the Global Positioning System] - provides some interesting discussion of relativistic effects as applied to GPS. Effects certainly have to be taken into account and neglecting the effects of both time dilation and gravitational (!) dilation can have dire consequences. Such a calculation is not too unfamiliar in typical undergraduate courses on SR/GR (see Hartle's book on GR for some good discussions on this topic). 14th August 2010 (EDT)

== Several Clarification/Corrections ==

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: Relativity does imply that space as well as space-time are curved. The observation of a flat universe does contradict what would be expected if Relativity were true.--[[User:Aschlafly|Andy Schlafly]] 10:03, 13 August 2010 (EDT)

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:: A trivial solution to Einsteins field equations for a vacuum can result in Minkowski spacetime. This is a 4D metric describing a pseudo-Riemannian manifold with no spatial curvature (i.e. flat). A requirement of GR is that in locally inertial frames (i.e. small enough regions of spacetime) we recover Minkowski spacetime. It's just that in GR the requirement of a locally Minkwoski spacetime does not always extend to a global case with curvature effects breaking down the notion of inertial frames for all observers. The observation of a flat Universe (spatial curvature parameter, K = 0 in the FLRW metric) is not in violation of GR and is a valid solution to Einsteins field equations (see e.g. [http://en.wikipedia.org/wiki/Friedmann_equations | Friedmanns Equations]) and a prediction of models of inflationary cosmology whereby a rapid expansion in the early Universe drives the Universe towards a spatially flat solution, certainly within the observable Universe. Predictions from GR are still obeyed... 14th August 2010

== Reversion explained ==

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::: Energy does not remain fixed as velocity increases to the speed of light. You seem to be avoiding the central point.--[[User:Aschlafly|Andy Schlafly]] 11:11, 11 August 2010 (EDT)

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:::: You need to distinguish between massless and massive objects. Energy is given by the relativistic formula: <math> E^2 = p^2 + m^2 </math> in units where <math> c = 1 </math>. For a photon: <math> E = pc </math>. A key point to take from the SR equations for energy is that you do get problems when you try to accelerate a massive object to <math> v = c </math>. Should also be mentioned that modern particle accelerators can accelerate particles to velocities <math> v \approx c </math>. See: [http://en.wikipedia.org/wiki/Mass_in_special_relativity | Mass in SR] , [http://en.wikipedia.org/wiki/Special_relativity | SR] and [http://en.wikipedia.org/wiki/Photon | Photon].

== Wormholes ==

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Talk:Counterexamples to Relativity (view source)

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