Quantum Spacetime Points & General Covarianceby stglyde Tags: covariance, points, quantum, spacetime 

#19
Dec411, 06:06 PM

Sci Advisor
P: 8,007

It is not so much that the LET aether frame is not "physical" as that it is not unique. The moment you have one LET aether frame, LET itself predicts that you have an infinite number of LET aether frames, all equally "physical". The equivalent statement in SR are that there is infinite number of Lorentz inertial frames, all equally preferred. Anyway, since you define LET as SR, let's just use the term SR to include LET. 



#20
Dec411, 06:46 PM

P: 275





#21
Dec411, 06:59 PM

Sci Advisor
P: 8,007





#22
Dec511, 03:25 AM

P: 275

"V > Velocity with respect to (wrt) the aetherial background (CMBR) v > Velocity of a second moving object (Frame), again wrt the aetherial frame dv > net differential speed LET and SR "are not 'identical' Lorentz says that velocity is dv = V  v and SR says dv = v. In SR one arbitrarily assumes a rest frame and in Lorentz's theory they do not. In Lorentz's theory it is ALWAY dv and in SR v relative to one's choice. Since the transform used only dv as in Sqrt(1  [dv/c]^2) the computed results are the same. Also, since dv is squared the sign (as in direction relative to V) is masked but actually important. There is NO symmetry in LET, the faster you move the more phyically time slowly and contracted you are, period! Finally, where in LET is relative simultaniety mentioned???" 



#23
Dec511, 04:07 AM

Astronomy
Sci Advisor
PF Gold
P: 22,808

Are you referring to the socalled Hole Argument? Are you saying that according to the (often cited) Hole Argument diffeo invariance implies that spacetime points don't have physical existence? 



#24
Dec511, 04:54 AM

P: 275

"It [the hole argument] is incorrectly interpreted by some philosophers as an argument against manifold substantialism, a doctrine that the manifold of events in spacetime are a "substance" which exists independently of the matter within it. Physicists disagree with this interpretation, and view the argument as a confusion about gauge invariance and gauge fixing instead." PeterDonis said: "In other words, the hole argument does not show that general covariance is inconsistent with spacetime being a "real thing". All it shows is that GR is a gauge theory." So it doesn't have to do with the Hole Argument. Unless you want to say it is indeed? What is your comment about "general covariance and diffeomorphism invariance require the spacetime points are not composed of any substance or something that can be tracked in time". Do you agree with it or disagree and why? Thanks. 



#25
Dec511, 08:37 AM

Sci Advisor
P: 8,007




Register to reply 
Related Discussions  
Distance between two points in spacetime  Special & General Relativity  22  
Spacetime Translational Invariance vs(?) Lorentz Covariance  Special & General Relativity  1  
Quantum mechanics holds only at discrete points in spacetime?  General Physics  1  
String irrelevant to quantizing General Relativity (quantum spacetime geometry)  General Physics  4 