On 04/01/2010 03:51 PM, Harry Veeder wrote: > > > > > ----- Original Message ---- >> From: Stephen A. Lawrence <[email protected]> >> To: [email protected] >> Sent: Thu, April 1, 2010 2:53:15 PM >> Subject: Re: [Vo]:checking my understanding of Lorentz contraction > > In short, acceleration >> does not slow down clocks. This is predicted > theoretically and has, >> IIRC, been confirmed experimentally. > > so contrary to Einstein's equivalence principle gravity and acceleration are > not equivalent?
Harry, please read the rest of what I wrote. The strength of the gravitational field doesn't affect time, and neither does the strength of acceleration. I'll say it again, but I'm getting a little hoarse with repeating it: Gravitational time dilation is a consequence of GRAVITATIONAL POTENTIAL, *not* GRAVITATIONAL FIELD STRENGTH. This is a confusing but important distinction. Gravitational time dilation can be predicted from an argument based on conservation of energy and the interconvertibility of mass and energy, as I showed in an earlier post. And it doesn't depend in any way on variations in the strength of the gravitational field. As to equivalence, an observer in a sealed spherical chamber in which there is a uniform "gravitational field" cannot determine by any experiment carried out within the chamber whether he is actually in an off-center spherical cave hollowed out of a uniformly dense spherical planet or is in a uniformly accelerating spaceship. But I am not going to go into the effects of an "acceleration field" on time measurements carried out over an extended volume, nor the Rindler horizon, in this post. > > Harry > > > > __________________________________________________________________ > Yahoo! Canada Toolbar: Search from anywhere on the web, and bookmark your > favourite sites. Download it now > http://ca.toolbar.yahoo.com. >
