🚀 go-pugleaf

On Apr 10, 8:26 am, Pentcho Valev <pva...@yahoo.com> wrote:
> On Apr 9, 10:33 pm, Tom Roberts <tjroberts...@sbcglobal.net> wrote in
> sci.physics.relativity:
>
>
>
> > bill wrote:
> > > A person is located on a mountain top and is looking at a (very large)
> > > clock (B) at sea-level.
> > > He notices that clock B is ticking over at a slower rate than his own
> > > clock (A) as theorized by Einstein in general theory and as ratified
> > > by the Wallops Island experiment where a clock at sea-level, being
> > > located in a strong gravitational tidal area, will tick over at a
> > > slower rate than an identical clock on top of a mountain that is in a
> > > weaker gravitational tidal area.
>
> > Note that what you call "gravitational tidal area" is really called
> > "Newtonian gravitational potential", valid in the Newtonian
> > approximation to GR. Indeed, tidal forces/effects are not involved
> > (tidal forces are second derivatives of the Newtonian potential).
>
> > Note that while A _SEES_ B tick at a slower rate, this does not imply
> > that clock B actually ticks at a slower rate than clock A. Indeed, in GR
> > this is modeled as an artifact of the COMPARISON [#], not as an effect
> > or modification of the clocks themselves: both clocks tick at their
> > usual (proper) rates, but their tick rates appear different when
> > situated and compared as you describe.
>
> >         [#] This comparison is via EM signals in curved spacetime.
>
> > > Is he entitled to be of the opinion that if he were to move to sea-
> > > level his clock would be subjected to the same 'law' of physics thus
> > > it will then be ticking over at a slower rate than it is before he
> > > starts his descent?
>
> > No. See above -- this is not an effect ON THE CLOCKS, but rather OF THE
> > COMPARISON. Note that he is entitled to expect that if he carries his
> > clock down and puts it right next to B that the two clocks will tick at
> > the same rate.
>
> > Your statements are expressed with the implicit assumption there there
> > is some "global", "universal", or "absolute" way to determine a clock's
> > tick rate. In GR there is no such thing -- all you can do is compare
> > clocks to other clocks; the method of comparison can, and usually does,
> > affect the result.
>
> > Tom Roberts
>
> Honest Roberts, your cleverer brothers Einsteinians expose the
> "artifact of the COMPARISON" in a somewhat clearer way:
>
> http://www.people.fas.harvard.edu/~djmorin/book.html
> Chapter 14: "The equivalence principle has a striking consequence
> concerning the behavior of clocks in a gravitational field. It implies
> that higher clocks run faster than lower clocks. If you put a watch on
> top of a tower, and then stand on the ground, you will see the watch
> on the tower tick faster than an identical watch on your wrist. When
> you take the watch down and compare it to the one on your wrist, it
> will show more time elapsed."
>
> However, Honest Roberts, even your cleverer brothers Einsteinians
> would never answer the following question:
>
> Is the "artifact of the COMPARISON" (that is, gravitational time
> dilation) consistent with Einsteiniana's dicovery that the speed of
> light is CONSTANT in a gravitational field, or is it consistent with
> Einsteiniana's discovery that the speed of light is VARIABLE in a
> gravitational field and obeys e.g. Einstein's 1911 equation c'=c(1+gh/
> c^2) given by Newton's emission theory of light?
>
> Pentcho Valev
> pva...@yahoo.com

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changes    in 'time'
do not occur in a' static' situation
2
if you have a watch  that is operated say by a spring
its time will not be dependent on its movement
(it   depends only on the spring that operate it )

it i s   only  velocity  changes (distortions of )
  velocities **in comparison** to other
objects that move in different   reference frames
iow
 i would prefer  to   deal with relative velocities
rather than about 'Time' changes
that seems to  me a  much    better real    physics

ATB
Y.Porat
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