On Mon, Jan 27, 2014 at 8:50 AM, Edgar L. Owen <edgaro...@att.net> wrote:
> Hi Jesse, > > Sorry if I misunderstood you and for the dismissive comment.... I > apparently misread your comments... > > As for your other comments in this post. The slowing of the clock in a > gravity well is an absolute phenomenon, not a relative one. > Are you claiming this is true in relativity, or in your own theories about an absolute present? If you're talking about mainstream relativity you are incorrect, there is no "absolute" slowing of the clock. All arbitrary smooth coordinate systems are equally valid in general relativity, and one can certainly design a coordinate system whose simultaneity convention is such that the falling clock elapses more ticks in a given interval of coordinate time, not less (as in my example where both clocks read 0 when they pass next to each other, but simultaneity is defined in such a way that the falling clock reads 150 simultaneously with the hovering clock reading 100). If you disagree, please tell me which of my two claims you're disagreeing with (or if you disagree with both): 1. All smooth coordinate systems are equally valid in general relativity, the equations of GR work the same in all of them (see Einstein's statement at http://www.bartleby.com/173/28.html about arbitrary non-rigid reference frames, which he cutely calls "reference-mollusks", and his statement that "The general principle of relativity requires that all these mollusks can be used as reference-bodies with equal right and equal success in the formulation of the general laws of nature; the laws themselves must be quite independent of the choice of mollusk." Also see the "constructing an arbitrary reference frame" discussion on p. 8 of http://physics.mq.edu.au/~jcresser/Phys378/LectureNotes/VectorsTensorsSR.pdf) 2. Among all these arbitrary smooth coordinate systems, it's possible to come up with some where the falling clock ages more than the hovering clock between a pair of "simultaneous" moments in this coordinate system You could also try asking Brent, who mentioned that he's a physicist--I'm sure he would confirm what I'm saying. > > Finally there is no "pile up" at the horizon, as I thought you claimed > (you did use the term I think), because all infalling objects will fade > away proportionally to how much they appear to slow. > I did use the term, but only after I had already specified that I was talking about what would be true "in principle" if classical EM were exactly correct, and that the distant observer could detect EM waves that had been redshifted to arbitrarily high wavelengths. > So by the time they would begin to appear to pile up they are already > fading from view. Therefore NO PILEUP, period. I'm still not clear if you > understand this. It's NOT because of the red shift (which is occurring) but > because the slowing means fewer and fewer photons per unit time are > reaching the external observer. > As I said, I was talking about what would be true in classical EM, where light is not quantized into photons. > > That is because it takes them longer and longer to climb out of the > increasing gravity well. Contrary to what you seem to say that's an > absolute phenomenon, not just a matter of frames. > Not in relativity it's not. The arbitrary "reference mollusks" that Einstein talks about would include coordinate systems where the coordinate time for successive light signals to travel from the falling clock to the hovering clock was actually decreasing, not increasing. > The external observer is just in a minimally relativistic frame suitable > to measuring this effect fairly accurately. It will of course be measured > differently in other frames themselves subject to strong relativistic > effects. > > By GR, gravitational time dilation is an ABSOLUTE effect, contrary to the > time dilation of constant relative velocity, which is a RELATIVE SR effect. > The way you can tell is that if the black hole suddenly vanished the > previously infalling object's clock would still be reading a past clock > time even though it would now be running at the same rate as the clock of > the external observer. > I don't think there is any allowable spacetime (respecting the equations of GR) where "the black hole suddenly vanishes", so this isn't a physically meaningful scenario. One thing you could do would just be to bring the falling clock back up to the same position as the hovering clock, and compare their times locally--as I keep saying, the only objective truths in relativity are local comparisons at a common point in spacetime, all coordinate systems agree in their predictions about which events locally coincide. But even though it's true that the falling clock has elapsed less time when it's brought back up to the hovering clock and their readings are compared locally, you could have a coordinate system whose simultaneity convention was such that the falling clock had been ticking faster during its freefall towards the horizon, but then the hovering clock ticked even faster during the period when the fallen clock was brought back up to it, with the net result that the clock that fell had elapsed less time in total even though it elapsed *more* time during the freefall period. 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