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. There is an actual absolute slowing of clock time in a gravity well. However it is obviously true that it will be measured differently in different frames and my other posts have discussed some of those ways it is. 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. 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. 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. 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. But in the case of relative velocity (NO acceleration or gravitation) both observers each see the other's clock slow relative to their own and both effects are equal. In this SR case if the relative velocity instantly stops (assuming no acceleration needed to stop it) then both clocks would instantly be running at the same rate and reading the same clock time. Thus that effect is relative, not absolute, because it does not persist after the source effect stops. So contrary to what you seem to be saying Gravitational time dilation is ABSOLUTE. The time dilation of relative motion is RELATIVE. Best, Edgar On Monday, January 27, 2014 12:51:28 AM UTC-5, jessem wrote: > > > On Sun, Jan 26, 2014 at 10:42 PM, Edgar L. Owen <[email protected]<javascript:> > > wrote: >> >> Once again my initial response to Jesse was because he claimed there was >> a pile up and their isn't >> > > > No I didn't. The very first comment of mine on the subject (you can review > it at > http://www.mail-archive.com/[email protected]/msg47085.html), > which prompted your dismissive "you have a basic misunderstanding of > relativistic time in your first paragraph" response, clearly stated the > difference between what would be seen by the external observer "in > practice" and what could be seen "in principle" if classical EM were > exactly correct: > > "the redshift is continually increasing as it approaches horizon so in > practice an external observer can't see an object stuck on the horizon > forever, but in > principle you could if you could detect light with arbitrarily huge > wavelengths, and if light was a classical EM wave rather than being > quantized into photons." > > > >> and second that he claimed (or at least that's the way I read his post) >> that the slowing of velocity was due to the slowing of the clock of the >> object approaching the black hole which it isn't. >> > > What I said was that you can derive the fact that he would (in principle) > see the falling observer take forever to reach the horizon from the fact > that he would (in principle) see the falling observer's clock running > slower and slower as it approaches the horizon, never quite reaching the > time that the falling observer actually crosses the horizon. Again this is > a statement about how he *sees* the falling observer's clock behave (the > distant observer's own clock time when light from various ticks of the > falling observer's clock reaches his own local position), not about any > non-visual "slowing of the clock of the object", like the rate it's ticking > relative to coordinate time in some coordinate system. > > It's still not clear if you understand the difference between objective > statements about which events coincide locally (you never did answer my > question about whether you agree that all observers/frames agree about > which events coincide locally at the same point in space and time) vs. > coordinate-dependent facts that depend on one's choice of coordinate > system. For example, you say "the photons they emit take longer and longer > to climb out of the increasing gravity well to reach the external > observer", but do you understand there's no objective truth about how long > the light takes to climb out of the gravity well, that this depends > entirely on the choice of coordinate system? Likewise, the issue of how > much the falling clock slows down as it approaches the horizon can only be > defined relative to a coordinate system (looking at the rate the clock's > proper time increases relative to coordinate time). Even if we completely > ignore the issue of the time for light to travel from the falling observer > to the distant observer, in Schwarzschild coordinates it is true that the > falling observer's clock ticks more and more slowly as it approaches the > horizon, with the rate of clock ticks approaching zero as it gets > arbitrarily close, so that it takes an infinite coordinate time to reach > the horizon. But in other coordinate systems like ingoing > Eddington-Finkelstein coordinates or Kruskal-Szekeres coordinates, the > falling clock reaches the horizon in a finite coordinate time. Also note > that in KS coordinates, light emitted outward by the falling observer > travels at exactly the same coordinate speed no matter how deep in the > gravity well it was emitted--though in these coordinates the distant > observer hovering at a constant Schwarzschild radius is actually > accelerating away from the black hole, with an ever-increasing radial > coordinate in KS coordinates. > > Jesse > -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
