On Sun, Jan 26, 2014 at 10:42 PM, Edgar L. Owen <[email protected]> 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.
