On Sun, Jan 26, 2014 at 12:47 PM, Edgar L. Owen <edgaro...@att.net> wrote:
> Jesse, > > No, you are just plain wrong here. It's simple relativity theory. Just > because observer A sees observer B's clock slow down does NOT mean observer > A sees observer B's MOTION slow down. In fact it is the increase in > velocity (or equivalently gravitation) that CAUSES his clock to slow in > observer A's frame. > You seem to be confused about special relativity vs. general relativity, the idea that time dilation is a direct function of velocity is only true in inertial frames in special relativity, it doesn't apply in the type of arbitrary non-inertial coordinate systems used in general relativity (inertial frames can only be used in flat spacetime, all coordinate systems covering non-infinitesimal regions of curved spacetime are considered non-inertial...and even in flat spacetime you are free to use a non-inertial coordinate system where time dilation is not just a function of velocity, as with "Rindler coordinates" discussed at https://en.wikipedia.org/wiki/Rindler_coordinates ). Gravitational time dilation in general relativity is considered a separate phenomenon from velocity-based time dilation in special relativity, see for example https://en.wikipedia.org/wiki/Time_dilation#Time_dilation:_special_vs._general_theories_of_relativity What's more, I wasn't even talking about "frames" (coordinate systems) in my previous comment at all, I was talking about frame-independent claims about what the distant observer *sees* in terms of light-signals from the falling observer--in other words, what the distant observer's own clock (i.e. his own proper time) reads at the moment he receives various light signals from the falling observer. To say he sees the falling observer's clock tick slower and slower means he records a greater and greater proper time on his own clock between receiving light-signals showing successive ticks of the falling observer's clock, a statement that doesn't refer to any specific frame of reference. This is again a matter of which events *locally* coincide (which light signals arriving at his location coincide with which readings on his own clock), which is how objective frame-independent facts are generally defined in relativity. Can you please answer the question I asked in the previous comment about whether you understand that in relativity, all observers and all frames must agree on the question of which events locally coincide at the same point in spacetime? In other words, for statements like this: "at the moment that the falling observer passed locally next to marker A hovering above the horizon, his own clock read 10 seconds" and "at the moment that the distant observer received a light signal showing that the falling observer's clock read 10 seconds, the distant observer's own clock read 100 seconds" ...do you agree that such statements are totally objective in the sense that all observers and frames must agree about them? Please answer yes or no, and your answer will suggest how this discussion should proceed (if "yes" I can ask you some more specific questions about my thought-experiment involving markers hovering above the horizon and how long the distant observer sees the falling observer take to pass successive pairs...if "no" then that suggests you are confused about a really basic point in relativity, which might explain your confusion about subjects like the sense in which the twins in the twin paradox have different ages at the "same time" when they reunite and compare ages locally). 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 everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
