On Tue, Jan 28, 2014 at 7:17 PM, Edgar L. Owen <[email protected]> wrote:
> Brent, > > But the twins DO AGREE on whose clock ran slower. > > So I don't see your point if you use the twins as evidence... > > Edgar > Edgar, can you please answer my question about whether, when you talk about one clock running slower than the other, you are A) talking only about what each twin sees visually (how much time elapses on my clock between light signals from successive ticks of a distant clock reaching my eyes), or B) the rate as judged in some coordinate system used by one of the twins, or C) something else? (A and B are the only methods I know of for comparing rates of clocks at different locations in relativity, so if you have anything else in mind please give details...and if you're talking about B, please specify the coordinate system you're thinking of). If you're talking about comparing rates in a purely visual sense, it may be true that they both agree on the binary question of whose clock is ticking faster, but they do *not* agree on the actual ratio of the rates of the two clocks, so this is not evidence for any "absolute" truth about how clocks slow down due to gravity. For example, if the falling twin passes a particular hovering marker during his fall, it might be true that when the faraway twin sees him passing the marker he sees the falling twin's clock running at half the speed of his own clock, but it could also be true that as the falling twin was passing the marker, he saw the faraway twin's clock ticking a bit faster than his own, but considerably less than twice as fast as his own. Jesse > > On Monday, January 27, 2014 3:27:54 PM UTC-5, Brent wrote: >> >> On 1/27/2014 7:48 AM, Edgar L. Owen wrote: >> > Jesse, >> > >> > First this doesn't have anything to do with present moment theory, only >> with standard >> > physics. >> > >> > 2nd, hopefully it's just a matter of you using different semantics than >> me as to what is >> > meant by absolute and relative. I'll explain once more. >> > >> > In the case of time dilation effects caused by gravitation or >> acceleration the effects >> > are absolute in the sense that both observers agree on them. Take 2 >> observers A in a >> > gravitational well and B not. In this case B observes A's clock SLOW, >> and A observes B's >> > clock rate SPEED up. They AGREE as to this effect. >> >> They can't agree on that. They can only agree via signals the their >> clocks *appear* to >> run at different rates. Just like the twins in the SR twin paradox. >> >> > AND the clock time difference PERSISTS after A and B meet up afterwards >> when their >> > clocks are again running at the same rate. Therefore in my terminology >> it is an absolute >> > effect. It is a real and actual effect, that both observers agree upon. >> This is well >> > understood and confirmed because it's used in GPS calculation >> corrections all the time. >> >> Yes, it's real that they have traveled through different intervals of >> spacetime - just >> like the twins in the twin paradox. >> >> You seem determined to ignore the basic principle of GR, it is a >> *geometric theory of >> spacetime* Geometry doesn't make clocks change speed. >> >> Brent >> > -- > 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. > -- 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.
