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Results tagged with Search options questions only user 1325
19
votes
1answer
c \left(1 - \frac{r_s}{r}\right) \tag{1} $$ But this is a coordinate speed, a three-vector, not a covariant object and so it has no absolute meaning. Is there an easy way to see that this is just the speed for a particular observer and that other observers will measure a different speed? …
asked Apr 14 '18 by John Rennie
82
votes
8answers
Suppose we have two twins travelling away from each other, each twin moving at some speed $v$: Twin $A$ observes twin $B$’s time to be dilated so his clock runs faster than twin $B$’s clock. But tw …
asked Jan 30 '18 by John Rennie
120
votes
9answers
This question was prompted by Can matter really fall through an event horizon?. Notoriously, if you calculate the Schwarzschild coordinate time for anything, matter or light, to reach the event horizo …
asked Oct 29 '13 by John Rennie