On 3/4/2014 11:19 AM, Jesse Mazer wrote:
On Tue, Mar 4, 2014 at 2:02 PM, Edgar L. Owen <edgaro...@att.net
<mailto:edgaro...@att.net>> wrote:
Jesse,
You ask me to choose between 1. and 2.
1. If B's proper age at this point in spacetime is T, then C's proper age
at this
point in spacetime must be T as well (i.e. their proper ages are
"simultaneous" in
the sense that they must reach the same age simultaneously).
2. If B and C's worldlines both pass through a specific point in spacetime
P, and
B's age is T1 when she passes through P, while C's age is T2 when she
passes through
P, then B must be at age T1 simultaneously with C being at age T2 (i.e.
whatever two
specific ages they have at P, they must reach those two ages
simultaneously, even if
the two ages are different)
First I assume that by "passing through the same point in spacetime" you
mean that
the worldlines cross at P simultaneously by the operational definition of
no light
delay.
1. is true only in a SYMMETRIC case. In the symmetric case they would have
the same
ages as they pass through the same point P, but in that case they have the
same ages
during the WHOLE trip so no big surprise.
This isn't true. In the inertial frame of a third party passing by, B and C age at
different rates in different segments of their world lines even though those rates
integrate to the same total aging between their two meetings.
Brent
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