"Dirk Van de moortel" wrote
in message ...

"Simple Simon" wrote in message
.. .
Why is there no corresponding distance or mass phenomenon to the time
phenomenon of the "Twins Paradox" ? Where is the asymmetry?

I've seen a condition that space is isotropic but space and time are
homogeneous (isn't time also isotropic?) If this explains the lack of
symmetry, how does it do so?

According to the stay-at-home twin the trip takes a time T
and the total distance covered is L.
According to the travelling twin the trap takes a time T/gamma
and the total distance covered is L/gamma.
So there is no "lack of symmetry" between space and time.

Mass is an invariant:
http://math.ucr.edu/home/baez/physic...y/SR/mass.html

[followup set to sci.physics.relativity]

Dirk Vdm


Thank you.
I thought that without acceleration, when they are moving away from each
other with constant velocity, the application of gamma applies to each one
viewing the other's inertial frame symmetrically. It is only when one twin
returns to the other's frame (or accelerates at all) that an asymmetric
discrepancy accumulates. That is, without acceleration, if the distance of a
phenomenon is measured in stay-at-home twin's frame (they are both stay at
home and travelling without acceleration, but rather than A and B....) then
the distance of the phenomenon that is measured by the travelling twin is
L/gamma, and vice versa (if the distance of a phenomenon is measure in the
travelling twin's frame is L then the distance of the phenomenon measured in
the stay-at-home twin's frame is L/gamma).
After the travelling twin accelerates, and thereby changes it's inertial
frame, the times and distances measured of phenomena change (with no motion
within the frame itself to account for the changes in position). When the
travelling twin returns home, it's accumulated time (ticks of a clock) is
different than the accumulated time (ticks of a clock) for the stay-at-home
twin, yet no meter stick has an accumulated discrepancy (when the travelling
twin returns to the stay-at-home twin's frame; though there would be a
corresponding discrepancy in the accumulated distances traveled of cyclic
motion within the travelling twin's frame). Could this discrepancy (what I
called asymmetry) be that "local" time is "ordinal" and distance or length
is "cardinal"; that local time is an index of spatial recursion (cyclic
motion)? Or am I all wet?

I was apparently referring to "relative" mass.

Thank you.