kenseto wrote:

"jem" wrote in message
news:IGOae.32553$d43.18173@lakeread03...

kenseto wrote:


The SRians Said: Time is What the Clock Measures

This definition for time implies that a clock second represents the same
"duration" (universal time?) in all frames. The SRians compare the

passage

of clock seconds directly in the twin paradox scenario confirms this
interpretation for time..

Question:
Does this mean that a clock second is an interval of universal time?

Yes


Ah....but this would mean the existence of universal time (absolute time)
which is denied by SR. Also this is in conflict with what Alan Lightman said
in his book "Great Idea in Physics" page 120. He said: a clock second in one
frame correspond to less than a clock second in another frame. So how do you
explain these apparaent contradictory statements?

Everyday language isn't the appropriate tool for describing what's going
on in Relativity (look to the mathematics of the SR model instead).

A stationary observer measures the duration of one second on a moving
clock to be less than one second on a stationary clock, and in this
sense clock seconds are of different durations in different reference
frames.

However, SR assumes all clocks are identical and are unaffected by
motion, so in this sense one second has the same duration in all
reference frames. Moving clocks simply accumulate fewer seconds than
stationary clocks. This desription is probably the better of the two.