Entirely academic futile exercise, for the twins to EVER expect to
meet again! (and thereby compare their elapsed times/clocks/ages).

kenseto wrote:

"Tom Roberts" <tjroberts@lucent.com> wrote in message
news:d4j5om$4a4@netnews.proxy.lucent.com...

kenseto wrote:

[... something about clock seconds]

_YOU_ are the only person who tries to do that. And you repeatedly
display how confused you are, most likely because of this misguided
attempt to compare "clock seconds".

So are you saying that the traveling twin's clock has less clock seconds
than the stay at home clock when they rejoin is not a valid comparison??

think you are wrong.

Please LOOK up there and READ what I wrote. I am explicitly saying your
quest for "clock seconds" is doomed.

In SR, Each twin interprets the "passage of time" to be what a
collocated and comoving clock indicates. These clocks are _DIFFERENT_
for the two twins, because the two twins move differently.

This is just a different way of saying that the clocks are running at
different rate due to their different states of absolute motion.

No, it is not. Not even close.

There is no "absolute motion" in SR, and
all clocks "run at their normal rate" as long as they are at rest in
some inertial frame, _ANY_ inertial frame.

And yet clocks at rest in
different inertial frames do not remain synchronized -- the situation is
more subtle than your sound bites can discuss -- _THAT_ is your basic
problem.

But this is
still comparing the rate of passage of clock seconds in the two frames.

No, it is not. See above.

The comparison between the twins' clocks when they rejoin is of ELAPSED
PROPER TIMES, and not anything at all related to "clock seconds".

Between their
separation and rejoining, the two twins' clocks indicate different
elapsed proper times. The comparison is of ELAPSED PROPER TIMES and not
any sort of "clock second".

So are you saying that the accumulated clock seconds on each clock is

the elapsed proper time??

No. I'm saying that elapsed proper time is elapsed proper time. <shrug>

"jem" <xxx@xxx.xxx> wrote in message
news:g1rbe.33168$d43.26413@lakeread03...

Tom Roberts wrote:

kenseto wrote:

"Tom Roberts" <tjroberts@lucent.com> wrote in message
news:d4ivcm$2md@netnews.proxy.lucent.com...

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.

No, it does not.

Then why do you compared the twin's clock second directly with the

at
home clock second to reach the conclusion that the traveling twin ages
less?

_YOU_ are the only person who tries to do that. And you repeatedly
display how confused you are, most likely because of this misguided
attempt to compare "clock seconds".

In SR, Each twin interprets the "passage of time" to be what a

and comoving clock indicates. These clocks are _DIFFERENT_ for the two
twins, because the two twins move differently. Between their separation
and rejoining, the two twins' clocks indicate different elapsed proper
times. The comparison is of ELAPSED PROPER TIMES and not any sort of
"clock second".

Bottom line: compare only things that are DIRECTLY MEASURABLE. So just
before the twins separate, compare the values indicated on their clocks
(when they are together). And just after they rejoin, again compare the
values indicated on their clocks (when they are together). Anything

depends in gory detail on HOW you perform the comparison. Accept the
difference in elapsed proper times as a difference in elapsed proper
times, and make no attempt to interpret it as some sort of "clock
second".

But the measurement of the elapsed proper time *is* the number of "clock
seconds" (i.e. ticks) recorded on each clock, so Seto's question is a
natural one: if the "time content" of those clock seconds (i.e. tick
intervals) differs between the two clocks, then how is it that a direct
comparison of the tick counts reflects a difference in elapsed times?

Don't be caught by the trolling, Ken asked a
trick question.

Notice he wrote '"duration"
(universal time?)' but duration is proper time
while universal time implies a preferred frame
and hence any real clock measure would be a
coordinate time. He puts them together so that
whichever meaning you assume, he can choose the
other.

Similarly, he sometimes talks of comparing
"clock seconds" but if you give a sensible
answer to that he will switch to discussing the
duration of the trip which is the number of
seconds, not the length of a second.

There is no content in these posts, just word
games, pure trolling.

jem wrote:

But the measurement of the elapsed proper time *is* the number of "clock
seconds" (i.e. ticks) recorded on each clock,

If kenseto used normal English, one would imagine that to be the case.
But he doesn't, and he means something else by "clock second".

For instance:
kenseto said:

Clock time is not invariant.

The value displayed on a particular clock _must_ be invariant, because
the value it displays cannot possibly depend upon how one looks at the
clock.

Bottom line: In SR and GR the elapsed proper times shown by the clocks
in a twin scenario will differ. But one cannot infer from this that the
clocks themselves "ticked at different rates".

In SR/GR, clocks always tick at their usual rates,

but the elapsed proper time between two
points in spacetime depends on the path taken between them -- this is
_geometry_, not any sort of change in "tick rates".

Yhis is the same as the odometer distance between two points
on the globe depends upon the path taken between them. This is
directly analogous, as both odometer distance (on the globe)
and elapsed proper time (in SR) are measures of path length.


Tom Roberts

jem wrote:

But the measurement of the elapsed proper time *is* the number of "clock
seconds" (i.e. ticks) recorded on each clock,

If kenseto used normal English, one would imagine that to be the case.
But he doesn't, and he means something else by "clock second".

For instance:
kenseto said:

Clock time is not invariant.

The value displayed on a particular clock _must_ be invariant, because
the value it displays cannot possibly depend upon how one looks at the
clock.

Bottom line: In SR and GR the elapsed proper times shown by the clocks
in a twin scenario will differ. But one cannot infer from this that the
clocks themselves "ticked at different rates".

In SR/GR, clocks always
tick at their usual rates,

but the elapsed proper time between two
points in spacetime depends on the path taken between them -- this is
_geometry_, not any sort of change in "tick rates".

Yhis is the same as the odometer distance between two points
on the globe depends upon the path taken between them.

This is
directly analogous, as both odometer distance (on the globe)
and elapsed proper time (in SR) are measures of path length.

jem wrote:

But the measurement of the elapsed proper time *is* the number of
"clock seconds" (i.e. ticks) recorded on each clock,

If kenseto used normal English, one would imagine that to be the case.
But he doesn't, and he means something else by "clock second".

For instance:
kenseto said:

Clock time is not invariant.

The value displayed on a particular clock _must_ be invariant, because
the value it displays cannot possibly depend upon how one looks at the
clock.

Bottom line: In SR and GR the elapsed proper times shown by the clocks
in a twin scenario will differ.

clocks themselves "ticked at different rates".

tick at their usual rates,

points in spacetime depends on the path taken between them -- this is
_geometry_, not any sort of change in "tick rates".

Yhis is the same as the odometer distance between two points
on the globe depends upon the path taken between them. This is
directly analogous, as both odometer distance (on the globe)
and elapsed proper time (in SR) are measures of path length.