The SRians Said: Time is What the Clock Measures

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. There's nothing "universal in all frames" here. And the
interval between ticks of a clock is not "the same duration in all
frames", in that the comparison of clocks at rest in different inertial
frames does not yield equality.

The basic underlying problem is your lack of understanding of the words
you use -- "universal" is a many-nuanced word, and you apply
unacknowledged PUNs among its different meanings:

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

The word "universal" has several connotations. Some apply, some don't.

This is "universal-1" in the sense that any observer interprets the
passage of time as indicated on a clock that always stays with her (i.e.
is comoving and colocated). It is not "universal-2" in the sense of
being the same in every frame -- for instance, clocks at rest in
different inertial frames to not remain synchronized with each other. It
is "universal-3" in that any clock at rest in any inertial frame will
remain in synch with a standard clock also at rest in the same frame.

[Throughout I'm assuming ideal, standard clocks.]

Attempting to do physics via sound bites is hopeless. Understanding is
necessary.


Tom Roberts

"Tom Roberts" wrote in message
...
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 stay at
home clock second to reach the conclusion that the traveling twin ages less?

There's nothing "universal in all frames" here. And the
interval between ticks of a clock is not "the same duration in all
frames", in that the comparison of clocks at rest in different inertial
frames does not yield equality.

I agree with that. What this mean is that a clcok second will contain a
different amount of absolute time (universal time) in different frames
(different state of absolute motion). In fact that's the reason why the
speed of light is measured to be a constant math ratio in all frames as
follows:
Light path length of rod (299,792,458m)/the absolute time content for a
clock second co-moving with the rod.

Ken Seto

"kenseto" wrote in message ...

"Tom Roberts" wrote in message
...
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 stay at
home clock second to reach the conclusion that the traveling twin ages less?

Gasp.


There's nothing "universal in all frames" here. And the
interval between ticks of a clock is not "the same duration in all
frames", in that the comparison of clocks at rest in different inertial
frames does not yield equality.

I agree with that. What this mean is that a clcok second will contain a
different amount of absolute time (universal time) in different frames
(different state of absolute motion). In fact that's the reason why the
speed of light is measured to be a constant math ratio in all frames as
follows:
Light path length of rod (299,792,458m)/the absolute time content for a
clock second co-moving with the rod.

Gasp.
Imagine having something like Seto sitting in your sofa.

Dirk Vdm

kenseto wrote:
"Tom Roberts" wrote in message
...
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 stay 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
collocated 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 else
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".


Tom Roberts

"Tom Roberts" wrote in message
...
kenseto wrote:
"Tom Roberts" wrote in message
...
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 stay
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".

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?? I
think you are wrong.

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

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
the elapsed proper time?? Then why you SRians say that time is what the
clock measures?

Bottom line: compare only things that are DIRECTLY MEASURABLE.

Clock seconds are 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 else
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".

What you are saying is that a clcok will accumulate elapsed proper time at a
different rate in different state of motion. I can agree to that. However,
you missed the finer point: the different accumulate proper times between
the twin will contain the same amount of absolute time (the same duration)
for both accumulated proper times.

Ken Seto

"jem" wrote in message
news:GFPae.32562$d43.23992@lakeread03...
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,

I think you got it wrong. The stationary observer measures the duration of
one second on a moving clock to be more than one second on a stationary
clock.

and in this
sense clock seconds are of different durations in different reference
frames.

Right....a clock second will contain a different amount of absolute time
(duration) in different 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.

This is indeed a bogus assumption. It is designed to avoid the implication
of absolute time.

Moving clocks simply accumulate fewer seconds than
stationary clocks. This desription is probably the better of the two.

But this description contradicts what you said earlier: that a clock second
is an interval of universal time (absolute time or duration).

Ken Seto

kenseto wrote:
"Tom Roberts" wrote in message
...
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?? I
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
the elapsed proper time??

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


Then why you SRians say that time is what the
clock measures?

Because that is the only definition of "time" that is _measurable_.


Tom Roberts

"kenseto" wrote in message ...
"Tom Roberts" wrote in message
...
kenseto wrote:
"Tom Roberts" wrote in message
...
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 stay
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".

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?? I
think you are wrong.

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

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
the elapsed proper time?? Then why you SRians say that time is what the
clock measures?

Bottom line: compare only things that are DIRECTLY MEASURABLE.

Clock seconds are 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 else
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".

What you are saying is that a clcok will accumulate elapsed proper time at a
different rate in different state of motion. I can agree to that. However,
you missed the finer point: the different accumulate proper times between
the twin will contain the same amount of absolute time (the same duration)
for both accumulated proper times.

Ken Seto

Entirely academic futile exercise, for the twins to EVER expect to
meet again!
(and thereby compare their elapsed times/clocks/ages).
As their rendevous will depend on them both being at a certain
coordinate at a future time they agree BEFORE SEPARATING, and as their
clocks will DISAGREE as to what that "time " is, they shall NEVER meet
again (if you are a devotee of this SR crap). As many spacecraft
arrive back safe and sound, having used REAL time (instead of this
variable kind)............

Jim G
c'=c+v

kenseto wrote:
"jem" wrote in message
news:GFPae.32562$d43.23992@lakeread03...

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,


I think you got it wrong. The stationary observer measures the duration of
one second on a moving clock to be more than one second on a stationary
clock.


Whoops, yes I did.

and in this
sense clock seconds are of different durations in different reference
frames.


Right....a clock second will contain a different amount of absolute time
(duration) in different frames.

What's usually meant by "absolute time" is "invariant time" (i.e. like
the pre-20th century world view), and because, according to SR, time
isn't invariant, that isn't what I meant (or thought you meant) by
"universal time". As you indicated originally, "time" is the
measurement of a clock, and since SR assumes that clocks (ideal ones)
are identical and are unaffected by motion, it logically follows that
the time intervals on those clocks are equivalent regardless of the
overall state of motion. It's in this sense that the time intervals are
"universal".

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.


This is indeed a bogus assumption. It is designed to avoid the implication
of absolute time.

Well, the assumption isn't bogus, since "essentially ideal" clocks have
been constructed. However, the existence of ideal clocks doesn't
necessarily "avoid the implications of absolute time".

Moving clocks simply accumulate fewer seconds than
stationary clocks. This desription is probably the better of the two.


But this description contradicts what you said earlier: that a clock second
is an interval of universal time (absolute time or duration).

Definitely not. If two collocated and synchronized ideal clocks are
moved apart and later reunited, the only way to interpret a difference
in their readings as one clock having experienced less time than the
other, is to assume that the calibrated time intervals (i.e. the
"temporal content" of each interval) on both clocks are identical.

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

Nonsense. Twins separate and rejoin ALL THE TIME in the world we inhabit
-- just ask the next pair you happen to meet!

Perhaps you should actually LOOK AT THE WORLD before attempting to
pontificate on something you obviously know nothing about.


Tom Roberts