On 25/03/11 12:56, Androcles wrote:

wrote in message
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| On 24/03/11 22:34, PD wrote:
| On Mar 24, 4:40 pm, wrote:
| On 24/03/11 13:47, PD wrote:
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| On Mar 24, 7:40 am, wrote:
| On 23/03/11 13:50, PD wrote:
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| On Mar 23, 5:39 am, wrote:
| On 22/03/11 18:21, PD wrote:
| I think Einstein confused himself thinking that clocks measure
| time.
|
| Yes, indeed. Time is what clocks measure.
|
| You cannot have your cake and eat it either time is the reciprocal
| of frequency or it is what a clock measures.
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| Time is not the reciprocal of frequency. Time is benchmarked by a
| locally stationary reproducible process. See the NIST standards.
|
| You are ducking the issue:
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| a/The frequency of a transverse moving clock is reduced.
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| Yes.
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| Why do you accept this statement yet query the one below?
| Clearly in the context it is moving relative to you and you are
| measuring it in your FoR
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| b/The time interval between ticks is increased (dilated means
increased)
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| The time interval as measured by a clock at *rest* in this frame is
| increased between the ticks of the clock that is moving in this frame,
| yes.
|
| I am clearly talking about the same clock as in a/
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| Then the statement makes no sense. The time interval between ticks on
| the clock moving are *unchanged* in the frame in which that clock is
| at rest.
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| So is the frequency "*unchanged* in the frame in which that clock is at
| rest". You understood the first statement. The second statement relates
| to the same scenario. Are you deliberately being bloody minded
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| See the comment below about the absence of ethereal, standalone time.
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| c/ What the moving clock registers is reduced.
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| Reduced, relative to a clock at rest in this frame, yes.
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| Note that there is no ethereal, detached Time that is affected. What
| you are *always* doing is comparing the time measured on one clock
| between two events with the time measured on another clock between the
| same two events.
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| I never said otherwise
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| Ignoring Doppler shift (How in practice I don't know but never mind)
You
| have a moving clock transmitting ticks and locally you have two clocks
| one a normal clock counting locally generated ticks and a second
| counting transmitted ticks.
|
| You can measure how long the transmitted tick interval is. This is
| "measuring the time between two events" as you describe it - the
arrival
| of one tick and the next. It is this "tick interval" (units seconds)
| which dilates.
|
| What is registered on the clock counting the received ticks is a "tick
| count".
|
| What time is, is what a clock locally at rest measures.
|
| In note you say "measures" not "indicates".
|
| " We may say of it the following three things:
| Set I
| (a) The journey occurred in time.
| (b) The time of starting was 1 o'clock.
| (c) The time occupied by the journey was 2 hours.
|
| The same word, time, is used here in three quite different senses, as
| may be seen by considering the corresponding statements about space:
| Set II
| (a) The journey occurred in space.
| (b) The place of starting was London.
| (c) The length of (or distance covered by) the journey was 60 miles.
|
| Here we use three different words — space, place, length (or distance),
| none of that could be substituted for either of the others without
| depriving the sentence of meaning. The same distinctions, thus brought
| to light, exist in the set I, but they are obscured by the use
| of the same word, 'time', for three quite different ideas.
|
| To distinguish the three meanings of 'time' I will re-express the set I
| in the following not unnatural ways:
| Set III
| (a) The journey occurred in eternity.
| (b) The instant of starting was 1 o'clock.
| (c) The duration of the journey was 2 hours." Dingle
|
| Note that only (c) has units of seconds. I think that part of the
| problem is that we are all familiar with clocks# and think of them as
| something which tells time in hours minutes and seconds. In scientific
| terms we should perhaps not use the term clock but "duration meter" -
| envisaging something with a digital reading which increments at some
| interval 1/10^n seconds. The larger n then the better the resolution -
| which is started by one detected event and stopped by another event.
| Your statement:
| "What time is, is what a clock locally at rest measures".
| Becomes
| What time is, is what a "duration meter" locally at rest measures.
| In terms of my scenario the only interval which the duration meter can
| measure is the interval between the ticks - the reciprocal of which is
| the frequency of the ticks.
|
| #If one is pedantic the strict definition of a "clock" is something
| which chimes. If it doesn't chime the correct terminology is a
"time-piece".

The English "Clock" is derived from the German "Glocke" for "bell".
plural Glocken = bells. Glockenspiel = play bells.
Church towers had bells, then mechanical devices were added to ring
them once an hour.

Originally to call the monks to prayer. Originally with no dial.

Initially clocks only had an hour pointer,
the minute
hand was added later. The correct term is "chronometer."

Historically you may be correct but today the term "chronometer" is used
for a device with sufficient accuracy to be used for navigation.
Certainly in the antiques trade "timepiece" is used to describe a more
ordinary device which tells the time but doesn't chime.