Re: Should we synchronize clocks?

Python <jp@python.invalid> wrote:

Le 10/05/2025 à 11:40, Maciej Wo?niak a écrit :

Time is what clocks indicate.
 
If we synchronize clocks - they're
indicating t'=t; that's what clock
synchronization means.

 
This looks like a very fuzzy definition. I do have two clocks at my place
that may or not be synchronized. Each is showing a lot of different values
for t and t'. Which ones am I supposed to compare in order to check if
they are synchronized?
 
Of course if both clocks are broken i.e. are stopped I could compare two
constants values, but it would be pointless, as such clocks are not really
clock anymore, wouldn't it ?
 

We can do it - that  doesn't have to
be obvious or easy, but that's definitely
something we can manage in most
circumstances (with a good accuracy).

 
Could you describe at least one way to do it in a simple case? And how to
check accuracy of the applied procedure?

A simple case for simple minds, avoiding all unnecessary complications:
consider the  Indian Regional Navigation Satellite System. (IRNSS)
It (also) operates geostationary satellites.

The clock for such a geostationary navigation satellite
is set before launch to 10.229999994484488852 MHz
Once launched and in position the sat is stationary
with respect to someone on the ground below it, anywhere in India.

It is predicted by general relativity, and observed in practice,
that the clock in the sat is, and remains, synchronous
with an identical clock on the ground set to 23.00000000000000 Mhz.

What more could you want, clocks preset to different rates,
being at rest with respect to each other,
and being found to remain synchronous, pulse for pulse,
once the slower one is up in space?

Jan