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From: Thomas Heger <ttt_heg@web.de>
Newsgroups: sci.physics.relativity
Subject: Re: [SR and synchronization] Cognitive Dissonances and Mental
 Blockage
Date: Tue, 20 Aug 2024 08:30:49 +0200
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Am Montag000019, 19.08.2024 um 14:56 schrieb Python:
....
>> There is also no equation, which could eventually be interpreted as 
>> delay calculation.
> 
> As I've shown there is. A single step from the provided equations
> leads to t_A = t_B - (AB)/c
> 
>> Delay for a signal from A->B in distance x would be:
>>
>> x=c*t => delay (A->B)= x/c
>>
>> Extremely simple, isn't it?
> 
> Extremely stupid insteed x=c*t is not generally true. x/c is
> not at all the delay your asking for. (AB)/c is such a delay.

Einstein defined two coordinate systems (K and k).

System k was placed with its center upon the axis of x of system K.

So the value 'x' is a coordinate in respect to system K  with distance 
|x| to system K's center.

Now I use this setting and place A in the center of K and B in the 
center of k.

So: the distance from A to B is x.

Well, yes, this was a little bad, because I had to explain it in the 
first place, before I could use this setting.

I would agree, that another variable name for distance would have been 
better.

How about 'd'?

(d for distance)

So d = 'distance from A to B'.
then:
  delay(A->B) = d/c
> 
>> Now you need to measure this delay, because you cannot measure 
>> distance x with rods (at least in cosmology).
> 
> If rods are not practical, then use another method.
> 
> The point of synchronizing clocks is practically about clocks involved
> in a single experiment in a single laboratory by the way, not
> cosmological distances.


'empty space' and 'inertial motion' are not really possible upon Earth' 
surface.

Therefore, the 'environment' of SRT is usually something very remote 
from any other celestial object, in the far ends of the universe.

'In one single lab' isn't even remotely what SRT is about.

But smallness isn't actually an issue here, because it makes no 
difference in principle, if you place two floating spaceships into a 
distance of 1 lightyear or 1 nano-light-second.

What disturbs the measurements is actually air and gravity.


>> But where have you found such a calculation in Einstein's text???
> 
> Distance (AB) is assumed to be known.
> 
>> And where have you found any use of the value for delay?
> 
>  From both equation provided by A.E. I can derive t_A = t_B - (AB)/c
> i.e. t'_A = t_B - "delay"

https://ia601704.us.archive.org/23/items/einstein-1905-relativity/Einstein_1905_relativity.pdf

Einstein had a slightly different equation.

But he used it not as calculation of delay, but as definition of the 
speed of light.

(§1, page 3, last paragraph)
quote

"In agreement with experience we further assume the quantity
2AB/(t′_A − t_A)= c,
to be a universal constant—the velocity of light in empty space."

What you apparently quoted was on page 5 first paragraph.

But this didn't contain 'c' but 'c-v' in the denominator and was also 
meant for some other situation.

TH

....