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From: guido wugi <wugi@brol.invalid>
Newsgroups: sci.physics.relativity
Subject: Re: Space-time interval (2)
Date: Wed, 14 Aug 2024 21:01:30 +0200
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Op 13-8-2024 om 12:45 schreef Paul.B.Andersen:
> Den 12.08.2024 22:25, skrev Richard Hachel:
>> Le 12/08/2024 à 21:06, Python a écrit :
>>
>>>> Finally, what is ds²? It is just -c².Tr²
>>>
>>> No! ds^2 = c^2 dt^2 - dl^2. 
>>
>> LOL.
>>
>> Non : ds²=dl²-c²dt²
>
> https://paulba.no/pdf/TwinsByMetric.pdf
> Chapter 1.

Nice to have a TP simulation, but one needs an app to install.
Here's my Desmos "TP simulator" (only the linear case, admittedly, no 
continuous accelerations here)
4 cases (2x2) shown:
1. Lorentz description
("observed" meaning: measured, back-calculated; showing Lorentz 
transform effects)
1a: POV hometwin
1b: POV traveltwin
2. "Doppler/Einstein" description
("observed" meaning: actually seeing, looking at, the other twin! 
Besides Lorentz, additional Doppler effects)
2a: POV hometwin
2b: POV traveltwin

https://www.desmos.com/calculator/aoacey9t1v?lang=nl
More SRT Desmos examples: https://www.wugi.be/srtinterac.html

-- 
guido wugi