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From: Mikko <mikko.levanto@iki.fi>
Newsgroups: sci.physics.relativity
Subject: Re: Space-time interval...
Date: Fri, 16 Aug 2024 15:12:44 +0300
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On 2024-08-16 06:55:31 +0000, Thomas Heger said:

> Am Donnerstag000015, 15.08.2024 um 11:26 schrieb Mikko:
>> On 2024-08-13 13:10:33 +0000, Richard Hachel said:
>> 
>>> Le 13/08/2024 à 13:38, Mikko a écrit :
>>> 
>>>> In an orthogonal isometric coordinate system ds² = dt²-dx²-dy²-dz².
>>> 
>>>  Not really.
>>> 
>>>  ds² = dx²+dy²+dz²-dt²
>> 
>> Both sign conventions are used. It doesn't matter as long as one knows
>> which one is used. The information content is the same anyway.
>> 
>> If you represent vectors and position defferences with quaternions then
>> the real part of the square of the quaternion is ds² according to the
>> sign convetion that I used. But quaternions are rarely used in this
>> context so that is not important.
> 
> Yes, becaause quaternions are the wrong construct, but quite close.

They are not wrong but 4-vectors are better for purpose.

-- 
Mikko