Path: csiph.com!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail
From: Thomas Heger <ttt_heg@web.de>
Newsgroups: sci.physics.relativity
Subject: Re: New rewritten version of 'annotated version of SRT'
Date: Tue, 15 Feb 2022 10:49:29 +0100
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Xref: csiph.com sci.physics.relativity:577174

Am 14.02.2022 um 14:01 schrieb Thomas 'PointedEars' Lahn:
> Mikko wrote:
>
>> On 2022-02-13 08:15:27 +0000, Thomas Heger said:
>>> Am 13.02.2022 um 08:42 schrieb Michael Moroney:
>>>> You don't even know of the ordinary multiplication sign "×"? Really?
>>> Well, ordinary people may use it for multiplication.
>>>
>>> But theoretical physics is another kind of thing, where symbols are
>>> much more complicated than for common mortals.
>>>
>>> In theoretical physics there exist several types of multiplications,
>>> for which different symbols are used. The 'x' used for multiplication
>>> means 'cross product' and nothing else.
>>
>> Do you know any scientific article written in German before World War I
>> that uses "x" for cross product?
>
> I am not sure that this is true either.
>
> To clarify, if Einstein even wrote that, he simply did not mean the
> cross/*vector* product as he *knew* (because by contrast to his critics here
> he did study Physics at a university) that mass is *scalar* quantity.  This
> is just another example of the Dunning–Kruger effect where the incompetent
> (Thomas Heger, and probably you) have a cognitive bias that causes them to
> underestimate the competence of others/experts (Albert Einstein):

Well, possibly Einstein knew what a scalar product is and what the cross 
product is used for.

But my role was that of a (hypothetical) physics professor, who wrote 
corrections to the homework of a student.

In this role it is quite plausible to criticise the use of the cross in 
'Kraftzahl = Masse x Beschleunigung'.

Whether or not he knew the correct sign is irrelevant here.

I have also criticied the equation itself and also the word 'Kraftzahl'.

My aim, in my role as corrector of the homework, was to give the young 
student a hint, about what he should do better next time.


TH