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From: Thomas Heger <ttt_heg@web.de>
Newsgroups: sci.physics.relativity
Subject: Re: Division by zero
Date: Sun, 2 Feb 2025 07:52:34 +0100
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Am Samstag000001, 01.02.2025 um 10:36 schrieb Mikko:
> On 2025-02-01 08:14:08 +0000, Thomas Heger said:
> 
>> Hi NG
>>
>> I'm actually not really certain, but found an error in Einstein's 'On 
>> the electrodynamics of moving bodies' which is quite serious.
>>
>>
>> See page six, roughly in the middle:
>>
>> There we find an equation, which says this:
>>
>> ∂τ/∂y= 0
> 
> Do you mean on page 899 (9th page of the article) in §3?
> The operation is not division but a partial derivative.

τ was the name of the time coordinate in k and also the name of a 
function, which was meant as coordinate transformation between K and k.

The time coordinate of an event in K has also a value in respect to k, 
hence time t of K should belong to the parameters of this function τ.

But y should not, because the velocity along the y-axis was assumed to 
be zero and the axes of y and eta are assumed to remain parallel.

So we had a function of time tau, which is 'vertical' upon the value 
zero of y.

In my view, such a function would VERY steep, hence ∂τ/∂y= infinity 
(and not zero!)


....


TH