Re: Division by zero

Am Sonntag000002, 02.02.2025 um 07:52 schrieb Thomas Heger:

Am Samstag000001, 01.02.2025 um 10:36 schrieb Mikko:

On 2025-02-01 08:14:08 +0000, Thomas Heger said:
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Hi NG
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I'm actually not really certain, but found an error in Einstein's 'On the electrodynamics of moving bodies' which is quite serious.
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See page six, roughly in the middle:
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There we find an equation, which says this:
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∂τ/∂y= 0

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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!)
 

For me seemingly ∂y/∂τ= 0 was meant, but ∂τ/∂y= 0 was written.
∂y/∂τ= 0 would make sense for me, because that could be interpreted as:
the velocity along the y-axis is zero
(what is obviously correct).
But ∂τ/∂y would be the inverse, hence should be infinity.
TH