Re: Division by zero

Am Sonntag000002, 02.02.2025 um 03:19 schrieb Ross Finlayson:

On 02/01/2025 01:36 AM, Mikko wrote:

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:
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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.
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Now, 'tau' is a time belonging to the moving system k.

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Yes, but it is also a number that is computed from coordinates of K.
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This system k moves along the x-axis of system K with velocity v,
while x- and xsi-axis coincide and etha- and y axis remain parallel.
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In other words v_y is permanently zero,

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Yes,
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 or: ∂y=0.

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No. ∂y is not a number but a part of an operator. There are points with
different values of y and ∂/∂y refers to a line where t, x, and z (but not
y) have the same value at every point.
>
See https://en.wikipedia.org/wiki/Partial_derivative
>

 Zero meters/second is infinity seconds/meter.
 

yes, but that was my complain!
If there is not movement along the y-axis, then time tau would pass, but y would remain zero.
This would mean, that ∂τ/∂y= infinity  (and NOT zero).