Re: Division by zero

On 2025-02-02 08:26:00 +0000, Thomas Heger said:

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:
 

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!)

For me seemingly ∂y/∂τ= 0 was meant, but ∂τ/∂y= 0 was written.

That "seemingly" is only possible if you don't understand the text
you are attempting to discuss.
The topic at the point is to discuss how τ is determined from x, y, z, and t.
In that context ∂y/∂τ is irrelevat.
You should find out what the symbols in the formulas mean and how the
formulas relate to the surrounding prose before you continue this duscussion.
--
Mikko