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From: Thomas Heger <ttt_heg@web.de>
Newsgroups: sci.physics.relativity
Subject: Division by zero
Date: Sat, 1 Feb 2025 09:14:08 +0100
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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

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

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.

In other words v_y is permanently zero, or: ∂y=0.

So we have a 'divide by zero' case.

∂τ/∂y is a time value divided by a space value, hence has the form of 1/v.

Because it contains ∂y, the velocity along the y-axis was meant.

But for a straight lateral movement along the x-axis (only) there should 
be no movement along the y axis, hence ∂y remains zero, because the 
y-coordinate remains permanently zero, which is, of course, a constant 
value.


∂τ/∂y could approach a value, however, but if v_y goes to zero, the 
quotient ∂τ/∂y would go to infinity and NOT to zero (as the equation says).

Iow: this equation '∂τ/∂y= 0' is wrong!

TH