I'm trying to understand Einstein's "Simple Derivation of the Lorentz Transformations." Maybe I should be posting this in a basic math forum, but I thought I'd ask it here.

 

He gives us the two formulas (x' - ct') = Y(x - ct) and (x' + ct') = Z(x + ct). And then says when we add and subtract these two equations we get:

 

a = (Y + Z)/2

 

and

 

b = (Y - Z)/2

 

I don't get how he gets these. Perhaps I need to go back to high school and equation addition.

 

Any help would be greatly appreciated!

 

 

Is this not just a definition of a and b?

It is indeed unlikely that two equations not containing the letters "a" or "b" at all result in "a=..." or "b=..." after combining them. Unless further information is given that you missed out in your post. Chances are, "a" and "b" are defined somewhere else in the text you are reading.

 

EDIT: Or, as ajb mentions, this is supposed to be the definition of a and b, not a result of a calculation.

Edited April 17, 201312 yr by timo

Oh, I see. "a" and "b" are proposed, and then, given this,

 

x' = ax - bct and ct' = act - bx

 

are then derived.

 

Yes, no?

Yes, add the two equations together and you'll see where the derivation comes from.

Cool. Muchas gracias.