Lorentz Transformation: Derivation & Explanation

[JamesClarke]

Hi, I was looking at a basic derivation of the lorentz transformation on youtube. I was wondering at what point do you incorporate the fact that speed of light is same in every reference frame because the guy only uses some algebra on a few equations that come from basic geometry and classical mechanics and the lorentz factor just pops out of nowhere. You could represent a beam of electrons instead with the letter c and you`d still arrive at the same result.(I think) Why is that? Oh, and can anyone recommend a good site where i can get a well explained and simple derivation of the lorentz transformation for time dilaltion and length contraction?the video is /watch?v=oLffmNXLjv4

ps you can stop watching aroung 6:00
thanks

 

[JamesClarke]

Actually, I get it now. I was too hasty to post online. Sometimes a bit of serious thinking is the best option !