Hello,(adsbygoogle = window.adsbygoogle || []).push({});

I'm new to these forums so I hope this first post is ok.

I'm currently reading & (slowly) working my way through the book "The Essential Einstein - His Greatest works" published by Penguin books but I'm stuck on a derivation on page 11 !

I've attached the derivation as a jpg image to this post (I currently don't know how to work latex as yet) and it's just two lines of mathematics.

My question is, how does he get from the first line to the second ?

It looks to me as thought it's partial differentiation as there are partial derivatives on the second line but when I try doing so it just doesn't work out right. Am I right in thinking it's partial derivatives ? Also he quotes a function, Tau but does not define the function only its parameters so that confuses me slightly as to how he differentiates this and ends up with constants.

Your help is appreciated

Bongos

**Physics Forums | Science Articles, Homework Help, Discussion**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# The Principles of Relativity - Help Kindly Requested

**Physics Forums | Science Articles, Homework Help, Discussion**