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

I know these questions must sound ridiculous and I apologize, I'm a newbie. My textbook says that the inner product of the momentum four-vector is

P[itex]\bullet[/itex]P=P[itex]\bullet[/itex]P - E[itex]^{2}[/itex]/c[itex]^{2}[/itex]=-m[itex]^{2}[/itex]*c[itex]^{2}[/itex]

So my silly questions are: 1) where did the - E[itex]^{2}[/itex]/c[itex]^{2}[/itex] term come from? 2) I know I'm being a pain but what does the term 'Minkowski' mean in this context? I only have a passing familiarity with the Minkowski metric which I mentally make sense of using spacetime intervals so I'm not sure why the inner product of the momentum four-vector is being called the Minkowski inner product. 3) For the sake of intuition, what does the -m[itex]^{2}[/itex]*c[itex]^{2}[/itex] result 'mean'? (I'm particularly confused over the fact it's negative).

Thanks for your time.

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

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

# Why the Minkowski inner product is not positive-definite?

Loading...

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