Educational: Learn Special Relativity E=mc2 , then Einstein's Gravityequation
 

For serious students of philosophy, physics and, yes, mathematics of
those wanting to deeply understand instead of playing around with
nonsensical ideas and unprovable, fantastical theories.

This concise relativity course in pdf consists almost entirely in
algebra with pictures and diagrams where applicable as a single picture
is worth a 1,000+ equations. Ha!

Therefore go to:

https://www.relativitycalculator.com...2-gravity.html

The Relativity Man
Relativity Physics and Science Calculator