The universe of matter-energy unlike its apparent complexity could be extraordinary simple. For example, if you would like to know how much matter-energy can be squeezed into a volume of space as in a star without it shrinking under its own gravitational pull and turning into a blackhole you can solve Einstein’s field equations of curved spacetime to arrive at a simple equation that has been named after the physicist Hans Adolph Buchdahl who discovered it. The maximum mass-energy allowable inside a sphere to ensure a static Star is obtained from Buchdahl’s Theorem; that is providing a theoretical upper limit:
