Given E=mc^2, how much energy was needed to produce all the mass in the universe?

Answer 1

This is basically impossible to answer with any accuracy, because we don't know how big the universe is. We DO know how big the "observable universe" is, and the universe may be either larger or smaller than that (but not too much smaller). Further, we don't really have a good handle on whether there really is dark matter, and if so, how much of it there is.

But we do have a rough idea of the number of stars in the observable universe, and the average size of a star. So we can say that the mass of all stars in the OU is about 10^53 kg. Which means that the energy contained in that mass would be
e = 10^53 * 299792458 * 299792458 = about 9 x 10^69 joules.

Some scientists speculate that the amount of dark matter is 10 times greater than this.

Answer 2

Problem here is HOW MUCH MASS IS THERE IN THE UNIVERSE? Since this question is unanswerable, so is yours, I'm sorry to say.

Answer 3

Hi. All of it.