Did the mass of the universe change after the Big Bang?

Question

Physics

Did the mass of the universe change after the Big Bang? After all, according to the first law of thermodynamics, this is impossible. (by energy I mean both atoms and molecules)

Answer 1

Of course, it has changed, some part of the matter has passed into energy. Something has disappeared, don’t understand where, in general, theories have been redrawn for 100 years

Answer 2

Study the inflationary model of the Universe, when a colossal amount of energy came out of nowhere and turned into mass.