The first law of thermodynamics describes that the amount of ACTUAL energy in the universe remains constant and does not change.
The second law of thermodynamics describes that the amount of USABLE energy in the entire universe is decreasing. So in a nutshell the universe’s energy is running down and tending towards disorder with an eventual demise of the universe.
To put this into simpler terms, if the amount of actual energy stays the same, however usable energy is running down, then the amount of energy we started with was not an infinite amount. So if this is true then the universe could not possibly have been infinite, as you can’t run out of an infinite amount of energy. So the universe had to have a beginning as written by Moses in Genesis 1.