If energy can neither be created nor destroyed, then from where does it exactly originate?

Answer 1

All needed energy is already here, the sun is here that creates heat and light energy. Notice you left out part of that law, Energy cannot be created or destroyed, only CHANGED so energy that is in light can be changed into heat energy, that energy can in turn be transfered to other forms, steam energy that can be transformed to kinetic energy or potential energy. See all energy we need is here already!

Answer 2

No one knows, it wasn't 'created' during the big bang, thats against the laws of physics. The big bang was essentially this ball of energy that had such a gravitational pull on itself that it blew up, the energy being spread across the universe at many times the speed of light, some of the energy eventually was converted to mass by suns of pure energy creating a nuclear reaction that made very simple elements, those elements turned into other suns, that did the same thing, only making more complex atoms with the addition of mass. But the original energy that caused the big bang? No one really knows, I have heard a theory that it might had been caused by two other universes 'bumping' into each other.

Answer 3

The net energy content of the universe is zero so you don't need to explain where it comes from. Gravitational energy is negative and exactly balances all the other energy which is positive. This was such a gob-smacking idea that when it was explained to Einstein it stopped him in his tracks whilst crossing a road and nearly got him knocked over.

Answer 4

All energy, either in the form of mass or pure energy, is distributed throughout our universe. All energy first came into existence at the instant of the Big Bang which created the universe.