What will eventually happen to all energy in the universe?

Answer 1

After about another five billion years, the sun will burn out, and the process of nuclear fusion that has kept the force of gravity from collapsing it will cease to be powerful enough to counter it. The sun will then collapse into a White Dwarf, which is an incredibly dense and comparatively small piece of matter. The white dwarf, will, eventually, cool down into a small, black, non-radiant, cold cinder. The white dwarf is actually extremely dense, with one piece the size of a matchbox weighing in at the same weight as a full-grown African elephant.

Answer 2

The first Law of Thermodynamics states that energy can be changed form one form to another, but it cannot be created or destroyed, and the total amount of energy and matter in the universe remains the same, simply being changed from one form to another, so all the energy in the universe will exist into infinity, only changing into different forms.

Answer 3

The prevailing theory is that the universe will continue to expand indefinitely, leading to a state known as "heat death" where energy is evenly distributed and no more useful work can be extracted. This will result in a lowering of overall energy levels and a uniform temperature throughout the universe, leading to a state of maximum entropy.