Where does energy go?

Question

The law of the conservation of energy states that energy can't be created or destroyed. All energy that we have now was there at the big bang. We are using energy to exist. Since it can't be destroyed where is it going? We are using stored energy from oil and coal which is being depleted but energy can't be destroyed. Where is it? I don't think that it is becoming part of the mass of the planet.

At some point everything will collapse back to the initial state before the big bang with all the original energy. How? Have we existed without using anything?

Is all energy that we have used just sitting in space in some form?

Answer 1

Energy ends up in the form of heat. When everything in the universe is at the same tempersture it is called "heat death".
The energy is all still there but in an unusable form.

Answer 2

Energy can neither be created not destroyed. Add to that the law of conservation of mass too: So the law is that energy and mass (which is modified energy) can neither be created nor destroyed, but energy can be converted into matter and vice versa.

In the beginning, the energy was in a highly dense form and the initial temperatures were extremely high. As the universe expanded, it cooled down. So the energy is now occupying a larger volume. And energy is just changing from one form to another. Like when we burn carbon, we are changing chemical energy into thermal energy and we are converting carbon to carbon dioxide. Mass of the planet remains constant since the carbon and the oxygen were already there.

When the big crunch takes place, the energy density will again reach extremely high values because all the mass and energy of the universe will collapse into a singularity. Along with the universe, the space and time will also cease to exist!

Answer 3

The second part of energy can not be created or destroyed, says that it can only be transformed from one form to another.
We burn coal to make heat to generate electricity which can be used to cook so food becomes hot.As the food cools we or the room is warmed. All forms can be changed to heat.
Electricity runns a toaster which cooks bread causing the browning a chemical change in the bread.some heat escapes into the environment, we see some as light, maybe we burn ourselves on the toaster. The energy keeps turning from one form to another. Sunlight comes in and warms the earth and gives light which is used by plants in photosynthesis. At night the earth radiates heat back into space.Clear nights get much cooler. It goes on an on in circles.

Answer 4

All the energy that has ever been "used" is indeed somewhere in one form or another.