# Energy thought experiments

```Created: 08 Januari 2021
Published: 08 Januari 2021
Last updated: 08 Januari 2021```

Energy is a strange thing. I do not know what energy is. But we use it every day to make our lives more comfortable. At school in physics class we learn a lot about energy. It can never disappear, only be remodelled in another form. In my other page about ‘energy in the state of volume’ is stated that I think that the total energy balance for the entire universe and for every location in the universe:

Etotal ≡ ΣEvolume + ΣEradiation + ΣEmatter

This seems a solid vice-versa buffer/equilibrium law.

I also described that photon red-shift may occur because energy from the photon is transferred to the expanding volume of space. Otherwise energy would disappear.

So what about potential energy and kinetic energy?

The kinetic energy of a body with mass m is given by the formula:

Ekinetic = 1/2 * m * v2

But we also know that speed is relative between two masses. For instance a single space rock travelling trough our solar system has different speeds with regards to the reference, the sun or a planet. Thus the kinetic energy cannot be real. It is a potential energy for which the ‘possible to harvest amount’ is dependant on interaction with another body.

The same for potential or height energy of a body with mass m in the gravitational field g:

Epotential = m * g * h

This depends on the gravitational field of the other mass! Although is will cost energy to move a mass up, this energy will not be transferred to and stored into the mass being lifted.

So when no extra energy is stored inside a stone that fell down, where is the energy that is released at impact originate from?

1. From the matter?