Where does energy come from?

Energy can come from the complete destruction of matter (as in nuclear reactions), or the rearrangement of electrons or other charged particles inside matter (as in chemical reactions) or from electromagetic fields (as in light and heat radiation), or from the deceleration or pressure drop of moving matter (as in hydroelectric or wind power).

Here on Earth, most of the energy that we use comes from the sun, or from the combustion of fossil fuels that were produced by the light from the sun at an earlier time, or from nuclear reactions involving isotopes like U-235 and deuterium that were present before the Earth and sun were formed.

To understand where energy comes from, we need to delve into the different ways in which it can be generated.

1. Nuclear Reactions: Energy can be produced through the complete destruction of matter in nuclear reactions. Nuclear reactions involve the splitting (fission) or combination (fusion) of atomic nuclei. In fission reactions, such as those that occur in nuclear power plants, the nucleus of an atom is split, releasing a tremendous amount of energy. In fusion reactions, which take place in the sun and stars, hydrogen nuclei combine to form helium, generating enormous amounts of energy.

2. Chemical Reactions: Energy can also be obtained from the rearrangement of electrons or other charged particles within matter. This is commonly observed in chemical reactions, such as the burning of fuels. When a fuel combines with oxygen in the air, the electrons rearrange, leading to the release of energy in the form of heat and light. Fossil fuels, like coal, oil, and natural gas, are derived from ancient organic matter that underwent chemical reactions and stored energy from the sun over millions of years.

3. Electromagnetic Fields: Energy can be harnessed from electromagnetic fields, particularly in the form of light and heat radiation. The sun is a primary source of this energy on Earth. Through nuclear fusion, the sun emits vast amounts of electromagnetic radiation, including visible light, ultraviolet (UV) rays, and infrared radiation. Solar panels capture and convert this radiant energy into electricity.

4. Mechanical Energy: Energy can be obtained from the deceleration or pressure drop of moving matter. Examples of this include hydroelectric power from water flowing down a dam or through turbines and wind power generated by wind turbines. In both cases, the kinetic energy of the moving substance (water or air) is converted into electrical energy.

Overall, it is important to note that most of the energy we use on Earth can ultimately be traced back to the sun. Whether directly through sunlight or indirectly through the stored energy in fossil fuels, the sun is the primary driver of the energy production and consumption on our planet.