Dark matter and dark energy

Dark matter

Remarkably, only about 4% of the mass-energy content of the universe is the ordinary baryonic matter that we interact with everyday. The remainder is made out of mysterious substances: dark matter and dark energy. Dark matter, is suspected to make up about 23% of our universe. But what is it? This is a puzzling astronomical inquiry. Dark matter is, indeed, distinct from ordinary matter, however, has never been directly observed. It is “dark” because it does not interact with the electromagnetic spectrum. The existence of dark matter has been inferred from its influence of ordinary matter, such as gravitational lensing. The leading hypothesis for dark matter is that, it is composed of WIMPs. These are weakly interacting massive particles. They are called such, because, they interact only with the weak force and gravity (not with electromagnetism, hence, why it is dark). However, this proposal has not been made conclusive. 

We do not see dark matter, however, it influences its surroundings. Astronomers have used indirect methods to detect the presence of dark matter. 

Dark energy

The remaining 73% of the mass-energy content of the universe, is suspected to be dark energy. The idea behind dark energy is that it is:

• Permeating all of space

• Is accelerating the expansion of the universe.

This is related to the idea of the cosmological constant: a constant energy that acts to fill the vacuum of space.