It’s a part of the Universe that astronomers know exists, but they still don’t know exactly what it is. It is matter, because its existence can be measured through the gravitational force it exerts. And it’s dark, because it doesn’t emit any light. This second property is precisely what makes its study difficult. All observations of bodies in space are made from light or another type of electromagnetic radiation emitted or reflected by the stars. Since dark matter does none of these things, it is «invisible». Still, it is known that she is there. In the 1930s, astronomer Fritz Zwicky, a Hungarian living in the United States, calculated the mass of some galaxies and realized that it was 400 times greater than what the observed stars suggested! The difference is precisely in the mass of dark matter. And what a difference! According to Professor Fritz’ accounts, you must have realized that it is not just a detail in the composition of the Universe, but its main ingredient. Nowadays, it is calculated that it corresponds to more or less 95% of the Universe. It’s as if all the galaxies we know today were just a few pieces of chocolate embedded in the big cake of the Universe. There are several theories about what this dark mass would be. Most likely it is made of subatomic particles, smaller than neutrons, protons and electrons and still undetectable by scientists’ current measuring instruments. Finally, it is worth clarifying: despite the similarity in the name, dark matter has nothing to do with a black hole. “The dark mass is a component of the Universe, without light, while the black hole is an astrophysical object with a gravitational field so strong that it does not even let light escape”, says astronomer Enos Picazzio, from the University of São Paulo (USP) .
Read too:
– Is there a fifth dimension?
– What is the temperature of space?
– When did man begin to study space?