We know our Universe include Earth, the Sun, Stars, Planets, Comets, Asteroids, Black Holes and Galaxies, etc. which is made up of protons, neutrons and electrons bundled together into atoms. When scientists study our Universe, they see that it is expanding. But the question arises that if the Universe is made up of galaxies, stars, planets etc. then it should not expand. That is something else is there which make it expand. Isn’t! The most surprising discovery of the 20th century was baryonic matter which makes up less than 5 percent of the mass of the Universe.
Even in 1950s the studies of other galaxies first indicated that the Universe contained more matter than seen by the naked eye. Through this article, let us study about dark matter and dark energy.
By fitting a theoretical model of the composition of the universe to the combined set of cosmological observations, scientists have come up with the composition that we described above, ~68% dark energy, ~27% dark matter, ~5% normal matter. What is dark matter?
We have studied that in space there is a stuff which has gravity. It pulls matter like stars, galaxies etc. But this is not regular matter and is not a black hole. Scientists called it as Dark Matter. It seems to be 27% of the Universe. Normal matter interacts with the electromagnetic force but dark matter does not. This means that it does not absorb, reflect or emit light, making it extremely hard to spot. In fact, scientists come to know about its existence from the gravitational effect which seems to have on visible matter.
This observation of scientists shows that the matter we know and that makes up all stars and galaxies only accounts 5% of the content of the Universe.
According to some researchers dark matter could contain “supersymmetric particles” that is hypothesized particles that are partners to those already known in the Standard Model.
Further, experiments at the Large Hadron Collider (LHC) may provide more direct clues about dark matter. Some theories say that dark matter particles would be light enough to be produced at the LHC. If they were created at the LHC then they would escape through the detectors unnoticed. However, they would carry away some energy and momentum, so they could infer their existence from the amount of energy and momentum “missing” after a collision.
Therefore, we can say that together dark energy and dark matter make up 95% of the Universe. This means that only 5% matter we know and understand. Energy like heat, light and X-rays together with matter like people, planets, Sun, galaxies etc only makes 5% of the Universe.
We are much more certain what dark matter is not than we are what it is. First, it is dark, meaning that it is not in the form of stars and planets that we see. Observations show that there is far too little visible matter in the universe to make up the 27% required by the observations. Second, it is not in the form of dark clouds of normal matter, matter made up of particles called baryons. We know this because we would be able to detect baryonic clouds by their absorption of radiation passing through them. Third, dark matter is not antimatter, because we do not see the unique gamma rays that are produced when antimatter annihilates with matter. Finally, we can rule out large galaxy-sized black holes on the basis of how many gravitational lenses we see. High concentrations of matter bend light passing near them from objects further away, but we do not see enough lensing events to suggest that such objects to make up the required 25% dark matter contribution.
-We thought with powerful enough telescope and instruments we could see the universe, but it is 68% dark energy, and 27% dark matters. Everything we have ever seen is just a part of the remaining-