dark matter nature

What is Dark Matter and do they really exist

The universe is composed of matter, dark matter, and dark energy. Actually, whole stars, planets and galaxies, and what we see today are accounted for just 5% of matter. Rest 27% is dark matter and 68% is dark energy.

But how do we know that dark matter actually exists? Matter creates the gravitational field for a planet or a star. The higher the mass/matter of a star/planet, the higher will be its gravity. Earth’s mass is higher than the moon, so its gravity is more than the moon, the sun’s mass is more than the earth so its gravity is more than earth. Blackhole has such infinitely huge mass, that even light cannot pass through it.

Gravity in the universe is an attractive force that tries to keep the planets and galaxies together. But matter alone in the universe is not enough to generate such a high gravitational field that keeps the high orbiting galaxies together. So scientists belives that is some other thing that supports matter in generating a high gravitational field. Scientists called it “Dark Matter.”

In 1933, Swiss American astronomer Fritz Zwicky discovered that the stars in the Coma cluster of galaxies were moving so fast that galaxies could not stay by the gravitational bound and could have ripped apart unless they had 100 times more matter than he could see. But at time no-one believed him.

Then in 1970, American physicists, observed that the star’s orbit at the center of the galaxy is independent of the distance from the center. The orbital speed of stars increases as they move away from the center. That should not be the case, as distance farther from the center of a galaxy, the visible matter was very less. So gravitational pull should also be very minimal. Less gravitational pull means a decrease in the orbital speed of the stars.

To account for this effect, she proposed, a mass of the galaxy from the orbiting with stars should increase linearly from the galaxy center. This will increase gravitational pull and increase the orbital speed of stars at distance farther from the center of a galaxy. This unseen matter is present throughout the universe and helping matter to generate a strong gravitational field.

Now we know Dark Matter exists in the universe, but how can we detect it. Drak matter is really dark. It doesn’t emit reflecting light So we cannot see it as a regular matter. It is composed of unidentified subatomic particles.

Nature of Dark Matter

Physicists believe that dark matter is Weakly Interacting with Massive Particles or WIMPS. They wouldn’t interact with themselves or electromagnetic charges or normal matter. But they still exert a gravitational pull. The dark matter is cold, stable, and does not decay into lighter elements. If it decayed into other lighter particles, then it wouldn’t be here in such a large quantity after 13.8 billion years ago. The true nature of these particles is still unknown.

Scientists at the Large Hadron Collider (LHC) at CERN are still searching for dark matter particles.