Hello again, my fellow Steemians. Here I drop my another post on an active research field on a never-seen-before substance that physicists believe exists in our universe. Please have a read and do upvote and comment.
Since long we learnt that every tiny speck of matter in the universe is made of a very small fundamental particle called atom we have figured out a lot about the universe. Possibly we believe we have seen everything that is there in the universe. But wait!! May be not. Most of the scientists now believe that we have seen only a fraction of what constitutes the universe. There exists something else which we have not seen, but getting the initial glimpses of it.
Stars in the galaxies revolve around its centre very fast due to the force of gravity. Now, when we spin a ball tied to a string around our body very fast we cannot hold it very long. Failing to counter the escape we have to release the ball eventually. In a similar way the stars in the galaxies are revolving around the centre in an unimaginable speed. At such speed they should have escaped the gravitational attraction on them due to its centre. But they don’t!! What is still holding them together?
Fig: Stars Revolve Around The Centre of The Galaxy Very Fast
Physicists believe that an invisible substance exists which counters the escape and holds the stars together. They call it the Dark Matter. We cannot see them, but we can still see their gravitational influence on the stars. They don’t interact with ordinary matter. Ordinary matter have electromagnetic properties, they can emit light. But Dark Matter doesn’t. It means dark matter are not made of atoms. Physicists believe that there is more Dark Matter than ordinary matter in the universe .We cannot see them using telescope. We can picture them only by their gravitational interaction with ordinary matter. One way to detect them is Gravitational Lensing. Einstein in his General Theory of Relativity (1915) showed that large amount of mass bends space much in a similar way a metal ball stretches a sheet of trampoline downward. In such curved space around a large mass like sun light travels in a curved path. Thus we see distorted and multiple images of the stars behind the Sun.
Fig: Gravitational Lensing
This phenomenon is called Gravitational Lensing. Similarly Dark Matter also bends space. We can detect these matters by observing the Gravitational Lensing caused by them.
Physicists around the world are in a hunt for Dark Matter. No matter what, Dark Matter is what keeps our galaxies intact. Without Dark Matter our galaxies wouldn’t have been formed and we wouldn’t have existed. Galaxies are surrounded by a cloud of enormous amount of Dark Matter. In fact, Dark Matter works like a Cosmological Glue that holds the galaxies intact.