In 1920-1930, astronomer Edwin Hubble discovered about the expansion of the universe. He observed that our universe is expanding. All the galaxies existing in our universe are moving farther away from each other. In 1925, Edwin discovered one theory, today we know it by ‘Hubble Law’. This theory was he first observational basis for the measurement of expansion of the universe. Hubble said, the universe is expanding in a very high speed. But before this in 1992, Alexander Friedman already proved that through his equation, today it is known as ‘Friedman Equation’. He had said that ‘maybe the universe is expanding’. And after few years later, Edwin Hubble really proved that indeed the universe is expanding. This expansion is called as ‘Hubble Flow’. According to the Hubble Flow, all the galaxies, clusters of the universe are going away from each other and the speed at which the universe is expanding has been increasing, showing its weirder nature. Because according to physics, to set any object in motion a force should be applied to it. Then how can universe expand continuously without any force? Also, the speed of expansion of universe has been increasing. How is it possible?
It is a kind of theoretical energy, which work opposite to the gravity. Here the word ‘Dark’ does not mean black or darkness, it simply means that we cannot see. We cannot see the Dark Energy, neither through our naked eyes nor by using any high precise modern technology. But this energy exists in the universe and works in a giant way. It has been accelerating the expansion of universe continuously.
But in 1970, astronomers observed that our galaxy, along with lakhs of nearby galaxies, has been attracted towards a specific direction and this specific direction is opposite to the direction of the expansion of the universe. But according to Hubble Flow, all the galaxies should go farther away from each other due to the expansion of the universe. It means we, our galaxies and nearby all galaxies has been attracting towards a certain direction also with the Hubble Flow expansion.
Something exists that is attracting us towards itself in the space. Some astronomers named it as ‘The Great Attractor’.
What is “The Great Attractor” …Lets find out,
In 1970, some scientists had made a detailed map of cosmic microwave background (CMB). (To know what is CMB, please refer below the article).
At the time, when the scientists were completing the map, they observed that there is a temperature variation in the region where our galaxy exists and this is so weird! Because our universe is homogenous and isotropic at higher level. Homogenous means, our universe is distributed uniformly (i.e., distributed equally in all directions). It means, all the matters in the universe are distributed in equal level, in all areas, it doesn’t matter of what distance we observe the universe from. Isotropic means, there is no certain direction in the universe (i.e., it doesn’t expand or contract in a particular direction). It means that the universe expands in equal level in all direction. According to all these information, cosmetic microwave background, we can say, a ‘Map of Universe’ should be uniform (equal in all directions).
But when we observe this map, we observe temperature variation (different temperature at different areas). This temperature variations are present but in a very less quantity and this map is helpful to study the universe.
By studying this map of universe, scientist came to know that at one region of our milky way galaxy, it shows high temperature zones as compared to other corners of milky way galaxy. It means that more galaxies are present at that high temperature zone region. In the year 2000, more galaxies were discovered by the scientists and with these discoveries, we finally got The Great Attractor, attracting not only our galaxy but lakhs of other galaxies nearby milky way towards its side, with the speed of 600 km/s.
So, we, our earth, our galaxy and everything in it is getting attracted at the speed of 600 km/s towards The Great Attractor. But we don’t know exactly that what is this great attractor, also our main weak point is that we totally have no idea what it is nor can we see it. Because the Great Attractor is located at the region of the space, where we are not able to see. This region of the space is called as ‘Zone of Avoidance’. We cannot see this region because it is beyond the galactic plane of our milky way galaxy, whose light cannot reach to us.
Nobody knows what is The Great Attractor, but the scientists are sure of one thing, ‘Gravity’. Its gravity will be very powerful which is capable of attracting lakhs of galaxies towards its side.
Scientist has cleared that, it is not a blackhole, it is something that is even bigger than the blackhole. It is that mystery of space, that we are not able to solve yet. The Great Attractor is located in southern sky at a distance of 25 crore light years from the earth.
In February 1997, Hipass, (Astronomical Survey Organization) studied the southern sky and we succeeded to see ‘Zone of Avoidance’ upto some limits with the help of X-ray. From which we were able to discover ‘Norma Cluster’, a giant group of galaxies, which is located at the direction of the great attractor.
Though we were excited about the mysterious Great Attractor, but after all these discoveries there came to light another mystery, which is more surprising and greater in comparison to The Great Attractor!
From the studies, we observed that the great attractor has not enough gravitational pull to attract a huge quantity of galaxies. Scientists confirmed that, there present another mysterious existence whose gravitational pull is much higher as compared to the great attractor.
Scientists said that, this mysterious existence is maybe the super clusters of galaxies, which have been attracting all the things towards itself.
Super cluster is the biggest group of galaxies existing among all the nearest universe. Super cluster is the one responsible for attracting all the things, said scientists. It is located at a distance of 65 crore from earth. It is also known as ‘Shapely Attractor’.
Well, our present physics is not yet capable to solve all these mysteries, but in future, we will be able to uncover this giant existence.
What is Cosmic Microwave Background (CMB) ?
It is thought to be leftover radiation from the Big Bang, or the time when the universe began. As the theory goes, when the universe was born, it underwent a rapid inflation and expansion. We know that the universe is still expanding today and the expansion rate appears different depending on where you look.
The CMB represents the heat leftover from the Big Bang. You cannot see the CMB with the naked eye, but it is present everywhere in the universe. It is invisible to human eye because it is very cold. This means that its radiation is most visible in the microwave part of the electromagnetic spectrum.
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