What do you know about the universe? Let's not know?

 What do you know about the universe ? Let's not know ?

Even in the modern era of the twenty-first century, have we come to know how big this universe is? At the end or where? If you are asked what is the size of the table you are reading or the house you are staying in, you can easily measure it. But when the same question arises about the universe, it becomes very difficult to imagine.

By calculation, scientists tell us that our Earth is about 40,000 kilometers long in the middle. But the world that seems so big in our eyes, how much is the world compared to this universe?

Curiosity is the spice of life. Literary Sunil Gangopadhyay once said this through the mouth of vagabond Nilohit. People have been asking questions since prehistoric times by tasting this spice. The answer has been sought for thousands of years. Some of it has been found, some is still unknown. One such question: What is our universe made of?

In answer you may say, I, you, that brick, that brick, that stone, that stone, paper, polythene, moon, sun, planets, stars, etc. our universe is made up of. But there is a big problem with this list method. First of all, the list of objects in this way will get progressively longer. But that list will never end. Because all the objects or substances in the world have to be added to it one by one. Even all the stars in the universe, all the planets and satellites have to be added.

Again, the real answer to the question cannot be found in this way. In fact, we need an answer that can simply express the almost infinite variety of objects around. It is for this purpose that the ancient Greek philosophers thought that the basic elements of the universe were four. They are: Fire, Water, Air and Earth. 

Indian philosophers of that time also had almost similar thoughts. According to them, the world is made up of five bhutas or elements: kshiti (soil), apa (water), teja (energy), marut (air) and vyoma (sky). It is called panchabhuta. When someone dies, it is said to be Panchatva. Because after death the human body dissolves into these five ghosts together. Scholars from many East Asian countries, including China, also believed that the earth was made up of five elements. They are water, fire, earth, wood and metal.

Of course, the Greeks undoubtedly had a third argument for the earth being round. If the earth was not round, why would a ship approaching the coast from the horizon see its sails first and its mast much later? Aristotle thought that the earth was fixed and that the sun, moon, planets and other stars moved in circular orbits around the earth. The reason behind his belief was spiritual. That is why he realized that the earth is the center of the universe and the circular path is the most perfect in this case.

Aristotle's idea was elaborated on a complete cosmological model by Ptolemy in the first century AD. In this model, the earth was at the very center and surrounded by eight spheres. These spheres carried the moon, sun, other stars and the five planets known at that time - Mercury, Venus, Mars, Jupiter and Saturn. 

In this model the planets themselves revolved in a miniature circle connected to the sides of their respective spherical orbits. This was done to explain the complex paths of the planets found in sky observations. The very last sphere in Ptolemy's model carried the so-called fixed stars. These fixed stars are always fixed in the same place relative to others and always rotate in the sky at the same time. Of course, what lies after this latest sphere is never made clear in this model. But whatever else there was, there was undoubtedly no part of the universe visible to mankind.

Ptolemy's model provided a fairly accurate method of predicting the positions of celestial bodies. But Ptolemy had to make some assumptions to accurately predict the positions of objects. As he had to assume that the Moon follows an orbit that sometimes brings the Moon twice as close to the Earth as at other times. That is, according to calculations, the moon should sometimes appear twice as large as usual. Of course, Ptolemy was aware of this flaw in his model. But still his model was generally, if not universally, accepted. Meanwhile, the Christian church supported the model by finding similarities with the scriptures as a picture of the universe. Because the greatest advantage of the model was that there was quite a bit of free space to place heaven and hell outside the sphere of the fixed stars.

However, in 1514 a simpler model was proposed by the Polish priest Nicolaus Copernicus. Copernicus initially published his model under a pseudonym. Because he was afraid of being accused of being against the prevailing religion. In his model, the Sun was stationary at the center of the universe and the Earth and other planets revolved around the Sun in various circular orbits. 

Unfortunately for Copernicus, almost a century later no one took this idea seriously. Two astronomers then began to publicly support the Copernican doctrine. One of them is German astronomer Johannes Kepler and another Italian astronomer Galileo Galilei. However, the orbits predicted by Copernicus' theory did not exactly match observations. But still Kepler and Galileo supported it. 

Thus the Aristotelian-Ptolemy theory died in 1609. In the same year, Galileo began observing the night sky through binoculars. Binoculars had just been invented then.

How old is the universe?

No one knows how old the universe is.

The age of the universe began to be calculated after the Big Bang theory. However, the time towards the emergence of the universe was zero.

At this time, the next step in the calculation is the formation of wimps or heavy particles in 0.001 nanoseconds.

  • In 0.01 milliseconds, neutrons and protons are formed from the quark soup.

  • The nucleus of an atom is formed in 100 seconds.

  • Atoms are formed in 300,000 years.

  • In 3 million years, stars form and electrons are ejected from atoms.

  • Formation of galaxies in 100 years.

  • In 300 years the inner galactic gas is reheated or heated.

  • Galaxy clusters formed in 1400 years.

Different scientists have proposed different theories at different times about the mystery of the creation of the universe. Below are some important ideas. In order to explain the universe in ancient times, the ancient Greek philosophers were the first to use mathematical models in this cosmology and formulated the idea of ​​an earth-centered universe.

According to their model, our earth is at the center of the universe and all the planets, sun and stars revolve around the earth. The Greeks thought the total volume of this universe was within the orbit of the now known planet Jupiter.

However, in the 1400s, after Copernicus presented the heliocentric universe logically in his book, this idea of ​​the Greeks changed or was discarded in the minds of people. Later, Newton determined the compatibility of the heliocentric universe with his deep understanding of motion and gravity.

Through this, astronomers gradually discovered that a galaxy was formed with billions of stars like the sun. For hundreds of years, astronomers thought that the entire universe included our Milky Way galaxy. But in the 1920s, with improved telescopes, astronomers discovered many more galaxies outside the Milky Way.

The most widely accepted theory of how the universe was created is the "big bang theory" or "big bang" theory. George Lamatter is called the originator of the modern big bang theory. He made it popular with everyone.

There are hundreds of billions of planets, stars, galaxies, constellations, etc. in the universe. And the essential part of the universe is energy. If E = mc2 according to Einstein's equation, particles and energy cannot be different forms. Now if we calculate the total number of particles in the universe we get a positive number.

If we calculate the total energy of the universe again, we will get a negative number. This is because gravity is a negative force. If we add these two powers, our result will be zero. So we find that no extra particles and energy are needed to create the universe.

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