A Few Things about the Universe

The Universe is the collection of all the things like stars, planets, galaxies, space and time. All the things that we know no matter how less we know are only the things of the Universe. Ever since the advanced form of life (human beings) began to work up in the horizon of super consciousness, he has explored everything he could and the universe has been one of his most interesting fields.

There are many theories and views regarding the origin and content of the universe but only the most accepted and popular is has been presented here.

Universe is mainly composed of three things -space, matter (and energy) and time. Space, which is between planets or galaxies, is just ‘Nothing. It has a very peculiar properties and energy of its own. Expansion of the space causes the whole universe to expand and its contraction causes the universe to shrink.  Matter and energy are the other aspects of universe. They consist of all the heavenly bodies such as planets, satellite, galaxies, etc. and the energy coming from them. Time is very hard to define but it is one of the constituents of the universe. We have only experience, one way flow of time. But time is affected by gravity for very distant observers, time runs very fast in those places where gravitational influence is very less. And in those places such as near the periphery of  a black hole, where gravitational power is strong, time runs very slowly and time may even stop at the center of a black hole, but that is known yet.

Birth of Universe:

According to the scientist, the age of the universe is somewhere between 10 billion to 20 billion years. The most powerful theory regarding the origin of the universe is the Big Bang theory. According to this theory, at the beginning all the space, matters, etc. and energy were confined to a single point, a point smaller than the size of a pea grain. Obviously, the universe was extremely hot and dense. Then about 14 billion years ago, that dense Universe exploded and began to expand (called The Big Bang). Space and time came into existence. At first all the forces electromagnetism, gravity and both strong and weak nuclear forces were unified or single and during the first second of big bang they separated. Protons, Neutrons, Electrons were also formed. At the instant of the Big Bang the temperature of the universe was about 10^32 kelvin and as the universe continued to expand the temperature to cool down to only 10 billion kelvin. Roughly after 3 minutes of the big bang the temperature cooled down to 1 billion degrees and then protons and neutrons combined to form element and most probably it was Helium. Likewise roughly after 300,000 years, the temperature cooled down to 3000 kelvin and proton and neutron could combine with electron to form neutral atoms and heavier elements. After all the electrons combined with atomic nuclei the space of the universe became transparent to radiation and the radiation began to travel to all the direction. One billion later the stars and galaxies began to form and since then the universe is continuing to expand and cool down.

There are many evidences supporting the Big Bang theory. This theory predicts that all least one fourth of the total mass of universe must be Helium that was formed within a few minutes of big bang. If we obverse the present constituents of stars and galaxies, it is just so.

Secondly, even thousands of years after Big Bang, the universe was still very hot and full of extremely heated matter. Those hot matters must have given out radiation and as the universe continued to expand those radiations continued to travel in new space. Scientists, using extremely sensitive instrument, have detected such light coming from all the direction in sky. Such light have travelled for billions of years to reach here. Two scientists, Arno Penzias and Robert Wilson have discovered such radiation call the cosmic background radiation. It is the glow left over from the explosion. In 1964, both scientists were rewarded with Novel prize for their discovery.

Lastly, the greatest support for the Big Bang is drawn from the fact that the universe is expanding!  Scientists have observed that all the galaxies are moving away from each other. Until a few years, scientist predicted although the universe is expanding it should gradually slow down and stop expanding due to mutual gravitation energy. But on the contrary to their prediction, the expansion of universe is speeding up, i.e., the universe is expanding faster and faster and scientist have concluded that there is some form of dark energy which drives the universe apart, contrary to normal energy which pulls the galaxies together. It has been calculated that 73%of our universe is made of this dark energy.
The remaining 27% of universe is no less mysterious. Out of that mysterious part 23% is made of dark matter whose nature we don’t know. Only 4% of the universe is made of ordinary matter and energy that we are familiar with.

Ending of universe:

Since dark energy is the dominant content of the universe, it will make universe expand continuously and it will never stop. The universe will continue to expand and cool down to such an extent that it will die a cold death, which, according to the astrophysicists, is likely to occur at least 10 billion years later.