Universe in a nut shell
What do we know about the universe we inhabit? well, let’s see our solar system is part of a medium sized galaxy (a group of stars, star-dust, planets,and other bodies) known commonly as the Milky Way, which in turn is part of a Universe (the only one yet known to us.) the Universe can also be understood as the known extent of time and space, which means that all the matter that is known to exist (matter being anything tangible) exists within this paradigm of time and space. Universe in and of itself means one such paradigm as the prefix “uni” denotes, although there is a debate as to the authenticity of this statement. How can we be sure there is only one universe? there can be hundreds more of them and therefore the concept of “parallel universes” but more on that later.
According to the most accepted theory on the origin of the Universe is the “Big Bang” theory which states that some 13 billion years ago this universe was created with a vast and terrible explosion hence the nomenclature. A very minuscule but extremely dense unit of energy exploded in a matter of nano seconds and all the matter dispersed in space to form stars and planets, the background hum heard by the observers in the universe on sonar telescopes is the radiation in space lingering from that explosion after eons! And what the Hindu yogis often refer to as the breathing of the universe signified by the word “OM”. With the big bang, matter that is atoms of hydrogen, carbon and other building blocks were scattered in every direction and as temperatures cooled down they coalesced to form gaseous planets, stars and comets. This expansion is taking place even today, as I write this, the Universe is expanding and the edges of the farthest galaxies are moving farther away from us. This trend can be reversed also and the Universe can start to shrink back on itself, gravity moving in the opposite direction like the ball u toss in air, it will go up till a certain point and then start to fall back to earth. Some people think that the end of the world would come about in this manner but then we are not talking of things that dismal at the present time. There is another very interesting thing about the Universe, you can actually go back in time if you observe it, just looking at the stars means you are travelling back centuries because they are so far away that although light travels at astonishingly fast speed yet it takes millions of years for it to travel to us so the lightthat we see today emitting out of stars left them thousands of years ago and the stars are not on that spot anymore at all but have moved.
Cosmos means order and chaos means disorder. The concept of cosmos is that all things work upon known laws of the universe which are the same at all places and at all times. So at whatever spot u are in the universe that is the centre and the space and time extends in all directions equally. Light will travel at the same speed which is about 186 thousand miles a second and nothing can travel at the speed of light. It takes 8 minutes for sunlight to reach us and traverse the huge amount of space in between. Moreover the laws of motion and gravity are constant in the universe which holds everything in place otherwise if it were not so the moon would collapse on to us by sheer force of the earth’s pull and we would be sucked into the sun and yes baked!!!! You may ask what is this space whose extent we don’t know made up of, well, most of it is just that space, sheer empty space, a vast nothingness through which sound cannot travel so very very quite. There are places in the cosmos where the sky is absolutely red like Mars, where planets have no solid ground like Jupiter and Neptune and where the horizon is half blocked by a huge moon, and where in the sky you see two suns instead on one. There are stars so close to each other that they touch.
Time is relative in the universe meaning it passes more slowly than it does on earth. So if you travel in space and come back after 50 years you would still be young while your friends and relatives would have considerably aged. Is there other intelligent life in the Universe? this question has dogged scientists for years and has hounded thinking man forever, man has always yearned for life on other planets, so far no evidence of it has been found anywhere but the quest goes on. There are more than 400 billion stars in the universe! one way of imagining the number is to liken them to the grains of sand on all the beaches of the world!!!! an amazing and mind boggling number. Wedon’t have the visual and the mental depth to fathom the magnitude of this universe.
You know that we are made up of star-dust? the atoms of hydrogen,carbon and oxygen in our bodies have circulated in this space forever and will continue to do so long after we are gone. They once made up stars and other heavenly bodies. At this very momentradiation from stars that is particles of electrons and protons from stars are piercing through our bodies at the speed of light and may soon be touching the surface of the sun or some other star. What is a star? it is a huge gigantic ball of fire that is burning its own fuel and will eventually burn itself out, Our sun is a medium sized star just at the right distance from the earth to induce life forming conditions. It will burn itself out in approx. 5 billion years (so we need not worry about it today) and while it is burning out will bloat into a big red ball, which is called a red giant before it collapses on itself. When it bloats it will increase in size and swallow all the planets surrounding it! (Armageddon) The stars do not have any solid surface they are literally balls of fire, huge nuclear explosions going on at every second in space. A star once burned out will eventually collapse intoitself and become so dense and exert such a huge gravitational pull that nothing will escape its event horizon (the beginning of its gravitational pull) even light cannot escape it and will be trapped in it, this is known as the dreaded “Black Holes” in the universe, places that are so dark and so strong that nothing can withstand its pull. Most of the Universe is not observable only a little part of it can be observed from this earth there are attempts to have a better vantage point hence the Hubble telescope in space and so on.