Friends, today we will talk about a problem that plagued the big bang theory of the universe for decades and the strange solution that physicists proposed to solve it.
In an earlier VERITAS we had studied about the cosmic background radiation. This is the radiation left by the big bang itself. It is the cosmic radiation “smoke” that tells us that a loooong time back an explosion ( the big bang ) happened. So if you point sensitive equipment to any part of the sky you will “hear” a dim background noise. Its source is something 14 billion light years away from us. IF you calculate the temperature at which matter would radiate like this you would find that it is about 4 Kelvin( 4 degrees above absolute Zero). And remember that when you look farther into the Universe you are looking backwards in time. Since light takes 14 billion years to come from the cosmic background radiation spot to us that means that we are looking 14 billion years back in time!!!
Look towards the east. You will find 4K cosmic bacground radiation 14 billion light years away. Look towards the west. You will find 4K cosmic background radiation 14 billion light years away. The cosmic background radiation(CBR) looks exactly the same whether you look towards the east or towards the west. They seem to be in an thermal equilibrium with each other. How much is the distance between the two horizons? It is 28 billion light years! So the east and west horizon have not met for atleast 28 billion years. And what is the age of the Universe? 14 billion years! Isnt that weird?????!!!! If the CBR at the east and west horizon came from the same big bang then they have been separated by 28 billion light years. But our universe is only 14 billion years old. SInce nothing can travel faster than light this means that these two parts of the CBR have never interacted!!! We say that the CBR in the east lies outside the light horizon of the CBR in the west.
Similarly the CBR in the north lies outside the light horizon of the CBR in the south. Since all these parts of the CBRs have never interacted how come they are soo similar? How come they are at thermal equilibrium with each other? This is the Horizon problem.
Physicists hace come up with a very strange theory to explain this. They propose that within a minute of the big bang there was a HUGE expansion in the universe. We know that the universe is expanding at a particular rate.
But this expansion was not this normal expansion. It was A MUCH MUCH BIGGER expansion. It expanded much faster than light! It just blew up. It blew up by a factor of 10^50 ( 10 followed by 50
zeros) in a very very short time ( .000000000000000000000000000000000001 i.e 10^-32 second). So in a small fraction of a second the Universe just blew up in a huge way! This would not violate Special Relativity which says that nothing can move faster than light because space and time themselves were expanding. If inflation happened then the east and west CBRs are within the light horizon of each other. So they have interacted in the past( within the lifetime of the Universe) to reach the same temperature.
But if inflation is true then there is a stranger consequence: the observable universe ( the 28 billion light year diameter) is a very small portion of the complete universe. There is a huge amount of stuff outside this. It is outside our light horizon so we will never be able to interact with it!
Not all Physicists believe in the inflation theory. SOme think that maybe the speed of light was much greater just after big bang than it is now and that would explain how these CBRs interacted within the lifetime of the universe.
But how do we verify these theories? We cannot experiment with the universe! Are we to just philosophise fruitlessly?
Friends, we exist for such a short time. And there is so much to learn. Would our lives finish without this thirst for knowledge quenched? And how does one quench this thirst for knowledge when we know how limited our tiny brains are???!!! I sometimes wish that there were a God. Then at least I would be able to ask him about the Universe. The human endeavour to search for truth, our Science, is too painful. How little we achieve through Science in our tiny lives!!!!!! If only we could ask God the questions. Without God life seems to be so useless and incomplete- a drop of water that will never reach the ocean.
Why cannot I be the one who sits in front of Krishna and Krishna says as he said to Arjuna: “I shall now declare unto you in full this knowledge, both phenomenal and numinous. This being known, nothing further shall remain for you to know.”
Why should I struggle endlessly with false knowledge, false books and a limited time on earth:
Study is like the heaven’s glorious sun
That will not be deep-search’d with saucy looks:
Small have continual plodders ever won
Save base authority from other’s books
These earthly godfathers of heaven’s lights
That give a name to every fixed star
Have no more profit of their shining lights
Than those that walk and wot not what they are.
Too much to know is to know nought but fame;
And every godfather can give a name.
Go, wondrous creature! mount where Science guides:
Go, measure earth, weigh air, and state the tides:
Instruct the planets in what orbs to run,
Correct old time and regulate the Sun;