LIFE IN THE UNIVERSE:IDEAS OF STEPHEN HAWKING IN A SIMPLIFIED PRESENTATION:
INTRODUCTION:Stephen William hawking is the best known living scientist with a Ph.D in cosmology and a prolific writer on Astronomy and theoretical physics. Stephen Hawking has worked on the basic laws which govern the universe. With Roger Penrose he showed that Einstein's General Theory of Relativity implied space and time would have a beginning in the Big Bang and an end in black holes. These results indicated it was necessary to unify General Relativity with Quantum Theory, the other great Scientific development of the first half of the 20th Century. One consequence of such a unification that he discovered was that black holes should not be completely black, but should emit radiation and eventually evaporate and disappear. Another conjecture is that the universe has no edge or boundary in imaginary time. This would imply that the way the universe began was completely determined by the laws of science.
Many of us may not take the trouble of going through his writings thinking that they are too complex ideas. But it is not so. He writes very lucidly on complex concepts. This is a humble attempt to abridge one of his famous articles ,so that it is a bit easier to read through and appreciate.
A.P.Jayanthram




The second law of Thermodynamics explains that the total amount of disorder or ENTROPY in the universe always increases with time .Life can be defined as an ordered system that can sustain itself against a tendency for disorder and reproduce itself. A living being has 2 elements: a set of instructions that tell the system how to sustain and reproduce itself, and a mechanism to carry out the instructions. Biologists call them gene and metabolism. Most forms of life including us are parasites as they depend for their survival on other forms of life.
When the universe was born 15 billion years with a big bang, there were no carbon atoms. Everything was so hot that there were only protons and neutrons. When universe expanded, it cooled. Some neutrons collided with protons and formed the simple element HELIUM. Expansion and cooling of the universe continued. Two billion years after the big bang, high density regions which had extra matter helped stop the expansion and collapsed to form galaxies and stars. These stars bigger than our sun, burnt the original Hydrogen and Helium to heavier elements such as Carbon Oxygen and Iron.
Our solar system was formed four and a half billion years ago. That is 10 billion years after the big bang. Earth was formed out of heavier elements, including Carbon and Hydrogen. Somehow, some of these atoms got arranged as DNA molecules which can reproduce genetic information coded in their sequences of nucleic acids .These sequences could also make proteins and other chemicals which can help DNA reproduce itself.
In a universe with infinite number of stars, formation of DNA could happen in a few stellar systems even if widely separated.
Biological evolution was very slow. It took two and a half billion years for cells to develop into multicell animals, another billion years to fish and reptiles to mammals .Then the process speeded up and humans came just in a 100 million years. Human DNA contains about 3 billion nucleic acids. It has taken us several million years to develop from apes to humans. We are today much more than our genes. What distinguishes us from cavemen is the tremendous amount of knowledge that we have accumulated in the last 300 years.
If you today decide to 1 book per day, it will take you 15000 years to read all books in a big national library. This means people will have to specialize in narrow fields. A danger for future generations is the aggression instinct that came with us from the cave days. But, today a nuclear war or a genetically engineers virus can cause grave danger.
During the next century, we will learn how to map the DNA sequence and modify intelligence and instincts.
If human race manages to redesign itself and eliminate the risk of self destruction, we may perhaps spread out to other planets and stars. But the problem is with our limited life length. It will take 8 years even to a near star. One solution could be to send machines to stars, and they can be a new form of life consisting of electronic and mechanical components rather than macromolecules.
There could be other stars with life on them. May be the probability of spontaneous life is so low that earth is the only planet with this feature in our galaxy. It is not clear that intelligence has long term survival value. Even if all life on earth is wiped out by our actions, bacteria and other single cell organisms will live on. .Intelligent life on earth might have developed on earth only because of the lucky chance that there have been no major collisions on our planet in the last 70 million years. There is a possibility that there is life out there somewhere with extra terrestrial intelligence. Who knows when we will pick up radio frequency signals from alien civilizations?

(Abridged by A.P.Jayanthram)