Friday, December 16, 2011

The end of Life

.         I knew from my very young days that we will have to die once. When I was 15,  I was afraid that I would be dying very soon.  Later, I understood that all living and non-living things are doomed to go. The Sun, the Earth, planets, Milky Way galaxy and the Universe will all have to end. The Sun, which looks mighty now, is dying gradually. It converts 5 million tons of hydrogen into helium through atomic fusion every second to shine as it does now. After 5 billion years the fuel will all be spent up and it will then swell up to a red giant star engulfing Mercury and Venus.   Astronomers even think it will swallow up the Earth too.  Even if the Earth survives, the intense heat from the red Sun will scorch our planet and make it completely impossible for life to survive. The Sun will still have enough heat and pressure at its core to begin another type of fusion, burning helium this time to carbon. When the helium runs out, the Sun won’t have enough gravity to keep the core temperature high to burn carbon. At this point, the Sun will blow out off its outer layers. The dying core of the Sun will become an Earth-sized object of carbon and oxygen called a white dwarf. It will slowly cool off over billions of years, eventually reaching the temperature of the Universe. It will then turn into a black dwarf and the Sun’s death will be complete.
The life on our planet Earth is totally dependent on the sequences of the Sun. But will the planet live as long as its Sun does? Not probably. It is almost certain that planet Earth will die much before. As soon as the Sun becomes a red giant it may swallow up the Earth or melt it to a slag. It could be a few billion years before the final death of the Sun.  
But what about life supported by this planet? Can it survive as long as the planet? Again it is an emphatic no. It would  have disappeared millions of years ahead.  When the heat from the Sun becomes unbearable life here simply vanishes.
But will humans survive until then?. Human life here will probably end up much before the fiery end of the planet Earth. As the Sun heats up, (already its heat is 30% more than that at its beginning) and expands, the atmosphere will disappear, the oceans will evaporate and life will end once and for all.
Yet again will we last that far (it is a few billion years from now). Not at all.  
The earth is subjected to certain cycles. We are into an ice age now. At present its pace is very slightly put on hold by the rapid increase in the carbon dioxide emissions due to human activity.  But the ice will slowly advance and the human civilization will end up with the next glacial phase five million years from now. After the ice age a supercontinent will again be formed and with the accompanying climatic changes complex life forms will end. The last vicissitudes of life will be obliterated with the sun becoming a red giant. Complex life will then be finished not only on the earth but in a vast section of the Milky Galaxy, if not the entire universe.   
 Is there a possibility for the humans to escape into the outer space? Well, yes if we succeed in establishing huge bases in the Moon or in the Mars. We will have to transport huge quantities of air, water, hospitals, food and sufficient numbers to stay for a prolonged period (over half a million years?) just to escape the incoming ice age. But as the sun heats up beyond life’s endurance levels everything will end. Even simple single-celled organisms cannot survive. Life is over once and for all.  An eternal darkness descends. There is no question of an escape as the whole solar system and much beyond would be scorched up. 

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