The Universe and Man

If I were to be asked "Which is the most useful instrument that man has invented since yore?", I would unhesitatingly say "the Telescope". Indeed, the telescope does not serve any material purpose on the Earth, but it does a very important thing; it teaches man humility, by revealing his position in the cosmos.

For centuries man believed in a geocentric model of the Universe, in which every object of space was thought to rotate around the planet Earth. But the observations of Copernicus and Galileo revealed that this was not the case, the Earth is an ordinary planet that revolves around the Sun along with five other planets. Then discoveries in the 18th and 19th centuries revealed the existence of Uranus and Neptune. The study of other stars shattered the heliocentric model of the universe; it was proven that the sun was just an ordinary star. Then the study of the Milky Way galaxy revealed that the Sun is near one edge of the Galaxy, around 25,000 light-years from the centre. Then the discovery of other galaxies in the universe revealed that the Milky Way is just another ordinary galaxy. Every time we tried to fix ourselves in the centre of the universe, fresh evidence shattered the hypothesis.

Light-years are enormous distances compared to our terrestrial units of metres and kilometres. By knowing that light travels approximately 300,000 km/s, a light-year (distance covered by light in one Earth-year) would be a colossal 9,460,000,000,000 km.

The study of the stars in our galaxy and others has enhanced our knowledge of stellar evolution. Scientists now know that the Sun is not a permanent source of energy, but will extinguish itself after some 5 billion years. The same holds true of all the other stars, though the lifetime may be varying. It has also been found that all stars are not like the sun. Exotic stellar objects like novae, supernovae, neutron stars and black holes have been observed. Science is yet to fully unravel their mysteries.

The universe is believed to have started by what scientists call 'The Big Bang'. It is said that the universe was condensed in an incredibly small volume, and it exploded all of a sudden some 15 billion years ago. Now, it is said that the observable universe is 93 billion light-years in diameter. I am yet to work it out in terms of kilometres; probably all I would be doing is to count the endless string of zeros.

When we see things in space, we don't see things as they are now. We seem them as they were in the past, depending on how far they are (or were). Thus, observational astronomy, is in a sense, a time-machine, one we use to see into the past.

Astronomy and Astrophysics are wonderful branches of science. They deal with most of what is known; by them we also know of our insignificant position in the universe. But we need not be unhappy over this. The Earth is a very special place for us in this Universe; extra-terrestrial life has not been discovered till date. The Earth is as intriguing a place as the rest of the Universe is.

The facts of astronomy leave us dazzled. We learn about phenomena that can never occur on the Earth, we deal with distances and time-scales that dwarf the ones we use on the Earth. Truly, man is really great, for he has learnt so much about the Universe without so much budging from the Earth (or the Solar System).