Monday, June 06, 2005

Getting Physical

It was a great day. I had taken the day off from work, and was glued to my monitor as usual. After 6 thrilling hours of endless googling into the sites of NASA, UCLA, UCSD and NCSA, I had read and wondered about an year's worth of information on our galaxy, the revered Milky Way, it's neighbours: the Magellenic Clouds, and the Andromeda, and how they all happily churn their way around in our local super cluster of galaxies. My father fondly refers to this as "our cosmic uppiTTu", to denote the boiling plasmic structure of space with a billion swirling pools of stars and galaxies. A truly south Indian analogy to match the older Raisin Bread comparison.

Also was on the cards today, was the need to know what exact work had gone into the research for finding out what lies in the centre of our galaxy. Until the 70's there had only been a speculation that the galaxy was centred on a super massive black hole.

Evidence collected in the recent years has indeed revealed a small cluster of stars found to be orbiting a super massive black hole called the Sagittarius A* ("Sag A star"). Studies of radio emission from this dense and compact point radio source, has shown that it measures just around 150 million kilometres in size, much smaller than our solar system, yet has the material of mass worth 2.6 million Suns. More recent observations of nearby galaxies have shown that they too contain similar dark super masses in their centres.

2005 is the World Year of Physics. It coincides with the first centennial of Albert Einstein's "Miraculous Year". 1905 saw an anonymous 26-year-old class 3 clerk at the Swiss Patent office literally rewriting the laws of Physics. Within a span of 7 months, he published 5 seminal works on topics like the Photoelectric Effect, Brownian motion and Special Relativity. It took decades for most of his works to be completely fathomed, and his equations demystified. But back then, a few scientists delved into his fresh findings, and came out with more shocking theories.

Karl Swartzchild, a German astrophysicist computed the gravitational fields of stars, using Einstein's new field equation, and ended up discovering a possibility of regions in space having an infinite space-time curvature, which got termed as the "Swartzchild Singularity". Much later in the 60's, John Wheeler (Richard Feynman's supervisor), termed this singularity as the "Black Hole".

The theories of 1905 had revolutionised Physics and Cosmology, and had forever changed the way people thought about space-time, matter and energy. 11 years later, in 1916, Einstein established another landmark through his General Theory of Relativity by proving that matter could curve space. Curved space could curve light too. Thus it had been proved that light could bend if the gravitational force of a body was sufficiently strong.

This leads to a funny (sorry for the trivialisation of the otherwise serious implication!) effect. Pretend that you were standing on Earth now, and looking at a star in your Northern sky. The actual existence of the star could be totally elsewhere, say in the eastern sky. As ludicrous as it may sound, it is possible if the light from the star went AROUND a huge black hole in your Northeast, and then struck you from the North, thus giving you a false direction to extrapolate its presence.

If you reapply this theory, then the light from a star could have sashayed around half a dozen black holes, and could have reached you in the sky in front of you, when the star was actually behind you. If you further stretch the assumptions, you can think of several images of a single star running loose in space, and the obvious delays in time could result in the images reaching you at different times, from different places in the sky.

Ok, so that means we might not be seeing this stellar mammoth, where exactly it is now. To add to this conundrum, let’s imagine our star to be probably a thousand light years away from us. So the light we DO see now was what the star pulsed out a thousand years ago. If the star had burned itself out exactly a thousand years ago, or had exploded as a grand Super Nova, we'd get the bad news a millennium late. Plus, a few later generations on earth could see the SAME explosion in a different place in space. As they say “History repeats itself.” Now history can repeat its replications.

It would be really hilarious if the image of me sitting on a small terrace (looking out at those notorious stars), went out of this solar system, bounced around our local downtown black hole, and took a complete U-turn (believe me, this is possible), and fell onto Earth 60000 years later (we are around 30000 light years from the Sag A*.) My great great grandson would have the pleasure of seeing a funny be-spectacled humanoid sitting on a blue planet peering curiously into the deep dark sky.

Can space really be believed??