Friday, November 17, 2006

Destined to be

These scientists are trying to go back in time... or something like that…

Even though what I am going to say is also a bit geeky, you should read on - if you are not totally brain-dead - because I am sure you will be able to pick the general idea. Actually, the first guy who thought about this is Richard Feynman while he was studying under John Archibald Wheeler. Those were the early days of quantum physics.
Nobody is still quite sure of what exactly ‘light’ is… they say it behaves like a wave at times and as bits of matter/energy at other times. (Einstein’s E=mc2 technically means that matter and energy is basically the ‘same thing’ in two different forms) they came up with a cool name for these waves/matter/energy things and called them “photons”. Anyway, stars emit light or any form of radiation as photons and these photons travel vast distanced through space. When we look at the sun, these photons from the sun directly enter our eyes, and they are in fact absorbed by the eye in the end (that’s why the little dot right in the middle of the pupil is always black – because none of the light that enters through it is ever reflected back). Some of the white light from the sun is reflected off objects that may absorb all the colours except green and so that object appears green (sorry if I am dumbing this down too much). The idea is that these photons are absorbed as light or heat or some other form of radiation by things on earth and their energy is transformed into other forms such as chemical energy, heat and so on. When you look at a star at night, you see it because light from that star just entered your eyes.
What happens if a photon that’s emitted by a star travels through space for ever without being absorbed by another object? Does the energy of that photon leave the universe? If it leaves the universe, where does it end up then?
Feynman, being the smart-ass he is, said that it is not possible because none of the astronomical observations supported the possibility that the Universe was loosing energy through radiation. So he explained it the only way he could by saying that a photon essentially had to be an exchange of energy between two atoms. This sounds simple enough, but what it means is that when you saw that star, it was as a result of a specific exchange of photons between that particular atom in the star which emitted that photon an a certain atom in the retina of you eye!
But think about the time difference! What this theory means is that the atom in that star which emitted that photon – say fifty thousand years ago – had to know that the particular atom in your retina would be precisely in the position that it was after fifty thousand years to absorb it!!! Could that be possible? Well, Feynman thought it was, because he agreed with Prof. Einstein that time was just another dimension and two different points in time could virtually merge - just the same way that one could bend a piece of paper in such a way that any two points on it could fall on top of the other.
But then, does that mean we are robots of destiny – doing precisely the things we were always destined to do and being precisely where we are destined to be? I don’t know and I don’t give a damn right now… I am off to bed… and for heaven’s sake, don’t wake me up unless you are absolutely destined to do so!

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