Monday, August 3, 2009

The lights in the sky are stars

"Seeing the blindness and misery of man, and looking over the muteness of the entire universe, and man without any light, abandoned and alone in this corner of the universe, without knowing who placed him there, what he has come to do, what will happen to him when he dies, incapable of knowing anything at all, I am seized with fear, like a man who has been carried in his sleep onto a desert island and who wakes up without knowing where he is, without any means of escape." Blaise Pascal - Pensees

Any time I feel cocky and start thinking what a great teacher and scientist I am, I look up to the stars and realize that we and the entire earth we live on are simply a tiny, tiny, tiny blip in the Universe. The light actually left the stars years or even thousands of years ago and just now arrived here. And the panorama of stars one sees (if one is lucky enough not to live in Los Angeles) does not really exist, but represents slices of history, with each star releasing its light at different times in the past, with some probably not even existing anymore. And the light from the billions of stars in the billions of galaxies was emitted millions to billions of years ago and has endured the most incredible trip one could imagine to get to us here on earth. Sometimes this is too just much to comprehend, so I start out by trying to visualize distances. I start with the understandable - the distance from here to the other side of my yard, then from my city to another city and from my country to another country. I understand this because I have walked across the yard and have stared out the small window of an airplane flying several miles above the earth for 10 hours. Looking at my flight from here to London on a globe gives me a feeling for the size of the earth. To get to the moon, it would take my jet plane around 16 days since it is around 30 earth-diameters distant; it even took the Apollo astronauts 3-4 days with a much bigger jet plane. I can see the moon and can easily grasp this distance with some stretching of the imagination and can even imagine that I see the lunar lander left behind when the astronauts departed. But then things get a little hairy. Light from the nearest non-sun star, Proxima Centauri, which I can easily see with my 10 inch telescope, took 4.2 years to reach me, and light travels really fast - around 670 million miles per hour. Now I am struggling with the concept, but worse is yet to come. Light from our closest neighboring galaxy, Andromeda, took 2.5 million light years to arrive here, and light from the farthest object yet observed, a stellar explosion that released an immense amount of gamma-rays, took 13 billion years to arrive here. Now it is just numbers, but numbers do have meaning and the meaning is that I myself am meaningless in the immensity of it all and am properly chastened.

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