Wednesday, January 13, 2010

Our tiny planet in our huge Universe

I have always been fascinated by astronomy and before I decided to go into neuroscience to study our amazing brain I had dreams about studying astronomy. I personally cannot understand how people can avoid being overwhelmed by our universe.

Our earth is a pretty big place, yet planets such as Saturn and Uranus are much bigger. Jupiter, however, is larger than all the other planets in our solar system combined into one planet - now that is big. Compare Jupiter to our sun and Jupiter looks like a pea next to
football, put another way - the sun is huge and massive! Still, our sun, which we rely on so intimately, is one of a hundred billion stars in our massive galaxy "the milky way". The Milky Way is a hundred thousand light years across - meaning that it takes light 100.000
years to reach us from the other end of the galaxy (yet the light can whizz around the earth 7 times in one second). Our sun, which is huge, is not even close to one light year across - rather it is about one light minute...

Our huge Milky Way galaxy containing a hundred billion stars and with a diameter of about 100.000 light years is small compared to the local cluster of galaxies (a small cluster of half a dusin galaxies), which measured millions of light years across.

I think you see where this is going... Our local cluster, which is absolutely humungous, is tiny compared to the observable universe. The most distant galaxies that can be seen are about 14 billion (that's light years away - suggesting that the observable universe has a diameter of maybe 28 billion light years. Our local cluster of galaxies is tiny in comparison...

Still, theory suggests that our 28 billion light year observable universe is just a small fraction of the true size of the universe (we cannot see the whole universe because galaxies far away may be travelling away from us faster than the speed of light in which case their light will never reach us). Maybe the observable universe is just "one billionth" of the size of our true universe.

At last - many theorists believe that our universe, in which we are much smaller than a grain of sand in the Sahara dessert, is but one out of a large number of universes...

I don't know about you, but these numbers make my heart beat faster. I feel small and improbable, but also grand, lucky and inspired - it turns all my daily woes into experiences - I feel lucky for having experienced what it feels like to be sad, angry or happy - I feel
lucky for being able to study all the grand aspects of nature - from our huge universe to our fantastic brains.

1 comment:

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