I’m gonna guess all of you have probably heard of the Hubble Telescope … That giant space camera up above that captures the images that you use as your screen-savers. You have , right? Of course you have. Odds are you have that annoying facebook friend that keeps uploading images of galaxies and nebulas etc everyday without knowing a damn thing about whats going on. “It’s pretty” they say
Well , outer space doesn’t always have Sandra Bullock floating about but it’s still pretty amazing!
Let us travel back in time a little and scare the living hell out of Einstein shall we? See , back when he was around showing off his fabulous brain , he thought ‘Hmm… space is huge… only gravity could affect a thing so huge (Galaxies aren’t charged , so electromagnetism doesn’t count) .. So , we should all be squeezed to a point object having ‘Yo mama’ mass one day or the other right?
Well , but astronomers that day told Einstein that the universe is stationary .. On a large scale it doesn’t move.. All the galaxies have a fixed point in space and have forever existed that way.
So , Einstein said that there must be something that is opposing gravity and called it ‘The cosmological constant’ . That’s the famous capital gamma symbol you must have seen in the Einstein field equations
Some time later , there came the physicist Edwin Hubble.
He at the moment was studying the spectra of hydrogen.
The experiment , in essense was as follows:
You take a glass tube , pull all air out , put hydrogen in , pass current and Viola! Colors!
The colors hydrogen shows appear kind of like this
He then observed the spectra of hydrogen in a star , the colors were there of course , but kinda shifted to the right. I.e shifted towards the red. Now , if you know what the doppler effect is , you already know what I’m heading.. if not , here it is , in essence.
If something move away from you , the waves of light spread out , the frequency decreases i.e it gets red shifted, and if it is moving towards you , the frequency increases. I.e it gets blue shifted … you can see that with sound too.. If a train comes towards you , you hear the horn at a higher frequency and when it moves away , you see it at a lower frequency.
So… if you see where I am heading with this… Galaxies , stars and everything else , as hubble correctly observed , are moving away from us.
In addition to this , he discovered that the starts which were further away , moved away from us faster. This was mind-boggling!
Want to know more? Stay tuned, 😉
Also , those who are interested in cosmology should check out Leonard Susskind’s lectures , on Stanford’s youtube channel. :
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– Rishikesh Jani