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Did Hubble get it backwards?

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SimonLeigh
(@simonleigh)
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I’m easily confused. 100 years ago, Edwin Hubble found that the more distant a galaxy, the more red shift it showed, (i.e. its wavelengths were stretched towards the longer, red end of the spectrum, like the Doppler effect ) so  the faster it was moving away from us. “The universe is expanding, faster and faster!” he announced. But I think he got it backwards. If the most distant, oldest galaxies are moving faster than the more recent, closer ones, then the universe is expanding slower, not faster. The early bits are accelerating faster, but the later ones are going slower, and the later ones are nearest to now.

 

 
Posted : August 31, 2017 12:54 am
sirat
(@sirat)
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Imagine an ordinary explosion, either in space or anywhere else. The particles fly away from the centre of the explosion in every direction. Now imagine that you live on one of the particles and you have the necessary technology to measure the speed at which distant particles are receding. Suppose that you discover that the speed at which they are doing this is actually increasing with time. How would you explain that? Where is the energy coming from that is causing them to speed up? They had their initial 'push' from the explosion, but (as far as you know) no further input of energy. Then surely they must slow down due to friction (collision with molecules or dust particles) or simply in response to the gravitational attraction of all the other particles, most of which are going to be 'behind' any given particle as the sphere of particles expands.

But substitute stars for those little particles, all of which were given an initial 'kick' by the big bang and  we find that far from slowing down with advancing time they are actually speeding up! What is causing them to do that? It needs an explanation. All we have at the moment is a name for it: 'dark energy'. 

I don't see any holes in Hubble's argument. I don't think he got anything 'backwards'.

 

 
Posted : September 6, 2017 7:28 pm
SimonLeigh
(@simonleigh)
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Thanks, sirat. I was confused because I'd read that the furthest (oldest) stars showed greater red shift than the closer ones. Not so. Less. It's the closer, newer stuff that's receding from us faster. So the whole show is speeding up. I'm still puzzled by dark energy (who isn't?). It's like anti-gravity; the further away, the harder it repels. Are we sure there's not some attracting force, like gravity that's outside the universe sucking everything out, faster and faster as stuff approaches...space? Coffee time! 

 
Posted : September 7, 2017 11:06 am
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