Into deepest time with the REAL big bang theory

My wife occasionally calls herself ‘Penny’, as in Penny off The Big Bang Theory. Especially when I get together with my mathematician friends and we talk geek.

I’m not sure which of us is meant to be Sheldon. Anyway, the ‘big bang’ theory itself was first proposed in 1927 by a Catholic priest, Monseigneur Georges Henri Joseph Édouard Lemaître (1894-1966). He was trying to explain Vesto Slipher’s discovery that distant galaxies were retreating. And he was ignored. Then, in 1929, Edwin Hubble (1889-1953) suggested the same thing. Like most academic fields, physics is all to do with in-crowds; when Hubble spoke, other physicists pricked up their ears.

Timeline of the universe - with the Wilkinson Microwave Antisotropy Probe at the end. Click to enlarge. Public domain, NASA.

Timeline of the universe – with the Wilkinson Microwave Antisotropy Probe at the end. Click to enlarge. Public domain, NASA.

Their logic went like this. Distant galaxies appear redder than they should.  This is because the wavelengths of light and other electromagnetic emissions from them are being stretched from our perspective, meaning they must be moving away. This effect was first discovered by Ernst Doppler who realised this was why fast-moving vehicles go ‘neeeeoooww’. The sound waves are being stretched from the perspective of a stationary listener as the source moves away, so to them the pitch appears to drop. (You can buy a Sheldon costume so you can be the Doppler Effect, like he was in Series 1 Ep. 6…here.)

It works the same with electromagnetic emissions, and red has a longer wavelength than other visible light, so things moving away appear redder to us. Hence the term ‘red shift. It’s used to describe the phenomenon, even if the wavelength isn’t visible light. (No costumes for this one).

Hubble discovered not only that distant galaxies retreat from us, but that the further away they are, the faster they retreat. Hubble’s Law followed: v = H0D, where v is velocity of recession, Ho is Hubble’s constant, and D is the proper distance. The value for Hubble’s constant has never been agreed, but recent work suggests it might be 71 +/- 7 km/sec per megaparsec. Probably. A bit.

It also turned out that distant galaxies are moving away from us whichever way we look, showing that space-time itself is expanding. Imagine a rubber balloon with equidistant dots on it. Inflate the balloon. The dots move apart equally – and the distant ones are moving away faster. That holds true for space-time.

The conclusion was that the universe had been smaller – a mathematical point, in fact, from which everything exploded into the reality we know and love today. Pretty much like the opening credits on The Big Bang Theory, in fact.

Of course, it wasn’t expansion into a void. It was an expansion of space-time itself. The very fabric of physical reality.

It was a kind of cool idea, but nobody had any way of proving it. Physicists argued over whether there had been a ‘big bang’, or whether the universe operated by a modified ‘steady state’ of constant but expanding existence. Then, in 1948, Ralph Alpher and Robert Herman predicted that we should be able to see cosmic background radiation from the ‘big bang’ – and it was found in 1965. The radiation has a black body (idealised) temperature of 2.72 degrees Kelvin, give or take a tad (I define +/- 0.00057 degrees as a ‘tad’).

Into deepest space: Hubble space telescope image of galaxies from the early universe. Public domain, NASA.

Into deepest space: Hubble Space Telescope image of galaxies from the early universe. Public domain, NASA.

And you know the coolest part? Albert Einstein figured it all out in 1917, before any of the evidence was available. His General Theory of Relativity made clear the universe couldn’t be static – it had to be expanding or contracting. Einstein thought that had to be wrong, so he added a ‘cosmic constant’ to eliminate the expansion. But expansion was true, and he later admitted the ‘constant’ fudge was a mistake. His original equations held good.

Einstein had, in short, figured out how the universe worked – so completely that his theory explained the bits that hadn’t been discovered yet.

How cool is that?

Copyright © Matthew Wright 2013

Coming up soon: ‘Write it now’ and ‘Sixty Second Writing tips’, more humour, more science…and, more.

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13 comments on “Into deepest time with the REAL big bang theory

  1. bevrobitai says:

    Oh Matthew – you write a post like that and you’re not sure which one of you is meant to be Sheldon? :)

    • What I find most amazing is the way that physicists have to think creatively sideways to imagine all this stuff. Einstein especially – stunning displays not just of intellect but of imagination. Seriously cool!

  2. EagleAye says:

    The Big Bang Theory has been a slam-dunk for me since I understood it. But now we’re learning that the universe is expanding faster than expected. Oy! Now what? Now we need a repulsive force and that’s dark energy (to go along with dark matter to explain why the universe weighs much more than is observed). The dark energy idea makes sense, but I wonder if this isn’t like Einstein’s constant which is a patch upon an inconvenient hole. Hmm. I’m waiting for the gang (physicists) to figure this one out.

    • Yes, I wonder too – it seems kind of funny that we have to rely on a single imagined phenomenon that nobody can see or detect to explain what is observed, and I do wonder if we’re not missing something. Or if it’s a combination of several phenomena not yet fully known or understood. Will ‘dark matter’ and ‘dark energy’ go the same way as phlogiston and the interplanetary ether? Maybe. I’d give odds on at this stage, but I may be wrong…

      • EagleAye says:

        Certainly if the physicists can’t be certain at this time, how can I? I must confess that I like the elegance of a zero sum universe, which means the total energy value of the universe is zero. To have that, we would need a negative energy to balance out the positive energy. In nature, we see balance everywhere, yin-yang, life-death, self-organization – self-destruction, and so on. A self-balancing universe makes sense. And then if the total value is 0, that means you could create a universe from nothing which would make the big bang not only possible, but probable.

  3. If those guys could figure all this out without the technology we have today, why the hell can’t we figure out something equally cool, like how to get out here and visit all those neat planets? Huh, Sheldon?

    • That would be supremely cool. What’s more, the McGuffinite to justify the cost just got discovered on Titan. Massive liquid methane ocean. Of course, trucking the stuff back to Earth and burning it raises all sorts of other issues. But hey…

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