Thursday, 12 November 2015

The Many Live of the Multiverse

What is it about cosmology that turns clever people's brains to mush? Well, some of them they think that if they can't come up with a good idea, then the religious fundamentalists will claim that God is behind it all. And only a handful of people notice that believing in a Creator God does not mean that you have to buy the Old and New Testament, the Koran, beards, niqabs, circumcision, and every last condemnation of your local rabbi, priest, parson or mullah. That's just what Richard Dawkins and your local mullah want you to believe.

The alternative to a scientific theory isn't a few verses in the Bible, it's another scientific theory. And if there isn't one, then the scientific community needs to invent three. Unanimity is not a sign of truth, it's a sign that your scientists aren't imaginative enough, or that you need to get the dogmatists off the grants committee.

Another reason is that people get far too emotionally involved in their cosmological theories. They shudder at the infinity of space, or at the idea of the universe turning into a luke-warm sludge. And then they get horribly confused over some philosophical points. The result of this confusion, emotional involvement and the feeling that they are responsible for keeping the lunatic fundamentalists from the door, are mutliverses, Big Bangs and the Many-Worlds theory, surely the most lunatic piece of nonsense ever to be taken seriously by people much smarter than me.

We live on the planet Earth, The Solar System, The Milky Way, The Universe. Most modern theories of cosmology want to give The Universe a postcode as well: The Multiverse GH23 7FF. Except there's a lot of universes in a multiverse and the post-code would be a lot longer.

It seems it's important to us to know how the universe got started, or if it was always here and always will be. Nothing hangs on this: of all the things we could know, it's about the most useless. Large numbers of people don't even know who their father is, and they get on kinda okay.

Is there something outside "the universe"? No. Because otherwise it wouldn't be the universe. Was there something before it and will there be something after it? No. Because ditto. Might the bit of the universe that we see not be all of the universe? Undoubtedly. Could there be places elsewhere in the universe we can't see where robins have green breasts? Depends how important red breasts are to your definition of a robin. Could there be places in the universe where conservation laws don't arise as a symmetry through Noether's Theorem? Now, that's an interesting question. Is there an inaccessible part of the universe where energy isn't conserved? I'd go with a NO on that, but I'm open to argument. Maybe energy could just vanish, but not be created.

But General Relativity says the Big Bang, doesn't it? It's not compulsory. There are all sorts of solutions to the equations, but the equations can't tell us which solutions actually apply to this universe. Only the initial conditions can, and there's a lot of ambiguity in those.

But fine-tuning and the Anthropic Principle? Stop it. Just like God is not the answer to where the universe came from, nor are zillions of universes the answer to why we all got stuck in this one. Fine-tuning is how we know the laws of nature we're using are about right, and say that an interesting universe can only really be made one way.

Laplace spent a long time thinking he had to prove the Solar System was stable or there was something wrong with the whole edifice of Newtonian Dynamics. Well, now we know there's no reason it should be stable. Now people think they have to prove that the universe is always going to look something like it does now. But it won't. It will look exactly what it is going to look like.

Leverrier spent a long time trying to find Vulcan so he could get rid of Mercury's anomalous perihelion. A lot of people are now trying to find Dark Matter and Dark Energy so they can fix some galactic rotations. Does anyone else smell a generous helping of ad-hoc here? If Newtonian Dynamics needed a planet that wasn't there, or a fine adjustment to the inverse power, to be right, then it was wrong. And if General Relativity plus cosmological constants and simplifying-assumptions-so-we-can-calculate-anything-in-the-first-place needs dark energy and dark matter, well, then, it's wrong. And if we can only understand Quantum Field Theory via a Many-Worlds theory, then we just don't understand Quantum Field Theory either.

Until we do, and until someone comes up with a better General Relativity, I guess we're still going to get more whacky cosmology that in a couple of hundred years' time will read like Aristotle does now.

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