Entanglement

I bought a book today: Entanglement, by Amir D. Aczel. I currently think it’s fascinating and amazing, but that is only because I have never tried ensuring that 100 young people could all answer the same questions about it. I’m sure it could become tedious somehow. What’s not why I’m mentioning it. I’m only two chapters in, so I can’t write a review yet, either.  So far I have been struck by two things — two ways in which actual life is more like fairy tales than not (until we have grown too used to it, and tried bludgeoning it into the minds of our reluctant youth). Mr Aczel begins with a story of how, as Quantum Mechanics was being discovered, or invented, as the case may be, Einstein and some other excellent physicists noticed a peculiarity in their model: it predicted that two particles could effect each other instantly at some distance — any possible distance. This is in opposition to our understanding of causality, and so they said that quantum mechanics must not be a complete system (or something like that — I get my terms confused). They put this out as a challenge to other scientists. It’s not possible. It’s not causal. There must be something wrong with the equations. Later other scientists managed to show that the irregularity wasn’t with the math, or the system, but with the world.

I was struck by this account because of the ways in which we can and cannot properly and truthfully utilize rational consistency. The first place I recall encountering this idea was in G K Chesterton’s Orthodoxy: he had found that when he encountered an oddity in Christianity, it was generally because there was an oddity in the world as well. For some reason I cannot even begin to fathom, mathematical physics has something of that quality as well. It’s very strange that there should be irrational numbers as well, but they must be well suited to the reality of things or we wouldn’t calculate with them.

The second thing I was struck by was the way in which the experiments were done. The first experiment described is the one where you shoot a single photon of light through a double slit, and end up with a wave-like interference pattern, leading the scientist to conclude that the two possible states of the photon was (were?) interfering with it (them?) selfe(s). Then they did this experiment with single atoms, leading to similar results. Very strange and creepy. But it’s also pretty strange and creepy that some people know how to send off light one photon at a time, and then measure the results. Perhaps I’m only saying this because the most technical part of my college education consisted on melting resin onto zinc, smashing flowers onto it, and then etching the parts the flowers had taken off onto it in acid — but… of course we know how to do this stuff. I mean, we apparently know how to breed genetically modified mice with florescent neurons and then count their neural receptors. But still. All the same. We can send atoms through some kind of screen with holes on it one at a time and then measure the results. I knew this, but all the same… how do people do that? What does an atom meter look like? How does it work? How does someone make it? How do they measure their results? How do they move single molecules about without them getting lost? Is there a special molecule cage, so that you know that you have the same one you started with — the entangled one — instead of an impostor?

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One thought on “Entanglement

  1. Very nice post. As to how they do it? I don’t have a clue. But in general, science is kind of like well-controlled art. Melting resin onto zinc is a good example. It can become a perfectly useful science experiment by controlling all the variables. How fast it melts, at what temperature, what type of resin. Moving atoms is similar. Moving atoms is something you do all the time. Controlling all the variables is what makes it a useful experiment, and understanding what the results mean is where the hard work is.

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