So a couple of days ago, I went to this physics talk by Miles Padgett, a professor of physics at Glasgow University. The talk was called ‘Does god play dice with Angles’ and was basically about Quantum Physics and how we know that the laws of Quantum Physics supersede those of deterministic nature (basically that everything has a cause and there’s been a logical sequence of events since the big bang. Therefore, if you have all the variables, you can predict anything).
He started off by talking about some pretty basic(ish) stuff. Wave particle duality, the double slit experiment and the collapsing wave function and stuff. I’ve talked about this before on the blog, so I won’t go into much detail, but it’s still pretty interesting to think about how counter-intuitive these ideas seem at first, but if you look at the evidence, how much sense they actually make.
He then went on to talk about quantum entanglement. Basically, the principle is that it is possible to get two particles (like photons) and somehow link the two, so that if, for example, one of the photons started spinning upwards, the other would spin downwards. This makes it possible to make a measurement of just one of the particles and know what the same property would be like on the other particle, even if you haven’t observed it at all. This makes for some very interesting ramifications. He showed us at one point the image of a skull that had been formed by passing photons through a stencil of some sort. The image was formed on a screen. He then showed us the image formed on a screen which another proton stream had gone to, and miraculously, an image of a scull was formed on that screen as well. So what’s interesting about that? Well, it leads to faster-than-light information.
Think of it this way. Imagine that there are two screens which are two light years apart. And while you’re at it, imagine that you’ve somehow managed to get two streams of photons which are perfectly entangled. So you have an emitter in the middle, and so one light year away from each screen. The emitter emits these two photon streams, and for one of them, there’s this stencil of a skull, and so the image of a skull is formed on the sheet. Now, if we accept that the two photon streams are perfectly entangled, the image of a skull will be formed on the other screen as well. And if you have an observer staring at the screen with stenciled image of the skull, as soon as they see the image of the skull, they know there will be a scull on the other screen as well. So the knowledge that there’s a scull on the other screen is with you instantly.
So what does this mean? It means that this information travels the two light years from one screen to the other instantly. So it seems like the information has travelled faster than the speed of light, right? But this doesn’t mean that we’ve had faster than light communication, simply because no message has actually travelled from one screen to the other, just an assumption.
This was a really interesting talk, and it brought up a lot of questions, most of which give a lot of food for thought. Quantum physics is more and more interesting the more you know.
Abzonnian Ramblings 