Posts Tagged ‘wave interference’

Making Waves 3

April 30, 2012 Leave a comment

In the last couple of posts, I’ve been showing you how to go about simulating quantum effects in the comfort of your own laptop. Sound impossible? It should do.

Quantum Mechanics is usually described as mysterious, truly random, and inherently non-computable. We’re told that it’s a topic that should cause us to ask deep and difficult questions about the nature of reality, and that it might even be connected to human consciousness.

This, in my humble opinion, is hogwash. I think QM is straightforward, mundane, and something that can be understood concretely by anyone by using simple algorithms. No complex numbers. No wave equations. No Hilbert spaces. This is not to say that I have a new theory of physics to trumpet, because I don’t. My purpose is simply to demonstrate that if people are having trouble reconciling Quantum Mechanics with Relativity, it might simply be because they’re looking in the wrong place.

Last time, I got as far as showing you how to make a self-interfering excitation wave. Let’s remind ourselves what that looked like.

Mostly, at this point, this just looks like a pink smush. Not terribly impressive. So in order to show you a little more about what it can do, let’s first cover a little background about the nature of waves to make sure we’re all on the same page.

Issac Newton thought that light was made up of particles and everyone agreed with him for a while. Then Robert Young came along (as well as several others), and pointed out that light experiences diffraction, and so it had to be a wave.

Cut two slits in a cardboard sheet and shine a light through it, and you get wave interference on the other side. Here’s his famous sketch of the process.

And here’s what that looks like if you hold a second screen up to look at the pattern that the interference makes.

As you can see, we get stripes. The reason why this pattern is important is because if light is a particle, it can only be in one place at a time, and so can’t interfere with itself. So getting a pattern like this shouldn’t happen for particles.

So before we get on to talking about quantum effects, let’s first check to see how our excitation wave works when we put it through a screen with two slits in it. We do this by taking our network and cutting a line in it. Then we only allow nodes on either side of the line to join up if they’re sitting very close to a pair of points we’ve selected.

Here the wave has hit the first screen, and is just starting to peek through the two holes.

And here the waves from the two holes have started to overlap.

The results look a little fuzzy perhaps, but our method appears to be working. Try comparing it to Young’s sketch above. However, I still haven’t said anything about quantum effects. And that’s where things get interesting. So next time, I’ll make a point of revealing all.