Question: What is quantum tunneling?

Claire Lee answered on 27 Jun 2013:

Quantum tunneling basically says that there is a non-zero possibility that if you run into the wall an infinite number of times, you will eventually go through it 🙂

(I gotta log off now – will post a more complete answer later tonight!)

EDIT: Ok… here we go:

So the thing about quantum mechanics is probability. Everything is described by probabilities, and everything carries that probability around with it as a wave. Basically, instead of thinking about a particle as a dot, you should think about it as a wave (or function) telling you what the likelihood is for that particle to be in a given place at a given time.

Now imagine you take your particle and you put it in a box, one that it can’t get out of. In our everyday lives, we would think that, if the particle was in the box, it’s in the box. It could be anywhere in the box, but it’s still IN the box.

Quantum mechanics is a bit more open minded (it thinks outside the box, so to speak 🙂 ). When you stop thinking of a particle as a dot and start thinking about it as a probability function, then you get something strange happening… If you solve the function, you get something that tells you “Most likely inside the box, but a small likelihood that it is outside too”. If you like betting against-the-odds, quantum mechanics is a good game for you!

The strange part is that it’s not that the particle even travelled through the box, or made a hole in it. It didn’t. It just could be on the other side.

Actually, in the real theory, the boxes walls are made of energy, kind of like a hill, and the particle doesn’t have enough energy to go over the hill. Except that you have a chance of finding it on the other side. It hasn’t gone over – it’s just gone through the hill. Tunneled through!