What's physics like at small scales?

18 June 2019


Abstract art of an atom



Does physics become unusual at that small a scale?


Chris - Here's a question for you Colm: does physics become unusual at a small scale? It’s kind of getting at quantum mechanics isn't it? So when you're playing around with individual groups of atoms at the scale that you do what actually happens to them that would be different than if you're dealing with something at the scale that we can see like a coffee mug or a knife and fork?

Colm - Well there are so many things. I mean, at a very basic level when you make something small enough, so let's say you take a particle that’s just a few nanometres across. You can do a similar calculation you can figure out how many of the atoms in it are on the surface and how many are inside. And if you think about it atoms inside a material are surrounded on all sides by other atoms so they are energetically in stable states. They’re in bonding configurations that are low energy and stable whereas atoms on a surface are not surrounded on all sides. They basically have higher energy, but you also have quantum mechanics coming into play as well. And what that's all about is we think of the world around us as comprising particles and waves. So we think of light as being a wave and we think of matter being made up of particles that are hard solid objects. It turns out that that way of looking at things while it's very intuitive and it makes sense and fits in what we see everyday, that breaks down when you're at atomic dimensions and below. Even things like simple electrons do not actually behave like solid particles when they're moving through material. So when you've got an electric current flowing through something it's made up of all of these little particles, which under the right conditions, can display wave like characteristics. Which means they have interference, you know, you can get electrons communicating with each other over vast distances because of this wave nature. In nanotechnology what we what we're doing is because we're working with pieces of matter that are just nanometres across, the nanometer is the length scale associated with a lot of quantum effects. So yes. So in order to do nanotechnology properly you'd need to understand quantum mechanics and physics gets very strange


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