# Video: Understanding the Interactions between Matter and Antimatter

The diagram shows an electron and a positron colliding. The two particles are destroyed and a high-energy photon is created. What is the name given to this process?

01:54

### Video Transcript

The diagram shows an electron and a positron colliding. The two particles are destroyed and a high-energy photon is created. What is the name given to this process?

Okay, now before we answer this question, let’s first take a look at the diagram that we’ve been given. This diagram shows an electron, a positron, and a photon. Now the way that we understand or read this diagram, which by the way is known as a Feynman diagram, is the following.

What we do is we actually assume that this is a graph, not just a diagram, where the vertical axis shows position and the horizontal axis shows time. In other words then, at this point in time, let’s say time 𝑡, what we have is an electron and a positron a certain distance away from each other. Now this distance is the distance represented on the position axis.

And then as time progresses as we move right on the graph, so let’s say at a time 𝑡 prime, we can see that the electron and the positron get closer together. And we can see that they keep moving closer together until at a time, let’s say capital 𝑇, the electron and the positron meet.

And we’ve been told in the question that when they do meet or rather when they collide, the two particles are destroyed and instead in its place is a high-energy photon. Now as we continue progressing along the time axis or, in other words, as time progresses, the position of the photon doesn’t change.

So from time 𝑇 forward, the electron and the positron don’t exist anymore. And there’s just a photon in their place. So that’s how we read a Feynman diagram.

But let’s get back to the question. We’ve been asked to state the name given to the process where an electron and a positron meet. They collide with each other and they destroy each other to form a high-energy photon. Well, this process is known as annihilation because the positron and electron get annihilated when they meet each other.

And so that is our answer to this question. The name given to the process where an electron and positron collide and destroy each other forming a high-energy photon is annihilation.