Question: What is the use in trying to create antimatter? Accelerating particles and causing collisions to produce antimatter seems like a lot of effort for the purpose of discovering particles.

Joel Goldstein answered on 8 Dec 2022: last edited 8 Dec 2022 4:35 pm

Not all antimatter is made in collisions: in fact, antimatter (specifically anti-electrons or “positrons”) are probably being made in a hospital near you right now through radioactive decay, for use in Positron Emission Tomography (PET). This is a very important medical tool, and is a great example of an application of particle physics.

As a particle physicist though, I want to do experiments with antimatter particles either to directly measure their properties (e.g. do antiparticles fall downwards in gravity?) or to use them as a tool for other measurements. For this we generally do need to accelerate and collide other particles, which as you say is a lot of effort so we will only do it when there is no other way to access the science we want.

As an example, I used to work on a particle collider called the Tevatron. For many years this was the highest energy collider in the world and discovered the top quark. In order to get the most energy out of each collision, it collided protons with antiprotons, but the antiprotons took a huge amount of effort to produce and store. The highest energy collider in the world is now the LHC at CERN. Although the LHC would gain something from colliding protons with antiprotons as the Tevatron did, it is not worth the effort so it collides protons with other protons instead.