Looking forward a century, I am very optimistic that the particle making up dark matter will have been discovered.
A: Dark matter. Astronomical measurements show that the Universe contains much more matter than is observed directly. This excess matter gives off very little visible light and is therefore called ‘dark matter’ (DM). Almost nothing is known about what makes up the DM but the leading proposal is that it consists of one or more new, as-yet undiscovered elementary particles. (All known matter is made up of a set of elementary particles that interact with others through the fundamental forces, but none of these particles has the right properties to be DM.)
The search for the particle that makes up the DM is currently underway with theoretical proposals for DM candidates, laboratory experiments designed to detect DM directly and astrophysical observations looking for signals of DM in the cosmos. While no definitive discovery of DM has yet been made, these efforts have significantly narrowed the range of possibilities of what DM could be.
Looking forward a century, I am very optimistic that the particle making up the DM will have been discovered. This discovery will certainly be momentous, but it is also just the first step in a complex research program to measure the properties of the DM particle in great detail. These properties include its mass and what types of forces it feels.
An exciting and well-motivated possibility is that DM particles are attracted to each other by a new type of fundamental force that is not felt by ordinary matter. If this is true, the discovery of DM would be the first step in a series of discoveries of new particles and forces. Finding the DM particle and determining its properties will also provide a powerful new tool to investigate astrophysical structures such as stars and galaxies.
A: My current work focuses on investigating potential candidates for the DM particle. I develop new theories for what the DM particle might be, I investigate how to test them with current and future experiments, and I look for new experimental methods that might be able to do even better. Since we do not know what the DM particle is, it is not obvious how to search for it. The best we can do is make specific proposals for the DM particle and then test these proposals experimentally. I hope that my own contributions to theories of DM will help guide future experiments to a concrete discovery in the next century.