Ask Ethan: Can we detect dark matter if it’s truly collisionless?
Dark matter’s hallmark is that it gravitates, but shows no sign of interacting under any other force. Does that mean we’ll never detect it?
One of the great mysteries in all the Universe is the question of what, exactly, makes it all up? The science of experimental particle physics revealed an incredible part of that story, discovering that everything that makes up ourselves and all the objects we can directly interact with is represented within the Standard Model: quarks, charged leptons, neutrinos, photons, gluons, and even heavy, unstable bosons like the W, Z, and Higgs. Yet all of this — all that we see, know, and detect — makes up only about 5% of the total energy budget of the Universe. A whopping ~27%, meanwhile, is made of a mysterious substance that behaves like a massive particle, known as dark matter, and the remaining ~68% is known as dark energy, which behaves as though it’s a form of energy inherent to space itself.
While there’s an overwhelming suite of observational evidence indicating dark matter’s existence and influence on cosmic structures, from galaxies to galaxy groups, clusters, filaments, and the large-scale cosmic web, all direct detection experiments to date have only turned up null results…
