Physicists assemble the LUX (Large Underground Xenon) detector, which was one of the world’s most sensitive searches for the direct detection of dark matter particles. When in place inside the Homestake mine, the liquid-xenon-filled capsule hoped to detect three or four particles of dark matter a year. It wound up detecting zero. (John B. Carnett/Bonnier Corporation via Getty Images)

This Is The Real Reason We Haven’t Directly Detected Dark Matter

Finding the particle we assume is responsible for dark matter has always been a guessing game. We guessed wrong.

You can’t get mad at a team for trying the improbable, hoping that nature cooperates. Some of the most famous discoveries of all time have come about thanks to nothing more than mere serendipity, and so if we can test something at low-cost with an insanely high reward, we tend to go for it. Believe it or not, that’s the mindset that’s driving the direct searches for dark matter.

In order to understand how to find dark matter, however, you have to first understand what we know so far, and what the evidence points to as far as direct detection goes. We haven’t found it yet, but that’s okay. Not finding dark matter in an experiment is not evidence that dark matter doesn’t exist. The indirect evidence all shows that it’s real. The question before us is how to demonstrate its reality, hopefully by finding the particle responsible for it directly.

The particles and antiparticles of the Standard Model of particle physics are exactly in line with what experiments require, with only massive neutrinos providing a difficulty and requiring beyond-the-standard-model physics. Dark matter, whatever it is, cannot be any one of these particles, nor can it be a composite of these particles. (E. SIEGEL / BEYOND THE GALAXY)

Let’s begin with a basic recap of dark matter: the idea, the motivation, the observations…