Although dark matter makes up around 80 percent of the observed mass of the universe, physicists still don’t know what it actually is. Part of the problem is that dark matter doesn’t interact with light, which most of our telescopes use to collect information about the universe.
To overcome this challenge, many researchers are working to leverage the fundamental laws of physics and develop new methods to detect dark matter. One way to do this is to use atomic clocks, one of the most precise instruments we have today.
In a recent Physical Review Letters paper, researchers from the Physikalisch-Technische Bundesanstalt (PTB) institute in Germany compared two atomic clocks to try to find the smallest differences in their “ticking” — which may be a signature of dark matter.
What Is an Atomic Clock?
Atomic clocks work by carefully measuring the energy of atoms as they transition from a higher energy state (typically triggered by a laser pulse) to a lower energy state. In some instances, this transition results in the emittance of a photon, or light particle. This can also be used to measure the energy gap between an atoms’ lower and higher states.
