Detectors of gravitational waves, created largely thanks to Rainer Weiss, catch space tremors using laser beams traveling at the speed of light. Short signals are usually attributed to black hole mergers. But there's an idea that what passes through the instruments are giant invisible walls made of dark matter — a mysterious substance first discovered by Vera Rubin through the anomalous rotation of galaxies. It's like ripples on water: a stone leaves rings, but a fish swimming underneath also creates waves — good luck guessing the cause.

Scientists compared both versions for two strange events — GW190521 and GW231123. The black hole merger still explains the data slightly better, but its advantage is shaky. Usually, the black hole version is far more convincing in such cases. It's striking that both signals pointed to almost identical properties of a hypothetical quantum field: the mass of its particles, the wall's speed, and other parameters. This doesn't look like a coincidence.

Future observations at LIGO will allow testing the wall hypothesis. Then gravitational detectors will become a tool for dark matter searches. And if the walls are also linked to dark energy, a single experiment could reveal two of the greatest mysteries at once: what makes up the hidden mass and why the universe's expansion is accelerating.