The Universe is pervaded by an invisible substance — ultralight dark matter, which doesn't collide with ordinary matter but can tremble like a taut string. Its oscillations alter the world's most fundamental properties: the electron charge, the speed of light — as if the tuning of a single cosmic note slightly drifts. Only ultrasensitive instruments can catch this quiver.
Future space antennas LISA and Taiji, designed to register gravitational waves — ripples in curved spacetime, — will also notice the fluctuations of constants. Inside the devices, gold test masses float freely; laser beams track their motion. The tremor from dark matter accelerates the masses differently than it shifts the laser's frequency, and clever algorithms extract the pure 'note' from the noise. A new local observation method compares the mass's drift relative to the housing — boosting sensitivity to effects on electrons by a factor of a thousand. It's like picking out a whisper over the roar of the surf. Thus, the Standard Model gets a chance to directly perceive the Universe's most elusive substance.
The tremor frequency of dark matter depends on its mass — like strings of different thickness. Perhaps the cosmos vibrates on one such string, and we are tuning in to its note for the first time.
In Liu Cixin's 'The Three-Body Problem', dark matter is the key to interstellar travel. Its real tremors may become the first clue in unraveling this cosmic mystery.