The Earth orbits the Sun at a brisk 107,000 km/hr (66,486 mi/hr). The Sun, in turn, circles the Milky Way at a staggering 828,000 km/hr (514,495 mi/hr). And deep in the galactic core, stars whirl around the supermassive black hole at relativistic speeds, up to 36 million km/hr (22,369,363 mi/hr). Gravity is the architect and master of this motion: the invisible hand that not only initiates these velocities but binds our galaxy into a luminous spiral of unity.

Except it shouldn’t. Not with the piddling amount of mass that we can see.

The Milky Way contains 60-100 billion solar masses, an impressive sum, but a puny, gravitationally insufficient amount. With only that amount of ordinary matter, the galaxy would disperse like dry leaves in a breeze. Its stars would drift apart, its spiral arms dissolve, and the universe itself would remain a diffuse fog of light and entropy, never coalescing into structure or verse. No Halley’s Comet. No seasons. No Vivaldi.

To hold the Milky Way together at its observed rotation speeds requires about 1.4 trillion solar masses, seven times the visible amount. And we know this mass is there not because we’ve seen it, but because the galaxy exists. Much like Descartes’ Cogito, ergo sum (“I think, therefore I am”), we reason: The Milky Way is; therefore, it must possess sufficient mass.

The problem is that 85% of that mass is missing; from view, from touch, from detection. Enter stage right: Dark Matter. It does not emit, absorb, or reflect light. It does not interact with ordinary matter in any known way. It is invisible, intangible, a Platonic ether of shadow reality. Without it, the sacrament of gravity and being floats away like a balloon on a huff and puff day. And the universe loses its meaning.

Much like the neutrino, predicted by theory, is a particle once postulated to preserve the sanctity of conservation laws, a piece of the quantum world long before it was ever seen. Dark Matter is another elusive phantom, inferred by effect, but physically undetected. Dark Matter bends light, sculpts galaxies, and governs gravitational dynamics, yet it inhabits a metaphysical realm that requires faith to make it real. Unlike the neutrino, it lacks a theoretical platform. The General Theory of Relativity insists it must have mass; the Standard Model offers it no space. It is an effect without a cause: a gravitational fingerprint without a hand.

Yet, physicists are trying to tease it out, not so much to grasp a formless ghost, but rather to catch a glimpse of a wisp, a figment, without knowing how or where to look. To bring light to the dark one must grope around for a switch that may or may not exist.

Researchers at the University of Zurich and the Hebrew University of Jerusalem have devised an experiment called QROCODILE: Quantum Resolution-Optimized Cryogenic Observatory for Dark matter Incident at Low Energy (One can only guess at the amount of time and gin the Docs spent on that acronym 😊) to help tease out the existence of Dark Matter.

The experiment is designed to detect postulated ultralight dark matter particles that may interact with ordinary matter in currently unfathomable ways. To find these particles they have built a detector of superconducting nanowire sensors, cooled to near absolute zero, that achieves an astounding sensitivity to detect an infinitesimally small mass of 0.11 electron-volts (eV).

0.11 eV is roughly the energy difference between two quantum states in a molecule. An imperceptible shiver in the bond between two hydrogen atoms: a mass so slight, it might provoke a murmur of dark matter itself.

Using this detector over a 400-hour run (16.66 days) the team recorded a handful of unexplained signals that are real but not necessarily dark matter. Eventually they hope to achieve detections that resolve directionality, helping distinguish dark matter from background noise. The next phase of the experiment: NILE QROCODILE, (groan*) will move the detectors underground to reduce cosmic interference.

QROCODILE is a shot in the dark. It’s an epistemological paradox: how do you build a detector for something you don’t understand? How, or why, do you build an energy detector for a substance, if it is indeed a substance, that doesn’t emit or absorb energy.

While dark matter is known through its gravitational pull, that detection at a particle level is infeasible. Energy detectors, then, are a complementary strategy, betting on weak or exotic interactions beyond gravity.

Whether it finds Dark Matter or not, QROCODILE reminds us that science begins not with certainty, but with the courage to ask questions in the dark, and the craftsmanship to build instruments that honor the unknown.

* NILE QROCODILE: an acronym that evokes remembrance of the socially awkward Dr. Brackish Okun, a secluded researcher of aliens and their tech at Area 51 in the 1996 movie Independence Day.

Source: …Dark Matter Search with QROCODILE… by Laura Baudis et al, Physical Review Letters, 2025. Graphic: Nile Crocodile Head by Leigh Bedford, 2009. Public Domain.