A magnet with one pole. Predicted in 1931. Still missing. We keep looking.

monopole.systems — a quiet observatory for a particle that has never been found

Why It Should Exist

Maxwell's equations are almost symmetric. Electric charge sits on one side; the magnetic side is empty. Dirac noticed that if even one monopole existed anywhere, it would force electric charge to come in neat, quantized lumps — which it does. So the universe behaves as though a monopole is out there, even though nobody has ever held one.

Grand unified theories go further. They don't permit monopoles; they require them — heavy, stable, made in the first fraction of a second. The early universe should have minted a great many. We see almost none. That gap is not a footnote. It is a hole in the floor of physics with a label on it.

We build instruments. We point them at the gap where the monopole should be. We have not caught one. The instruments are good anyway — that is the part this site is about.

the field a monopole would make

The Instruments

Beads on the field's own wire — each one a thing we built, pointed at the gap.

MoEDAL — passive nuclear-track plastic at the LHC, read once a year
induction loops — a superconducting ring that would notch on a passing pole
scintillator arrays — watching the sky for one slow, heavily ionizing track
balloon-borne sensors — thin air, long flights, patient counting
beam-pipe cross-sections — the collision point, surrounded, just in case

The Search Log

1931

Dirac writes it down. A single magnetic pole, if it exists, makes electric charge come in whole numbers. He calls it "not too unreasonable."

1975

A balloon experiment claims a track consistent with a monopole. The community looks hard. The track is later read as a heavy nucleus. A near-miss, filed.

1982 — feb 14

Blas Cabrera's induction loop registers exactly one clean step — the size a single Dirac monopole would make. On Valentine's Day. It never repeats. It worked once. We are still a little embarrassed about how excited we got.

1995–2014

Big detectors come online. No second step. The non-detections get steadily more precise — which is its own kind of result. We now know rather a lot about where a monopole isn't.

today

The instruments run. The plastic sits in the beam. The loops stay cold. Nothing has stepped through. We keep the log open; that is the job.

What We're Building

A bench of detector simulations — field integrators that take a candidate monopole mass and charge and tell you what it would leave behind in plastic, in a coil, in a paddle. Plain numerical work, kept honest, used to design the next stack of nuclear-track sheets before they go anywhere near a beam.

A reanalysis toolkit for the archive — the old runs, the balloon flights, the cold-loop logs, re-read with current methods so the bounds tighten without anyone having to fly anything again. Most of what we do is making old non-detections say more than they used to.

And the watch itself — the slow, unglamorous habit of leaving the instruments on. The field on this page is doing roughly what we do: integrating outward from one point, forever, in case the point is real.

One pole. We'll hold the light for it.

monopole.systems — instruments pointed at an absence, kept warm