The 1982 Magnetic Monopole That Never Came Back | The Cabrera Event

On 14 February 1982 at 01:53 Pacific Standard Time, a small superconducting loop in a basement physics laboratory at Stanford University recorded a single anomalous event matching, almost exactly, the signature Paul Dirac had predicted in 1931 for the passage of a magnetic monopole. Blas Cabrera was alone in the lab. The chart recorder drew a perfect step. Four decades later, the event remains unrepeated and unexplained. This is the full story of the Valentine's Day monopole: Dirac's 1931 quantisation argument, the 1974 't Hooft-Polyakov derivation that the grand unified theories of the early 1970s required monopoles to exist, the late-1970s cosmological monopole abundance problem, Cabrera's superconducting loop detector, the actual event on the chart recorder at 01:53, the years of expanded search that followed without a second event, and the modern hunt at IceCube and at the LHC's MoEDAL detector. What survives is a strange historical fact. On one specific night, a chart recorder drew exactly the line theory said a monopole would draw. The universe has been silent since. Referenced research: Dirac, P. A. M. (1931). Quantised singularities in the electromagnetic field. Proceedings of the Royal Society A, 133(821), 60-72. https://doi.org/10.1098/rspa.1931.0130 't Hooft, G. (1974). Magnetic monopoles in unified gauge theories. Nuclear Physics B, 79(2), 276-284. https://doi.org/10.1016/0550-3213(74)... Polyakov, A. M. (1974). Particle spectrum in the quantum field theory. JETP Letters, 20(6), 194-195. Cabrera, B. (1982). First results from a superconductive detector for moving magnetic monopoles. Physical Review Letters, 48(20), 1378-1381. https://doi.org/10.1103/PhysRevLett.4... Milton, K. A. (2006). Theoretical and experimental status of magnetic monopoles. Reports on Progress in Physics, 69(6), 1637-1711. https://doi.org/10.1088/0034-4885/69/... IceCube Collaboration. (2022). Searches for relativistic magnetic monopoles with IceCube. European Physical Journal C, 82, 134. https://doi.org/10.1140/epjc/s10052-0... MoEDAL Collaboration. (2019). Magnetic monopole search with the full MoEDAL trapping detector in 13 TeV pp collisions. Physical Review Letters, 123, 021802. https://doi.org/10.1103/PhysRevLett.1... #MagneticMonopole #BlasCabrera #ValentineDayEvent #DiracQuantisation #GrandUnifiedTheory #tHooftPolyakov #StanfordSQUID #IceCube #MoEDAL #QuantumMind #Physics #LongForm 00:00 The Valentine's Day Event 01:11 Dirac's 1931 Argument 02:37 Grand Unification and the Monopole Problem 03:53 Cabrera's Loop 05:04 What the Detector Saw at 01:53 06:05 Years of Silence 06:52 The Search Continues