A San Francisco startup says it turned mercury into gold last month & beat CERN's record by a factor of ten. CERN's record is 29 picograms. That's the entire yield of 86 billion gold nuclei created across four LHC experiments between 2015 & 2018, about three hundredths of a billionth of a gram, and it didn't survive. The nuclei flew off, struck the beam pipe and shattered within a fraction of a second. CERN wasn't trying to make gold either; it was measuring how lead nuclei shed protons during near-misses, because those losses limit how hard you can run a collider. The physics Marathon is using is more interesting than the headline, though. Natural mercury is about 10% mercury-198. Hit one with a fast enough neutron & it ejects two, leaving mercury-197. That isotope is unstable & here's the part worth pausing on: it doesn't decay by spitting anything out. A proton inside the nucleus captures one of the atom's own orbiting electrons and turns into a neutron. The nuclear charge falls from 80 to 79. Half-life, about 64 hours. Element 79 is gold. And gold-197 is the only stable isotope gold has, so what's left is permanent, ordinary gold - made by an atom quietly swallowing one of its own electrons. This needs fusion specifically. Knocking a neutron out of mercury-198 takes something above roughly 8.5 MeV & fission neutrons average around 2. Deuterium-tritium fusion throws them off at 14.1 MeV, comfortably over the line. The gold is downstream of what fusion already does anyway. And gold was never really the business. The same neutron flux makes copper-64 & other medical isotopes, where the shortages are real & the customer isn't the bullion market.