Zack Savitsky in Science:
Reclusive and disaffected, Ettore Majorana liked to work in the shadows. But after his friend Emilio Segrè dragged him into Enrico Fermi’s elite Roman physics club in the late 1920s, Majorana’s stature in atomic physics quickly grew. His mostly unpublished premonitions were eerily prescient: Among others, he famously intuited the existence of the neutron from prior experiments. And in 1937, he conjured up a completely new kind of particle. Physicists had learned that every fundamental particle seems to have an antimatter counterpart, an idea Segrè would later earn a Nobel Prize for verifying. Majorana realized the equation that leads to this duality could also describe a single particle with identical matter and antimatter personas, making it prone to annihilate itself.
Months later, the 31-year-old withdrew a large sum from his bank account, took a boat across the Tyrrhenian Sea, and vanished. To this day, nobody’s sure what happened to him, and the jury is also still out on whether his proposed particle exists. For example, some physicists still believe the neutrino—a wispy particle that pervades the universe—might be its own antiparticle, which could also help explain why the universe is filled with more matter than antimatter. But tests have so far proved inconclusive. However, scientists think they are close to approximating a Majorana particle in a much different guise. By confining electrons on flat surfaces, researchers can coax them into peculiar dances that collectively masquerade as a Majorana particle, much as the undulations of a flock of birds might appear like a swimming fish.
More here.