This paper traces how a widely used name in particle physics — “neutrinoless” — came to define an important process by what is missing, rather than by what is created. The author shows that the label grew out of a 1953 experimental claim and a period of caution in the field. He argues that this choice of words has helped obscure the deeper physical question: whether certain nuclear decays can actually produce matter in the laboratory.

To make this case, the essay follows a short history of the idea. Ettore Majorana proposed in 1937 that neutrinos might be their own antiparticles. In 1939 W. H. Furry pointed out that Majorana’s idea would allow a special kind of double beta decay in which two electrons are emitted without outgoing neutrinos. Starting in the early 1950s, papers and reviews began to call this channel “neutrinoless” decay. The author documents key moments: H. Primakoff’s 1952 wording, J. A. McCarthy’s 1953 experimental paper that used the term, and the rapid global spread of the phrase through the 1950s into standard reviews by 1960.

At a basic physics level, the paper contrasts two modes of double beta decay. The ordinary mode emits two electrons plus two antineutrinos and follows established conservation rules. The Majorana-driven mode would emit just two electrons because the neutrino acts as its own antiparticle and is reabsorbed inside the nucleus. Observing this would amount to creating net matter — two electrons — in a process that does not produce the expected compensating antimatter. That makes the decay a rare and powerful test of ideas about conservation laws and the origin of matter in the universe.

The essay also describes why the field became cautious. Early experimental hints, including McCarthy’s 1953 excess, later proved to be spurious. At the same time, theoretical advances in the mid-1950s (the parity revolution and the V–A theory of weak interactions) led Kenneth Case and others to show that the Majorana-driven decay would be much slower than originally thought, suppressed by the square of the Majorana neutrino mass. Those developments, combined with ambiguous data, encouraged a retreat into an agnostic, absence-focused label. The author calls this “semantic bleaching”: the loss of a term’s original theoretical meaning.