Although many physicists remain skeptical about the Los Alamos findings, the new experiment has attracted wide interest. The Fermilab auditorium was filled with about 800 people, and talks were given at the 16 additional institutions by other collaborating scientists. That reflected in part the hope of finding cracks in the Standard Model, which encapsulates physicists’ current knowledge about fundamental particles and forces.

The Standard Model has proved remarkably effective and accurate, but it cannot answer some fundamental questions, like why the universe did not completely annihilate itself an instant after the Big Bang.

The birth of the universe 13.7 billion years ago created equal amounts of matter and antimatter. Since matter and antimatter annihilate each other when they come in contact, that would have left nothing to coalesce into stars and galaxies. There must be some imbalance in the laws of physics that led to a slight preponderance of matter over antimatter, and that extra bit of matter formed everything in the visible universe.

Image A schematic of the detection chamber and, inside it, a cascade of subatomic particles. Credit... Fermilab

The imbalance, some physicists believe, may be hiding in the dynamics of neutrinos.

Neutrinos come in three known types, or flavors. And they can change flavor as they travel, a process that can occur only because of the smidgen of mass they carry. But the neutrino transformations reported in the Los Alamos data do not fit the three-flavor model, suggesting four flavors of neutrinos, if not more. Other data, from experiments elsewhere, have said the additional neutrinos would have to be “sterile” — completely oblivious to the rest of the universe except for gravity.