Scientists create "doubly magic" oxygen-28, a heavy oxygen isotope.

Oxygen-28 has 12 more neutrons than regular oxygen. Expected to be ultra-stable.

Instead, it decayed in a zeptosecond. This baffled the physics community.

This challenges our understanding of the nuclear strong force that binds particles in an atom's nucleus.

The isotope was created by blasting fluorine-29 with a hydrogen target in Japan.

Under the Standard Model, oxygen-28 should have been "doubly magic" and super stable. But it wasn't.

The results push for more research on the mysterious forces in an atom's nucleus.