In recent years physicists have pushed to higher and higher energies, because much of the complexity observed at low energies may disappear when the energy becomes sufficiently high. Thus while radioactivity and electromagnetism have been separately known for 100 years, it is only in the last 25 years that particle accelerators have provided beam energies sufficiently high to "unmask" the fundamental relationship between the two phenomena.

Why? In collisions involving high energy particles, some of the incoming energy can be used to create new particles (E=mc² means energy can be transformed into mass). The more massive the new particles, the larger the incoming energy must be to create them. The particles that underlie radioactivity turn out to be very massive (about 100 times as massive as a hydrogen atom), and therefore can only be created in the collisions of very high energy beams.

The W particle, which is masked in beta decay, can be produced and detected in high-energy proton-antiproton collisions or in high-energy electron-antielectron collisions such as: