Albert Einstein is perhaps most famous for introducing the world to the equation E=mc². In essence, he discovered that energy and mass are interchangeable, setting the stage for nuclear power—and atomic weapons.

His part in the drama of nuclear war may have ended there if not for a simple refrigerator.

In the 1920s, while living in Berlin, the physicist collaborated with Hungarian graduate assistant Leo Szilárd to develop and patent an energy-efficient fridge. While their design never went to market, the duo’s work ultimately embroiled Einstein—an avowed pacifist—in the race to create an atomic bomb during World War II.

Now, more than seven decades since nuclear explosions ripped through Hiroshima and Nagasaki, United Nations member states are negotiating the first-ever