December 5, 2012

A better understanding of how atoms soak up their surroundings




No man is an island, entire of itself, said poet John Donne. And no atom neither. Even in the middle of intergalactic space, atoms feel the electromagnetic field---also known as the cosmic microwave background---left over by the Big Bang. The cosmos is filled with interactions that remind atoms they are not alone. Stray electric fields, say from a nearby electronic device, will also slightly adjust the internal energy levels of atoms, a process called the Stark effect. Even the universal vacuum, presumably empty of any energy or particles, can very briefly muster virtual particles that buffet electrons inside atoms, further shifting their energies; this form of self-interaction is known as the Lamb shift.