Science Fact of the Day August 11, 2009
Posted by spatialrift47 in SFoTD.trackback
Superconductors do their thing by forming pairs of electrons, called Cooper pairs, that then move together to conduct electricity. Normally they repel, but at very low temperatures both electrons are attracted to a flavor of ice cream called “atomic lattice ripple”.
Ooooh, can I have a scoop of atomic lattice ripple in my cosmic latte?
Coming right up! That’ll be $137.
(For those of you playing along at home, this is a reference to the fine-structure constant of the Universe, which is equal to 1/137, and frequently shows up inverted (i.e. as 137) in the equations.)
So why can Cooper pairs conduct with no resistance?
The Cooper pair state is, below the critical temperature, a bound state. The energy of that state is lower than the solitary state. At such low temperatures, the electrons don’t have enough energy to jump the band gap up to the “free floating” state in which they can scatter. No electron scattering = no resistance.