Footnotes for "Scientists Put the Deep Freeze on Light"
1A microkelvin
is 10-6 Kelvins.
2A nanokelvin
is 10-9 Kelvins.
3Cryogenics
is the science of low temperatures.
4A photon is
a "particle" of light. Due
to quantum mechanics, light of a particular color
comes in packets of fixed energy called photons.
5One centimeter
per second is about a half an inch a second.
6A millikelvin
is 10-3 Kelvins.
7Evaporation is
the process in which the
constituents of a substance -- usually atoms or
molecules -- exit from the surface of a substance
into the surroundings. Because the more energetic
constituents are more likely to escape, less
energetic constituents are left behind thereby
cooling the substance. All of us are familiar
with evaporative cooling -- water in perspiration
evaporates to keep our skin cool.
8A bound state consists
of two or more particles tied together by attractive forces.
9A neutron star
is the dead remains of a star that has exploded
as a supernova. A typical neutron star is
sphere with a radius of about 10 miles having
a mass of about the Sun. A neutron star is
like a giant, incredibly dense, heavy nucleus
of mostly neutrons. About 7% of it, however, consists
of protons and electrons.