See Inside March 2011  Demons, Entropy, and the Quest for
Absolute Zero  A 19th-century thought experiment has turned into
a real technique for reaching ultralow temperatures, paving the
way to new scientific discoveries as well as to useful
applications  Photograph by Adam Voorhes  As you read these
words, the air’s molecules are ­zipping around you at 2,000
miles per hour, faster than a speeding bullet, and bombarding
you from all sides. Meanwhile the atoms and molecules that make
up your body incessantly tumble, vibrate or collide with one
another. Nothing in nature is ever perfectly still, and the
faster things go, the more energy they carry; the ­collective
energy of atoms and molecules is what we call, and feel as,
heat.  Even though total stillness, corresponding to the
temperature of absolute zero, is physically impossible,
scientists have edged ever closer to that ultimate limit. In
such extreme realms, weird quantum effects begin to manifest
themselves and to produce new and unusual states of matter