NASA
has cooled a cloud of rubidium atoms to ten-millionth of a degree above
absolute zero, producing the fifth, exotic state of matter in space. The
experiment also now holds the record for the coldest object we know of in
space, though it isn't yet the coldest thing humanity has ever created. (That
record still belongs to a laboratory at MIT.)
The
Cold Atom Lab (CAL) is a compact quantum physics machine, a device built to
work in the confines of the International Space Station (ISS) that launched
into space in May. Now, according to a statement from NASA, the device has
produced its first Bose-Einstein condensates, the strange conglomerations of
atoms that scientists use to see quantum effects play out at large scales.
Despite
that difficulty, NASA said, the project was worth the effort. A Bose-Einstein
condensate on Earth is already a fascinating object; at super-low temperatures,
atoms' boundaries blend together, and usually-invisible quantum effects play
out in ways scientists can directly observe. But cooling clouds of atoms to
ultra-low temperatures requires suspending them using magnets or lasers. And
once those magnets or lasers are shut off for observations, the condensates
fall to the floor of the experiment and dissipate.
In
the microgravity of the ISS, however, things work a bit differently. The CAL
can form a Bose-Einstein condensate, set it free, then have a significantly
longer time to observe it before it drifts off, NASA wrote — as long as 5 or 10
seconds. NASA to create condensates far colder than any on Earth. As the
condensates expand outside their container, they cool further. And the longer
they have to cool, the colder they get.
taken
from external source...
No comments:
Post a Comment