Most people think outer space is the coldest place in the Universe. But, they're wrong. Heat left over from the Big Bang that created the universe keeps the temperature in space from going any lower than 3 Kelvin. Absolute zero is 0 Kelvin. This is the coldest temperature it's possible to get down to and still obey the laws of physics. The amazing thing is that scientists at JILA (in Boulder, Colorado) can cool clouds of atoms down to less than a millionth of a degree above absolute zero. That's a millions of times colder than outer space!

When it's less than a millionth of a degree above absolute zero, things happen that can't occur in the regular warm world. For instance, some kinds of atoms suddenly lose their identities and form a single blob. The blob is too cold to move or do anything. Other kinds of atoms have to start dancing with each other before they lose their identities and form a blob.

Debbie Jin is one of the scientists at JILA. She studies dancing atoms because they are so interesting. She's discovered that when it's less than a millionth of a degree above absolute zero, different kinds of dancing atoms behave pretty much the same way. When it's that cold, it doesn't seem to matter much whether you're an atom of potassium or lithium or hydrogen. You have to start dancing with a partner to form a blob. Your speed, temperature, and energy change for similar reasons.

What's amazing is that the protons, neutrons, and electrons that make up atoms behave just like dancing atoms at the very, very cold temperatures found in the JILA labs. And, so do the neutrons in neutron stars and the quarks that make up protons, neutrons, and electrons, we think. The coldest place in the universe is actually pretty weird. —Julie Phillips

Back