In 1900, mathematician David Hilbert presented his colleagues with a list of problems he believed both captured the present state of mathematics and the shape of its future. This year, 125 years later ...

How cold is space? Does it ever drop to absolute zero, and what happens if you fall into it without a spacesuit? When you purchase through links on our site, we may earn an affiliate commission.

Classical and quantum mechanics don’t really get along as the science of the subatomic can get, well, weird. Take, for instance, quantum entanglement, which says that the state of one particle can be ...