Little is rarer than an observable quantum spin liquid, but now, tests reveal that a synthetic crystal with ytterbium as its base may house one at near absolute zero.
Scientists behind a theory that the speed of light is variable -- and not constant as Einstein suggested -- have made a prediction that could be tested.
For centuries, scientists believed that light couldn't be focused down smaller than its wavelength. Now, a magnifying glass focuses light a billion times more tightly, to the scale of single atoms.