It's not altogether clear whether this whole rare earth/critical minerals saga is a masterstroke by the Ukrainians, in ...

Rubies and emeralds have the colors they do because, like many substances, they absorb some colors of light. Most visible light, like sunlight, is composed of all the colors of the rainbow: red, ...

Atomic clocks are more accurate than those used to define the second, suggesting the definition might need to change ...