To a nonmathematician, having the letter “i” represent a number that does not quite exist and is “imaginary” can be hard to wrap your head around. If you open your mind to this way of thinking, ...

Mathematicians were disturbed, centuries ago, to find that calculating the properties of certain curves demanded the seemingly impossible: numbers that, when multiplied by themselves, turn negative.

It should be impossible to measure an imaginary number in the lab, but a group of researchers have found a way to do so. They produced the equivalent of a magnetic field of imaginary strength, meaning ...