Imaginary Numbers May Be Essential for Describing Reality
Kevin Hartnett, Quanta
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.
All the numbers on the number line, when squared, yield a positive number; 22 = 4, and (-2)2 = 4. Mathematicians started calling those familiar numbers "real" and the apparently impossible breed of numbers "imaginary."