New research shows that imaginary numbers are not just convenient, they might be a fundamentally necessary part of quantum theory

Imaginary numbers are a fundamentally necessary part of quantum theory. Using real numbers only can lead to arbitrarily large errors (Credit: iStock/Piranka)

Imaginary numbers first appeared in the 16 th century as a mathematical invention, introduced to solve equations that real numbers could not. As the name implies, many treated them as kind of trick to get results, rather than an underlying truth about the nature of reality. Although highly controversial at the time, these numbers are now ubiquitous in many fields of physics and mathematics.

One such field is quantum mechanics. Researchers routinely use complex numbers, which include both imaginary and real parts. For many simple quantum systems, you could think this is a mathematical convenience rather than a physical necessity.…