An Etymological Dictionary of Astronomy and Astrophysics

The first 10^-43 seconds of the Universe’s existence, when the size of the Universe was roughly the Planck length and
during which quantum effects of gravity were significant. Also called Planck epoch. Our understanding of the Planck era is poor because theory which encompasses both quantum mechanics and general relativity is needed to be
developed.

See also: → Planck; → era.