Smallest unit of length
Planck length
Not Applicable ()

The smallest possible size for anything in the universe is the Planck Length, which is 1.6 x10-35 m across.
Equivalent to around a millionth of a billionth of a billionth of a billionth of a cm across (a decimal point followed by thirty four zeroes and a one), this is the scale at which the quantum foam is believed to exist: the laws of quantum physics cause minute wormholes to open and close constantly, giving space a rapidly-changing, foam-like structure. If we were ever able to exploit the tremendous energy of the quantum foam, then the power contained within one cubic centimetre of empty space would be enough to boil the Earth's oceans.