![Planck Size Image source: SimpleRNA Planck Size Image source: SimpleRNA](http://www.timeone.ca/wp-content/uploads/2013/03/Planck-size-e1403807191940.jpg)
Classification: concept
Chapter: The Problem of Small Numbers
The Planck size or length or scale is exquisitely small – about a hundred-millionth of a billionth of a billionth of a billionth of a meter. Exactly why it figures so importantly in physics is not clear.