View Full Version : Planck Unit

jim knight
2008-Jul-14, 12:38 AM
How long is a Planck unit in nanometers? In looking up the question on the web I read it is the unit of measure where classical physics turns in to a "foam" and where quantum mechanics starts to apply.

Given that new computer chips are built in the realm of quantum mechanics and that the width of a "transistor" bridge is about 65 nanometers, the explanation of a Planck unit sounds as if it is not that many nanometers long - but I suspect that assumption is very wrong.

Chris Hillman
2008-Jul-14, 12:45 AM
The Planck length defines the length scale where physicists since the late John Archibald Wheeler have generally expected that spacetime becomes "foamy". Numerically

65 nanometers is about 6.5 x 10^{-10} m
The Planck length is about 1.6 x 10^{-35} m or 1.6 x 10^{-26} nm.

Source: the on-line encyclopedia where :rolleyes: absolutely anyone can move any decimal point any number of decimal places at absolutely any time en.wikipedia.org/wiki/Planck_length

2008-Jul-14, 12:46 AM
The Planck length is about 1.6x10-26nanometer. Thus the length of that transistor bridge is about 4x1027 times the Planck length.

jim knight
2008-Jul-14, 01:58 AM
Thanks Chris & Hornblower.
Chris you spotted my source -Wikipedia!