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Re: Planck mass



At 01:08 PM 1/18/01 -0700, Larry Smith wrote:
I keep forgetting--what is the significance of the Planck mass?

The usual value is 2.1767 x 10-8 kg
http://physics.nist.gov/cgi-bin/cuu/Value?plkm

The significance is that this is the conversion factor for mass, when
converting to SI units from cosmic dimensionless units.

To say the same thing another way: Suppose you choose units such that c=1,
G=1, and hbar=1. You find an object of unit mass. That same object has
mass 22 micrograms in SI units.

Note: I don't recommend it, but some people choose units such that h=1
rather than hbar=1, which changes the details.
http://www.treasure-troves.com/physics/PlanckMass.html