Natural Units

http://en.wikipedia.org/wiki/Natural_units

Plank Unit

"Natural units" (particle physics) [edit]

Unit	Metric value	Derivation
1 eV−1 of length	1.97×10−7 m
1 eV of mass	1.78×10−36 kg
1 eV−1 of time	6.58×10−16 s
1 eV of temperature	1.16×104 K
1 unit of electric charge (L–H)	5.29×10−19 C
1 unit of electric charge (G)	1.88×10−18 C

In particle physics, the phrase "natural units" generally means:^[4][5]

where  is the reduced Planck constant, c is the speed of light, and k_B is the Boltzmann constant.

Like the other systems (see above), the electromagnetism units in Planck units can be based on either Lorentz–Heaviside units or Gaussian units. The unit of charge is different in each.

Finally, one more unit is needed. Most commonly, electron-volt (eV) is used, despite the fact that this is not a "natural" unit in the sense discussed above – it is defined by a natural property, the elementary charge, and the anthropogenic unit of electric potential, the volt. (The SI prefixed multiples of eV are used as well: keV, MeV, GeV, etc.)

With the addition of eV (or any other auxiliary unit), any quantity can be expressed. For example, a distance of 1 cm can be expressed in terms of eV, in natural units, as:^[5]