Tuesday, January 13, 2009

Crazy Units

There are some rather odd units out there (Wikipedia has an extensive list of real and humorous units. My favorites are the Sagen, the ASTA Pungency unit, and the Smoot). But the units that I think are the best are the real units that are used in non-standard ways. That is, sometimes there are some very standard units that are used in very non-standard ways, but if you understand where they come from they make complete sense.

The two that I have personally run into recently are the centimeter as a unit of mass (try explaining that one to undergrads), and degrees Kelvin as a measure of surface brightness. Surely there are more of these kinds of units that you have run into out there and would care to share them here.


  1. One part of a question on my comprehensive exam asked us to describe the difference between two photons in kilometers per second.

  2. We all know there is only two real units: length in meters or energy in eV. Everything else is unnecessary.

  3. Isn't it funny how things "we all know" are often things we all disagree on. Meters are completely unnecessary. All physical quantities can be measured in eV!!! (Actually, I just said that to be obstinant. Personally, I see no problem with foot-pounds, cubits (not qubits), and BTUs. Metric is just for people who don't want to think about math and unit conversions (and yes, I admit I fall into that category along with most of the rest of the world).)


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