Sunday, August 15, 2010

Dimensional analysis and natural units

I found a blog post that discusses dimensional analysis and introduces the concept of natural units - that is setting numerical constants to 1. This is supposed to make conceptualising equations easier and give a more physical meaning to them. I think this method would make doing the maths much easier when problem solving.

What do you guys think?



  1. Yeah, I've seen some physics were they use units like these, that are normalised to the value of certain constants. While it makes equations neater, I don't think there is any real advantage to this. Changing the standard unit system would be such a massive task that I don't think it would be worth it. Most constants are pretty easy to remember. And for those that aren't, I wrote a handy program on my calculator that sets the variables on my calculator to a long list of them.

  2. I have spent some time over the last couple weeks thinking about the mess in electromagnetic units. Specifically, the difference between SI units, "electrostatic" CGS units and "electromagnetic" CGS units. It's maddening. Its nice to think there's a simpler system. This would probably be useful for derivations. On the other hand, if the fundamental constants are the base units in the natural system, and if they are not known to sufficient precision, wouldn't it be very hard to make accurate predictions for phenomena at intermediate scales? It may not be a good idea to assume that the fundamental constants are known to arbitrary accuracy (although many of them are known quite well...).

  3. Velocities are expressed as a fraction of c and have no units!?!
    I am definitely not one for the natural units. I have enough trouble doing dimensional analysis.