As part of their job, experimental physicists must have a very good feeling for the size of the quantities that they are trying to measure when those quantities are expressed in the practical units of measurement commonly used in engineering. On the other hand, in order to make their equations clearer and simpler, theoretical physicists (especially high energy physicists) usually use natural units where Planck’s constant divided by 2 pi, the speed of light, and Boltzmann’s constant are all set to one. (i.e., ). But when the time comes to compare a theory with lab measurements, even theorists are forced to deal with engineering units. Even if a theorist writes his theory in natural units, it’s still prudent for him to have a good idea of the typical size of the quantities involved in his theory, with those quantities expressed in engineering units.
I wrote a little proof of concept unit conversion application last night. It inter-converts between
- temperature (in degrees Kelvin)
- energy (in eV)
- frequency (in Hz)
- wavelength (in meters)
assuming that , where temperature, energy, frequency, wavelength.)
Though trivial, I find this little application very useful and highly mesmerizing. I keep plugging numbers into it and trying to remember physical situations I am familiar with in which those sizes arise.
Of course, there already exist lots of websites and computer widgets that do unit conversion for you. The advantage of my little application is that it is easy to customize and it runs on your computer’s web browser, without any need to download supplementary software libraries and without any need to be connected to the internet.
Besides using this application as is, you can use it as a template to write other unit converting applications that suit your taste and needs. Just change the details such as the number of rows, the text, the numerical constants and the formulas being used, and presto, you can change this to an application that, for example, expresses area in different units like acres, square feet, square miles, square meters, etc.