Thursday, May 31, 2007

Annoying conventions

What do you find to be the most annoying conventions in physics? The classic example is the choice (darn you, Ben Franklin) of sign for the charge of the electron. Franklin had a 50/50 chance, and we ended up with the often confusing situation that current flow and particle flow are oppositely directed, that "up" on energy level diagrams corresponds to more negative voltages, etc. [EDIT: I think my earlier statements here about UPS conventions stem from a particular paper that isn't representative; never mind.... ]. Do any of you out there have other examples of really bad/misleading conventions?


(Ryan) said...

It isn't so much a bad convention per se but the term "recombination" to describe the era in the universe when electrons and protons combined to form atoms for the first time has always bothered me. "Combination" being the obvious, and more accurate alternative.

N. Peter Armitage said...

>Unfortunately it appears that the
>naming convention for at least part
>of the UPS community is for the
>photoelectron energy to be called
>the "binding energy" (when, to my
>nonexpert intuition, it's about 20
>eV minus what I would want to call
>the binding energy).

Doug, where did you see this? I got my Phd. as a UPS jock and I have never heard of anyone saying such a nonintuitive thing. Maybe it was an isolated case and someone was being sloppy?

People do say "high energy" electrons, when they really mean "high binding energy".... which can be confusing because all the energies are being refered to the zero of the vacuum state and so they are more negative.... but what you write I haven't heard.

Carl Brannen said...

In elementary particles, the standard model was defined at a time when the neutrinos were assumed massless. So the degrees of freedom were split up according to how they (weak force) interact with the electron, muon and tau.

Then they discovered that the neutrino has mass. And the diagonalization according to mass is different from the weak diagonalization.

In actual experiments, the neutrino mass is negligible, so according to the laws of QM, the three different mass neutrinos interfere with each other. This is just like the rest of QM. But because of the convention, it is described in terms of "electron neutrinos" which "oscillate" into "muon neutrinos" while propagating through free space.