# How to pronounce $\textrm{eV}\!/c^2$

It seems that $\textrm{eV}\!/c^2$ (and its multiples) is commonly used as the unit of mass in particle physics. For example, David Griffiths uses it quite naturally in Introduction to Elementary Particles, so does Wolfram Alpha.

However, a problem occurs when one is to pronounce a quantity expressed in this unit. My question is: What is the common, or most widely used pronunciation of this unit? Is it even ever pronounced? Video or audio recordings to back up individual cases are welcome.

I say "ee-vee per see-squared" or "ee-vee over see-squared."

If it's convenient to assume $c=1$, I'll say "ee-vee" or "electron volts." I can't remember ever having said "electron volts over see-squared."

For MeV and GeV I'll say "em ee vee" or "gee ee vee." I know people who say "mev" or "jev", to rhyme with the first syllable of "Beverley", but in low-energy nuclear physics they're in a minority.

Tangential to your question, essentially everyone I know (US/Canada bias) says giga as /ˈɡɪɡə/ with two hard G sounds, rather than /ˈdʒɪɡə/ with an initial J sound. This is probably why "jev" grates on me so hard.

When I'm talking about cold neutron reactions I have to be careful to distinguish between milli-ee-vee (meV) and mega-ee-vee (MeV), since both scales occur in the same reaction. Occasionally I'll say "milli electron volts" (or similar), if I especially want to emphasize the energy to the listener.

When I'm talking to someone who's not a physicist, I'll sometimes say "Energy is measured in volts" and then talk about volts, megavolts, etc.

• Energy in volts? Even to non-physicists, I don't think that's justified. (Otherwise I largely agree with this answer.) May 10 '14 at 19:21
• Interesting, I've always thought that eV is pronounced as electronvolt. It never occurred to me that one could simply say ee-vee. May 10 '14 at 19:27
• @DavidZ You've been at parties where there are people who are interested in what you do, but they're afraid of learning things. You're getting towards something interesting and you can tell by their eyes they are about to interrupt to tell you how physics was hard and they never understood it. Those folks already know that "volts" have something to do with energy; accommodating this background can draw them back in, while introducing more-technically-correct magic words like "ee-vee" or insisting on saying "electron volts" might send them off to the punch bowl.
– rob
May 10 '14 at 19:34
• I do usually have the decency to feel a little dirty about it afterwards.
– rob
May 10 '14 at 19:34
• @MatějGrabovský : everyone would read it as they find best, but the point of communication is to get your point across in the manner you want. It may be beneficial to just say "ee-vee" when you are sure the person would be thinking in the same context, while it may be safe to say "electronvolt" to specify what e and V mean when you would have said "ee-vee" for someone who might interpret it as some improved TV May 10 '14 at 19:37