What Sets the Electron Charge?

Most recent answer: 11/24/2013

Why do all electrons in our universe have a charge of 0.12080855*sqrt(h/Z0), where h is Planck's constant and Z0 is the characteristic impedance of free space? Is this a consequence of some property of our universe, like the Higgs field, or is this something that is independent of any property of our universe? This is similar to the existing question about why charge is quantised, but I am interesting in knowing whether another universe could, theoretically, have a different value (expressed in terms of h and Z0) for electron charge.
- Clifford Greenblatt (age 61)
Owings Mills, MD USA

You've put your finger on a deep question. No one knows what sets the strength of the electrical interaction. It's often described in just slightly different terms than the ones you used, by the "fine structure constant" (a good search term), e2/ħc = 7.3×10−3 .()

It's one of some 30 or so unexplained pure numbers (no units needed) that appear in the fundamental physical laws as they are currently known. One possible guess is that there in fact universes (other branches of some multiverse) in which other values would be found, if anybody were there to find them. Only certain values lead to complex chemistry and the possibility of life. Or maybe there's some altogether different explanation.

Mike W.

(published on 11/24/2013)