It was 1909 when Robert Millikan and Harvey Fletcher carried out their famous oil drop experiment in which they determined that the smallest unit of charge possible was  1.592x10^-19 Coulombs, a value we now refer to as e, the fundamental charge (the modern accepted value is 1.602176565(35)x10^-19 C).  It is the magnitude of the negative charge carried by the electron, as well as the positive charge of a proton. It is also the smallest unit of charge that any stable, independent particle can possibly have—no particles can have -3/4e charge, nor can they carry +2.8e of charge—barring technicalities. A paper published in this week's edition of Science examines in detail one of the technical loopholes to the preceding statement.

We have spent a large amount of time breaking up hadrons to our heart's content, resulting in a spew of quarks, bosons, and other fundamental particles. But no particle collider could ever hope to split an electron (or other lepton) into smaller pieces, so we have no way of looking at something that is, say, one half of an electron. 

But there may be a way to split up something that looks a lot like an electron. Quasiparticles are collections of fundamental particles that have an emergent behavior similar to that of a single fundamental particle. But they are not bound by the rules that govern stable individual particles.

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