I’ve been reading the very fine book Superconductivity: A Very Short Introduction, by Stephen Blundell, about which I’ll have more to say in a subsequent post. The book is very well written, with only a very few editorial infelicities in the book, the most striking of which is the following phrase, which appears on page 49:
… however, an electron is almost two thousand times lighter than either a proton or a neutron …
Suppose that Alice is 6 ft. tall, and Basil is 3 ft. tall. Would you say the following?
Basil is twice as short as Alice.
That would be awkward to the extent of being weird. The quantity being measuring here is height, and Alice has twice as much of it as Basil, so it would be simpler, more direct, more natural, and easier to understand to say that
Alice is twice as tall as Basil.
Saying that Basil is twice as short as Alice is weird, because it implies that there is a quantity (shortness??), and that Basil has twice as much of it as Alice. This is highly misleading, and difficult to understand.
The phrase about the electron implies that there is some quantity that one can measure about electrons, protons, and neutrons, and that an electron has about 2000 times as much of this quantity (whatever it is) than either protons or neutrons. This is weird, and hard to understand, because the quantity being described is the reciprocal of the mass.
It’s much easier (and more direct, and more comprehensible) to speak about mass instead, which is what we normally refer to. So it would be much better to say:
… the mass of a proton or a neutron is almost 2000 times greater than the mass of an electron …
End of rant. I’ll tell you why Blundell’s book is great in a subsequent post.