This is a special post for quick takes by MikkW. Only they can create top-level comments. Comments here also appear on the Quick Takes page and All Posts page.
A recent Astral Codex Ten post contained this bit:
Fewer than 50% (ie worse than chance) can correctly answer a true-false question about whether electrons are bigger than atoms.
The linked source seems to indicate that the survey's expected answer to the question "electrons are smaller than atoms" is "true". However, I think this is likely based on a faulty understanding of reality, and in any case the question has a trickier nature than the survey or Scott Alexander give it credit for.
There's a common misconception that electrons (as well as e.g. protons and neutrons) are point particles, that is to say, that they can be said to exist at some precise location, just like a dot on a piece of graph paper.
Even when people talk about the uncertainty principle, they often lean into this misconception by suggesting that the wave function indicates "the probability that the (point-like) particle is found at a given location".
However, an electron is not a point, but rather a wavefunction which has a wide extent in space. If you were to examine the electron at the tip of my pinky finger, there is in fact a non-zero (but very, very small) part of that electron that can be found at the base of the flag which Neil Armstrong planted on the moon (n.b. I'm not looking up whether it was actually Armstrong who did that), or even all the way out in the core of Alpha Centauri.
We could still try to talk about the size of an electron (and the size of an atom, which is a similar question) by considering the volume that contains 99% of the electron (and likewise a volume that contains 99% of a proton or neutron).
Considering this volume, the largest part of any given atom would be an electron, with the nuclear particles occupying a much larger volume (something something strong force). In this sense, the size of the atom is in fact coextensive with the size of its "largest" electron, and that electron is by no means smaller than the atom. There are of course in many atoms multiple electrons, and some of these may be "smaller" than the largest electron. However, I do not think the survey had this in mind as the justification for the answer it considered "correct" for the question.
I think the appropriate next step for Scott Alexander is to retract the relevant sentence from his post.
(For one thing, I think that definition may imply that an electron is bigger than me?)
An electron's wavefunction is actually more spread out than yours is (if we could do a quantum measurement on the position of your center of mass - which we can't because it's too hard to isolate you from the environment - it would be very precise).
But because you're a macroscopic object, how big you are isn't determined by your center of mass wavefunction, but by the distance between the different atoms comprising you. So you're bigger than a standard electron.
For a hydr... (read more)