Important Science Question, said ![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png)
sebastienne yesterday. Do batteries weigh more when they're fully charged?
"... what?" thought I. "N- nnnnno? Why would they? You're just shifting electrons around, right?"
But I felt a twinge of unease about this, so I did the internet a quick search, and the internet very rapidly informed me that the answer is yes, because E = mc2, innit. If the battery's got more energy in it, it's more massive. Not a lot more massive! But excited electrons Weigh More. They Just Do.
This is approximately the point at which I bluescreened.
As best I can tell -- and you must understand that this is a reconstruction after the fact -- my issue here is twofold.
Part the first: I am currently paid good money to spend a lot of time thinking about small relative differences in mass between atoms, and the effects of same on chemical (and other) behaviour. It is, insofar as I have a job, Literally My Job.
And we just... ignore the electrons. I mean, I care a very little about whether my thallium atom is neutrally charged, or in the 1+ or the 3+ state, but mostly because of what that does to the chemistry; in terms of what it does to the mass, I have been blithely completely ignoring it.
In a context, right, of "we only got good enough at instrumentation to even detect these differences for thallium in the late 90s" (i.e. around the time I had discovered Stimming With Velcro, and deliberately began cultivating tiny handwriting, and was excluded from a lesson I really didn't want to participate in because I'd been reading a book instead of listening... so got to keep reading a book in the corridor, and was Very Distressed about colour saturation) -- like, for all possible practical purposes, Electrons Don't Weigh Anything, and I've been slowly but steadily internalising this as an unexamined-to-the-point-of-axiomatic Truth about the world for at least, er, the past six years.
The second part is that I have no memory of, at any point during any of my undergrad chemistry lectures, when we were sketching graphs of potential wells and generally fucking about with electron excitation and spin states and so on and so forth, ever having anyone say "oh, by the way, excited electrons weigh more", even though that seems to me an obvious and straightforward Way To Upset The Undergraduates.
I mean. Maybe I knew this during A-level physics? Maybe I've just forgotten since?
But I was very upset about it on the way to sleep last night, which Adam seemed to find hilarious. If somewhat disconcerting that, in contrast, I don't have any issue with the concept of light having mass. "It's just," I sort-of-attempted-to-explain, plaintively, "that I've spent so long assuming a perfectly spherical cow on an infinite frictionless plane--"
"-- moo?"
"COWS CANNOT MOO," I protested.
"... Alex," says the Adam patiently (or something to this effect; I was quite sleepy) "... it... is in the fundamental nature of cows... to moo."
"NO IT ISN'T," I wailed, "THEY CAN'T. THEY'RE PERFECT SPHERES."
sebastienne yesterday. Do batteries weigh more when they're fully charged?"... what?" thought I. "N- nnnnno? Why would they? You're just shifting electrons around, right?"
But I felt a twinge of unease about this, so I did the internet a quick search, and the internet very rapidly informed me that the answer is yes, because E = mc2, innit. If the battery's got more energy in it, it's more massive. Not a lot more massive! But excited electrons Weigh More. They Just Do.
This is approximately the point at which I bluescreened.
As best I can tell -- and you must understand that this is a reconstruction after the fact -- my issue here is twofold.
Part the first: I am currently paid good money to spend a lot of time thinking about small relative differences in mass between atoms, and the effects of same on chemical (and other) behaviour. It is, insofar as I have a job, Literally My Job.
And we just... ignore the electrons. I mean, I care a very little about whether my thallium atom is neutrally charged, or in the 1+ or the 3+ state, but mostly because of what that does to the chemistry; in terms of what it does to the mass, I have been blithely completely ignoring it.
In a context, right, of "we only got good enough at instrumentation to even detect these differences for thallium in the late 90s" (i.e. around the time I had discovered Stimming With Velcro, and deliberately began cultivating tiny handwriting, and was excluded from a lesson I really didn't want to participate in because I'd been reading a book instead of listening... so got to keep reading a book in the corridor, and was Very Distressed about colour saturation) -- like, for all possible practical purposes, Electrons Don't Weigh Anything, and I've been slowly but steadily internalising this as an unexamined-to-the-point-of-axiomatic Truth about the world for at least, er, the past six years.
The second part is that I have no memory of, at any point during any of my undergrad chemistry lectures, when we were sketching graphs of potential wells and generally fucking about with electron excitation and spin states and so on and so forth, ever having anyone say "oh, by the way, excited electrons weigh more", even though that seems to me an obvious and straightforward Way To Upset The Undergraduates.
I mean. Maybe I knew this during A-level physics? Maybe I've just forgotten since?
But I was very upset about it on the way to sleep last night, which Adam seemed to find hilarious. If somewhat disconcerting that, in contrast, I don't have any issue with the concept of light having mass. "It's just," I sort-of-attempted-to-explain, plaintively, "that I've spent so long assuming a perfectly spherical cow on an infinite frictionless plane--"
"-- moo?"
"COWS CANNOT MOO," I protested.
"... Alex," says the Adam patiently (or something to this effect; I was quite sleepy) "... it... is in the fundamental nature of cows... to moo."
"NO IT ISN'T," I wailed, "THEY CAN'T. THEY'RE PERFECT SPHERES."