More than the integral of r squared dm.

[mrissa]

One of the things you discover when you are a physics student, or even a former physics student, is that a great many people will automatically assume that any objections you have to colloquial misuse of physics terms are 1) abstruse and 2) fundamentally stupid. The assumption here is that in catching the technical detail, the physicist (or ex-physicist!) is missing the larger and possibly more poetic analogy.

This is too bad, because sometimes the actual meaning of the word would be really useful if only we could get at it. No, this is not a rant about "quantum." Alas.* The word I want this time is "inertia."

See, I keep hearing people talking about having a lot of inertia as though it means that a body at rest tends to stay at rest unless acted upon by an outside force, full stop. But it also means that a body in motion tends to stay in motion unless acted upon by an outside force. Inertia is not just sitting there like a lump, it's barreling down the tracks full speed ahead. It's a tendency to keep on with what you were doing before, and what you were doing before isn't always nothing.

So when I say I'm having trouble with inertia, it's not getting started that's the problem. It's starting and stopping and changing directions and going in circles. It's the whole thing. And really mostly not the body at rest part. If we were better at the body at rest part, the other stuff might be easier. But not all of it, because sometimes I really don't like the vectors of change here.

*Short version of the rant: "quantum" does not mean "really big." Go ahead and say, "great leap" or "huge leap" or "ginormous leap" when this is what you mean; "ginormous" will make you sound less clueless than misusing quantum here. Mini-rant over; we now return you to your main ramble.

Comments

[zwol.livejournal.com]

I'm told that, friction being so ubiquitous, people just don't have any intuitive sense of inertia working both ways; and it leads to industrial accidents, when Heavy Object On Rollers is harder to stop than people are expecting.

Maybe if everyone got ice skating as part of elementary school P.E. that would help. And ice Sokoban.

[mrissa.livejournal.com]

Hockey saves the world yet again!

[kemayo.livejournal.com]

I suppose I could see "quantum leap" meaning "very big", if one interprets it in the sense that the shift between classical physics and quantum physics was a ginormous thing...

[ckd]

I don't remember where I saw this, but I like the explanation that "A quantum leap is the smallest possible change, if you're a physicist, or the largest change imaginable, if you're a marketing person. These are not necessarily contradictory."

[mrissa.livejournal.com]

Heh.

[guppiecat]

OK. I really really like this.

Probably more than I should.

My marketing friends are going to be pissed tomorrow. :)

[ashnistrike.livejournal.com]

Is it possible that people mean "moving from point A to point B without having to move through the points between"? I say this as a psychologist with no physics training, who uses "inertia" as a metaphor the same way that you do. And who never says "quantum leap" unless I'm talking about the show.

I like the marketing explanation better, though.

[mrissa.livejournal.com]

That's a very charitable interpretation of "quantum leap" in colloquial speech, and probably even a correct assessment of some of the smarter/more informed people's meaning.

[poeticalpanther.livejournal.com]

It is, in fact, how I use it metaphorically: not for a "large" leap, but for a significant one. That is, one which shows a serious shift between one state and a discrete second state. Almost as though they were some sort of...quanta. Hmm. :)

[redbird]

Quite. It's not easy to stop a tanker. Or a falling rock.

With regard to colloquial misuse of technical terms, see also "positive feedback" and "negative feedback." Yes, sometimes if I praise your work you'll do more good things, but that's nowhere near the heart of it, and "negative feedback" is not remotely a synonym for criticism.

[evangoer.livejournal.com]

It annoys me when someone refers to an unwanted electronic communication as a "waste of electrons".

[poeticalpanther.livejournal.com]

This.

Everyone knows it's a waste of pixels.

Fine, Belgian-mountain-grown pixels, picked by only the cleanest of day labourers, transported on the backs of Belgium's beautiful native komodo unicorns, before being slow-roasted over a terminal-velocity-powered furnace.

*very serious nod*

[zwol.livejournal.com]

I think this might be worthy of metaquotes.

[poeticalpanther.livejournal.com]

*bows*

By all means, if you so choose. :)

[zwol.livejournal.com]

http://community.livejournal.com/metaquotes/7135919.html

[evangoer.livejournal.com]

Now *that* was not a waste of pixels or electrons. :)

[poeticalpanther.livejournal.com]

:D Thanks.

[indigofire-net.livejournal.com]

Thank you for the trail that lead to here. It was a fun little excursion.

... and interesting, in that inertia's been a theme this week - in the correct sense of the word. Things are rolling now, and attempts to slow them down aren't working very well - a good thing in this case.

-iF

[indigofire-net.livejournal.com]

BTW: are those fair-trade pixels?

'Cause you know, those day labourers should get their due for such fine delicacies.

[poeticalpanther.livejournal.com]

Mais certainement! Otherwise, where would they get the supplies to be the cleanest of day labourers? :)

[indigofire-net.livejournal.com]

Never underestimate the power of the Schwartz - for good or evil! =D

[dichroic.livejournal.com]

Maybe we need a new word for what e.g. exercise programs have, because as you point out it isn't inertia. If for example you're working out 5 times a week at 6AM, it is much easier to keep doing it than it is to start. But it's not easier to keep going than to stop.

[akitrom.livejournal.com]

"Friction" or "resistance".

[ken-schneyer.livejournal.com]

Yes.

[aedifica]

Oh good, one I already know! (I never passed physics. I do believe I could, given different life circumstances than prevailed at the time I was trying to take it, but the fact remains that all that physics knowledge is not inside my head.) I do know what inertia means! Though I'm quite fuzzy on "quantum," at least I don't throw it around in casual speech either.

[rosefox]

I used to complain about not getting anything done due to emotional/psychological inertia until one day fangorn said, "No, that's not your problem, because even when you're on a roll you stop pretty quickly. If it were inertia, you'd keep going. What's getting in your way?" And that turned out to actually be a very useful metaphor.

[mrissa.livejournal.com]

Yay real physics metaphors!

[columbina.livejournal.com]

It's my fault.

Because, for some 15 years and counting now, when I have said I've had a problem with inertia, it means a problem with tending to remain at rest, not tending to remain in motion. (On the rare occasions when I remain in motion, I do not consider this a problem, I consider it "productivity.")

I know perfectly well what inertia means, but I have unintentionally misled all of North America. I will take full blame.

I also claim sometimes to have a lack of ertia, simply because ruly back constructions gruntle me. I apologize for that too. In fact I apologize for it twice.

[scyllacat.livejournal.com]

Please do not apologize for last paragraph. I think you've given me a new hobby--or annoying party trick.

[mrissa.livejournal.com]

I, too, am gruntled by ruly back constructions.

[scyllacat.livejournal.com]

Ah. I like this. I had to stop and say. Here from metaquotes.

I feel you on the inertia thing. I often need that full meaning... I'm not accustomed to sitting still, but I am accustomed to inertia as in, "Stop the world! I want to get off!"

I love funny words (and lolcats), I think that using words creatively or poetically should reflect our understanding of the word, not our misunderstanding. It's not fair to just pick up a word and, because you hardly ever need it, stick another meaning to it. I would never use "quantum" like that because I have a hard enough time with discussing its real meaning. (James Bond flick--ARGH. Can't stand the title.)

Humpty Dumpty (a la Through the Looking Glass) and I would be mortal enemies.

[mrissa.livejournal.com]

Yah, the Bond movie title was a "you what now?" moment for me. I haven't seen the movie in question, but I wondered if it was signaling, "Really bad physics content here! So bad you'll wish for that totally implausible time Denise Richards played a physicist back again just to improve the science! That's how bad!"

[columbina.livejournal.com]

Actually, in the Fleming original, while I realize the title is a slight non sequitur, I see what he's getting at. He's using "quantum" in the sense of "amount of something needed to change state/energy level." One of the characters is telling the story of a failed relationship, and says that when a person drops below the quantum of solace, he fails to see the other party in the relationship as a human anymore and does not feel any compassion or obligation to the other party.

Incidentally, it's not a spy story at all; bit of deceptive labelling there. Bond is a passive listener, and it's a very quiet little drawing-room tale which some people think was Fleming's salute to the style of Somerset Maugham. Nothing but the title was used for the movie.

[mrissa.livejournal.com]

Oh, that's somehow even worse, that Mr. Fleming got it right and then the movie destroyed it. Ack.

[zunger.livejournal.com]

Don't worry. There are plenty of cases where Mr. Fleming got things wrong and the movies fixed it, so the balance of something or other has been maintained.