Newton's First Law Redux
September 14, 2023 7:40 AM Subscribe
You will recall it as "“Every body perseveres in its state of rest, or of uniform motion in a right line, unless it is compelled to change that state by forces impress’d thereon.” Or words to that effect.
Newton, however, wrote in Latin, and his first translator either took a liberty with or had his own views of a critical word.
All this time later, Prof Hoek went back to the record. His take, in his own words.
See also here, and, for the those with access to CUP, a Serious Academic write-up here.
All this time later, Prof Hoek went back to the record. His take, in his own words.
See also here, and, for the those with access to CUP, a Serious Academic write-up here.
I remember it as “Yakka foob mog. Grug pubbawup zink wattoom Gazurk. Chumble spuzz.”
posted by TedW at 8:15 AM on September 14, 2023 [16 favorites]
posted by TedW at 8:15 AM on September 14, 2023 [16 favorites]
I gave up on it before I heard him say "model" and qualified with "all models wrong; some are helpful." I don't think it's a big deal -- maybe I'm wrong and it's a "missing stair" for someone's onward progression in science or engineering.
This "rectilinear forces" thing, it's a habit of people who think in Cartesian three-dimensional space. Tensor notation for general relativity has curved spacetime, plus it's got neat notation.
Thank you for this post, insofar as I learned that quatenus means 'insofar'.
posted by k3ninho at 8:19 AM on September 14, 2023
This "rectilinear forces" thing, it's a habit of people who think in Cartesian three-dimensional space. Tensor notation for general relativity has curved spacetime, plus it's got neat notation.
Thank you for this post, insofar as I learned that quatenus means 'insofar'.
posted by k3ninho at 8:19 AM on September 14, 2023
> Substituting “unless” for “except insofar” makes all the difference. Motte makes it sound as though the law makes an exception for bodies subject to forces, instead of adding a qualification.
Look, I'm sorry, but this is dumb. "Unless" is perfectly cromulent usage for adding qualifications. This whole thing is splitting hairs.
posted by smcdow at 8:30 AM on September 14, 2023 [10 favorites]
Look, I'm sorry, but this is dumb. "Unless" is perfectly cromulent usage for adding qualifications. This whole thing is splitting hairs.
posted by smcdow at 8:30 AM on September 14, 2023 [10 favorites]
I can guarantee you that if I gave my AP Physics students a quiz right now asking "If a spaceship in empty space (no air, no planets around) shuts off its engines, what will happen to its motion?
(A) It will gradually slow to a stop
---
(D) It will keep going in a straight line forever"
- some of them will choose (A). I guarantee this because I always see a few wrong answers on this question, even after teaching the unit. I'd wager that many freshmen in college would get it wrong, too.
The idea that objects only deviate from straight-line, unacccelerated motion when acted on by a force is not obvious, it is profound. Aristotelian physics held that the motion of e.g. a thrown rock was "violent" or unnatural, and that the property that made that rock move would just run out on its own. And then the (highly conceptual here, way simplifying the science stuff) idea that the moon in its orbit or a thrown football in a parabolic path is in straight-line, unaccelerated motion, just through curved space-time, gives us General Relativity.
posted by kikaider01 at 8:35 AM on September 14, 2023 [17 favorites]
(A) It will gradually slow to a stop
---
(D) It will keep going in a straight line forever"
- some of them will choose (A). I guarantee this because I always see a few wrong answers on this question, even after teaching the unit. I'd wager that many freshmen in college would get it wrong, too.
The idea that objects only deviate from straight-line, unacccelerated motion when acted on by a force is not obvious, it is profound. Aristotelian physics held that the motion of e.g. a thrown rock was "violent" or unnatural, and that the property that made that rock move would just run out on its own. And then the (highly conceptual here, way simplifying the science stuff) idea that the moon in its orbit or a thrown football in a parabolic path is in straight-line, unaccelerated motion, just through curved space-time, gives us General Relativity.
posted by kikaider01 at 8:35 AM on September 14, 2023 [17 favorites]
"sci-fi" authors who write prose that implies they would answer (A), I am giving you the stink eye right now.
posted by the antecedent of that pronoun at 8:44 AM on September 14, 2023 [6 favorites]
posted by the antecedent of that pronoun at 8:44 AM on September 14, 2023 [6 favorites]
I’m ill with an unspecified lurgy and my cognition is way down: could someone do a school-level explainer comment here?
posted by lokta at 9:00 AM on September 14, 2023 [1 favorite]
posted by lokta at 9:00 AM on September 14, 2023 [1 favorite]
I mean, A is the more correct answer. That's the entire point of the article, and also the first law!
I feel like anyone who would answer D has never done a physics lab (or is playing to the prof's biases, which is always the right move on a test.)
Technically, I would be hoping for "(C) it will appear to continue in a straight line for a while, until external forces inevitably cause its apparent motion to change."
posted by surlyben at 9:15 AM on September 14, 2023 [1 favorite]
I feel like anyone who would answer D has never done a physics lab (or is playing to the prof's biases, which is always the right move on a test.)
Technically, I would be hoping for "(C) it will appear to continue in a straight line for a while, until external forces inevitably cause its apparent motion to change."
posted by surlyben at 9:15 AM on September 14, 2023 [1 favorite]
Someone determines there's a translation they like better and declares the other one objectively wrong.
What a needlessly tendentious framing on the part of Daniel Hoek, hammering on a distinction without meaningful difference.
Ten bucks says this guy is a dyed-in-the-wool linguistic prescriptivist and considers the colloquialisms and slang of his youth to be the one true correct language and modern slang abominable.
posted by tclark at 9:18 AM on September 14, 2023 [7 favorites]
What a needlessly tendentious framing on the part of Daniel Hoek, hammering on a distinction without meaningful difference.
Ten bucks says this guy is a dyed-in-the-wool linguistic prescriptivist and considers the colloquialisms and slang of his youth to be the one true correct language and modern slang abominable.
posted by tclark at 9:18 AM on September 14, 2023 [7 favorites]
They seem pretty different to me? One is binary, the object either continues forever at rest or uniform motion if no forces act upon it, or it doesn't continue forever if forces act on it.
The other is analog, and talks about how much the object will change its course (exactly as much as it's compelled to do so by external forces, and no more or less).
Seems meaningful to me. I have an undergrad Physics degree.
posted by subdee at 9:22 AM on September 14, 2023 [3 favorites]
The other is analog, and talks about how much the object will change its course (exactly as much as it's compelled to do so by external forces, and no more or less).
Seems meaningful to me. I have an undergrad Physics degree.
posted by subdee at 9:22 AM on September 14, 2023 [3 favorites]
I mean, A is the more correct answer.
Uh, it's really not? Neither result (going straight forever vs. slowing to stop) are the likely real-world results, because external forces such as gravity or asteroids or that planet over there will intervene in some way. But "gradually comes to a stop [on its own]" definitely won't happen. Moving off in a straight line also isn't likely either (depending on your definition of straight line), but it's at least technically possible and the least-wrong of the two choices.
posted by axiom at 9:25 AM on September 14, 2023 [2 favorites]
Uh, it's really not? Neither result (going straight forever vs. slowing to stop) are the likely real-world results, because external forces such as gravity or asteroids or that planet over there will intervene in some way. But "gradually comes to a stop [on its own]" definitely won't happen. Moving off in a straight line also isn't likely either (depending on your definition of straight line), but it's at least technically possible and the least-wrong of the two choices.
posted by axiom at 9:25 AM on September 14, 2023 [2 favorites]
We can rephrase the First Law this way: whenever a body’s speed or direction changes, that change is always due to a force.
That's actually the second law.
posted by grog at 9:32 AM on September 14, 2023 [2 favorites]
That's actually the second law.
posted by grog at 9:32 AM on September 14, 2023 [2 favorites]
Uh, it's really not
It depends on what you mean by "really". Over the time period of "forever" there will be some times and places where its motion has slowed enough to be undetectable, from some reference frames, which is to say "stopped". And sometimes it will arrive in such a state gradually. It'll start moving again, to be sure, and how much and how long it is stopped might depend on the accuracy of the measuring instruments, but that's quibbling, when the alternative is "moves in a straight line forever".
It's also the case that as soon as the engines shut off, the most useful answer might be "the space ship is already stopped"
posted by surlyben at 9:46 AM on September 14, 2023
It depends on what you mean by "really". Over the time period of "forever" there will be some times and places where its motion has slowed enough to be undetectable, from some reference frames, which is to say "stopped". And sometimes it will arrive in such a state gradually. It'll start moving again, to be sure, and how much and how long it is stopped might depend on the accuracy of the measuring instruments, but that's quibbling, when the alternative is "moves in a straight line forever".
It's also the case that as soon as the engines shut off, the most useful answer might be "the space ship is already stopped"
posted by surlyben at 9:46 AM on September 14, 2023
I guess if you want to get all quibbly about it, doesn't the second law ("f = ma") already imply the first law ("stuff doesn't start or change motion except for forces on it"), because if there is no net force, there is no acceleration, and therefore, the object stays put or stays moving in a straight line?
posted by aubilenon at 9:49 AM on September 14, 2023 [1 favorite]
posted by aubilenon at 9:49 AM on September 14, 2023 [1 favorite]
I think the article is saying that the problem with the first law is that it doesn't describe *any* real world cases in the original translation, but in the new translation it does.
posted by surlyben at 9:57 AM on September 14, 2023 [1 favorite]
posted by surlyben at 9:57 AM on September 14, 2023 [1 favorite]
I'm under the impression that the Voyager probes will continue traveling through space forever unless they are stopped by something. Are there some who think that they are going to slowly glide to a stop and at some point be not moving?
posted by hippybear at 10:02 AM on September 14, 2023 [1 favorite]
posted by hippybear at 10:02 AM on September 14, 2023 [1 favorite]
Wait why are we writing up stuff in languages we were taught at school? And then someone who also learned said language at school misinterprets us? And the someone else who also learned said language at school gets to split semantic hairs?
Newton, we're doing it wrong!
PS: All you native speakers feel free to totally misinterpret us and split semantic hairs.
PPS: i'm fairly sure this wouldn't have happened if science hadn't been run by non-native latin speakers for far too long.
posted by flamewise at 10:13 AM on September 14, 2023 [1 favorite]
Newton, we're doing it wrong!
PS: All you native speakers feel free to totally misinterpret us and split semantic hairs.
PPS: i'm fairly sure this wouldn't have happened if science hadn't been run by non-native latin speakers for far too long.
posted by flamewise at 10:13 AM on September 14, 2023 [1 favorite]
needlessly tendentious
To be fair, this is Newton we're talking about.
posted by mittens at 10:20 AM on September 14, 2023 [8 favorites]
To be fair, this is Newton we're talking about.
posted by mittens at 10:20 AM on September 14, 2023 [8 favorites]
I always remembered it as "A body at rest remains at rest unless compelled by an external force", because that describes my body perfectly.
posted by MtDewd at 10:23 AM on September 14, 2023 [5 favorites]
posted by MtDewd at 10:23 AM on September 14, 2023 [5 favorites]
The article needs to be more clear on what it means by “governed by.” Because laws do not actually impose their will on anything.
posted by oddman at 10:26 AM on September 14, 2023
posted by oddman at 10:26 AM on September 14, 2023
I always read the first law as being part of that whole school of "Assume a spherical cow" rules. The natural outcome of the First Law is that "this is true until an external force acts on it". The only practical difference I read is does Newton expect us to think that spherical cows are the norm or not
posted by drewbage1847 at 11:03 AM on September 14, 2023 [1 favorite]
posted by drewbage1847 at 11:03 AM on September 14, 2023 [1 favorite]
It's interesting to me that, to me, this distinction seems utterly pedantic: That is to say that the two translations say the same thing as far as I'm concerned. Yes, no bodies exist in an utter vacuum of external forces, but physics constantly concerns itself with theoretical vacuums of that sort so that understandings may be built.
But what's interesting to me is that, per the links, this is a hangup for some people, so if working with "except insofar" instead of "unless" helps folks get over that hangup, great! But I don't really see the practical difference myself.
posted by Navelgazer at 11:05 AM on September 14, 2023 [12 favorites]
But what's interesting to me is that, per the links, this is a hangup for some people, so if working with "except insofar" instead of "unless" helps folks get over that hangup, great! But I don't really see the practical difference myself.
posted by Navelgazer at 11:05 AM on September 14, 2023 [12 favorites]
I'm finding the very notion that cows would not be Naturally spherical tremendously off-putting and may have to cancel my subscription to Science.
posted by riverlife at 11:09 AM on September 14, 2023 [5 favorites]
posted by riverlife at 11:09 AM on September 14, 2023 [5 favorites]
Just wait until we find out about the actual translation of Newton’s description of a cat door!
posted by GenjiandProust at 11:48 AM on September 14, 2023 [1 favorite]
posted by GenjiandProust at 11:48 AM on September 14, 2023 [1 favorite]
OK how many GeV/TeV or whatever in virtual particle per cubic meter of space is there and how big does a ship need to be and how long for this force against the motion of the ship as it blips into existence possible. At some point is not that energy/force acting against the motion of the ship? Spherical Cow Perfect Vacuum, etc... Angels/Pinheads.
posted by symbioid at 11:59 AM on September 14, 2023
posted by symbioid at 11:59 AM on September 14, 2023
I'm under the impression that the Voyager probes will continue traveling through space forever unless they are stopped by something. Are there some who think that they are going to slowly glide to a stop and at some point be not moving?
Yes, there are certain reference frames relative to which, individual voyager probes will slowly glide to a stop. Here's an example: Imagine that you are in a spaceship moving at Voyager speeds, almost but not quite parallel to a Voyager probe. Then the Voyager probe passes near a star, which bends its trajectory slightly so it becomes parallel to yours. From your perspective, it will look like the voyager probe was moving, and then it slowly stopped.
posted by surlyben at 12:35 PM on September 14, 2023
Yes, there are certain reference frames relative to which, individual voyager probes will slowly glide to a stop. Here's an example: Imagine that you are in a spaceship moving at Voyager speeds, almost but not quite parallel to a Voyager probe. Then the Voyager probe passes near a star, which bends its trajectory slightly so it becomes parallel to yours. From your perspective, it will look like the voyager probe was moving, and then it slowly stopped.
posted by surlyben at 12:35 PM on September 14, 2023
Imagine your are a spherical cow inside the spherical cow universe. F) You follow the space-time gradient of equal energy neither gaining nor losing energy yourself. Change in energy requires change in your spherical cowness. Inside the spherical cow there is no external force. Sadly most spherical cows aren't spherical in the grand sense. There are fluxuations in spherosity so the question becomes to those actually cancel each other out because the fluxuations are balanced inside your spherical cow of infinite size or now. A non-self-force producing cow follows the non-energy changing spacetime path.
posted by zengargoyle at 12:39 PM on September 14, 2023 [1 favorite]
posted by zengargoyle at 12:39 PM on September 14, 2023 [1 favorite]
Then the Voyager probe passes near a star, which bends its trajectory slightly so it becomes parallel to yours.
Oh, so a force acted upon it. That sounds like something in the 1st Law happened.
posted by hippybear at 12:47 PM on September 14, 2023 [11 favorites]
Oh, so a force acted upon it. That sounds like something in the 1st Law happened.
posted by hippybear at 12:47 PM on September 14, 2023 [11 favorites]
The force also acted upon the other thing. They are both moving. Minus the spherical cow, both of them are interacting with each other. They would eventually collide unless their energy was the same and they were truly massless cows, but if they were, the outside force wouldn't be effecting them in the first place.
posted by zengargoyle at 12:53 PM on September 14, 2023 [1 favorite]
posted by zengargoyle at 12:53 PM on September 14, 2023 [1 favorite]
this thread, right here, is why i love metafilter. as a nerd-adjacent art school grad, i truly love getting this kind of thoughtful, snarky, and accessible insight to a wonderfully geeky topic that i don't fully understand. :)
posted by rude.boy at 12:56 PM on September 14, 2023 [3 favorites]
posted by rude.boy at 12:56 PM on September 14, 2023 [3 favorites]
The second law, by saying the change is "proportional to the force", implies the first law as the special case of no force. The first law is a rhetorical or pedagogical move, stating the really counterintuitive behavior under no force.
The author seems to want more of the second law's content stuffed into the first law, and I don't really get why. If you object to talking physics about a zero-force situation because it's not perfectly realistic, aren't you going to keep running up against using frictionless surfaces, point masses, straight lines?
posted by away for regrooving at 1:17 PM on September 14, 2023 [10 favorites]
The author seems to want more of the second law's content stuffed into the first law, and I don't really get why. If you object to talking physics about a zero-force situation because it's not perfectly realistic, aren't you going to keep running up against using frictionless surfaces, point masses, straight lines?
posted by away for regrooving at 1:17 PM on September 14, 2023 [10 favorites]
Inside the spherical cow there is no external force.
We can’t inquire inside the spherical cow because it is also a windowless monad.
(cannulated cows are in Applied Biology, a couple buildings down the way.)
posted by clew at 1:25 PM on September 14, 2023 [1 favorite]
We can’t inquire inside the spherical cow because it is also a windowless monad.
(cannulated cows are in Applied Biology, a couple buildings down the way.)
posted by clew at 1:25 PM on September 14, 2023 [1 favorite]
As a free range child who grew up near a state university that started out as an ag school, I would occasionally get over to the field where I could shine a flashlight into the cows.
posted by hippybear at 1:29 PM on September 14, 2023 [3 favorites]
posted by hippybear at 1:29 PM on September 14, 2023 [3 favorites]
Inside the spherical cow there is no external force.
It's also too dark to read Newton's laws, whether in Latin or in English.
posted by Artifice_Eternity at 1:30 PM on September 14, 2023 [6 favorites]
It's also too dark to read Newton's laws, whether in Latin or in English.
posted by Artifice_Eternity at 1:30 PM on September 14, 2023 [6 favorites]
If a spaceship in empty space (no air, no planets around) shuts off its engines, what will happen to its motion?
(A) It will gradually slow to a stop
---
(D) It will keep going in a straight line forever
I would answer A in that phrasing of the question, because my thinking would be that it will eventually encounter forces that slow its motion. But I can see that the point is to answer D, because no forces are mentioned in the problem that would cause it to slow. I would probably prefer a write-in!
If the question was "in an infinite perfect vacuum" I would answer D without hesitation. But it seems like over a "forever" timespan in the real universe with no air of planets "around," the spaceship would eventually be worn down by encountering space dust and radiation that eat away at its forward velocity.
On preview: what zengargoyle said.
posted by BlackLeotardFront at 1:39 PM on September 14, 2023
(A) It will gradually slow to a stop
---
(D) It will keep going in a straight line forever
I would answer A in that phrasing of the question, because my thinking would be that it will eventually encounter forces that slow its motion. But I can see that the point is to answer D, because no forces are mentioned in the problem that would cause it to slow. I would probably prefer a write-in!
If the question was "in an infinite perfect vacuum" I would answer D without hesitation. But it seems like over a "forever" timespan in the real universe with no air of planets "around," the spaceship would eventually be worn down by encountering space dust and radiation that eat away at its forward velocity.
On preview: what zengargoyle said.
posted by BlackLeotardFront at 1:39 PM on September 14, 2023
Inside the spherical cow
there are fleets of ships... light aircraft... hamburger stands, but no fucking hamburgers...
posted by flabdablet at 1:42 PM on September 14, 2023 [1 favorite]
there are fleets of ships... light aircraft... hamburger stands, but no fucking hamburgers...
posted by flabdablet at 1:42 PM on September 14, 2023 [1 favorite]
Well, if we're going to thought experiment this, our object/spaceship could also encounter forces that speed up its motion. We as a species have used this to great effect ourselves, in fact using the slingshot effect through the gravity well of our own star and various planets to achieve velocities which we could not possibly achieve through direct propulsion. This is why the Voyager spacecraft are as far away as they are.
posted by hippybear at 1:44 PM on September 14, 2023
posted by hippybear at 1:44 PM on September 14, 2023
Yeah, it'll speed up, it'll slow down. Eventually it (or its component particles) will succumb to the heat death...
posted by surlyben at 1:54 PM on September 14, 2023
posted by surlyben at 1:54 PM on September 14, 2023
It's also why humpback whales are alive and well in the 23rd century!
posted by TwoWordReview at 2:09 PM on September 14, 2023 [3 favorites]
posted by TwoWordReview at 2:09 PM on September 14, 2023 [3 favorites]
surlyben: "Uh, it's really not
It depends on what you mean by "really". "
It actually depends on what you mean by "it".
posted by signal at 2:40 PM on September 14, 2023 [1 favorite]
It depends on what you mean by "really". "
It actually depends on what you mean by "it".
posted by signal at 2:40 PM on September 14, 2023 [1 favorite]
zengargoyle: Inside the spherical cow
flabdablet: there are fleets of ships... light aircraft... hamburger stands, but no fucking hamburgers...
I've seen grills on fire off the shoulder of the spherical cow...
posted by k3ninho at 2:44 PM on September 14, 2023 [5 favorites]
flabdablet: there are fleets of ships... light aircraft... hamburger stands, but no fucking hamburgers...
I've seen grills on fire off the shoulder of the spherical cow...
posted by k3ninho at 2:44 PM on September 14, 2023 [5 favorites]
Okay, so I don't know what the argument is, then. The first law says an object either is still or is moving, unless something acts upon it. I am not certain what argument is being made that says this isn't what the first law says, or how any example given is somehow not implying that the object has had something act upon it to change its state.
Maybe explain it to me like I'm five, how the first law of thermodynamics says something other than what it says, and how these examples being offered are supporting this new definition?
posted by hippybear at 2:46 PM on September 14, 2023
Maybe explain it to me like I'm five, how the first law of thermodynamics says something other than what it says, and how these examples being offered are supporting this new definition?
posted by hippybear at 2:46 PM on September 14, 2023
Okay but 'except insofar as' and 'unless' do actually mean different things? (I have up to college junior physics but my calculus wasn't good enough to finish a double major, if that helps.)
"An object at rest remains at rest, and an object in motion remains in motion at constant speed and in a straight line unless acted on by an unbalanced force" - means that as soon as that external force comes into play, this law not longer applies and anything can happen. Which is obviously nonsense.
e.g. your spaceship is going in the general direction of Alpha Centauri, in a region of space where gravity is negligible and there is remarkably little space dust. It will continue to do this until a meteor or stray bit of planet or Elon Musk's Tesla hits it, at which point, fuck, we don't know what will happen because there's an unbalanced force so the First Law no longer applies.
"An object at rest remains at rest, and an object in motion remains in motion at constant speed and in a straight line except insofar as it is acted on by an unbalanced force" - means that this law continues to apply when the force comes into play (which is uh... all real situations ever) because the default state of the object is 'at rest' or 'going that way at that speed', and now both that default state and the external force are dictating what the object will do.
e.g. your spaceship is going in the general direction of Alpha Centauri, in a region of space where gravity is negligible and there is remarkably little space dust. It will continue to do this until a meteor or stray bit of planet or Elon Musk's Tesla hits it, at which point, we know how fast and what direction the spaceship was going, we know how fast and what direction the obstacle was going, we know the obstacle is the only thing imparting an unbalanced force, so the first law still applies and we know we can calculate what's going to happen next.
This is cool and important and I'm glad you shared it, BWA! Will be passing it along to my partner for his physics students.
posted by ngaiotonga at 3:11 PM on September 14, 2023 [8 favorites]
"An object at rest remains at rest, and an object in motion remains in motion at constant speed and in a straight line unless acted on by an unbalanced force" - means that as soon as that external force comes into play, this law not longer applies and anything can happen. Which is obviously nonsense.
e.g. your spaceship is going in the general direction of Alpha Centauri, in a region of space where gravity is negligible and there is remarkably little space dust. It will continue to do this until a meteor or stray bit of planet or Elon Musk's Tesla hits it, at which point, fuck, we don't know what will happen because there's an unbalanced force so the First Law no longer applies.
"An object at rest remains at rest, and an object in motion remains in motion at constant speed and in a straight line except insofar as it is acted on by an unbalanced force" - means that this law continues to apply when the force comes into play (which is uh... all real situations ever) because the default state of the object is 'at rest' or 'going that way at that speed', and now both that default state and the external force are dictating what the object will do.
e.g. your spaceship is going in the general direction of Alpha Centauri, in a region of space where gravity is negligible and there is remarkably little space dust. It will continue to do this until a meteor or stray bit of planet or Elon Musk's Tesla hits it, at which point, we know how fast and what direction the spaceship was going, we know how fast and what direction the obstacle was going, we know the obstacle is the only thing imparting an unbalanced force, so the first law still applies and we know we can calculate what's going to happen next.
This is cool and important and I'm glad you shared it, BWA! Will be passing it along to my partner for his physics students.
posted by ngaiotonga at 3:11 PM on September 14, 2023 [8 favorites]
But... and correct me if I'm wrong... People have been using this as a basis for calculations that have been remarkably accurate for generations BEFORE this somehow revelatory wording change...
Which leads me to believe that it really doesn't matter at all because people have treated it like your second e.g. even though per the wording they SHOULD have been, but haven't been treating it like your first e.g.?
I'm still unable to see why this matters at all. Except that the people who think a thing will just eventually coast to a stop without any forces acting upon it I still think are wrong.
posted by hippybear at 3:16 PM on September 14, 2023 [2 favorites]
Which leads me to believe that it really doesn't matter at all because people have treated it like your second e.g. even though per the wording they SHOULD have been, but haven't been treating it like your first e.g.?
I'm still unable to see why this matters at all. Except that the people who think a thing will just eventually coast to a stop without any forces acting upon it I still think are wrong.
posted by hippybear at 3:16 PM on September 14, 2023 [2 favorites]
It's hard to see how it matters, because the First Law is immediately followed by the Second and the Third, which specify exactly how the forces operate on an object.
Hoek seems to think it's odd to specify initial or default conditions, which seems like a weird quibble, because the initial conditions matter. Before saying what a force does to an object, you have to say what the object will do if the force doesn't apply. Plus it was important pedagogically since he was directly contradicting Aristotle.
As for the spaceship with no engines... "a straight line" would be true only if we define "straight" as physicists do, i.e. along the geodesics of spacetime. That is, the spaceship is influenced by the mass of everything else in the universe.
As space is unbounded, I think the spaceship can't avoid other masses forever— it's probably going to get captured by a star someday. Though I think current theory is that expansion continues forever, which means that space gets less and less dense, so maybe it can avoid all collisions. But good luck getting AAA to rescue you, that far out.
posted by zompist at 3:27 PM on September 14, 2023 [2 favorites]
Hoek seems to think it's odd to specify initial or default conditions, which seems like a weird quibble, because the initial conditions matter. Before saying what a force does to an object, you have to say what the object will do if the force doesn't apply. Plus it was important pedagogically since he was directly contradicting Aristotle.
As for the spaceship with no engines... "a straight line" would be true only if we define "straight" as physicists do, i.e. along the geodesics of spacetime. That is, the spaceship is influenced by the mass of everything else in the universe.
As space is unbounded, I think the spaceship can't avoid other masses forever— it's probably going to get captured by a star someday. Though I think current theory is that expansion continues forever, which means that space gets less and less dense, so maybe it can avoid all collisions. But good luck getting AAA to rescue you, that far out.
posted by zompist at 3:27 PM on September 14, 2023 [2 favorites]
Yes, because, nicely, math is not expressed in English (or Latin), math is expressed in math.
The 1729 wording requires people to understand that 'unless' holds a different meaning to the meaning it usually holds (the meaning it usually has: "except if (used to introduce the case in which a statement being made is not true or valid)". The meaning the 1729 wording requires you to be okay with: "Except insofar as". The normal meaning is an absolute, the 1729-wording meaning is relative.)
If the sun will expand and consume the earth unless Flash Gordon stops it, we can be saved, if Flash Gordon can stop it. It's a binary either/or. Either the sun will expand or it won't. If the sun will expand and consume the earth except insofar as Flash Gordon stops it, we're dead. It's a scale. The sun will expand more or less depending on the actions of Flash Gordon, which, given the implacable nature of the sun, are unlikely to have much effect.
The 1999 wording requires people to understand what the word 'insofar' usually means, and use it. I don't have a problem with requiring people to know the meaning of words and use them appropriately. I do have a problem with knowingly using words inappropriately and handwaving about it to students you are supposed to be teaching. "This core principle of how we understand the fabric of the universe doesn't really mean that" has no place in a science classroom.
(A thing with no forces acting on it will not eventually coast to a stop, no, but I'm aware of literally no situations anywhere in the known universe where that applies.)
posted by ngaiotonga at 3:30 PM on September 14, 2023 [2 favorites]
The 1729 wording requires people to understand that 'unless' holds a different meaning to the meaning it usually holds (the meaning it usually has: "except if (used to introduce the case in which a statement being made is not true or valid)". The meaning the 1729 wording requires you to be okay with: "Except insofar as". The normal meaning is an absolute, the 1729-wording meaning is relative.)
If the sun will expand and consume the earth unless Flash Gordon stops it, we can be saved, if Flash Gordon can stop it. It's a binary either/or. Either the sun will expand or it won't. If the sun will expand and consume the earth except insofar as Flash Gordon stops it, we're dead. It's a scale. The sun will expand more or less depending on the actions of Flash Gordon, which, given the implacable nature of the sun, are unlikely to have much effect.
The 1999 wording requires people to understand what the word 'insofar' usually means, and use it. I don't have a problem with requiring people to know the meaning of words and use them appropriately. I do have a problem with knowingly using words inappropriately and handwaving about it to students you are supposed to be teaching. "This core principle of how we understand the fabric of the universe doesn't really mean that" has no place in a science classroom.
(A thing with no forces acting on it will not eventually coast to a stop, no, but I'm aware of literally no situations anywhere in the known universe where that applies.)
posted by ngaiotonga at 3:30 PM on September 14, 2023 [2 favorites]
Then we're safe because
FLASH . . . . . . .
AAAAAAHHHHHHHH!
HE'LL SAVE EVERY ONE OF US!
-guitars-
posted by hippybear at 3:39 PM on September 14, 2023 [9 favorites]
FLASH . . . . . . .
AAAAAAHHHHHHHH!
HE'LL SAVE EVERY ONE OF US!
-guitars-
posted by hippybear at 3:39 PM on September 14, 2023 [9 favorites]
If a spaceship in empty space (no air, no planets around) shuts off its engines, what will happen to its motion?
(A) It will gradually slow to a stop
---
(D) It will keep going in a straight line forever
A is obviously more correct than D because only forever is forever. If it takes 10^42069 years for distant gravitational forces, patches of gas and dust it might pass through, the effects of its own decay, and so on to slow whatever remains of its decayed matter to a halt (relative to what?), that's still not forever.
posted by GCU Sweet and Full of Grace at 3:42 PM on September 14, 2023 [3 favorites]
(A) It will gradually slow to a stop
---
(D) It will keep going in a straight line forever
A is obviously more correct than D because only forever is forever. If it takes 10^42069 years for distant gravitational forces, patches of gas and dust it might pass through, the effects of its own decay, and so on to slow whatever remains of its decayed matter to a halt (relative to what?), that's still not forever.
posted by GCU Sweet and Full of Grace at 3:42 PM on September 14, 2023 [3 favorites]
I think those saying that it's just quibbling because ultimately both phrasings are expressing the same law are missing the point. It's a question of changing the emphasis from 'a body will follow a uniform path, except where there are forces acting on it' to 'a body deviates from a uniform path to the extent that forces act on it'.
The second more clearly suggests that a body will experience forces, and the extent to which they act determines the motion (i.e. changes in motion are caused by forces). I suppose it kind of depends on whether you believe that nuance of wording meant anything to Newton, or whether that even matters.
Also, if something's badly translated, especially an important cultural document, a more accurate translation is a good thing regardless.
I've no idea what 'slow to a stop' means. Relative to what? I presume it'd end up in orbit around something - a star or a galaxy, itself in orbit around something else. Can't imagine any of the piles of dust on the spaceship caring by that time.
posted by pipeski at 4:06 PM on September 14, 2023 [5 favorites]
The second more clearly suggests that a body will experience forces, and the extent to which they act determines the motion (i.e. changes in motion are caused by forces). I suppose it kind of depends on whether you believe that nuance of wording meant anything to Newton, or whether that even matters.
Also, if something's badly translated, especially an important cultural document, a more accurate translation is a good thing regardless.
I've no idea what 'slow to a stop' means. Relative to what? I presume it'd end up in orbit around something - a star or a galaxy, itself in orbit around something else. Can't imagine any of the piles of dust on the spaceship caring by that time.
posted by pipeski at 4:06 PM on September 14, 2023 [5 favorites]
I was going to suggest that, to a modern ear, "to the extent that" might be more immediately clear than "insofar as," but it looks like pipeski beat me to it by a few minutes. An object will stay at rest/motion except to the extent that forces are acting on it.
posted by nobody at 4:16 PM on September 14, 2023 [1 favorite]
posted by nobody at 4:16 PM on September 14, 2023 [1 favorite]
This isn't a law in the sense that is a concrete definition of the cosmos, it's a law in the sense that it should be useful to predict what happens next across the cosmos. It had limitations, so we've developed better models to help predict what we'll happen in the cosmos.
This subtext should be made explicit:
- We make simplifying assumptions about the world so we can predict what happens next.
- They're useful to a limited extent, and we add new ideas that improve the predictions when they fail us.
- If you want to predict what's going to happen to a body at rest or in motion, start with the assumption it will keep doing that ... insofar as it doesn't have forces acting on it to change that state of motion. This is the first law.
- If you want to predict how much the motion changes, the force you applied will cause a change in momentum proportional to that force. This is the second law.
- If you apply a force to change momentum of a thing, it has inertia that does the considerate thing and pushes back with a force in equal magnitude and opposite direction to your force. This is the third law.
posted by k3ninho at 4:16 PM on September 14, 2023
This subtext should be made explicit:
- We make simplifying assumptions about the world so we can predict what happens next.
- They're useful to a limited extent, and we add new ideas that improve the predictions when they fail us.
- If you want to predict what's going to happen to a body at rest or in motion, start with the assumption it will keep doing that ... insofar as it doesn't have forces acting on it to change that state of motion. This is the first law.
- If you want to predict how much the motion changes, the force you applied will cause a change in momentum proportional to that force. This is the second law.
- If you apply a force to change momentum of a thing, it has inertia that does the considerate thing and pushes back with a force in equal magnitude and opposite direction to your force. This is the third law.
posted by k3ninho at 4:16 PM on September 14, 2023
Fudd's First Law of Opposition: If you push something hard enough, it will fall over.
Tesler's Deviant to Fudd's Law: It goes in -- it must come out.
posted by hippybear at 4:29 PM on September 14, 2023 [1 favorite]
Tesler's Deviant to Fudd's Law: It goes in -- it must come out.
posted by hippybear at 4:29 PM on September 14, 2023 [1 favorite]
To those here who say what’s the big deal, we all know what it means, a lot of the discussion here illustrates that maybe we do know, but our ability to put it into words requires some work. Language has impact. Word choice requires thought.
posted by njohnson23 at 4:45 PM on September 14, 2023 [2 favorites]
posted by njohnson23 at 4:45 PM on September 14, 2023 [2 favorites]
I'm perfectly satisfied that "unless" is a good translation for the First Law, because "except insofar as" and the alternate proposal in this thread which uses "to the extent" is already accounted for explicitly in the mathematical formulation of the second law, namely F = ma.
posted by tclark at 5:02 PM on September 14, 2023 [1 favorite]
posted by tclark at 5:02 PM on September 14, 2023 [1 favorite]
Surely Newton was alive when his Principia was translated into non-Latin languages. Do we have any evidence that he thought his laws of motion were misconstrued? (If his first law was mistranslated, then what about the others?). Also, there is a mathematical formulation of his physics that is much harder to mistranslate.
posted by TedW at 5:17 PM on September 14, 2023 [2 favorites]
posted by TedW at 5:17 PM on September 14, 2023 [2 favorites]
I'd argue that while "unless" may or may not be a good way of stating the First Law in a way intelligible to the modern ear, it's not a good translation of the First Law as Newton wrote it in Latin. It leaves out an entire word that was clearly deliberately included and that, as this thread testifies, has an effect on the meaning. (The size of the effect is up for debate, but that's physics for you)
So it comes to, do we care if it's the most accurate translation as long as it's the most accurate expression of the physical concept, and if you're a translator you might say god yes and if you're a physicist you might say god no and if you're me you might say but the 1729 wording is actually neither, so, now we know that, we should use something that's both a better translation and a better expression of the concept.
posted by ngaiotonga at 5:19 PM on September 14, 2023 [1 favorite]
So it comes to, do we care if it's the most accurate translation as long as it's the most accurate expression of the physical concept, and if you're a translator you might say god yes and if you're a physicist you might say god no and if you're me you might say but the 1729 wording is actually neither, so, now we know that, we should use something that's both a better translation and a better expression of the concept.
posted by ngaiotonga at 5:19 PM on September 14, 2023 [1 favorite]
I'd like to quibble on what we mean by a 'straight' line. I feel that a geodesic in gravity-warped space (ie: all of it) is a straight line in many senses.
posted by signal at 6:06 PM on September 14, 2023 [1 favorite]
posted by signal at 6:06 PM on September 14, 2023 [1 favorite]
A is obviously more correct than D because only forever is forever. If it takes 10^42069 years for distant gravitational forces, patches of gas and dust it might pass through, the effects of its own decay, and so on to slow whatever remains of its decayed matter to a halt (relative to what?), that's still not forever.
I mean, if we're being pedantic, as a result of Newton's laws. the space surrounding it cannot be empty; the engines would have to have pushed some mass in the other direction for the spaceship to have gone anywhere. So there is a non-zero amount of mass to act on it gravitationally, even if you take the problem at face value and assume an otherwise empty universe.
A slightly more interesting/advanced question might be whether that gravitation over the course of eternity will slow the spaceship to a stop...
posted by Zalzidrax at 6:11 PM on September 14, 2023 [1 favorite]
I mean, if we're being pedantic, as a result of Newton's laws. the space surrounding it cannot be empty; the engines would have to have pushed some mass in the other direction for the spaceship to have gone anywhere. So there is a non-zero amount of mass to act on it gravitationally, even if you take the problem at face value and assume an otherwise empty universe.
A slightly more interesting/advanced question might be whether that gravitation over the course of eternity will slow the spaceship to a stop...
posted by Zalzidrax at 6:11 PM on September 14, 2023 [1 favorite]
people who think a thing will just eventually coast to a stop without any forces acting upon it
have a lot of work to do to clarify what constitutes a "stop".
posted by flabdablet at 7:31 PM on September 14, 2023 [2 favorites]
have a lot of work to do to clarify what constitutes a "stop".
posted by flabdablet at 7:31 PM on September 14, 2023 [2 favorites]
I don't think anyone has said that a thing will come to a stop without any forces acting on it.
I'd say if object has no detectable motion relative to some inertial frame of reference over some amount of time, then it's stopped relative to that frame for that amount of time.
posted by surlyben at 8:05 PM on September 14, 2023 [1 favorite]
I'd say if object has no detectable motion relative to some inertial frame of reference over some amount of time, then it's stopped relative to that frame for that amount of time.
posted by surlyben at 8:05 PM on September 14, 2023 [1 favorite]
But if matter is energy and thought is energy, then thought is matter, and, as money is time, and time is space, and in space there is a plate of beans...
posted by DeepSeaHaggis at 8:18 PM on September 14, 2023 [1 favorite]
posted by DeepSeaHaggis at 8:18 PM on September 14, 2023 [1 favorite]
... how much is an English breakfast on the moon?
posted by DeepSeaHaggis at 8:22 PM on September 14, 2023
posted by DeepSeaHaggis at 8:22 PM on September 14, 2023
To those here who say what’s the big deal
I think some people might be getting confused about the scope of the article's retranslation. Restoring the missing word doesn't affect the science itself one bit. No one's saying this means Newton's science was misunderstood for years. It's more about the philosophy/history/literature of science, how, precisely, someone as influential as Newton decided to express his work, right?
posted by nobody at 9:29 PM on September 14, 2023
I think some people might be getting confused about the scope of the article's retranslation. Restoring the missing word doesn't affect the science itself one bit. No one's saying this means Newton's science was misunderstood for years. It's more about the philosophy/history/literature of science, how, precisely, someone as influential as Newton decided to express his work, right?
posted by nobody at 9:29 PM on September 14, 2023
And this, girls and boys, is the typical arse-clownery that happens when philosophy tries to muscle up to science.
posted by Pouteria at 10:01 PM on September 14, 2023 [5 favorites]
posted by Pouteria at 10:01 PM on September 14, 2023 [5 favorites]
I'm an engineer and a student of the history of science, does that give me enough bonafides? I thought this was very interesting.
To me the "new" translation (from 1999) seems important because it defines the meaning of a "force." This is often unstated and I wonder how high school physics students today would answer "what is a force?"
posted by muddgirl at 10:33 PM on September 14, 2023 [2 favorites]
To me the "new" translation (from 1999) seems important because it defines the meaning of a "force." This is often unstated and I wonder how high school physics students today would answer "what is a force?"
posted by muddgirl at 10:33 PM on September 14, 2023 [2 favorites]
Also space travel thought experiments come from special relativity. Newton was more about balls rolling down inclined planes.
posted by muddgirl at 10:35 PM on September 14, 2023 [2 favorites]
posted by muddgirl at 10:35 PM on September 14, 2023 [2 favorites]
I always understood the First Law to mean something like this:
"It may seem like moving things have some natural tendency in themselves to stop moving. This is false. Things only change their motion when some outside force acts upon them."
Once you start doing any math, what Newton says makes perfect sense. Every object starts with an acceleration of zero and then you add the forces. Sometimes (actually all the time) you don't know the value of all the forces acting on an object. But you don't have a term in your equations that means "We know this thing is accelerating, but we don't know how much." You just assume it's zero and add all the forces that you know of (or that are relevant to the question you are trying to answer).
The car is at rest. Or the car is moving at 25 mph. Then you add the forces that accelerate the car. This isn't assuming a spherical cow. This is measuring the cow's perimeter with a sensible number of significant digits.
posted by straight at 2:58 AM on September 15, 2023 [5 favorites]
"It may seem like moving things have some natural tendency in themselves to stop moving. This is false. Things only change their motion when some outside force acts upon them."
Once you start doing any math, what Newton says makes perfect sense. Every object starts with an acceleration of zero and then you add the forces. Sometimes (actually all the time) you don't know the value of all the forces acting on an object. But you don't have a term in your equations that means "We know this thing is accelerating, but we don't know how much." You just assume it's zero and add all the forces that you know of (or that are relevant to the question you are trying to answer).
The car is at rest. Or the car is moving at 25 mph. Then you add the forces that accelerate the car. This isn't assuming a spherical cow. This is measuring the cow's perimeter with a sensible number of significant digits.
posted by straight at 2:58 AM on September 15, 2023 [5 favorites]
This is often unstated and I wonder how high school physics students today would answer "what is a force?"
I'm not sure we need Newton's Laws except as a part of history. You don't need the concept of Forces, just that of Fields. You can define the latter as how the potential energy changes as a function of space and time. That then determines the Lagrangian and, along with properties of the particle such as mass or charge, the equations of motion.
posted by vacapinta at 5:10 AM on September 15, 2023
I'm not sure we need Newton's Laws except as a part of history. You don't need the concept of Forces, just that of Fields. You can define the latter as how the potential energy changes as a function of space and time. That then determines the Lagrangian and, along with properties of the particle such as mass or charge, the equations of motion.
posted by vacapinta at 5:10 AM on September 15, 2023
"'sci-fi' authors who write prose that implies they would answer (A), I am giving you the stink eye right now."
I am still angry about a book where they stopped the spaceship to make repairs.
(And no, it wasn't in one of the specific hypothetical situations you can think of where that might make sense. It was as dumb as you can possibly imagine.)
posted by kyrademon at 5:15 AM on September 15, 2023 [3 favorites]
I am still angry about a book where they stopped the spaceship to make repairs.
(And no, it wasn't in one of the specific hypothetical situations you can think of where that might make sense. It was as dumb as you can possibly imagine.)
posted by kyrademon at 5:15 AM on September 15, 2023 [3 favorites]
angry about a book where they stopped the spaceship to make repairs
On the upside, a universe that allows for them to do that also permits spaceships to make spectacular screeching U-turns in space dogfights.
posted by flabdablet at 5:19 AM on September 15, 2023 [5 favorites]
On the upside, a universe that allows for them to do that also permits spaceships to make spectacular screeching U-turns in space dogfights.
posted by flabdablet at 5:19 AM on September 15, 2023 [5 favorites]
That then determines the Lagrangian and, along with properties of the particle such as mass or charge, the equations of motion.
High school students typically didn't learn Lagrange, at least in 1999. I didn't encounter it until college sophomore year mechanics.
posted by muddgirl at 6:50 AM on September 15, 2023
High school students typically didn't learn Lagrange, at least in 1999. I didn't encounter it until college sophomore year mechanics.
posted by muddgirl at 6:50 AM on September 15, 2023
There is science and then there is science pedagogy. I feel like this article is addressing the second and readers are trying to address the first.
posted by muddgirl at 6:52 AM on September 15, 2023 [2 favorites]
posted by muddgirl at 6:52 AM on September 15, 2023 [2 favorites]
Surely Newton was alive when his Principia was translated into non-Latin languages. Do we have any evidence that he thought his laws of motion were misconstrued? (If his first law was mistranslated, then what about the others?).
FTA:
"It turns out that for most of its history, almost every available translation of Newton’s Latin Principia was based on the original 1729 English translation by Andrew Motte. Motte’s edition was published two years after Isaac Newton’s death, and he almost certainly prepared it without Newton’s knowledge or permission. "
posted by a non mouse, a cow herd at 7:09 AM on September 15, 2023 [3 favorites]
FTA:
"It turns out that for most of its history, almost every available translation of Newton’s Latin Principia was based on the original 1729 English translation by Andrew Motte. Motte’s edition was published two years after Isaac Newton’s death, and he almost certainly prepared it without Newton’s knowledge or permission. "
posted by a non mouse, a cow herd at 7:09 AM on September 15, 2023 [3 favorites]
As a physics professor with too many strong feelings about exactly this topic, I was both excited by the post and then disappointed by the link.
The key problem with the First Law in the way it is usually stated is that it is already covered by the Second Law: Forces cause changes in velocity, so it is already obvious that zero force implies constant velocity.
I don't really care about what Newton said originally, but if you really want an axiomatic Newtonian theory you need:
(II) Fnet = ma
(III) F_A = - F_B
and then you need a statement about when those laws can be applied:
(I) An inertial frame is one in which an object experiencing no net force moves with a constant velocity. Axioms (II) and (III) apply only in inertial frames.
So the first law is really a definition for (and a presecription for an experimental test of) an inertial frame, along with the statement that we must be in an inertial frame to use the other laws.
You are in a closed box and you place a ball on the floor. If you suddenly see that ball move to the side (without there being any evident force to cause its motion), then you know you are not in an inertial frame. To apply Newton's laws you'd have to view that scene from outside the box. Then you'd see that the box was actually on the back of a truck that just started moving. The observed motion of the ball was actually it failing to move (maintaining its constant zero velocity relative to the road) when the truck accelerated.
posted by pjenks at 8:27 AM on September 15, 2023 [6 favorites]
The key problem with the First Law in the way it is usually stated is that it is already covered by the Second Law: Forces cause changes in velocity, so it is already obvious that zero force implies constant velocity.
I don't really care about what Newton said originally, but if you really want an axiomatic Newtonian theory you need:
(II) Fnet = ma
(III) F_A = - F_B
and then you need a statement about when those laws can be applied:
(I) An inertial frame is one in which an object experiencing no net force moves with a constant velocity. Axioms (II) and (III) apply only in inertial frames.
So the first law is really a definition for (and a presecription for an experimental test of) an inertial frame, along with the statement that we must be in an inertial frame to use the other laws.
You are in a closed box and you place a ball on the floor. If you suddenly see that ball move to the side (without there being any evident force to cause its motion), then you know you are not in an inertial frame. To apply Newton's laws you'd have to view that scene from outside the box. Then you'd see that the box was actually on the back of a truck that just started moving. The observed motion of the ball was actually it failing to move (maintaining its constant zero velocity relative to the road) when the truck accelerated.
posted by pjenks at 8:27 AM on September 15, 2023 [6 favorites]
I think this says more about philosophy professors than Newton.
posted by Phanx at 8:52 AM on September 15, 2023 [4 favorites]
posted by Phanx at 8:52 AM on September 15, 2023 [4 favorites]
I dunno man, I like hair splitting over exact semantics as much as everyone else but I think "except insofar" doesn't seem to be superior to "unless" except insofar as it uses bigger words that sound more sciency to some people.
While there's people who don't get the 1st law, that's not due to the word unless, that's due to it being counterintuitive and people taking time to really grasp the concept.
The people who believe that a space ship will eventually drift to a halt are either a) incredibly pedantic and talking about the ship being acted on by minute forces and collisions with occasional hydrogen atoms, or b) don't understand the 1st law. In neither case is that due to the word unless being bad or inaccurate.
It is absolutely true that most people have a really skewed idea of physics, even physics that can be observed.
At the beginning of the physics module I taught way back then I gave my 8th graders a non-graded survey to see what their idea of physics was like and then the exact same survey after we did the classes on physicsto see if any of it stuck. I did that because in college my intro to physics prof did and i liked the idea.
One question was about a person spinning a weight on a string and the path the weight would take when the person let go of the string. Almost all of them picked the answer that the weight would follow a curved path away from the person.
I found that one especially interesting because most people have spun stuff around on strings and let go, and you can clearly see that it travels in a straight line when you do. But for some reason that real world experience just fell out of their heads when they started thinking of it as a physics question.
But I used the unless wording and they got it after a while and some struggle to understand. Because as kikaider01 said the 1st law is profound and completely against our intuitive understanding based on our experience on Earth.
posted by sotonohito at 8:53 AM on September 15, 2023 [5 favorites]
While there's people who don't get the 1st law, that's not due to the word unless, that's due to it being counterintuitive and people taking time to really grasp the concept.
The people who believe that a space ship will eventually drift to a halt are either a) incredibly pedantic and talking about the ship being acted on by minute forces and collisions with occasional hydrogen atoms, or b) don't understand the 1st law. In neither case is that due to the word unless being bad or inaccurate.
It is absolutely true that most people have a really skewed idea of physics, even physics that can be observed.
At the beginning of the physics module I taught way back then I gave my 8th graders a non-graded survey to see what their idea of physics was like and then the exact same survey after we did the classes on physicsto see if any of it stuck. I did that because in college my intro to physics prof did and i liked the idea.
One question was about a person spinning a weight on a string and the path the weight would take when the person let go of the string. Almost all of them picked the answer that the weight would follow a curved path away from the person.
I found that one especially interesting because most people have spun stuff around on strings and let go, and you can clearly see that it travels in a straight line when you do. But for some reason that real world experience just fell out of their heads when they started thinking of it as a physics question.
But I used the unless wording and they got it after a while and some struggle to understand. Because as kikaider01 said the 1st law is profound and completely against our intuitive understanding based on our experience on Earth.
posted by sotonohito at 8:53 AM on September 15, 2023 [5 favorites]
I'm also pretty sure that if I used the "except insofar" wording my 8th graders wouldn't have had a clue what I was talking about because they wouldn't have known the word insofar.
posted by sotonohito at 8:54 AM on September 15, 2023 [1 favorite]
posted by sotonohito at 8:54 AM on September 15, 2023 [1 favorite]
most people have spun stuff around on strings and let go, and you can clearly see that it travels in a straight line when you do
Throwing a ball goes from a curved to a straight line path and we depend on that a lot! (Personally terrible at it, but I know what I intend to happen.)
posted by clew at 9:23 AM on September 15, 2023
Throwing a ball goes from a curved to a straight line path and we depend on that a lot! (Personally terrible at it, but I know what I intend to happen.)
posted by clew at 9:23 AM on September 15, 2023
Everything is curved. Your ball goes from curved path to another curved path or if you threw it up it would never come down. Parabola. Aim a gun at a monkey and fire and the monkey drops the moment you fire, what happens? The bullet still hits the monkey because both are falling at the same rate (to a degree, there's actually a (GmM)/d^2 in there but the M is the Earth and the m is the monkey/bullet and the M is humongous humongous compared to the m, so forget the m, things fall at the same acceleration (but they really don't)).
I had three semesters worth of Physics at CalTech before high school Physics. This thread is a flashback to my Physics teacher asking me a question and then telling me to go to the back of the class and keep my mouth shut and never asked me to come up to the board and solve a problem again. Fucking space-time geodesic paths and whatnot.
It was Galileo that did the inclined plane stuff.
posted by zengargoyle at 12:20 PM on September 15, 2023 [1 favorite]
I had three semesters worth of Physics at CalTech before high school Physics. This thread is a flashback to my Physics teacher asking me a question and then telling me to go to the back of the class and keep my mouth shut and never asked me to come up to the board and solve a problem again. Fucking space-time geodesic paths and whatnot.
It was Galileo that did the inclined plane stuff.
posted by zengargoyle at 12:20 PM on September 15, 2023 [1 favorite]
"It turns out that for most of its history, almost every available translation of Newton’s Latin Principia was based on the original 1729 English translation by Andrew Motte. Motte’s edition was published two years after Isaac Newton’s death, and he almost certainly prepared it without Newton’s knowledge or permission. "
Is it not reasonable to think that two English speakers would infer the same meanings to words written by commonly non-native Latin speakers. What is the likelyhood that those mostly of the same age and time would use Latin in the same way? We're not talking about Romans here, both are English. What would be the common usage among them and their peers? Maybe the both of them used that word the same way.
posted by zengargoyle at 12:50 PM on September 15, 2023
Is it not reasonable to think that two English speakers would infer the same meanings to words written by commonly non-native Latin speakers. What is the likelyhood that those mostly of the same age and time would use Latin in the same way? We're not talking about Romans here, both are English. What would be the common usage among them and their peers? Maybe the both of them used that word the same way.
posted by zengargoyle at 12:50 PM on September 15, 2023
You sometimes speak of gravity as essential & inherent to matter: pray do not ascribe that notion to me, for ye cause of gravity is what I do not pretend to know, & therefore would take more time to consider of it Sr I am
Yor most humble Servant
Is. Newton
Trin. Coll. Ian. 17.
1692/3
The idea that objects only deviate from straight-line, unacccelerated motion when acted on by a force is not obvious, it is profound
That it is. It's counter intuitive.
After all you throw a ball up in the air and the ball will come down. Not continue in a straight line moving upwards.
Newton invents gravity because it is necessary for it to exist as a force.
Yet he was also troubled by spooky action at a distance.
posted by yyz at 2:09 PM on September 15, 2023 [3 favorites]
This being the Spooky-action-a-a-distance Season, we're all a bit troubled these days.
posted by hippybear at 2:34 PM on September 15, 2023
posted by hippybear at 2:34 PM on September 15, 2023
And so are those people over there!
posted by hippybear at 2:34 PM on September 15, 2023 [1 favorite]
posted by hippybear at 2:34 PM on September 15, 2023 [1 favorite]
What is the likelyhood that those mostly of the same age and time would use Latin in the same way?
Pretty much all scholarship was in Latin in Newton's time. While the Romans might not have understood the pronunciation, Latin was the lingua franca in science, religion and much else, and used to precisely communicate ideas. One scientist's Latin would have been pretty close to another's.
posted by pipeski at 4:02 AM on September 16, 2023
Pretty much all scholarship was in Latin in Newton's time. While the Romans might not have understood the pronunciation, Latin was the lingua franca in science, religion and much else, and used to precisely communicate ideas. One scientist's Latin would have been pretty close to another's.
posted by pipeski at 4:02 AM on September 16, 2023
I prefer Newton's subsequent, unpublished revision: "Corpus omne perseverare in statu suo quiescendi vel movendi uniformiter in directum, nisi quatenus donec velit prohibere ad tacos."
"The whole body must continue in its state of rest or of moving uniformly in a straight direction, except insofar as it wants to stop for tacos."
posted by indexy at 8:49 AM on September 16, 2023
"The whole body must continue in its state of rest or of moving uniformly in a straight direction, except insofar as it wants to stop for tacos."
posted by indexy at 8:49 AM on September 16, 2023
Latin was the lingua franca in science, religion and much else, and used to precisely communicate ideas. One scientist's Latin would have been pretty close to another's.
And therefore this mistranslation junk is bunk. They knew what each other was saying, they grokked the same Latin.
posted by zengargoyle at 4:46 PM on September 19, 2023 [2 favorites]
And therefore this mistranslation junk is bunk. They knew what each other was saying, they grokked the same Latin.
posted by zengargoyle at 4:46 PM on September 19, 2023 [2 favorites]
I've always read the First Law as a description of what the word "force" refers to rather than some claim about the inherent nature of objects. A force is exactly and only an identifiable influence that we can quantify and invoke to help account for the motion of an arbitrary body, and the First Law says that if we observe a body in a state of constant velocity then the net force acting on it is zero.
If we observe a body whose velocity is near enough to constant for practical purposes, then we can use the First Law to conclude that net force on it is near enough to zero for practical purposes. Vice versa works too.
Taking the "strictly speaking, force-free bodies do not exist at all, therefore the First Law is a bit of a dud" argument to its logical conclusion, I could claim that sufficiently strictly speaking, the boundary between any body and its surroundings is never exactly identifiable, therefore strictly separable bodies do not exist at all, therefore all laws describing interactions between such bodies are a bit of a dud. But, as it turns out, not much of a bit. Natural law is demonstrably useful enough for somebody to have put in the work required to codify it.
"In principle" is the favourite phrase of handwaving wannabe philosophers everywhere. In principle, any claim can be true because principles are inherently arbitrary. I can just keep on tweaking my principles until my favoured claim becomes true in principle.
In particular, I hew to a principle that says hard and fast rules exist only for the sake of administrative convenience. By that principle, "unless" has a sense that's exactly equivalent to "except insofar as", and failing to read it in that sense in this instance is the reader's error, not the translator's.
posted by flabdablet at 8:55 AM on September 20, 2023
By Newton’s own lights, every body in the universe is subject to forces, in particular gravity. So strictly speaking, force-free bodies do not exist at all. But if that is so, then Newton’s celebrated First Law of Motion starts to seem like a bit of a dud. What good is a law of nature that governs nothing? Why make that your First Law?I think it's pretty lame as well. The way I would have tackled it is to point out that every law of nature is inherently an idealization, that the predictive power of any such law is always limited by practical considerations, and that one of the most important things to understand about any mathematical model of nature is the extent to which uncertainties in the measurements used as its inputs translate to inaccuracies in its predictions, especially when we're using such predictions in extrapolative ways.
“Well,” said my teacher, “the law tells us that if there were force-free bodies then they would move in straight lines.” I thought it was a lame excuse.
If we observe a body whose velocity is near enough to constant for practical purposes, then we can use the First Law to conclude that net force on it is near enough to zero for practical purposes. Vice versa works too.
Taking the "strictly speaking, force-free bodies do not exist at all, therefore the First Law is a bit of a dud" argument to its logical conclusion, I could claim that sufficiently strictly speaking, the boundary between any body and its surroundings is never exactly identifiable, therefore strictly separable bodies do not exist at all, therefore all laws describing interactions between such bodies are a bit of a dud. But, as it turns out, not much of a bit. Natural law is demonstrably useful enough for somebody to have put in the work required to codify it.
"In principle" is the favourite phrase of handwaving wannabe philosophers everywhere. In principle, any claim can be true because principles are inherently arbitrary. I can just keep on tweaking my principles until my favoured claim becomes true in principle.
In particular, I hew to a principle that says hard and fast rules exist only for the sake of administrative convenience. By that principle, "unless" has a sense that's exactly equivalent to "except insofar as", and failing to read it in that sense in this instance is the reader's error, not the translator's.
posted by flabdablet at 8:55 AM on September 20, 2023
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It’s really weird that an extremely central and fundamental document of physics has been misread for so long, centuries, because of the mistranslation of one word. It makes me wonder how many other things like this exist in that oh so empirical world of science.
posted by njohnson23 at 8:14 AM on September 14, 2023 [4 favorites]