Righting a Wrong Understanding of Newton's Law with Daniel Hoek

Travis Williams (02:04.406)

Well, I guess to begin this interview, I'm really curious. At what point, when did you become interested in Newton's first law?

Daniel Hoek (02:08.461)

Yeah, exactly. Yeah, good. That's an interesting question. I mean, in a way, I've always thought it was odd. So that really is something that started way back in high school when it just didn't seem like any of the other laws of nature. And it also, there was also just some odd puzzles about it. But I wasn't at that point yet interested in it, right? I just sort of shrugged and moved on. The point where I started to get really interested and puzzled by this was much later in college when I was taking a class on philosophy of physics. And then, you know, I started reading some Newton because that's what they make you do. And I realized that, you know, Newton...really has a reputation for being very smart, but it's very deserved, right? The text is really extremely precise and deliberate. I noticed that a lot of other smart people who'd written about Newton were kind of puzzled about exactly the same thing that I had found strange in high school. And at that point...those two things kind of came together, where one, I thought all of a sudden, oh, OK, well, that wasn't just me being stupid that I was puzzled about this thing. And on the other hand, realizing this kind of kind of dissonance that on the on the one hand, Newton was this very careful and precise thinker. On the other hand, a lot of people seem to be saying that he made this pretty stupid mistake. Where I started thinking, okay, well, maybe we should have a closer look.

Travis Williams (04:22.277)

What was the mistake? What were you struggling with?

Daniel Hoek (04:27.05)

So here's how the first law usually goes. It says, objects that don't have any forces working on them, so objects that aren't being tugged or pushed or pulled along by anything, either they just keep standing still, if that's what they're doing or if they're moving, they'll just keep on moving in the same direction in which they're moving in a straight line at uniform speed. That's how they tell you the first law. And there are a few things actually that are odd about it, but perhaps the oddest thing is that these objects that it's supposed to be about, these objects on which no forces are acting, don't exist.

So at first you think like, OK, maybe the pen on my table, right? That seems like it's just sitting still and there are no forces acting on it. But if you think about it, it's not really sitting still. And there really are forces acting on it, right? Because for one thing, the Earth is pulling it down and then my desk is pushing it back up. And it's not sitting still either, right? It's spinning around the axis of the Earth right together with the desk and everything on it. And the Earth is going around the sun and so on. So it's not really an example of an object in which no forces are acting. And then once you start thinking it through, it turns out that on Newton's own account, nothing is such that no forces are acting on it because everything is under the influence of gravity at the very least everything is getting tagged by gravity. And so it's really weird that Newton would have this law of nature that just doesn't apply to it.

Travis Williams (06:30.922)

Okay, and so you found that you, I guess you found that you questioned this and other people you started to realize, how did you go about or what was the moment you decided like I'm gonna dig in and figure this thing out?

Daniel Hoek (06:45.93)

Well, I mean, I don't think I... It sort of happened more by accident, I would say. So...So I was interested in this puzzle. It did seem weird to me. There is also another kind of similar puzzle that again, people realized very early on about the first law, which is the way that you're taught it, it's just a special case of the second law. So that's another side issue. And at some point, I had been thinking about this question and some of the stuff that people have said about it. Because this is, you know, this was really not just me noticing this. Philosophers and also physicists have been writing about this for ages. And in some sense, you know, it's kind of a search for like something for the first law to do, right? Because it seems like it's just this law that doesn't apply to anything. Let's find a way to interpret it or really squint at it where it has something to do. And so I looked.

I looked it up in Newton's actual Procipia, and with the thought of like, okay, well, what does Newton do with it? Maybe that'll give us some hint of how he was thinking about it, right? Because presumably he thought there was a reason it needed to be there, right? It's not even his third law. It's like the first law.

Right? So clearly he thought that there was something it had to do. And then actually immediately Newton tells you, right? So right after he states the first law, he talks about how it applies, according to him, to phenomena in the real world. And the examples are very puzzling. So people used to think that the first law is all about objects that just sort of move in straight lines at uniform speed, right? Even if they're not real, right, people sort of have conjured this picture where you're supposed to imagine an empty universe in which, you know, something really was free of forces and really sort of doing that lone trajectory through the universe in a straight line. But then you look at Newton's application and it is not like that at all. So...The first example is a little bit like that, but then the second example he gives is a spinning top. He says, a spinning top just keeps on spinning and going round, unless there's friction slowing it down. And you're like, hang on. Well, first of all, that's not an example of linear motion, clearly, right? Just going round and round.

And secondly, it's not force free. Newton even says that, right? He says the reason it's going round and round and round is because there are these sort of internal forces in the spinning top, right? Each bit of the spinning top sort of wants to move out, but the rest of the spinning top also is trying to move out. And the result is that every sort of is pulling each other in circles instead. And so that doesn't seem like an application of the first law as we know it at all. So that was my first realization where I'm like, oh, hang on, so not only did Newton think that there was something for the first law to do, but he was thinking of a very different kind of application than what all these other philosophers and physicists that I was reading was thinking about. And then I...I fortunately, I read the newest translation, right, which was done in 1999. And that translation is correct. There was a mistake in the other version, so we'll probably talk about that later. And so I read carefully what the law said, and then I realized that it also doesn't quite say what people normally think it says. So...the law as Newton writes it down says, an object will keep on going in a straight line or standing still. So, so far that sounds really familiar. And then he says, except in so far as forces prevented from doing so. And that phrase, I thought, you know, with this sort of puzzling spinning top example in mind, right? That doesn't really say that there's an exception for objects that have forces acted on them, right? It says, no, those still keep on going in straight lines, right? Except in so far, right, as the forces stop it from doing that, right?

And then you think again about the spinning top and these little bits going around and around, right? They are sort of going forward, right? To the extent that they can, right? And then these other bits of the spinning top are kind of like messing with that a little bit, but you know, they keep going forward as much as you can. And then you think about other kinds of examples, like for instance, you know, the more typical example that people give of the first law is like an ice puck right, on an ice rink, right? So, you know, after you hit it, right, you only hit it once, right, it has some force acting on it then, but then it just keeps on speeding along, right, along the ice rink. And, you know, until, you know, eventually friction forces slow it down. But that seems like a sort of nice visual illustration of the first law. And then people say, yeah, but yes, of course, actually, it's not really going in a straight line, right, because it's still going around the earth and so on, and actually there are also friction forces acting on it and so forth. And so, you know, it turns into one of those disappointing things where you think you've found an example of the first law and it isn't really because it's not really a force-free body. But then I realised, no, hang on, hang on, it is an example of the first law, because that ice puck keeps on going in a straight line, except to the extent that forces...prevent it from going in a straight line. So it's this phrase, except to the extent people hadn't really realized, what it was doing kind of makes it so that the law actually has much wider application that people thought.

Travis Williams (13:59.278)

Yeah, and I don't know the history of this, but it sounds like to me that prior to figuring out this language issue, that maybe folks were trying to look for this magical example that didn't have any forces on them at all. And I don't think that they found it. It doesn't sound like it.

Daniel Hoek (14:11.497)

Mm-hmm. Yeah, no, that's right. Exactly. Yeah. And I'm in fact, there was this sort of basic reason why there couldn't even be examples like that, right? Because anything, you know, because of gravity, like, you know, this pen attracts this pen a little bit, right? There's a little bit of gravity pulling, pulling one pen to the other. And so as long as you don't have just like one little lonely object in the universe, everything has forces acting on it. And so yeah.

And so that was the problem. It's sort of always been a problem for physics teachers as well, because they try and get these examples. And then they've got the annoying student at the back of the room pushing up, putting their hand up and saying, well, hang on, is that really a body on which no forces are acting? And then they have to say, no, but it's good enough.

Travis Williams (15:09.482)

Yeah, so what do you think some of the practical applications of this would be just for someone like me?

Daniel Hoek (15:17.858)

So, I mean, I don't, so, you know, the, it is a sort of subtle mistake I found. So I don't think it's going to make a difference for physics. It's not like all physicists tomorrow are going to do physics differently because of this. But I do think it makes a practical difference for physics education because, you know, out of respect for the great man, right? Most physics texts, most introductory physics texts do still teach the first law, but it's always kind of this awkward thing where it's quite confusing really. And not just to me, I mean, it's actually been nice since this has gotten some publicity. I get emails from people from time to time saying, ah, I'm so glad I...I came across this article because I was confused about exactly this thing. So that's, you know, it's been confusing people for a long time. And like physics, it's confusing enough. So I hope we can sort of set it straight and, you know, get to the fun bits, put fewer people off.

Travis Williams (16:41.278)

Yeah, I hope so too, because I'm pretty sure that was, if that would have been talked to me in high school, me in high school would have been like, that doesn't make sense. I'm going to go play on my phone.

Daniel Hoek (16:51.358)

Exactly, that's right, that's right, that's right. So if only one fewer person goes play on his phone because they think whatever this Newton dude was smoking it doesn't make any sense, that would be awesome.

Travis Williams (17:07.798)

That's fascinating, that's really cool. I'm curious too, what do you think that this might do to help maybe bridge, maybe that's a bad question. I'm curious, how do you think that a discovery like this can help foster a relationship between people that study physics and maybe philosophy like yourself?

Daniel Hoek (17:28.406)

Yeah, well, I mean, I was kind of pleasantly surprised that there's already a little bit of that happening here at Virginia Tech. So the wonderful John Simonetti from the physics department invited me to give a talk for the first year physics students who were great to talk to and very interested in this. Again, because a lot of them had actually been kind of puzzled about this. this thing already. And so it's kind of just nice to find out that actually it fits together even more neatly than it seemed. And in general, so there's actually like a long relationship of physicists talking to philosophers. At the start of the 20th century, this was happening all over the place.

For instance, Einstein was very influenced by reading the 19th century German philosopher Ernst Mach. So there was a lot of physics philosophy collaboration happening. And then more recently, physicists have become a little bit more suspicious of philosophers trying to meddle in their affairs. But I have actually found that, that about this particular issue, they've been a little bit more open-minded. So I'm hoping, maybe it's partly because it's not really on their turf, right? I mean, after all, it's not really physics, it's history to an extent. And also, Newton is a hero for a lot of physicists, and this is so showing that.

In a way Newton was smarter than people have given him credit for. So it's good news for the physicists. So if this could make a tiny contribution to making physicists and philosophers like each other a little bit more again, like they used to, that would be great because I think they have great, great conversations to have with each other.

Travis Williams (19:45.258)

That's awesome. Well, thank you so much for talking to me. I don't really think I have any other questions for you. I thank you. You explained it really well. Like I understand it now. And I'm not sure that I did. I don't think I did when we started.

Daniel Hoek (19:56.43)

Well that's great, that's great. I was worried that I was rambling a little bit but yeah you feel like you feel like we go right?

Travis Williams (20:06.958)

I think, yeah, I think so. I think you explained it well. And I had watched the video and I had read Andrew's piece, which was more about the intersection of humanities, and which is really cool. And that's why I asked you that last question, because I think what you've done has really, I think what you've done has kind of naturally proved that the idea of interdisciplinary work is really valuable.

Like without maybe purposely trying to. Like all the things we talk about wanting to do.

Daniel Hoek (20:40.382)

Yeah, yeah, that is a nice thing. I mean, maybe I'll say a little bit about that. I mean, this is a nice puzzle for showing that, right? Because I think people on different sides had seen different puzzle pieces, right? Maybe clients need to see this. Yeah. Sure, yeah. Yeah.

Travis Williams (21:02.068)

Yeah, well, let me, can I ask you that question again? And then we can, well, what do you hope that your discovery and that your work does as far as elevating the importance of cross-disciplinary work?

Daniel Hoek (21:17.578)

Good. Well, I mean, I think cross-disciplinary work can be really good, what it's good, and I think philosophy is sort of a natural home for it, right? Back in the day, you know, before there were universities, right, there was already philosophy, and anybody who was interested in explaining anything was a philosopher. And this has just been a nice puzzle that brings together a little...a little bit from different disciplines, a little bit of language, a little bit of history, a little bit of logic, and a little bit of physics. And you really needed these different perspectives to put it all together because physicists have been puzzled about the physics puzzle, but they have been using the wrong translation, right? And Newton's experts already but they didn't realize the sort of physical significance of that kind of nuanced translation issue. So if you bring those things together, great things can happen. And I think that's true more generally, right? If you build a bridge between two disciplines, then all of a sudden you get this sort of like new input, right? Insights from one place can be used somewhere surprising.

Travis Williams (22:45.714)

Yeah, I think that that's totally true. Awesome, well thank you. So I'm gonna hit stop on this thing and it'll upload.