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What is a non-Newtonian fluid? · Daniel and Kelly’s Extraordinary Universe

0:08
Speaker 1: Hey, Daniel, what are physicists favorite foods? Dark chocolate, heavy water,
0:13
Speaker 1: dark chocolate.
0:14
Speaker 2: Studded with chunks of dark matter. Now I heard that
0:16
Speaker 2: Newton liked chicken pot pie weirdly enough.
0:20
Speaker 1: Well, yeah, was it because of the nutrients?
0:25
Speaker 2: I heard actually that he likes a really thick gravy
0:28
Speaker 2: as high specific gravity.
0:30
Speaker 1: Mmm. I heard he was more of a cookie man.
0:33
Speaker 2: What really, Isaac Newton eating something as silly as a cookie?
0:36
Speaker 1: Yeah? It didn't even invent the fake newtonts.
0:40
Speaker 2: I think actually those cookies were named after the town
0:43
Speaker 2: of Newton, Massachusetts, where they were first baked.
0:46
Speaker 1: Uh, But then wasn't the town named after Isaac Newton,
0:50
Speaker 1: So technically he's grandfathered in.
0:52
Speaker 2: I think its name comes from it being invaded by
0:55
Speaker 2: a huge swarm of Newts.
0:56
Speaker 1: The next thing you're gonna tell me is that Einstein's
0:58
Speaker 1: brothers bagels was not invented by iceland on his brother.
1:02
Speaker 2: No, but if you need enough of them, youal curve space.
1:04
Speaker 1: I feel like it's a big hole in that story.
1:21
Speaker 2: Hi.
1:21
Speaker 1: I'm Jorhem mccartoonists and the author of Oliver's Great Big Universe.
1:25
Speaker 2: Hi I'm Daniel. I'm a particle physicist and a professor
1:28
Speaker 2: at uc Erine, and I'll always love the Everything Bagel.
1:32
Speaker 1: Do you like everything about bagels or the bagel that's
1:35
Speaker 1: called the everything Bagel?
1:36
Speaker 2: I like the Everything Bagel, though I expected you to
1:38
Speaker 2: criticize it for not being accurately named. I mean, it's
1:41
Speaker 2: not literally everything on the bagel.
1:44
Speaker 1: If it did, it would maybe collapse into a black
1:46
Speaker 1: hole and collapse in multiverse, as some movies would happen.
1:48
Speaker 2: If it literally had everything on it, it would also have
1:51
Speaker 2: to have everything bagels on it, so it'd be like
1:53
Speaker 2: a recursive bagels with bagels on it, and bagels on those,
1:55
Speaker 2: and bagels on those forever down to the tiniest little bagels.
2:00
Speaker 1: It goes all the way down to the center of reality.
2:03
Speaker 1: Big of the movie was.
2:04
Speaker 2: Right, everything bagel, everywhere, all at once.
2:06
Speaker 1: Welcome to our podcast Daniel and Jorge Explain the Universe,
2:09
Speaker 1: a production of iHeartRadio.
2:11
Speaker 2: Where we think about the universe as a huge tasty snack.
2:14
Speaker 2: You can put smeer on it, you can slap locks
2:17
Speaker 2: on it, or you can just try to understand it.
2:20
Speaker 2: We hope that the universe is intellectually devourable at least
2:23
Speaker 2: that we can gather all of the knowledge and observations
2:25
Speaker 2: that humanity has been making for thousands of years and
2:28
Speaker 2: somehow weigh them together into a story about how everything works,
2:32
Speaker 2: how the tiniest little bits interact, how they come together
2:35
Speaker 2: to make weird fluids and goofy stuff and solids and
2:38
Speaker 2: metals that we live with all the way up to
2:40
Speaker 2: planets and galaxies and black holes.
2:43
Speaker 1: Yes, it is a pretty delicious universe full of amazing
2:46
Speaker 1: things that will fill you up in your brain, fill
2:48
Speaker 1: up your head with knowledge and amazing facts and incredible
2:51
Speaker 1: processes going out there in the cosmos, in between galaxies,
2:55
Speaker 1: inside of galaxies, and inside of all of us sometimes
2:58
Speaker 1: because we ate it.
3:00
Speaker 2: One of my favorite things about physics is that it's
3:02
Speaker 2: fascinating at so many different levels. I mean, on this podcast,
3:06
Speaker 2: we usually focus on the very very very tiny, trying
3:08
Speaker 2: to understand the fundamental nature of matter, or like they're
3:11
Speaker 2: really really big thinking about the whole universe, and it's
3:15
Speaker 2: incredible that there are stories at both of those levels
3:18
Speaker 2: that we can think about, that we can understand that
3:20
Speaker 2: give us some like intuitive grasp on the workings of
3:23
Speaker 2: the universe. But don't forget that there's lots of levels
3:27
Speaker 2: in between, like the ones we live on, things about
3:30
Speaker 2: a meter scale and moving kind of slowly, and so
3:33
Speaker 2: much fascinating physics that happens here on Earth.
3:36
Speaker 1: Wait are you saying physics is happening everywhere, all at once,
3:41
Speaker 1: on everything, everywhere, all at once.
3:43
Speaker 2: I'm saying you have to have physics as a topping
3:45
Speaker 2: on your bagel if it's got everything on it, But.
3:47
Speaker 1: Then to put it on top would require physics.
3:49
Speaker 2: And I'm not saying physics on top of everything. You know,
3:51
Speaker 2: I have deep love and respect for chemistry as well.
3:54
Speaker 1: Maybe everything bagel is physics. That's why Eistein and his
3:57
Speaker 1: brother invented the baggel.
4:00
Speaker 2: Or haes bagel theory of the universe.
4:02
Speaker 1: Isn't a bagel a possible shape of the universe, like
4:05
Speaker 1: a taurus?
4:05
Speaker 2: Yeah right, yeah, I think the mathematicians call it a
4:08
Speaker 2: taurus or a doughnut, rarely a bagel. But yeah, that's possible.
4:10
Speaker 2: But I think the fact that your theory is shaped
4:12
Speaker 2: like a zero might give you a.
4:14
Speaker 1: Clue because it's the first thing and that the universe
4:17
Speaker 1: was made out of. It's the zero theorem.
4:22
Speaker 2: Yeah, let's go with that. But there is so much
4:24
Speaker 2: fascinating physics that happens, not just at the tiny scale
4:27
Speaker 2: and at the huge scale, but right here on Earth.
4:30
Speaker 2: The way the particles weave themselves together creates all sorts
4:33
Speaker 2: of fascinating chemistry and biology and of course life here
4:37
Speaker 2: on Earth. And along the way, there's lots of really
4:40
Speaker 2: interesting questions we can ask, not about the fundamental nature
4:43
Speaker 2: of stuff, but what that stuff does when it comes together.
4:46
Speaker 1: Yeah, because as we said, physics is happening everywhere. It
4:49
Speaker 1: doesn't just happen in a laboratory and a big research
4:52
Speaker 1: institution or a university. It also happens all the time everywhere,
4:55
Speaker 1: even in your kitchen. There are all kinds of interesting
4:58
Speaker 1: examples of physics everywhere all around us, in the foods
5:01
Speaker 1: we eat and the foods that you prepare, and also
5:04
Speaker 1: in things like slime.
5:07
Speaker 2: And a couple of years ago, during the pandemic, there
5:09
Speaker 2: was this huge trend of kids making slime in their kitchens,
5:12
Speaker 2: which seem to explode everywhere, all over the Internet and
5:15
Speaker 2: all over the walls of our kitchen.
5:17
Speaker 1: Wait literally explode or figuratively explode.
5:20
Speaker 2: Well, my daughter made all sorts of various kinds of
5:22
Speaker 2: slime I remember at least one of them blew up
5:24
Speaker 2: on her.
5:25
Speaker 1: It isn't the definition of slime that it gets all
5:27
Speaker 1: over the place and it's a big mess. Like we
5:31
Speaker 1: just made slime and kept it in a cup. It's
5:32
Speaker 1: not really slime. It's only sime if you like, pick
5:35
Speaker 1: it up and pull it apart with your fingers.
5:37
Speaker 2: Slime is as slime does.
5:39
Speaker 1: But yeah, there are all kinds of amazing physics we
5:41
Speaker 1: can observe and ask questions about it in our everyday lives.
5:44
Speaker 1: And one of those questions that we often get is
5:47
Speaker 1: about a very specific kind of liquid.
5:50
Speaker 2: People playing around in their kitchens and making slime and
5:53
Speaker 2: wondering about the physics of solids and gases and liquids.
5:56
Speaker 2: A bunch of them wrote in to ask us about
5:58
Speaker 2: the physics of this but particular kind of goo.
6:01
Speaker 1: So today on the podcast, we'll be asking the question,
6:09
Speaker 1: what is a non Newtonian fluid?
6:12
Speaker 2: Isn't that just something Newton wouldn't have on his.
6:14
Speaker 1: Chicken or his fake newtonts. Maybe it's a a schmeir
6:19
Speaker 1: on a Einstein bagel.
6:22
Speaker 2: There you go. I'd like the Newton shmer and the
6:24
Speaker 2: Einstein bagel, please.
6:26
Speaker 1: Yeah, but not everyone likes it. You know, it's all relative.
6:29
Speaker 1: But yeah, it's an interesting question. I feel like this
6:31
Speaker 1: is one of those terms non Newtonian fluids that you
6:33
Speaker 1: hear all the time, sort of in like physics shows
6:36
Speaker 1: or physics explanations that's used like as an explanation for
6:40
Speaker 1: a phenomenon. But it's not really an explanation to say
6:43
Speaker 1: that the fluid that has a name on it.
6:45
Speaker 2: Well, it's sort of weird that you define it by
6:46
Speaker 2: what it Isn't like I could serve you dinner and say, hey,
6:49
Speaker 2: this is not a bagel. I've made it for dinner.
6:51
Speaker 2: Doesn't really tell you what it is, right, It could
6:53
Speaker 2: still be lots of different things.
6:55
Speaker 1: Oh right, Yeah, I guess maybe that only works that
6:59
Speaker 1: there are only two kinds of something in the world,
7:02
Speaker 1: Like is this an everything bagel or not everything bigel?
7:05
Speaker 1: Technically every bagel doesn't have everything on it is a
7:09
Speaker 1: non everything bagel.
7:10
Speaker 2: It's true that every meal any human is ever eaten
7:13
Speaker 2: is either an everything bagel or it's not an everything bagel.
7:16
Speaker 1: Right, or nothing bige.
7:19
Speaker 2: That sounds kind of like a nothing burger.
7:21
Speaker 1: Exactly, it's a nothing bagel burger.
7:24
Speaker 2: But this is not a nothing burger of physics. There
7:27
Speaker 2: are Newtonian fluids that follow certain rules, and then weird
7:31
Speaker 2: kinds of fluids that don't follow Newton's strict laws about
7:35
Speaker 2: how fluids should go.
7:37
Speaker 1: Yeah, so this is an interesting question what is a
7:39
Speaker 1: non Newtonian fluid? And so, as usually, we were wondering
7:42
Speaker 1: how many people out there had thought about this question
7:44
Speaker 1: or wondered what exactly is going on in a non
7:46
Speaker 1: Newtonian fluid.
7:47
Speaker 2: So thanks very much to everybody who answers these questions.
7:51
Speaker 2: If you're up for us playing your answers to questions,
7:54
Speaker 2: please write to us to questions at Danielandjorge dot com.
7:58
Speaker 1: So think about it for a second. Are you in
8:00
Speaker 1: the non Newtonian or the pro Newtonian? Can here's a
8:04
Speaker 1: depled to say.
8:05
Speaker 3: Maybe it's when the molecules in a fluid don't react
8:08
Speaker 3: according to Newton's laws of gravitation.
8:12
Speaker 2: I don't know.
8:13
Speaker 3: I've heard of non Newtonian fluids, but I'm not sure
8:15
Speaker 3: what makes them non Newtonian. I think it means that
8:19
Speaker 3: you don't use the usual fluid mechanics that you would
8:22
Speaker 3: with fluids that we're used to. Examples of non Newtonian
8:25
Speaker 3: fluids might be liquid helium, and maybe the fluid in
8:30
Speaker 3: the interior of a neutron star, possibly ferrofluids, but that
8:35
Speaker 3: doesn't mean I know why they're non Newtonian.
8:37
Speaker 1: Non Newtonian fluid. I didn't know there is Newtonian fluid,
8:41
Speaker 1: but I'm guessing that this non Newtonian fluid doesn't follow
8:46
Speaker 1: the like three Newton's laws.
8:47
Speaker 4: The first example that comes to mind is a mixture
8:49
Speaker 4: of cornstarch and water. If you mix those two things
8:52
Speaker 4: together in a glass and try to pour it out,
8:56
Speaker 4: it will flow like a viscous fluid, but if you
8:58
Speaker 4: impact it quickly with your finger, will solidify. So I
9:01
Speaker 4: think a non Newtonian fluid is one that displays properties
9:07
Speaker 4: of more than one phase of matter, either liquid, solid
9:11
Speaker 4: or probably gas.
9:13
Speaker 5: Well, non Neutonian fluids, that's a pretty cool one. I mean,
9:15
Speaker 5: non Newtonia makes me thinks of quantum mechanics, So this
9:20
Speaker 5: must be some fluids made of super small particles, elementary particles,
9:27
Speaker 5: maybe electrons, maybe subparticles. So and then this fluid will
9:33
Speaker 5: respond to quantum chemistry quantum physics, so it would be.
9:37
Speaker 2: A pretty crazy fluid. What is a non Netonian food?
9:40
Speaker 3: I don't even know what a non Newtonian fluid is,
9:43
Speaker 3: so I'm going to say a non Newtonian fluid is
9:46
Speaker 3: most fluid.
9:48
Speaker 2: I don't know what a non Newtonian fluid is. I
9:50
Speaker 2: assume it's of some sort of fluid that's not like
9:54
Speaker 2: the ones I'm familiar with.
9:55
Speaker 1: I have a vague feeling that a non Newtonian fluid
9:57
Speaker 1: is one that is compressible, whereas a Newtonian one is uncompressible.
10:04
Speaker 3: I think a non Newtonian fluid is one that doesn't
10:08
Speaker 3: obey the equations made by Newton.
10:11
Speaker 1: A lot of interesting answers here. I guess a lot
10:14
Speaker 1: of people did assume that it has something to do
10:16
Speaker 1: with Isaac Newton.
10:17
Speaker 2: M hm, though I particularly like the suggestion that maybe
10:20
Speaker 2: it's an anti gravity liquid.
10:22
Speaker 1: Oh interesting, that'd be pretty awesome if you can make
10:26
Speaker 1: that in your kitchen.
10:27
Speaker 2: Yeah, Like Newton did so much in physics, it's not
10:30
Speaker 2: clear what non Newtonian means, Like which of Newton's laws
10:34
Speaker 2: are you breaking? Are you like, violating the fundamental laws
10:36
Speaker 2: of calculus or of gravity or of motion or what?
10:40
Speaker 1: I think the fluid kind of gives it away a
10:42
Speaker 1: little bit, right, It's not a non Newtonian math ages
10:48
Speaker 1: Newton's laws in relation to liquids or as they relate
10:51
Speaker 1: to liquids.
10:52
Speaker 2: It really is incredible that one of like the minor
10:54
Speaker 2: things that Newton did is still an important work of physics,
10:58
Speaker 2: one that would get any other physicists their name on
11:01
Speaker 2: an equation forever. But for Newton it's like the ninth
11:04
Speaker 2: and most important thing he did.
11:05
Speaker 1: Yeah, although if if something named something after not you would,
11:10
Speaker 1: can you still take credit for it? Like I have
11:13
Speaker 1: invented the non Daniel Whitson particle. That would be almost
11:18
Speaker 1: like a very passive aggressive move there.
11:21
Speaker 2: Hey, slap my name on something famous forever as an insult,
11:24
Speaker 2: I'll take it.
11:25
Speaker 1: M Like if someone discovers the truth about everything, the
11:28
Speaker 1: core nugget of reality and called it the not Weissen theorem, we.
11:32
Speaker 2: Have the anti white syn theorem. Go ahead and do it.
11:35
Speaker 2: You name it after me forever. Any publicity is good publicity.
11:38
Speaker 1: All right, Well, Stasty, you heard it on the podcast.
11:41
Speaker 1: You have it on his permission to not not name
11:45
Speaker 1: things not after it.
11:47
Speaker 2: You just want to be part of the conversation.
11:48
Speaker 1: Man, I guess if your name being spoken in a
11:52
Speaker 1: negative way, they're still talking about it.
11:54
Speaker 2: Yeah, I mean, what if the announce like Black Panther
11:56
Speaker 2: three not starring or hey, cham, you'd be pretty thrilled.
11:59
Speaker 1: Still mmm, I think I'd rather just stay out of
12:02
Speaker 1: that conversation. You know, I'm not that desperate yet. All Right, Well,
12:08
Speaker 1: let's get back to non Newtonian fluids, and maybe let's
12:11
Speaker 1: start at the beginning, like what is a pro neutuinin
12:14
Speaker 1: or regular in Neetonian fluid?
12:16
Speaker 2: Yeah, So fluids are fascinating things, right because they have
12:21
Speaker 2: constant volume, like they don't grow or shrink, but they
12:25
Speaker 2: don't have a fixed shape. So you can like take
12:28
Speaker 2: a glass of water and you can pour it into
12:30
Speaker 2: a bowl and the volume of it doesn't change, but
12:33
Speaker 2: it'll fill the bowl, it'll take that new shape. Or
12:36
Speaker 2: you can put it into a baggie, or you can
12:37
Speaker 2: dump it on the floor and they can do a puddle.
12:40
Speaker 2: Total volume of stuff won't change, but its overall shape
12:43
Speaker 2: is totally flexible. And that's really cool because it sits
12:46
Speaker 2: right between gases and solids. Gases don't have constant volume,
12:51
Speaker 2: they'll grow to fill any box you put them in.
12:53
Speaker 2: Solids have constant volume, but they also have a fixed shape.
12:56
Speaker 2: So fluids are this fascinating sort of half step between
13:00
Speaker 2: and solids.
13:01
Speaker 1: Well, you just sort of blew my mind or a
13:03
Speaker 1: little bit. I hadn't thought about the definition of the
13:05
Speaker 1: states of matter in that way. I guess, huh, is
13:08
Speaker 1: that basically what divides the three states of matter? Is
13:12
Speaker 1: that the technical definition or is there something more specific
13:15
Speaker 1: about the molecules or something.
13:17
Speaker 2: Well, there's fascinating history there because originally, of course, we
13:20
Speaker 2: didn't understand that matter was made out of molecules and
13:23
Speaker 2: little particles. Now we do have a molecular understanding for
13:26
Speaker 2: these phases of matter, but originally we didn't, and we
13:29
Speaker 2: still define them. It was just observational, the way a
13:32
Speaker 2: lot of physics is currently, Like, here's the kind of
13:34
Speaker 2: stuff we see in the universe. We notice there's this
13:36
Speaker 2: kind of stuff. There's drippy stuff, and this solid stuff,
13:39
Speaker 2: and there's puffy stuff. And that's how we begin. We
13:42
Speaker 2: start with observations, and we describe it, we categorize it,
13:45
Speaker 2: and then later we hope to get a microphysical understanding
13:48
Speaker 2: of where that comes from. Now, of course we know
13:51
Speaker 2: that everything is made out of molecules, and in gases,
13:54
Speaker 2: things are flying apart and basically not interacting, and in
13:57
Speaker 2: liquids there are still some bonds there, and then in
14:00
Speaker 2: solids they often form this crystal structure which is the
14:03
Speaker 2: source of their rigidity. Right, So we have an understanding now,
14:06
Speaker 2: but I think originally it just comes from observing different
14:09
Speaker 2: kinds of drippiness and gooiness.
14:11
Speaker 1: Yeah, that's what I mean. It's like, did we get
14:12
Speaker 1: it right all those hundreds or thousands of years ago,
14:15
Speaker 1: Like our physic is still using the same definition for
14:18
Speaker 1: the states of matter.
14:19
Speaker 2: It's changed a little bit and gotten a little bit
14:20
Speaker 2: more complicated as we've understood the microphysics. So now there's
14:24
Speaker 2: like thermodynamic definitions of phases and multiple versions of each
14:28
Speaker 2: of these things. You know, water, for example, has multiple
14:31
Speaker 2: different solid phases, not just ice. There's like ice one
14:34
Speaker 2: through ice nine, or maybe even ice twelve. Chemistry experts
14:38
Speaker 2: can tell you all about the different kinds of ice
14:40
Speaker 2: because water forms lots of different crystal structures under different
14:43
Speaker 2: pressures and temperatures.
14:45
Speaker 1: Is that why some cultures have like a lot of
14:47
Speaker 1: different words for snow sort of right? Sort of?
14:50
Speaker 2: Maybe there's definitely lots of different crystal structures for ice.
14:53
Speaker 2: I don't know if the linguistic history of some of
14:55
Speaker 2: those languages recognizes those subtle differences, or if that's just
14:59
Speaker 2: an accident. But it is true that there's lots of
15:01
Speaker 2: different ways to form ices, especially waters and especially complicated
15:05
Speaker 2: chemical other things only form one kind of solid, So
15:08
Speaker 2: there's definitely a lot more going on once you understand it.
15:11
Speaker 2: And there's lots of different kinds of phase transitions, the
15:14
Speaker 2: kinds that we think about gas, liquid, solid. Those are
15:16
Speaker 2: what we call first order phase transitions. We have like
15:19
Speaker 2: a discontinuity in the density. Things get much thicker as
15:22
Speaker 2: they get colder and change their density. They are also
15:25
Speaker 2: second order phase transitions, where you don't change from like
15:28
Speaker 2: a liquid to a solid, but you change like your
15:30
Speaker 2: heat capacity or other thermal properties. So there's definitely a
15:33
Speaker 2: lot more going on. But yeah, we sort of got
15:35
Speaker 2: the big picture right early on. But you know, remember,
15:38
Speaker 2: the physics is all about explaining the universe to humans,
15:41
Speaker 2: and this is our experience. We see these different kinds
15:43
Speaker 2: of things in the world. We want to understand what's
15:45
Speaker 2: going on and have explanations for that. So we're always
15:48
Speaker 2: going to want to explain the basic experience we have
15:50
Speaker 2: when interacting.
15:51
Speaker 1: With the world. Okay, So then you're saying that a
15:54
Speaker 1: fluid is a stuff that, when you put it inside
15:59
Speaker 1: of a cup, moves and changes its shape to adapt
16:02
Speaker 1: to that space, that volume, but it keeps its volume.
16:06
Speaker 1: That's the basic definition of a fluid.
16:08
Speaker 2: H that's technically the definition of a liquid, and all
16:12
Speaker 2: liquids are also fluids. Fluids, in addition, can encompass actually
16:16
Speaker 2: solids because some solids can flow. We don't need to
16:20
Speaker 2: dig into the differences between fluids and liquids. That's for
16:23
Speaker 2: like law school types. But essentially, yes, that's what we're
16:26
Speaker 2: talking about. Fluids, things that have constant volume but not
16:29
Speaker 2: a fixed shape.
16:30
Speaker 1: Oh. I see, some solids like sand can act in
16:34
Speaker 1: a fluid way, but it's technically not in a different
16:37
Speaker 1: state of matter.
16:38
Speaker 2: So liquid refers to the state of matter, fluid refers
16:41
Speaker 2: to the properties of the object, and they're very closely connected.
16:45
Speaker 2: But they're exceptions in both directions.
16:46
Speaker 1: I see. So which one are we talking about here? Today?
16:49
Speaker 1: Are we talking about non Newtonian fluids or non Newtonian liquids?
16:53
Speaker 2: We're talking about non Newtonian fluids, almost all of which are.
16:56
Speaker 1: Liquids, but there are some that are not.
16:59
Speaker 2: There might be, but I don't have an example for you.
17:01
Speaker 2: The fluids themselves also have a huge range of properties,
17:04
Speaker 2: Like you know that pouring honey is very different from
17:06
Speaker 2: pouring water. Right, One of them flows very very quickly,
17:09
Speaker 2: one of them flows very very slowly. Like there's a
17:11
Speaker 2: huge range of the goopiness of the fluid itself.
17:14
Speaker 1: Right, right, thinks are more or less viscous, But that
17:17
Speaker 1: has nothing to do with the state of matter, right
17:21
Speaker 1: of it, stickness of matternness of it. It's more some
17:24
Speaker 1: sort of other dimension of properties, kind of.
17:26
Speaker 2: Exactly within this fluid category, you have viscous fluids and
17:31
Speaker 2: non viscous fluids, basically like how thick is the fluid?
17:34
Speaker 2: This is like the subject of the pilot episode for
17:36
Speaker 2: our TV show, right, the goopiness of stuff.
17:39
Speaker 1: Our show ellenor Wonders Why which by the way, Arizona,
17:42
Speaker 1: Pbius Kids and under streaming apps just wanted to put
17:46
Speaker 1: that plug in.
17:47
Speaker 2: Yeah, exactly. So you pour water into a box, it
17:50
Speaker 2: flows very very quickly, and you pour honey into a box.
17:53
Speaker 2: You could be standing there for ten minutes right before
17:55
Speaker 2: the honey finally pours out of the jar, and even
17:58
Speaker 2: once it's in the box, it takes a while else
18:00
Speaker 2: to spread out and eventually fill up that box. Still
18:03
Speaker 2: categorized as a fluid, it still will flow, keep the
18:05
Speaker 2: same volume and fill out the box, but feel very
18:08
Speaker 2: different from water because of this difference in viscosity. So
18:11
Speaker 2: as you say, this is like another axis along which
18:14
Speaker 2: to think about fluids.
18:15
Speaker 1: Right, And it has maybe something to do with a
18:18
Speaker 1: different set of sort of physics, maybe unrelated to the
18:20
Speaker 1: states of matter, right or is it all just physics
18:23
Speaker 1: all of one.
18:25
Speaker 2: It's all just physics all the way down.
18:27
Speaker 4: Man.
18:28
Speaker 2: In the end, there is a microphysical understanding of this viscosity,
18:31
Speaker 2: which does come from how the molecules talk to each other,
18:34
Speaker 2: So in that sense it's kind of related to the
18:36
Speaker 2: states of matter. But this is just within fluids. You
18:40
Speaker 2: can understand why some things are viscous, why things are
18:43
Speaker 2: thick and goofy, and why some things are thin, and
18:46
Speaker 2: it does have to do with the intermolecular forces. Like basically,
18:49
Speaker 2: in honey, the molecules grab at each other more than
18:52
Speaker 2: they do in water. So as layers of honey slide
18:54
Speaker 2: past each other, there tends to be more friction between
18:57
Speaker 2: those layers, which makes it slower. We try to pour
19:00
Speaker 2: honey down a garden hose, it would take forever to
19:03
Speaker 2: come out the other side.
19:04
Speaker 1: M Okay, we're getting into a bit of a sticky
19:06
Speaker 1: subject here, and so let's get into what viscosity actually
19:11
Speaker 1: is and what it has to do with being pro
19:14
Speaker 1: or non Newtonia. So let's dig into that. But first
19:18
Speaker 1: let's take a quick break. All right, we are not
19:33
Speaker 1: talking about non Newtonian fluids today, asking the question what
19:37
Speaker 1: are they, what makes them cool? And why are there
19:41
Speaker 1: so many YouTube videos about them?
19:42
Speaker 2: Non Newtoni fluids are a famous physics demonstration because they
19:46
Speaker 2: do something weird and dramatic when you like bounce them
19:50
Speaker 2: on top of a speaker. But we can get into that.
19:53
Speaker 1: Yeah, and they're also kind of everywhere, right, like in
19:55
Speaker 1: the ketchup we eat and this lime our kids play with,
19:58
Speaker 1: even in the paint we used to thinks.
20:00
Speaker 2: Yeah, the phrase non Newtonian gives you the impression maybe
20:03
Speaker 2: it's like a weird edge case, like a rare exception,
20:06
Speaker 2: but actually non Newtonian fluids are everywhere. Maybe Newtonian fluids
20:10
Speaker 2: should be the ones that have non in front of them.
20:12
Speaker 1: You mean they should be non non Newtonian.
20:14
Speaker 2: Fluids I'm not not saying that.
20:16
Speaker 1: But you're not not denying it.
20:20
Speaker 2: Did you know that humans can process about foreign negations
20:22
Speaker 2: in a sentence before they get totally confused?
20:24
Speaker 1: I did not not know that.
20:25
Speaker 2: Well before you did not know it, you used to.
20:29
Speaker 1: Yes, I did not know that also, which I think
20:32
Speaker 1: puts it in like a twelve negation.
20:34
Speaker 2: There, Yeah, which is turning my brain into a non
20:36
Speaker 2: white Sunian fluid.
20:38
Speaker 1: Yeah, which might be a thing out there maybe somebody
20:42
Speaker 1: by the time we got to this point in the conversation,
20:44
Speaker 1: somebody already invented a non whites and.
20:48
Speaker 2: Something something good to dip your newtons into.
20:50
Speaker 1: All right, well, I get the sense, and I know
20:53
Speaker 1: this from what I know about non netunin fluids is
20:56
Speaker 1: that it has to do with their viscosity. There's something
20:58
Speaker 1: weird about the viscosity of non Tunian fluids. And so
21:01
Speaker 1: you were talking about a little bit earlier about what
21:04
Speaker 1: viscosity actually is or how it presents itself in some fluids.
21:08
Speaker 1: Some fluids are thick like honey, and some fluids are
21:11
Speaker 1: super fluid, super liquid like water, Daniel, Is there an
21:14
Speaker 1: official definition of what viscosity is?
21:17
Speaker 2: There is an official definition of what viscosity is and
21:20
Speaker 2: it's a little bit technical and mathematical, but you can
21:23
Speaker 2: get a grip on it by imagining the garden hose. Like, say,
21:27
Speaker 2: you take a liquid and you pour it through a
21:29
Speaker 2: garden hose, and you measure the speed of that liquid
21:32
Speaker 2: through the garden hose. For something that's very very viscous,
21:34
Speaker 2: you're going to get the center traveling a lot faster
21:37
Speaker 2: than the edges because the wall of the garden hose
21:40
Speaker 2: drags on the fluid. And then if it's a viscous fluid,
21:43
Speaker 2: that first layer of fluid near the wall then drags
21:46
Speaker 2: on the next one, which drags on the next one,
21:48
Speaker 2: which drags on the next one. By the time you
21:50
Speaker 2: get to the center, it's going a lot faster than
21:52
Speaker 2: it is at the edges. In a non viscous fluid,
21:55
Speaker 2: you flow it through and basically everything travels at the
21:58
Speaker 2: same speed because the layers aren't rubbing against each other.
22:01
Speaker 2: So the definition of viscosity relates to like how quickly
22:04
Speaker 2: the friction adds up to slow things down. It's like
22:08
Speaker 2: that slope between what they call the sheer stress, which
22:11
Speaker 2: is essentially the friction and the velocity of the fluid.
22:15
Speaker 1: Yeah, you're right that they get very technical. Well, I
22:18
Speaker 1: guess one way that I always thought viscosity was defined
22:21
Speaker 1: was like how hard is it to stir basically in
22:25
Speaker 1: a cup or a bucket, Like if you have hunting
22:28
Speaker 1: a bucket and you stick a laddle in it or
22:30
Speaker 1: a spoon, it's really hard to move that laddle and
22:33
Speaker 1: spoon around, whereas in water it's a lot easier, isn't
22:36
Speaker 1: it sort of also sort of or equivalently defined by
22:39
Speaker 1: the laddle test or sort of like what's the resistance
22:43
Speaker 1: it gives you when you try to move through it.
22:45
Speaker 2: I think it's technically defined as the friction inside the liquid,
22:49
Speaker 2: So you're talking about like a lathle and the friction
22:51
Speaker 2: on the liquid. I think if you want to be
22:53
Speaker 2: really strict about it, probably viscosity is you know, fluid
22:56
Speaker 2: to fluid layers of friction. But that's definitely really like
23:00
Speaker 2: you could measure the viscosity by taking a ladle and
23:03
Speaker 2: using it to stir one liquid versus another and measuring
23:06
Speaker 2: the viscosity, and they probably are machines that do exactly that.
23:08
Speaker 1: Even with the hose definition, there's still like what is
23:12
Speaker 1: the friction of the liquid with the hose material, right.
23:15
Speaker 2: But the viscosity is related to how the velocity changes
23:19
Speaker 2: as you go away from the wall, So it's all
23:21
Speaker 2: about the friction between the layers. I don't think it's
23:24
Speaker 2: a terribly important distinction, but it is defined just in
23:26
Speaker 2: terms of the liquid itself and not some external thing.
23:29
Speaker 1: But like, let's say I had a teflon hose, or
23:32
Speaker 1: a hose lined with teflon inside, or like impossibly slippery
23:36
Speaker 1: stuff inside of the hose. If I put pressure behind it,
23:38
Speaker 1: wouldn't all the honey's just come out like it's being extruded.
23:41
Speaker 2: Yeah, if you had a frictionless wall, then the honey
23:43
Speaker 2: would just slide through it. Absolutely. This definition assumes some
23:47
Speaker 2: friction from the wall, which creates different velocities, and then
23:50
Speaker 2: you measure the viscosity by how that velocity propagates through
23:53
Speaker 2: the fluid. So it's this slope between the sheer stress
23:57
Speaker 2: and the velocity.
23:58
Speaker 1: Yeah, But then the same thing sort of happens and
24:00
Speaker 1: you try to move a spoon through a honey, right,
24:03
Speaker 1: there is some friction, and maybe depends on whether you
24:05
Speaker 1: use a teflon spoon or a different kind of spoon,
24:08
Speaker 1: but I think generally just to give people an intuitive
24:11
Speaker 1: sense of what viscosity is. Couldn't we just sort of
24:14
Speaker 1: say that it is sort of like how hard this
24:16
Speaker 1: to move a spoon through it on a cup?
24:18
Speaker 2: Yeah? Absolutely, that gives you a good intuitive sense. If
24:20
Speaker 2: you take the same ladle with the same friction on
24:23
Speaker 2: its surface in two different fluids, the one with higher
24:26
Speaker 2: viscosity will be harder to stir for sure, right.
24:28
Speaker 1: And I think at least in engineering, how we define
24:32
Speaker 1: viscosity is like, as you move your spoon with a
24:34
Speaker 1: different velocity through the liquid, what is the force that
24:36
Speaker 1: it pushes back to you. That's how at least engineers
24:39
Speaker 1: define it.
24:40
Speaker 2: Yeah, And in the end, what's happening deep down is
24:43
Speaker 2: that you have these molecules and either are gravy on
24:45
Speaker 2: each other or they're not. And if they're not gravy
24:48
Speaker 2: on each other, they can just slide past each other
24:51
Speaker 2: and in a really not very viscous fluid. Even if
24:54
Speaker 2: you put a rough surface laddle, it might move one
24:56
Speaker 2: layer of that fluid, but then that fluid will slide
24:59
Speaker 2: right by the next lege and so be very easy
25:01
Speaker 2: to move and be very low viscosity. And so it
25:03
Speaker 2: all comes down to how these layers of fluid grab
25:06
Speaker 2: onto each other or don't grab onto each other. So
25:09
Speaker 2: that's what viscosity is in these fluids.
25:12
Speaker 1: It's sort of like the molecules of the fluid hanging
25:15
Speaker 1: on to each other. And this is due to what
25:17
Speaker 1: kinds of forces like chemical forces or you know, electromagnetic forces,
25:21
Speaker 1: vendor Wolf forces, what makes the molecules hang on to
25:24
Speaker 1: each other or not.
25:26
Speaker 2: Yeah, well, all those things are electromagnetic, like what we
25:28
Speaker 2: call chemical forces, covalent and ionic bonds, those are electromagnetic.
25:32
Speaker 2: They have to do with where the electrons are and
25:34
Speaker 2: how they're grabbing onto each other. Even Vanderwall's forces come from,
25:38
Speaker 2: like how the electromagnetism is distributed around an atom, whether
25:42
Speaker 2: it's a dipole or whether it's balanced or not. So
25:45
Speaker 2: on these distant scale it's all electromagnetic forces. Like the
25:48
Speaker 2: strong force is all tightly bound inside the proton and neutron,
25:51
Speaker 2: the weak force is basically irrelevant, and gravity is also irrelevant.
25:56
Speaker 2: This is all in the end emergent phenomena of electromagnetism.
26:00
Speaker 2: Like in principle, you don't need any of this. All
26:02
Speaker 2: you need is quantum electrodynamics, and you could predict everything,
26:05
Speaker 2: But in practice that's a huge pain in the butt, right,
26:08
Speaker 2: it's like trying to do calculus. Just with arithmetic take
26:11
Speaker 2: you forever to do anything. So we like to come
26:13
Speaker 2: up with these clever shorthands, these emergent phenomena that we
26:16
Speaker 2: can use to describe the things we see in the
26:18
Speaker 2: world more easily. So in the end, it's all electromagnetism
26:21
Speaker 2: sort of zoomed out.
26:22
Speaker 1: Now does it have to do with the density of
26:24
Speaker 1: the fluid? Like I would imagine a really light fluid
26:29
Speaker 1: or fluid that's not very dense would have a lower viscosity,
26:34
Speaker 1: or it would be easier to push through, or would
26:36
Speaker 1: have less friction between the layers than a really dense fluid.
26:40
Speaker 2: Yeah, so this is where Newton's law comes in. Newton
26:43
Speaker 2: did a bunch of studies of fluids, and he found
26:45
Speaker 2: that the viscosity does not depend very much on the pressure.
26:50
Speaker 2: Like you squeeze the fluid or you don't squeeze the fluid,
26:53
Speaker 2: it doesn't really change the viscosity of the fluid very much.
26:56
Speaker 2: What does change it is the temperature, Like you heat
26:59
Speaker 2: the fluid up, you cool it down. That will change
27:02
Speaker 2: the viscosity. But Newton's law of viscosity basically says that
27:05
Speaker 2: the viscosity does not depend very much on.
27:07
Speaker 1: The pressure of the pressure of the liquid exactly, because
27:12
Speaker 1: I guess liquids can have different pressures, right, I guess,
27:15
Speaker 1: like the water at the bottom of the ocean is
27:16
Speaker 1: under a very different pressure than the water at the
27:19
Speaker 1: top of the ocean.
27:20
Speaker 2: Exactly, And for Newtonian fluids like water, the viscosity at
27:24
Speaker 2: the bottom of the ocean is not very different than
27:26
Speaker 2: the viscosity at the top of the ocean if they're
27:28
Speaker 2: the same temperature. Water's viscosity does depend on temperature a lot,
27:32
Speaker 2: Like if you heat water up from twenty ceed to
27:35
Speaker 2: fifty c then it gets fifty percent less viscous. So
27:38
Speaker 2: warm water is less viscous than cold water, but the
27:42
Speaker 2: pressure doesn't make a big difference. And that's essentially Newton's
27:45
Speaker 2: law of fluids.
27:46
Speaker 1: So Newton's laws of fluids, what you're saying, has only
27:49
Speaker 1: to do with pressure, not temperature.
27:51
Speaker 2: That's right. You can be a Newtonian fluid and have
27:54
Speaker 2: your riscosity depend on temperature. That's not a problem. But
27:56
Speaker 2: if you're a Newtonian fluid, you can't have your riscosity
27:59
Speaker 2: depend very strongly on the pressure.
28:01
Speaker 1: Well, I guess, just to be clear, and Newton didn't
28:03
Speaker 1: own any fluids, Well, let me say Newton's fluids. We
28:08
Speaker 1: just kind of mean like what Newton noticed about most fluids.
28:13
Speaker 2: Yeah, we don't mean like the literal cups of stuff
28:16
Speaker 2: in Newton's.
28:16
Speaker 1: Like, he didn't discover all of these fluids. He just
28:19
Speaker 1: discovered like, hey, most fluids behave in this very sort
28:22
Speaker 1: of nice way, right, And so that's why that's what
28:25
Speaker 1: got named Newton's fluids or Newton's laws of fluids.
28:29
Speaker 2: Yeah, exactly. Like if we had two kinds of mass,
28:32
Speaker 2: one that followed eth equals MA, and we'd call it
28:34
Speaker 2: Newtonian masses, and if there was some other weird kind
28:37
Speaker 2: of mass that didn't obey Newton's law ethicals MA, we
28:40
Speaker 2: might call that non Newtonian mass or something. It doesn't
28:43
Speaker 2: mean that Newtonian mass would only describe like the stuff
28:45
Speaker 2: Newton owned himself. So you're right, Newton noticed his behavior
28:49
Speaker 2: in some fluids, and so we call those Newtonian fluids
28:52
Speaker 2: ones that follow the laws that he described.
28:54
Speaker 1: Okay, and then just to repeat for folks, what is
28:56
Speaker 1: that law again?
28:57
Speaker 2: Essentially it's that the viscosity doesn't on the pressure.
29:01
Speaker 1: So, for example, water is a Newtonian fluid because it's
29:04
Speaker 1: viscosity at the bottom of the ocean is the same
29:07
Speaker 1: as its viscosity at the top of the ocean.
29:09
Speaker 2: If they're at the same temperature. Right, Viscosity does depend
29:12
Speaker 2: on temperature, and typically the bottom of the ocean can
29:14
Speaker 2: be colder than the top of the ocean. Like if
29:16
Speaker 2: you control for temperature, like maybe in your swimming pool,
29:19
Speaker 2: for example, where it's all the same temperature, then the
29:21
Speaker 2: viscosity the bottom is the same as the viscosity on
29:23
Speaker 2: the top. You don't like get down to the bottom
29:25
Speaker 2: of the swimming pool and find that you're suddenly swimming
29:27
Speaker 2: through honey.
29:28
Speaker 1: Right right, Although that sounds delicious and dangerous, you could
29:31
Speaker 1: dip your fake mutons and bagels just by walking out
29:35
Speaker 1: to your honeypool.
29:36
Speaker 2: Please, folks, do not fill your pool with honey. It's
29:39
Speaker 2: a terrible idea.
29:43
Speaker 1: Unless you really love honey and or wanted to know
29:46
Speaker 1: what it was like to swim in honey.
29:50
Speaker 2: I'm terrified to even type that into my Google search
29:52
Speaker 2: window over here.
29:53
Speaker 1: Oh, I'm sure there are YouTube videos about it.
29:56
Speaker 2: Some poor grizzly bear.
29:57
Speaker 1: But so that's an interesting definition of non of a
30:01
Speaker 1: Newtonian fluid, because the way they define it in engineering,
30:04
Speaker 1: or at least the way I've heard it define, is
30:06
Speaker 1: that a Newtonian fluid, or like regular viscosity, is when
30:12
Speaker 1: the force that the liquid pushes back on you when
30:16
Speaker 1: you try to steer it with a spoon is related
30:18
Speaker 1: or is proportional to how fast you're trying to move
30:21
Speaker 1: that spoon. So, like regular viscous fluid, like honey, the
30:27
Speaker 1: faster you try to stir it, the harder it is
30:29
Speaker 1: to stir it, but in a very linear way, like
30:32
Speaker 1: if you try to steer it slowly, it'll push back
30:34
Speaker 1: a little bit on you, and if you try to
30:36
Speaker 1: steer it really hard, it'll push back on you proportionally harder.
30:41
Speaker 1: I imagine they're the same thing, maybe, but it seems
30:43
Speaker 1: like you're approaching it from a different point of view.
30:46
Speaker 2: Yeah, they are the same thing. You're right that, technically,
30:48
Speaker 2: viscosity is this relationship between velocity and sheer stress, right,
30:53
Speaker 2: how fast the layers are sliding past each other and
30:55
Speaker 2: the friction that they exert on each other. And Newtonian
30:58
Speaker 2: fluids expressed in that life language. The relationship is linear, right,
31:02
Speaker 2: So higher velocity means higher shear stress, which means more friction.
31:06
Speaker 2: So as you say, the faster you try to stir,
31:08
Speaker 2: the more force you're feeling.
31:10
Speaker 1: Right, And I think you didn't sort of observe that
31:12
Speaker 1: that relationship was linear. Like if you plot how fast
31:15
Speaker 1: you're trying to stir the spoon versus how much force
31:18
Speaker 1: it's pushing back on you, it's like a straight line.
31:20
Speaker 1: That's what I thought was or heard was a Newtonian viscosity.
31:25
Speaker 2: Yeah, I think that's totally right. I was trying to
31:27
Speaker 2: avoid getting into the technical details of derivatives and slopes
31:30
Speaker 2: and sheer stresses, but I underestimated your appetite for the
31:32
Speaker 2: math of sticky fluids.
31:33
Speaker 1: Well, I think it's important because a non neetunin fluid
31:36
Speaker 1: then is something that doesn't have that linear relationship. Right.
31:39
Speaker 2: It still has that relationship, but it's non linear. It
31:42
Speaker 2: still has more friction as a velocity grows. It's just
31:44
Speaker 2: not a strictly linear relationship, right, Right.
31:47
Speaker 1: So I think when people say a Newtonian fluid, it's
31:50
Speaker 1: one where you kind of know what you're going to get,
31:52
Speaker 1: like if you if it's honey, you know that the
31:54
Speaker 1: faster that you try to stir it, the harder is
31:56
Speaker 1: going to push back on you proportionally, right, mm hmm.
31:59
Speaker 2: Yeah, And that's a frictory linear relationship in Newtonian.
32:02
Speaker 1: Fluids, right, that's sort of like what need and observe,
32:04
Speaker 1: and so that's why it's called a Newtonian fluid.
32:06
Speaker 2: Mm hmm exactly. And what that means, sort of less mathematically,
32:10
Speaker 2: is that the viscosity is essentially constant with pressure.
32:13
Speaker 1: Or maybe because of viscosity is constant with pressure. That
32:16
Speaker 1: gives that curve a linear shape.
32:18
Speaker 2: Yeah, that's right, And viscosity is like super important in
32:21
Speaker 2: fluid dynamics. Like the people who try to understand how
32:24
Speaker 2: fluids flow, they have to solve these really gnarrowly differential
32:28
Speaker 2: equations called the Navier Stokes equation, for which there is
32:31
Speaker 2: no like nice solution. There's like a million dollar X
32:34
Speaker 2: prize for anybody who can solve these equations. They're famously complex,
32:38
Speaker 2: and they're complex because of the viscosity. It's like this
32:41
Speaker 2: viscosity term in those equations, and often people just set
32:45
Speaker 2: that to zero because otherwise it's impossible to solve. And
32:48
Speaker 2: so viscosity is like a really important thing mathematically, and
32:50
Speaker 2: then like fluid dynamics and understanding like the atmosphere and
32:53
Speaker 2: the ocean and climate change. It's an important thing.
32:56
Speaker 1: All right. Yeah, so that's a Newtonian fluid. That's what
32:59
Speaker 1: the new To notice about most fluids. And that's because
33:02
Speaker 1: that's kind of true for most things around us, right,
33:04
Speaker 1: like water, milk, oil, honey. Those things all have different viscosity,
33:09
Speaker 1: but they all sort of have this regular type of viscosity,
33:12
Speaker 1: which is this linear viscosity, right, and.
33:15
Speaker 2: There's a huge range. What's really amazing is how many
33:18
Speaker 2: different kinds of fluids can be described in this way. Right.
33:22
Speaker 2: This is why this law persists for so long, because
33:24
Speaker 2: it describes so many different kinds of things, you know,
33:27
Speaker 2: like honey and water and oil. These are the things
33:29
Speaker 2: we experience. But we've also discovered things on both edges,
33:33
Speaker 2: like super low viscosity fluids and super duper high viscosity fluids,
33:37
Speaker 2: all of which obey these principles.
33:39
Speaker 1: Yeah, so fluids that have a linear viscosity law. There's
33:42
Speaker 1: stuff that has very little viscosity and stuff that has
33:45
Speaker 1: high viscosity. Right.
33:47
Speaker 2: Yeah, And one of my favorite experiments in science has
33:50
Speaker 2: to do with trying to measure the viscosity of super
33:53
Speaker 2: duper goopy stuff. There's an experiment that's been going on
33:57
Speaker 2: since nineteen twenty seven and finished. It's still going because
34:03
Speaker 2: it's so slow. They're trying to measure the viscosity of asphalt.
34:07
Speaker 2: They call it pitch, but it's basically like the tar
34:09
Speaker 2: you spread on the road, and this stuff is super
34:12
Speaker 2: duper thick, so thick that it takes like ten years
34:15
Speaker 2: for a single drop to form. So in nineteen twenty
34:19
Speaker 2: seven they poured some of this thing into a funnel
34:21
Speaker 2: and they've been watching it flow down that funnel and
34:24
Speaker 2: make drops that come out the bottom. It's been going
34:26
Speaker 2: for almost a century and they've only ever seen nine
34:29
Speaker 2: drops come out the bottom.
34:32
Speaker 1: So you're saying, asphalt, or this thing called pitch is
34:35
Speaker 1: a fluid like it'll eventually flow down to the bottom
34:38
Speaker 1: of a cup, but it's as super duper high viscosity,
34:41
Speaker 1: so it's going to do it really slowly.
34:43
Speaker 2: Yeah, it has like two hundred and thirty billion times
34:46
Speaker 2: the viscosity of water. So imagine like trying to take
34:49
Speaker 2: a spoon and stick it in the road and stir right,
34:52
Speaker 2: there's a whole lot of friction there.
34:53
Speaker 1: But you could technically do it, I think, is what
34:56
Speaker 1: you're saying. Like it is a fluid, it is viscous.
34:58
Speaker 1: You could stick a spoon an asphal defense their it.
35:01
Speaker 1: But like the force at which it would push you
35:04
Speaker 1: back is huge, right.
35:06
Speaker 2: Yeah, it might take you more than a century or
35:08
Speaker 2: just to get your spoon into the asphalt.
35:10
Speaker 1: Right, or you would need a huge amount of force
35:12
Speaker 1: to push through it.
35:13
Speaker 2: Yeah, exactly. And this experiment is really fun because they
35:16
Speaker 2: started it in nineteen twenty seven and you know, it
35:19
Speaker 2: takes like ten years for a drop to fall, and
35:22
Speaker 2: in all of that time, nobody has ever actually witnessed
35:26
Speaker 2: a drop fall because the drop takes like a tenth
35:28
Speaker 2: of a second to fall over.
35:30
Speaker 1: Ten years a tenth of a second.
35:32
Speaker 2: Once the drop actually breaks off the bottom, it falls
35:35
Speaker 2: in like a tenth of a second, and nobody's ever
35:37
Speaker 2: actually seen this happen. Like you can walk by this
35:40
Speaker 2: thing every single day. You can see it drop about
35:42
Speaker 2: to break off and fall, and people have been hoping
35:44
Speaker 2: to actually like see it fall this incredible moment. It
35:47
Speaker 2: takes like ten years to pass, but nobody's ever actually
35:50
Speaker 2: been there to see it.
35:52
Speaker 1: Mmmm. But I'm sure it's been recorded.
35:54
Speaker 2: Well, it's actually pretty funny because they tried and in
35:57
Speaker 2: nineteen eighty eight, the experiment was actually on display at
36:00
Speaker 2: a World Expo when a drop fell, but nobody noticed it.
36:04
Speaker 2: The professor who runs the experiment, Professor Mainstone, had stepped
36:07
Speaker 2: out to get a drink and he missed it. So
36:09
Speaker 2: ever since then they set up a webcam to watch
36:12
Speaker 2: this thing. The next drop happened in November two thousand,
36:15
Speaker 2: but the camera happened to be on the fritz and
36:17
Speaker 2: so it missed it again. And then twenty fourteen was
36:22
Speaker 2: the ninth drop, but it broke off when they were
36:25
Speaker 2: like adjusting the experiment because the beaker below the funnel
36:28
Speaker 2: had finally filled up and it was interfering with the experiment.
36:31
Speaker 2: So nobody's ever actually watched a drop form from this thing.
36:34
Speaker 2: Everybody's waiting for the tenth drop to happen.
36:37
Speaker 1: Oh man, sounds like a lot of falling here. Maybe
36:42
Speaker 1: I should put more than one camera on it.
36:45
Speaker 2: And the professor who started it in nineteen twenty seven, Mainstone,
36:48
Speaker 2: he died in twenty thirteen, never having seen a drop form.
36:52
Speaker 1: Mmmm, should have just picked the lower viscosity fluid, I guess.
36:56
Speaker 2: So it's a pretty awesome experiment that shows you the
36:59
Speaker 2: incredible range of Newton's law of viscosity.
37:02
Speaker 1: Mm. Interesting. All right, Well that's what a Newtonian fluid is.
37:06
Speaker 1: And now let's get into what a non Newtonian fluid is.
37:09
Speaker 1: What makes these weird? Why are they the subject of
37:12
Speaker 1: so many interesting physics demonstrations online? So we'll dig into that,
37:16
Speaker 1: but first let's take another quick break. All right, we're
37:31
Speaker 1: talking about non Newtonian fluids, and we talked a lot
37:35
Speaker 1: about viscosity and what it is and what makes a
37:38
Speaker 1: Newtonian fluid. So basically a Newtonian fluid is one where
37:41
Speaker 1: you said that the viscosity depends on pressure on the
37:44
Speaker 1: pressure of the liquid, which sort of we agree. I
37:47
Speaker 1: think translates to like how hard it pushes back on
37:51
Speaker 1: you when you try to steer it or when you
37:53
Speaker 1: try to swim through it, for example.
37:55
Speaker 2: Yeah, I think the most accurate way to describe it
37:58
Speaker 2: is how you did, which is a relationship between the
38:01
Speaker 2: friction and the velocity. As layers start moving faster and
38:04
Speaker 2: faster adjacent to each other, you get more and more
38:07
Speaker 2: friction on those layers.
38:09
Speaker 1: Right, So like if you try to swim at one
38:11
Speaker 1: meter per second through honey, it's going to push you
38:14
Speaker 1: back with a certain force. If you double your speed,
38:16
Speaker 1: if you try to swim through it at two meters
38:17
Speaker 1: per second, then it should push back with you with
38:20
Speaker 1: twice the force. That's what a Newtonian fluid is.
38:22
Speaker 2: That's a Newtonian fluid where that relationship is linear, and
38:25
Speaker 2: the slope of that linear relationship is the viscosity. So
38:29
Speaker 2: things that have different viscosity have a differently sloped line,
38:32
Speaker 2: but it's always still a line. For a Newtonian fluid,
38:35
Speaker 2: it follows this linear relationship. For non Newtonian fluids, you
38:38
Speaker 2: get away from that line, things change in a different
38:41
Speaker 2: way as you increase the velocity.
38:43
Speaker 1: Right, and again, like nothing is perfectly linear, right, Like
38:47
Speaker 1: I think maybe what Newton's was just kind of looking
38:50
Speaker 1: at things at a first approximation and he noticed that
38:52
Speaker 1: it's like roughly linear for all of these materials within
38:54
Speaker 1: a certain range, and so that he's like, oh, this
38:57
Speaker 1: is the law of viscosity. M hmm, Like in reality,
38:59
Speaker 1: not even water is perfectly linear, is it.
39:01
Speaker 2: Yeah, nothing is perfectly Newtonian, but these are a good approximation.
39:05
Speaker 2: But some things, as we'll talk about in a minute,
39:07
Speaker 2: are very non Newtonian. They deviate dramatically from this linear relationship.
39:11
Speaker 1: All right, let's talk about no in neetonia, or let's
39:13
Speaker 1: not not talk about Newtonians, let's not avoid talking about
39:17
Speaker 1: netunias non Newtonian fluids. So then what is a non
39:20
Speaker 1: Newtonian fluid?
39:22
Speaker 2: So non Newtonian fluid is one where this relationship is
39:24
Speaker 2: not linear, and so the amount of friction you get
39:28
Speaker 2: as you push on it can change very very quickly
39:30
Speaker 2: if you push on it fast or push on it slow.
39:33
Speaker 1: So like in our assumming example, like if you're swimming
39:35
Speaker 1: through a non Newtonian fluid at one meter per second,
39:38
Speaker 1: is going to push it back with a certain force.
39:40
Speaker 1: If you try to soon twice as fast, it's maybe
39:43
Speaker 1: not going to push back with twice the amount of force.
39:45
Speaker 1: It might push back with less than twice the amount
39:48
Speaker 1: of force, or push back with more than twice the
39:50
Speaker 1: amount of force, exactly.
39:52
Speaker 2: And the classic example of a non Newtonian fluid is
39:55
Speaker 2: this stuff called ublek, which is basically what happens when
39:57
Speaker 2: you take cornstarch and you mix it with water into
40:00
Speaker 2: a suspension, and what you find if you have a
40:02
Speaker 2: bowl of oubleck is. If you push on it very gently,
40:05
Speaker 2: you can slide through it just like it's water. Right,
40:07
Speaker 2: It just feels normally like water. But if you try
40:09
Speaker 2: to move really fast, all of a sudden it gets
40:12
Speaker 2: very very stiff. So if you just stick your finger
40:14
Speaker 2: and it slowly, you can go right through. If you
40:16
Speaker 2: try to slap it, then it feels like a solid.
40:19
Speaker 2: It's incredibly viscous very quickly if you try to move
40:22
Speaker 2: through it at higher speed.
40:23
Speaker 1: Yeah, that's the most famous kind of non Newtonian fluid.
40:26
Speaker 1: It's so you take corn stars it's just like regular
40:29
Speaker 1: kitchen cornstarch, and you add a little bit of water
40:31
Speaker 1: at a time until it feels liquid when you try
40:35
Speaker 1: to steer it really slowly. But then if you try
40:37
Speaker 1: to steer it really fast, it suddenly feels like it's
40:39
Speaker 1: a solid block of something.
40:41
Speaker 2: Right, Exactly. If it was a Newtonian fluid, it still
40:43
Speaker 2: would feel thicker as you stir it faster, but it
40:46
Speaker 2: would be linear, and here it's very nonlinear. It suddenly
40:49
Speaker 2: gets extraordinarily viscous as you try to move through it faster.
40:53
Speaker 1: Yeah, it's crazy. I mean, you can look up all
40:55
Speaker 1: kinds of demonstrations online. People have made pools of.
40:58
Speaker 2: Ublek right, Oh my gosh, I hope no. The bears
41:00
Speaker 2: have fallen into those pools.
41:02
Speaker 1: Yeah, they thought it was a honeypool, but really it
41:05
Speaker 1: was a hopit pool.
41:07
Speaker 2: You should have gone to Newton's house. Man, he's got
41:10
Speaker 2: a pool full of honey.
41:11
Speaker 1: No, he's got a pool full of fick Newtons.
41:14
Speaker 2: I don't think the bear cares.
41:17
Speaker 1: Yeah, either way, it's delicious. I think he barely cares.
41:20
Speaker 1: But yeah, people have made pools of this stuff, right,
41:23
Speaker 1: And so like, if you have a pool of this,
41:24
Speaker 1: you can actually run through it and step on it.
41:28
Speaker 2: It acts as a solid if you're applying enough pressure,
41:31
Speaker 2: Like you can slap the surface and it feels like concrete.
41:34
Speaker 2: But if you very gently put your finger through it,
41:36
Speaker 2: you pass through it just like.
41:37
Speaker 1: Water or like I think, like if you stand on
41:39
Speaker 1: top of it, you'll sink, but if you try to
41:42
Speaker 1: run across it, you can actually not sink and just
41:45
Speaker 1: stay on top of it. Or if you stay, if
41:47
Speaker 1: you keep jumping on it, you won't sink. You'll actually
41:51
Speaker 1: sort of bounce on it. But if you just stand
41:53
Speaker 1: and not do anything, you're gonna sink down.
41:54
Speaker 2: Exactly, you might wonder, like, what's going on in terms
41:57
Speaker 2: of the microphysics, how can we understand this weird behavior?
42:00
Speaker 2: And it has again to do with how the little
42:02
Speaker 2: bits inside are sliding past each other or not sliding
42:05
Speaker 2: past each other. And critically it's because you have two
42:08
Speaker 2: different things there. It's not just water, which is a
42:11
Speaker 2: Newtonian fluid, but it's this combination of water and corn starch,
42:15
Speaker 2: and cornstarch in particular is very grabby. It's not very
42:18
Speaker 2: easy for cornstars to slide past itself.
42:21
Speaker 1: Right, And it sort of also has to do with
42:24
Speaker 1: the fact that, like if you try to move through
42:26
Speaker 1: Oublick too fast, you actually sort of like sort of
42:29
Speaker 1: push the water out kind of in a way, and
42:31
Speaker 1: so then it's just cornstarch, and so then those grab
42:34
Speaker 1: onto each other, right.
42:35
Speaker 2: Exactly, if you're moving slowly, then it's dominated by the
42:37
Speaker 2: water because it's time for like the water to get
42:40
Speaker 2: between the corn starch and act like little ball bearrings.
42:43
Speaker 2: Doesn't really matter that the corn starch is there, because
42:45
Speaker 2: the water makes everything slippery. If you move really really fast,
42:48
Speaker 2: the water gets pushed out between the corn starch and
42:51
Speaker 2: then you're basically trying to push through just corn starch,
42:54
Speaker 2: which is very, very thick. So it's sort of like
42:56
Speaker 2: there's two different personalities to it, and one comes out
42:59
Speaker 2: when you move and slow, and the other one comes
43:00
Speaker 2: out when you're moving fast. It's like the juckle and
43:02
Speaker 2: hide of fluids.
43:04
Speaker 1: Yeah, and this is a really cool effect. Everyone can
43:06
Speaker 1: do it at home. Just take some corn starch to
43:07
Speaker 1: put it in a cup and add water a little
43:09
Speaker 1: bit at a time until you get this weird liquid exactly.
43:12
Speaker 2: And if you put it on top of a speaker,
43:14
Speaker 2: for example, you get this really weird effect where it
43:16
Speaker 2: just looks like a liquid, but then the balancing of
43:19
Speaker 2: the speaker makes it suddenly solid momentarily, and so it
43:23
Speaker 2: forms these weird globs which will like dance on top
43:26
Speaker 2: of your speaker.
43:27
Speaker 1: Yeah, it's pretty wild. I highly recommend that all of
43:31
Speaker 1: you at home to try making uplick with your kids
43:34
Speaker 1: or by yourself. I did it before I had kids.
43:36
Speaker 2: Super fun. Yeah, it's fun, it's easy, It's only a
43:39
Speaker 2: little bit messy. Don't try to eat it though.
43:41
Speaker 1: Oh what happens if you eat it? You turn into
43:44
Speaker 1: a fig neating or not. I guess In general, doing
43:51
Speaker 1: in just high large amounts of anything.
43:53
Speaker 2: Yeah, though there are some non Newtonian fluids which people
43:56
Speaker 2: eat every single day. They have them on their burgers,
44:00
Speaker 2: have them with their fries.
44:01
Speaker 1: Yeah. Ketchup is a famous non Newtonian fluid.
44:04
Speaker 2: Right, Yeah, ketchup is sort of the opposite kind of
44:07
Speaker 2: non Newtonian fluid ubleck. If you try to move through
44:09
Speaker 2: it really fast, the viscosity grows really really quickly. But
44:13
Speaker 2: ketchup is sort of the opposite. Like, if you want
44:15
Speaker 2: ketchup to flow better, you actually shake it. You get
44:18
Speaker 2: it moving fast, right, you shake the bottle and then
44:22
Speaker 2: it'll flow out.
44:23
Speaker 1: Wait, is that why, like a ketchup you have to
44:25
Speaker 1: hit the bottom of the bottle to put it on
44:27
Speaker 1: your burger.
44:28
Speaker 2: Yeah, that's exactly why. You shake the bottle or you
44:30
Speaker 2: slap the bottom, and then suddenly it will flow. So
44:33
Speaker 2: you like increase the pressure of this thing, the viscosity
44:35
Speaker 2: actually goes down. You can flow better when you squeeze it.
44:38
Speaker 1: Mmm. So it's non Newtonian because that viscosity relationship is
44:42
Speaker 1: not linear, But it's the opposite of ublick, where like
44:46
Speaker 1: the faster you try to strimp through ketchup, the easier
44:49
Speaker 1: it is exactly.
44:49
Speaker 2: So Newtonian fluids are the ones that are just along
44:52
Speaker 2: this line, but you could be non Newtonian either above
44:54
Speaker 2: the line or below the line, or anything that deviates
44:57
Speaker 2: from the line. Essentially, so ketchup is super you're to
45:00
Speaker 2: actually call it a pseudo plastic. And there isn't a
45:03
Speaker 2: good microphysical understanding for why this works. Like we have
45:06
Speaker 2: this whole story about water and corn starch for ubleack,
45:09
Speaker 2: but there isn't a similar story we can tell for
45:12
Speaker 2: what's going on in ketchup.
45:13
Speaker 1: Wait, what do you mean? Like it's a mystery.
45:16
Speaker 2: It's a mystery of physics. People are doing experiments trying
45:18
Speaker 2: to understand it, but there is not a good concise
45:21
Speaker 2: understanding for why ketchup behaves the way it does.
45:23
Speaker 1: I guess maybe the simplest way to understand it is
45:25
Speaker 1: like if you take a ketchup bottle and you turn
45:27
Speaker 1: it upside down. The ketchup is not going to float
45:30
Speaker 1: out necessarily or very fast or very quickly, but if
45:34
Speaker 1: you sort of shake it, then it becomes a more liquid.
45:38
Speaker 2: Exactly, the viscosity drops when you shake it, when you
45:40
Speaker 2: apply some pressure to it, or you increase the velocity
45:44
Speaker 2: between the layers, the viscosity drops and so then you
45:47
Speaker 2: can slide and it flows out onto your burger.
45:49
Speaker 1: Mmmm. All right, what are other examples of non Newtonian fluids?
45:53
Speaker 2: So other things you might find around your house, Like
45:55
Speaker 2: slime is a non Newtonian fluid, silly putty?
45:58
Speaker 1: Right, what do you mean slime? That's different.
46:01
Speaker 2: Slime is in the oublick category. Like it can flow,
46:03
Speaker 2: but if you pick it up and you squeeze it,
46:05
Speaker 2: you can feel more solid. Right, that's one of the
46:07
Speaker 2: things that makes it sort of slimy. I mean, I
46:09
Speaker 2: try to avoid playing with slime whenever my daughter makes it,
46:11
Speaker 2: But this is what I noticed when I'm cleaning up
46:13
Speaker 2: after her.
46:16
Speaker 1: Yeah, So meaning like if you try to steer it,
46:18
Speaker 1: you feel a certain resistance to it. Or if you
46:20
Speaker 1: try to swim through slime, but you try to swim fast,
46:22
Speaker 1: the faster it'll push back on you more.
46:24
Speaker 2: Yeah. The viscosity is not constant. It changes depending on
46:27
Speaker 2: the stress and the forces apply to it. You pull
46:29
Speaker 2: it apart quickly applying a large force, it becomes very
46:32
Speaker 2: viscous and can like break in half. So you take
46:35
Speaker 2: like slime, you just pull on it gently, it'll stretch
46:38
Speaker 2: you pull on it really really fast, it'll actually crack
46:40
Speaker 2: into two.
46:40
Speaker 1: Pieces because I guess the force gets higher the faster
46:45
Speaker 1: you try to do it. But at some point the
46:47
Speaker 1: material can't take it and it just breaks exactly, It
46:49
Speaker 1: just gives up. Also, silly putty is a non newton
46:52
Speaker 1: of fluid, right.
46:53
Speaker 2: Yeah, silly putty in the same way. And the weirdest
46:55
Speaker 2: non newton in fluid. The thing that surprises me most
46:58
Speaker 2: is paint. Paint is also a non Newtonian fluid.
47:02
Speaker 1: What do you mean?
47:03
Speaker 2: Imagine what would happened if you painted your walls with
47:05
Speaker 2: honey or with water. You take your brush, you dip it,
47:08
Speaker 2: and you spread it along. You expect to see lots
47:10
Speaker 2: of drips, right, But paint, when you apply it to
47:13
Speaker 2: the wall, it's very easy to apply. But then it
47:15
Speaker 2: becomes very very viscous, so it doesn't drip very much.
47:19
Speaker 2: So paint is like specially formulated chemically to not drip,
47:23
Speaker 2: to become viscous when you apply it to the wall.
47:26
Speaker 1: But isn't that because it's drying out.
47:28
Speaker 2: So the crucial thing is that you're applying paint to
47:31
Speaker 2: a vertical wall, right, and so the fluid starts to
47:34
Speaker 2: drip down the surface, but because of its non Newtonian nature,
47:37
Speaker 2: this acceleration then increases the velocity, so instead of slipping
47:41
Speaker 2: along the surface, it forms sort of large and dense
47:44
Speaker 2: droplets with limited dripping, So it forms like a little
47:47
Speaker 2: bit of texture, but the drops never actually form.
47:50
Speaker 1: Well what does that mean when I try to stir it?
47:52
Speaker 2: Though it's not as dramatic as Ubleck, but it's in
47:54
Speaker 2: the same direction as Ubleck that as you go faster,
47:57
Speaker 2: it rapidly becomes more viscous, which is what you want.
48:00
Speaker 2: So as drips are starting to form on the wall,
48:03
Speaker 2: it becomes more viscous in order to essentially prevent those
48:06
Speaker 2: drops from forming.
48:08
Speaker 1: And also I imagine it's also drying out right and
48:11
Speaker 1: solidifying a little bit too.
48:13
Speaker 2: Yeah, but you want to avoid drips forming while it's
48:15
Speaker 2: still liquid, because if you form drips then those dry
48:18
Speaker 2: it looks pretty ugly.
48:19
Speaker 1: Well, is there a sort of a quick explanation we
48:22
Speaker 1: can give us to why some things are non Newtunin
48:25
Speaker 1: or not, like why some things are not linear and
48:28
Speaker 1: some things are.
48:29
Speaker 2: We don't have a good overall understanding of it. It
48:31
Speaker 2: seems like the general direction of the explanation is that
48:35
Speaker 2: it comes from complex interactions between heterogeneous materials. So if
48:39
Speaker 2: you have something which is only made of one kind
48:41
Speaker 2: of thing, it's going to tend to have a pretty
48:43
Speaker 2: simple relationship between the velocity and the friction. If you don't.
48:47
Speaker 2: If you have complicated mixtures the way we do with
48:49
Speaker 2: oobleck water and cornstarch, then you sometimes get different relative
48:53
Speaker 2: densities of those two things. You can get a much
48:56
Speaker 2: wider range of behavior, and that behavior can emerge under
48:59
Speaker 2: different conditions. And so probably that's why like paint is
49:02
Speaker 2: non Newtonian whereas water isn't, because it has to do
49:05
Speaker 2: with like having droplets of these dyes in suspension and
49:09
Speaker 2: ketchup is a complicated combination of water and all sorts
49:12
Speaker 2: of other things. So how those molecules interact with each other,
49:15
Speaker 2: and whether you're having more of one kind of thing
49:17
Speaker 2: or another, it's probably the source of it. But the
49:19
Speaker 2: real takeaway I think is like, Wow, the world is
49:22
Speaker 2: complicated that these fairly basic interactions we understand about how
49:27
Speaker 2: molecules and particles interact with each other, but they can
49:30
Speaker 2: create all sorts of incredibly complicated behavior when you zoom.
49:33
Speaker 1: Out, Yeah, I know, it's amazing. I think you're saying,
49:36
Speaker 1: like it maybe has something to do with how complicated
49:38
Speaker 1: the liquid is inside, right, Like, if it's just one thing,
49:41
Speaker 1: like water molecules, only water molecules, then they sort of
49:44
Speaker 1: behave kind of predictively. But if you have more than water,
49:47
Speaker 1: if you have water and corn storage molecules, then maybe
49:50
Speaker 1: because they're so different, the faster you try to move
49:53
Speaker 1: through it, then they sort of gets into these different regimes. Maybe,
49:56
Speaker 1: like it it gets into things where're like, oh, now
49:58
Speaker 1: the cornstarch is dominant because all the water came out
50:02
Speaker 1: or things like that, and so the whole property how
50:05
Speaker 1: it behaves when you try to stir it is different
50:07
Speaker 1: depending on how fast you're trying to steer it.
50:09
Speaker 2: Yeah, exactly. So it can do many more different kind
50:11
Speaker 2: of complicated things because it's got two components to it,
50:14
Speaker 2: and sometimes you're seeing more of one and sometimes more
50:16
Speaker 2: of the other.
50:17
Speaker 1: Hmmm, all right, well that's great because I feel like,
50:21
Speaker 1: you know, sometimes people say, oh, they use the word
50:23
Speaker 1: non intonin fluid as an explanation like oh, why does
50:26
Speaker 1: oubleake do that or why does kets do that? And
50:28
Speaker 1: then people would say, oh, it's because it's a non
50:29
Speaker 1: intone in fluid as if that was the explanation.
50:32
Speaker 2: Right, Yeah, a label is not an explanation. It's just
50:34
Speaker 2: a name. You could give it any name, or you
50:36
Speaker 2: could call it a yaka block of fluid. It's not
50:38
Speaker 2: an explanation.
50:40
Speaker 1: Yeah, which is also the name of a great bagel,
50:43
Speaker 1: now it is. But maybe the point is that, you know,
50:46
Speaker 1: if you see this phenomenon, the phenomena is called the
50:49
Speaker 1: non Newtonian but it has maybe more to do with
50:52
Speaker 1: what's going on at the molecular level.
50:54
Speaker 2: Yeah, in the same way we think probably everything in
50:56
Speaker 2: the world comes out of these molecular interactions in different ways.
51:00
Speaker 2: But you know, it's amazing. It's not all just chaos.
51:02
Speaker 2: It's not just a crazy swarm of frothing nonsense. You
51:06
Speaker 2: get these weird behaviors that we can summarize and understand,
51:09
Speaker 2: and this like linear relationship between these two quantities. It's
51:13
Speaker 2: sort of amazing that that happens at all. So I'm
51:15
Speaker 2: just grateful that the universe is at all understandable at
51:18
Speaker 2: our level.
51:19
Speaker 1: Yeah, you can make lost and maybe predict things and
51:22
Speaker 1: then design things also, Right, it's really important for engineering
51:26
Speaker 1: to know how these things are going to.
51:27
Speaker 2: Behave, Yeah, absolutely, Thank you to all the engineers.
51:31
Speaker 1: Yeah, although sometimes you come up with a law and
51:33
Speaker 1: then people find exceptions and then they call those not laws.
51:37
Speaker 2: But your name is still on it, so you still win.
51:42
Speaker 1: I'm not sure I subscribe to the idea that all
51:44
Speaker 1: fame is good fame. I think there are plenty of
51:46
Speaker 1: examples in tabloids about that. But still, it's nice to
51:51
Speaker 1: be part of the mix.
51:52
Speaker 2: As you say, Hey, everybody remembers Benedict Arnold, right, not fondly,
51:55
Speaker 2: though not fondly, but they remember.
51:58
Speaker 1: It all right, set the future physicists, super villain.
52:03
Speaker 2: That's right. I'm gonna close out my movie with the
52:06
Speaker 2: line better to be hated than.
52:07
Speaker 1: Forgotten, And then people will forget your movie because they
52:13
Speaker 1: didn't like it because it has such a terrible message.
52:16
Speaker 2: Dude.
52:17
Speaker 1: All right, Well, as you said, it's interesting to think
52:19
Speaker 1: about the physics of everyday objects like cornstarch and ketchup
52:23
Speaker 1: and slime and even paint.
52:25
Speaker 2: And swimming pools filled with honey.
52:27
Speaker 1: Thanks for joining us, See you next time.
52:37
Speaker 2: Thanks for listening, and remember that. Daniel and Jorge Explain
52:40
Speaker 2: the Universe is a production of iHeartRadio. For more podcasts
52:44
Speaker 2: from iHeartRadio, visit the iHeartRadio app, Apple podcasts, or wherever
52:49
Speaker 2: you listen to your favorite shows.