Slippery Science: The Physics of Ice

What makes ice slippery? Neil deGrasse Tyson and co-hosts Chuck Nice and Gary O’Reilly uncover the complex physics of ice and cool facts we’re still learning about it with physicist and author, Laurie Winkless.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Neil deGrasse Tyson?

  This is StarTalk Sports Edition. Neil deGrasse Tyson, your personal astrophysicist and host. Today, we're discussing the topic of ice. Ice, every which way you would see it, think about it, and find it on Earth and in the heavens. We're going to talk about why ice is slippery. I bet you never really thought about that one, huh? Well, there's interesting surface physics related to it. We're going to talk about ice in sports. Not all sports use ice in the same way as one another. So that's a whole other frontier

• 0:40Neil deGrasse Tyson?

  of winter sports. And we're going to talk about glaciers. What are they? How they move and why and what they do to Earth's surface? All on this episode of StarTalk Sports Edition.

• 0:56Neil deGrasse Tyson?

  Welcome to StarTalk, your place in the universe where science and pop culture collide.

• 1:05Neil deGrasse Tyson?

  StarTalk begins right now.

• 1:09Neil deGrasse Tyson?

  Jack. Hey, Neil. I also got Gary Riley. Gary.

• 1:13Gary O'Reilly?

  Hey, Neil.

• 1:13Neil deGrasse Tyson?

  How you doing, man?

• 1:14Gary O'Reilly?

  I'm good. I'm good.

• 1:15Neil deGrasse Tyson?

  So Gary, what show have you and your producers assembled today?

• 1:20Gary O'Reilly?

  All right. So it's been coming and going for ages, ice. And right now, I guess everyone knows it's packed its bags and it's heading for the ocean. And we'll get to that, I'm sure, later. Humankind has learnt to live with it, use it, try to understand it, and even try and have fun with it. And I can't think of anyone better to ride a Zamboni with than our guest, Laurie Winkless. If you don't remember, I'll explain. If you do, then you'll know you're in for a treat. Laurie is a physicist, an astrophysicist, an author, a science communicator, and storyteller.

• 1:54Gary O'Reilly?

  She's a science journalist and lecturer and her books include Science in the City and Sticky, The Secret Science of Surfaces. So Neil, Murray Winkler's is back.

• 2:04Neil deGrasse Tyson?

  And that must have been the most beautiful thing anyone has ever said to anyone. Will you ride the Zamboni with me?

• 2:11Speaker 02

  I'm so flattered. I would do anything, Gary, to have that opportunity. I've never been on a Zamboni.

• 2:18Gary O'Reilly?

  It just seemed like the best thing to, to, to, you know, what, what can we use on the, on ice? A Zamboni.

• 2:24Speaker 02

  I'm in, I'm in. Can't we in, Gary?

• 2:27Neil deGrasse Tyson?

  All right. Well, we'll try to make that happen. So.

• 2:30Chuck Nice?

  The only thing more unique than riding a Zamboni is being hit by one.

• 2:35Gary O'Reilly?

  Or trying to run away from one while on ice.

• 2:39Neil deGrasse Tyson?

  Oh, yeah. Yeah. So Laurie, I just want to lead off by asking, what makes ice slippery? There are people say, well, because it gets wet and you slip on the wet ice. But on a ice skating rink, the ice isn't, you know, if it's been skated on, it's kind of frosty, right? From everybody kicking up the top layer of shaved ice, but that's slippery too. And no matter what I'm wearing. So you see people at the end of a hockey game, the coach comes out, he's got to step lightly on the ice lest he slip. So just wondering, what's going on there?

• 3:18Chuck Nice?

  And does it have anything to do with the sketchy character of ice?

• 3:24Gary O'Reilly?

  Perhaps.

• 3:25Speaker 02

  Ice cannot be trusted.

• 3:26Chuck Nice?

  That's why it's slippery. It's very sketchy, its character.

• 3:33Speaker 02

  Yeah, exactly. And I honestly, that is true. And that's true scientifically too, Chuck, because ice is not always slippery. If you get ice cold enough, the friction that it generates is really high. So it actually becomes a very grippy surface. So if you're way down at like minus 100 degrees C, the friction that a skate or a shoe that would experience on that ice is extremely high. It's as if you're walking on a very rough surface. But as the temperature of ice increases and kind of heads towards its melting temperature. So I'm sorry, I'm speaking in centigrade, but I'm useless.

• 4:07Chuck Nice?

  We'll forgive you.

• 4:08Speaker 02

  Um, but yes, okay, thank you. So yeah, it starts very high friction. And then the friction actually gradually decreases and it reaches a minimum at about minus seven degrees C. And that's quite a useful temperature because that's the type of temperature that we would quite often interact with on an ice skating rink. And although there've been theories around what, how that happens, why friction decreases gradually over that range. It wasn't really until about 2018 that researchers, I think, probably got closest to kind of nailing down the answer to why. And it's that there is always a presence of what they call a quasi-liquid. There's always this ultra-thin, like just a few nanometers thin layer of quasi-liquid,

• 4:52Speaker 02

  which Daniel Bond, the scientist who wrote this paper in 2018, would not let me call a liquid. A quasi-liquid that exists on ice even at temperatures well below freezing. So ice always has this layer on there and, and that contributes to its slipperiness.

• 5:08Neil deGrasse Tyson?

  Just to be clear, a nanometer is a billionth of a meter. So.

• 5:12Speaker 02

  Yeah.

• 5:12Neil deGrasse Tyson?

  You, you just, uh, you know, we hear the word nano so often that it's almost lost its precision. Nano-box, nano, there's nano and, but you're using the word within its precise metric prefix way. Um, nanometers, billionths of a meter. And just to clarify that, yeah.

• 5:30Chuck Nice?

  Quasi-liquid. I mean, that's, that's rather vague and amorphous.

• 5:38Speaker 02

  Indeed.

• 5:39Chuck Nice?

  Quasi-liquid. I mean, come on, really?

• 5:43Speaker 02

  Yeah, well, yeah, this is it. I, I had this argument with the scientist as well. But his, his argument, and it's a reasonable one, is that if it's below freezing, it should be a solid. So we shouldn't be calling it a liquid, right? But what it actually is, is that on the surface of ice, you have little ice molecules, water molecules that are bound to all the other water molecules around it. And, and normally ice is bonded to four neighbors, right? On the surface of ice, it's bonded to three or four because it's on the surface. There's air above it. It's no longer surrounded by more ice. Um, but what these guys realized, and actually I should say they're brothers, the two lead scientists on on this paper. One's a chemist, one's a physicist.

• 6:26Chuck Nice?

  Okay, that's that's problematic right there.

• 6:28Speaker 02

  Indeed, indeed. Hence the quasi liquid argument, I believe. Um, so they, what they realized is that on the surface of ice at these temperatures, at this kind of minus seven degrees C, it's not just three or four bonds. It's sometimes ice is only bonded to two neighbors. And those doubly bonded ice molecules, they don't just kind of wiggle around on the surface, which is what creates this this quasi liquid layer. They can actually roll around the surface of the ice. They're very, very mobile. And it's actually those hardly bonded to their neighbors, molecules of ice that cause, that create this this liquidy, liquidy layer that creates that slipperiness.

• 7:10Chuck Nice?

  So you know what we, you know what we call that in in in just the regular world? This kind of semi-formed liquid that you're talking about, we call it gel. Gel, okay.

• 7:24Gary O'Reilly?

  So Laurie, the Bond brothers are doing their research in 2018. Right? And they have all of the technology to do it. But back in the day, way back in the day, Michael Faraday in about 1850 was coming up with terms like regelation. Am I right? And but although molecules, the kind of the the theory back then wasn't popular about molecular and atoms, all the rest of it. But he was already on it.

• 7:49Speaker 02

  He totally was. Yeah. Michael Faraday had this idea that there was some sort of liquid layer on the surface of ice. And that if you brought two ice cubes together, those liquid layers would interact and it would allow the ice cubes to to kind of freeze together. So that's the process of regelation. But because, like you said, Gary, because this theory of atoms that didn't exist yet, it was kind of ignored. Faraday was kind of like, yeah, okay, you're a great scientist, et cetera, et cetera. But that doesn't seem to make sense to us. And it was kind of revisited again another hundred years later by a different scientist. And that was where, you know, we then had the theory of atoms and molecules. So that started to really kind of open the floodgates,

• 8:33Speaker 02

  as it were, to this theory that there's some sort of permanent liquidy layer on the surface of ice.

• 8:39Neil deGrasse Tyson?

  Just to be more precise here, I think we had a theory of atoms, but atoms were not yet demonstrated to exist.

• 8:46Speaker 02

  Yes.

• 8:46Neil deGrasse Tyson?

  So because we had the periodic table of elements.

• 8:49Speaker 02

  Absolutely.

• 8:49Neil deGrasse Tyson?

  An element, and it would be an atom in its smallest form. So we had some suspicions that atoms mattered, but not in what way. And quantum physics was was a distant dream, not even a dream. So, yeah, I just want to distinguish between

• 9:05Speaker 02

  Good point.

• 9:06Neil deGrasse Tyson?

  what we thought might have been true and what would later be confirmed. That's all.

• 9:09Chuck Nice?

  God, those, those guys were idiots back then.

• 9:16Gary O'Reilly?

  Is there a difference between the ice that forms here on Earth and ice that goes and forms in deep space on comets and moons and?

• 9:24Chuck Nice?

  Ooh.

• 9:25Speaker 02

  That's a good question. I mean, I can only answer a tiny bit of it, but I'm sure Neil can answer way more than this.

• 9:30Chuck Nice?

  Yeah, but wait a minute, before you answer that, doesn't that change based on what the ice is? Because when we talk ice, we're talking water. But in space, you got to have different kinds of ice other than water, right?

• 9:42Speaker 02

  Yeah, good point. But yeah, even even water ice forms differently on different planets, as far as I understand.

• 9:48Chuck Nice?

  Delicious.

• 9:49Speaker 02

  Yeah.

• 9:49Chuck Nice?

  Delicious water ice.

• 9:50Speaker 02

  Water ice. Well, yeah, it's crystalline ice is is the most common form of ice on Earth. But my understanding is that amorphous ice, so not ice that forms these lovely crystals, but ice that's more kind of uniform, that is what dominates in the rest of our solar system. But I'm sure Neil will correct me if I'm wrong.

• 10:09Chuck Nice?

  Oh, man, this is good stuff. Now let's get into this. Neil, what's up with the ice, bro?

• 10:15Neil deGrasse Tyson?

  You know, it's a new wrapper, amorphous ice. You see, that's when it's got to be.

• 10:20Gary O'Reilly?

  And is is amorphous ice slippery?

• 10:25Speaker 02

  Oh, yeah.

• 10:25Gary O'Reilly?

  Does amorphous ice have character traits, like slippery?

• 10:30Neil deGrasse Tyson?

  Oh, yeah, yeah, a new superhero.

• 10:32Chuck Nice?

  Yeah.

• 10:32Neil deGrasse Tyson?

  But, but wait, so, so I'm just astonished here, Laurie, that here it is, we're going into the year 2023, and you're telling me that a research paper five years ago is still shedding light on our understanding of the surface of ice.

• 10:51Speaker 02

  Yeah, precisely that. And I really love that because I think when I started to research ice, I thought, we know all this, right? We know it all.

• 10:58Neil deGrasse Tyson?

  But, but Laurie, Laurie, one of your expertises is material physics, right? So shouldn't you be embarrassed by this, that your field didn't even know this until, you know, just before COVID?

• 11:12Speaker 02

  There's so many questions to answer and only so much available funding. That's why.

• 11:17Neil deGrasse Tyson?

  Oh, okay.

• 11:18Chuck Nice?

  Oh.

• 11:18Neil deGrasse Tyson?

  Look at that. Too many surfaces, too little time.

• 11:21Chuck Nice?

  Too little, too little money.

• 11:22Speaker 02

  Too little time, yeah.

• 11:23Neil deGrasse Tyson?

  All right, Gary, where we, where did I leave off with you?

• 11:25Gary O'Reilly?

  Um, well, it was just a case of if the ice is different in deep space as opposed to here on Earth, would it be, as Chuck said, from different molecules, not water molecules, but other properties?

• 11:39Neil deGrasse Tyson?

  Yeah, we've got ammonia ice, there are other things that are, there's carbon dioxide ice, ooh, which on Earth we call, Laurie.

• 11:46Speaker 02

  Dry ice? Isn't that dry ice?

• 11:48Neil deGrasse Tyson?

  Dry ice, yeah, yeah.

• 11:51Chuck Nice?

  Don't stick your tongue to that, by the way.

• 11:52Speaker 02

  Do not.

• 11:55Neil deGrasse Tyson?

  Chuck's speaking from experience, it sounds like.

• 11:59Neil deGrasse Tyson?

  Whatever you do.

• 12:02Chuck Nice?

  Whatever you do, don't stick your tongue on dry ice, you know? Believe me, this thing I'm talking to you with is a prosthetic.

• 12:09Neil deGrasse Tyson?

  Your tongue?

• 12:11Chuck Nice?

  Exactly.

• 12:12Neil deGrasse Tyson?

  I'm, so, so a couple more things. So it seems to me be interesting if you had a, a race, let's say, you know, a quarter.

• 12:21Neil deGrasse Tyson?

  You know, a 400 meter race or, or, or a kilometer, where the beginning of the race, the surf, the whole race is run on ice. But at the beginning, it's like 100 below, so you get very high friction. And so they're just running and running, but the, the, the track gets warmer and warmer until the finish line. And then there's a some point where it's no longer high friction, it's low friction, so they have to run differently. And then the last 50 yards, they just slide in.

• 12:49Speaker 02

  I love it.

• 12:50Chuck Nice?

  It's a, it's a pretty cool event. It is also the most expensive ice rink in the world. It started here.

• 12:57Speaker 02

  True.

• 12:57Chuck Nice?

  Okay.

• 12:58Speaker 02

  It does take them a long time to make ice for the Winter Olympics. So yeah, don't know if they could do that gradient. Maybe, maybe they could.

• 13:06Neil deGrasse Tyson?

  So, so Laurie, tell me about the attachment to other molecules. When I think of a, a, a crystal, I think you have a molecule in its place. And the crystal has certain symmetry to it. So I'd be looking different directions and I'd find neighbor molecules.

• 13:22Speaker 02

  Yeah.

• 13:22Neil deGrasse Tyson?

  Attached to me in crystal in form. But you tell me as you get to the surface, I'm missing one or more of these. And on some level, it can actually roll around. If I'm attached at all, how am I rolling around?

• 13:35Speaker 02

  Yeah, it's a good question. And the, the answer is not that straightforward because they had to model these, they had to model these doubly bonded molecules. So they haven't seen them. They haven't actually seen what they look like. But what they found was that as the temperature increased towards minus seven degrees C, the mobility of these molecules in their model increased. So it was as if they were rolling around on the surface. Now, we haven't seen that, so we haven't seen it experimentally. It is, it is a model result, but it does match very nicely with the, with the decreasing friction that we see at the same increasing temperature.

• 14:10Neil deGrasse Tyson?

  Okay, so that's the vocabulary they have available to them to reference it that way.

• 14:13Speaker 02

  Yeah.

• 14:14Neil deGrasse Tyson?

  But it's interesting. So if, if a molecule only rotated a little bit, you know, moved around a little bit, and then the next one picks it up. You don't, the, the molecule wouldn't have to move very far to still give the impression of a very slippery surface, it seems to me.

• 14:28Speaker 02

  Precisely that. And I think it's what was really surprising to them was, was just how different the mobility, this, this movement of these molecules, just how different it was between three bonds and two bonds. They really were not expecting that. It was significantly more mobile.

• 14:43Gary O'Reilly?

  So Laurie, do we, are we now consigned pressure melting to the bin? To the trash can, to the bin, whatever you want to call it.

• 14:51Neil deGrasse Tyson?

  Well, describe pressure melt. Pressure melting, that was my only understanding of any of this. Now you're going to put it in a trash bin?

• 14:57Gary O'Reilly?

  Yeah, no, I'm asking. I mean, yes, it's got.

• 15:00Neil deGrasse Tyson?

  Me, me, me, outside.

• 15:03Gary O'Reilly?

  What's the temperature? So, thank you. It's that situation where, yes, pressure melting must still happen, but it's not the reason when you put your foot directly onto ice that you slip. Because you've got, there's no pressure really happening there to melt the ice.

• 15:19Neil deGrasse Tyson?

  There's no high pressure like on the edge of an ice.

• 15:21Gary O'Reilly?

  Yes, on the edge of a blade, yeah.

• 15:23Chuck Nice?

  Exactly.

• 15:23Gary O'Reilly?

  So are we consigning that theory to, nah, and it's more this unstable group of molecules that will and will not float around the surface of ice?

• 15:34Speaker 02

  And pressure melting does play some sort of a limited role, and it actually plays a role in one of the winter sports like curling, for example.

• 15:41Gary O'Reilly?

  But see, we're going to get to that.

• 15:45Chuck Nice?

  But you've got to explain pressure melting.

• 15:47Neil deGrasse Tyson?

  We're going to save that for the second segment.

• 15:50Neil deGrasse Tyson?

  What is pressure melting? All right, when we come back, Laurie tells us how you get pressure melting with ice on StarTalk Sports Edition when we return.

• 16:11Neil deGrasse Tyson?

  We're back, StarTalk Sports Edition. We've got our favorite ice expert in the whole world, Laurie Winkler, is coming to us from, where are you, Laurie?

• 16:24Speaker 02

  I'm in Wellington in New Zealand, where it is summer.

• 16:28Neil deGrasse Tyson?

  Okay, sorry, yeah, there's summer and winter here. That's evidence that the distance of Earth from the Sun is not what causes seasons, if you had ever wondered that. It's just how we are tilted either toward the Sun or away. So Laurie, tell us what pressure melting is. I think it's one of the most interesting phenomenon involving water, and it's not other materials. I think water is almost unique in this property. And then we want to find out how that relates to all the sports that people know and love that take place on the ice.

• 17:00Speaker 02

  Yeah, pressure melting, you're right Neil, water is a very weird molecule in some ways. So pressure melting is what happens that when when you apply pressure to solid ice, what you actually do is you push the atoms in that ice closer together. Now, you think about that as as making it denser. But because water is denser than ice, when ice is under pressure, it turns into, some of it turns into liquid water.

• 17:29Neil deGrasse Tyson?

  Even though the temperature is below freezing.

• 17:32Speaker 02

  Even though the temperature is below freezing, yes.

• 17:35Neil deGrasse Tyson?

  Right, right. So you will have, you would have created water in a liquid state that is stable below the freezing temperature because you put pressure on it.

• 17:43Speaker 02

  Yes, and if you remove the pressure and the temperature stays the same, usually it will freeze again, right? So it does need the continuous supply, application of pressure to to keep that layer of water. But that that weird quasi liquid that we talked about, that exists regardless of whether there's pressure on the ice or not.

• 18:02Chuck Nice?

  So is that why when you have a container in the freezer?

• 18:10Chuck Nice?

  And before the container bursts,

• 18:15Chuck Nice?

  you, it's complete liquid, but then you twist the top and the whole thing goes and freezes up all at once?

• 18:23Speaker 02

  Yeah, that's another, that's a thing called nucleation. And it's what happens when if you have the liquid can stay, can stay liquid, excuse me, the water can stay liquid below freezing. But the act of kind of hitting it or, you know, banging it in some way causes some of the water molecules, because they're cold, to line up in a line. And then what you see is that ice just going and it forms out into the liquid.

• 18:47Neil deGrasse Tyson?

  But don't you need very pure water for that?

• 18:49Speaker 02

  No, you can actually do it. No, it doesn't need to be that pure. You can actually do it with kind of, you know, pretty decent bottled water. Or if you have a filtered water, if you're very careful and you put it into your freezer and leave it there for a few hours and very carefully take it out and then give it a smack on on the countertop, you can quite often see the ice forming. Yeah, it's a pretty cool experiment. I recommend.

• 19:11Neil deGrasse Tyson?

  It's very cool. Watch ice form right in front of your eyes. It's very, it's very cool.

• 19:16Gary O'Reilly?

  Laurie, the Bond brothers and their their research in 2018, right? Came up with that minus seven. Specific temperature. Yeah, you can't tell me that for centuries, ice meisters, as they're known, I believe, weren't already well ahead of them.

• 19:33Speaker 02

  Yeah.

• 19:34Neil deGrasse Tyson?

  What's an ice, what's an ice?

• 19:35Gary O'Reilly?

  So someone, okay, Chuck, so from to my knowledge, and Laurie's going to either tell me I'm talking absolute rubbish or I'm right. Um, an ice master is, is someone who lays the ice. They will construct a skating rink, a skate, a track, a curling ice, whatever it is, because they're all different types of ice. Figure skating ice is not the same as ice you play ice hockey on. It has to have different qualities. Now, the ice meisters knew this. So why didn't the Bond brothers just go and speak to an ice master?

• 20:05Speaker 02

  Well, I think they, they did. But I think the other thing is, you know, there's, there's knowing through kind of experimentation. And then there's understanding from a fundamental point of view. And you're absolutely right, Gary. Ice meisters have known about the, the changing behavior of ice at different temperatures for a very, very long time. And it is the basis of all winter sports, really. But it's only really now that we start to understand the very fundamental mechanism that reflects that observation. So it's, you need both, I think. But yeah, for sure. And, and the ice meisters I spoke to have such an incredible instinctive understanding of ice, like some of them described, being able to listen to the ice to know whether it was good enough quality.

• 20:49Neil deGrasse Tyson?

  Ice whisperers.

• 20:51Speaker 02

  Yeah.

• 20:51Neil deGrasse Tyson?

  Ice whisperers, well, we need. Oh, that's hilarious. But, but Gary, this, this is a very common arc of discovery and understanding in science where people just, observant people notice something. And then they write it down or, or share the information. And it's, they might even exploit it in whatever way they need. And then science comes later typically. And figures out what's actually going on. And then when you do that, you can usually exploit it even further.

• 21:21Speaker 02

  Yeah.

• 21:22Neil deGrasse Tyson?

  Right? So, so Laurie, in the era of modern science, have they improved on what the ice meisters had been doing? I think seems to me they could or should.

• 21:31Speaker 02

  Yeah, in terms of their understanding, yes. But the ice makers still do what they do as they've always done. What's helped them a bit is the ability to purify water. So for ice makers, they really do want very, very pure water because they want to know exactly how the ice will form with as few kind of dirty bits in there as possible or any other contaminants. So that has science has helped them hugely in that regard because you now have technologies that allow you to filter the water. But they still very much see it as a kind of an instinctive art, really, and curling ice particularly because it's different from the other ice. Like, they are artists, those ice makers. They, they have,

• 22:12Speaker 02

  they've tried different machines to create curling ice, but nothing has managed to create it as uniformly as a human walking up and down the ice with effectively a shower head.

• 22:23Chuck Nice?

  And that's because the machines can't listen to the ice.

• 22:26Speaker 02

  Exactly.

• 22:28Gary O'Reilly?

  Laurie, before we get on to curling, and I do want to get on to curling because it's fascinating sport for physics. And I mean, it's, it's how many hundreds of years old and we still.

• 22:38Neil deGrasse Tyson?

  But Chuck, you hear, you hear what Gary said there? It's a fascinating sport for physicists.

• 22:42Gary O'Reilly?

  No, it is.

• 22:43Neil deGrasse Tyson?

  Not, it's a fascinating sport.

• 22:45Gary O'Reilly?

  No, in terms of it's fascinating and it's hundreds of years old and we still don't know all of its secrets. But before we go there, please explain the impemba effect that I believe, right? Yes, thank you. Suggest that hot water can freeze faster than cold water because now I, I, I need some illumination on that because that sounds.

• 23:05Neil deGrasse Tyson?

  No, no, that's bullshit. No, I don't believe that for a minute.

• 23:09Speaker 02

  Thanks Neil.

• 23:10Neil deGrasse Tyson?

  Laurie, here's what I think happens there. Cause I've seen people do this experiment. Here's what I think happened. They put boiling water in an ice tray and cold water in an ice tray, then they put them both into the freezer. And then the boiling water, that ice tray freezes faster. What I think happened there, it was, is that it evaporated water out? And there was less water to freeze by the end. Is that not what happened there?

• 23:32Speaker 02

  No, I think that's my understanding of it as well. Like, there's been lots of papers and lots of, uh, you know, observations of this over the years. But yeah, I'm, I'm kind of with you on that, Neil. I think that's what happens.

• 23:42Neil deGrasse Tyson?

  Yeah. In the end, it's just, it's less water to freeze.

• 23:45Speaker 02

  Yeah. So it happens quicker. Yeah.

• 23:47Chuck Nice?

  All right. That's my explanation. That, that makes perfect sense because otherwise it would have to be some manipulation of temperature. Like where you don't have the same rate of freezing. Cause I don't care what you do, you gotta go from hot to cold.

• 24:03Speaker 02

  Yeah. Yeah.

• 24:04Neil deGrasse Tyson?

  You gotta pass through the temperature that the other ice cube was.

• 24:08Chuck Nice?

  Right.

• 24:08Neil deGrasse Tyson?

  It wasn't in the fast lanes.

• 24:10Chuck Nice?

  Right.

• 24:10Neil deGrasse Tyson?

  So what the way to do that experiment properly is you put boiling water in a vessel that's sealed. And that way nobody can evaporate out and then it's pure temperature. Race, that's why it's a bit boo shit. That's why I thought I'd tell you that.

• 24:23Chuck Nice?

  All right. I had my answer.

• 24:26Neil deGrasse Tyson?

  Okay. Okay. So Laurie, so I'm, I'm at a loss. Why is the ice for curling different than for hockey, different than for figure skating?

• 24:37Speaker 02

  So figure skating ice and hockey ice and, um, long, like speed track skating ice, they're all smooth ice. Now they're different from each other. They're at different temperatures. They have different thicknesses, et cetera, et cetera. Um, because each of those sports want to do something different, right? Like long track speed skating is all about going as fast as you can. Like 50 kilometers an hour with your legs on the ice. And so there you want really hard, really low friction ice. So it's at the magic temperature of minus seven degrees C and then it gets warmer from there. But curling ice is not smooth ice. So curling ice, they do make a flat rink, a flat surface of ice first. And then one of these ice meisters will walk up and down

• 25:20Speaker 02

  the whole length of the curling rink. And they will use basically a shower head which had, they've got a bucket of water on their back and they spray, they swing a shower head from side to side, different little nozzle sizes on the shower head. And it creates a layer of pebbles, they call them pebbles, but ice bumps all over the surface. So if you look at a curling ice rink, it's, it's quite dull. It's not smooth and shiny like a speed skating rink.

• 25:45Neil deGrasse Tyson?

  And why aren't they trying to reduce the friction?

• 25:47Speaker 02

  So what they're trying to do really is that if you try and curl a curling stone, so if you try and make a curling stone, take that big curvy path on smooth ice, you, it will not do that.

• 25:57Chuck Nice?

  Uh huh.

• 25:58Neil deGrasse Tyson?

  Oh, you need the friction to change direction.

• 26:01Chuck Nice?

  Exactly.

• 26:02Gary O'Reilly?

  So the thing, Neil, the thing is, don't, don't forget the origin of curling. It's on a frozen pond or a frozen lake. And therefore Mother Nature just organically produces this pebbles, these ice bumps, as Laurie calls it.

• 26:15Neil deGrasse Tyson?

  Right, right. Nothing bumpier than a, than a, than a frozen lake surface.

• 26:19Speaker 02

  Yeah.

• 26:19Neil deGrasse Tyson?

  Tell you that.

• 26:21Speaker 02

  Well, yeah, so they, they have kind of, if due forms on an ice surface, you will get these bumps. So yeah, it's, and like Gary said, it's been around, curling as a sport's been around for at least 500 years and started in Scotland and has kind of gone everywhere that Scottish settlers have. So it's, it's kind of relatively big. It's not really, but it's relatively big in New Zealand as well, where we had a lot of Scottish settlers down the bottom of the South Island.

• 26:45Chuck Nice?

  All right. That makes a lot of sense now. The whole thing makes sense to me now.

• 26:50Neil deGrasse Tyson?

  Why, there's no curling in Africa? Because there's Scottish people in Africa.

• 26:54Chuck Nice?

  I mean, yeah, it's that, because there's not, not because of the ice, just because of the Scottish people. Yeah.

• 27:00Speaker 02

  It's delightful. The, the teams even like the teams, I met some teams who play here and they all have like these, these kind of woolly hats with a bobble on them, like very kind of traditional Scottish garb that they still wear and they have tartans and stuff for each of the teams. So it's still very much seen as a Scottish sport.

• 27:18Chuck Nice?

  Wow.

• 27:19Neil deGrasse Tyson?

  Cool.

• 27:21Chuck Nice?

  So the Scots are actually responsible for two of the world's most boring sports. Golf and curling.

• 27:29Speaker 02

  I agree on golf. I love curling though.

• 27:32Gary O'Reilly?

  No, I love curling too. So Murray, there's been a little bit of a, an argument, a spat, a tiff, call it what you like. Those people that believe. Dust up, yeah. Well, yes. Pressure warming theory and then scratch guiding theory and then there's the pivot slide model. Two.

• 27:50Speaker 02

  Yeah.

• 27:50Gary O'Reilly?

  As to which one is the most, the most explanatory for why a curling stone does what it does. But before we get to that, would you explain actually what the bottom is of a curling stone is like? Cause I think people, people have got one idea of it. I have no idea. There you go. So this for Neil is for you. I have no idea.

• 28:11Speaker 02

  Okay. So the reason that there are so many theories about curling is that a curling stone moves in a way that you wouldn't expect if you were just looking at really basic physics, right? So the base of a curling stone is not flat. It's actually concave. So there's only a very narrow ring and these stones are granite. They're made from a really particular granite from one place in Scotland. And it's this really narrow band of granite that actually touches the ice. And then as we've established, the ice itself is pebbles. So it's kind of rough. So it's really only touching the tops of these pebbles, right? So you have this slightly odd interaction anyway. You've got a rough granite surface and a rough textured ice.

• 28:54Speaker 02

  And if you were to say, take like a beer bottle, I recommend it being empty before you do this and slide it along a table. And you know, it will just slide forward. If you slide it and rotate it as you release it, which is what a curler will do before they release a curling stone. The, the beer bottle will veer away from that straight line. It'll kind of go off to the right or the left, depending on which direction you've rotated it. Okay. So if you rotate a beer bottle to the right as you let it go, it will curl to the left. And this is called asymmetric friction. So that's kind of something that we kind of know in the world of physics. It's because of the way the bottle decelerates as it moves forward

• 29:38Speaker 02

  and friction is stronger on the front than on the back of the bottle. It's not surprising. So yeah, so this is how a beer bottle will move, right? But if so, you have you curl to the right and it will, sorry, you rotate to the right, it'll curl to the left. A curling stone will curl in the same direction in which it rotates. So from a physics point of view, that is weird, right? If it was following this basic like asymmetric friction, it would curl in the opposite direction to the one that it spins. So that's why people have been like, what is going on with this weird sport? And again, like Gary said earlier, there's a case of people understand instinctively how to rotate a stone, how to deliver a curling stone. They understand all of this. They understand what happens when they move a

• 30:23Speaker 02

  stone the way they do. But the fundamental understanding of what's happening, where that kind of rough granite surface is touching the rough pebbled ice is still a little bit up for debate. Now, I'd argue that there's probably a couple of leading theories, but probably one leading theory at the moment. But I just love that it's still up for debate, given that this is a sport that's been around for centuries.

• 30:46Chuck Nice?

  Well, I will tell you this, Laurie, what you have done is given the world a way to make curling infinitely more interesting.

• 30:57Speaker 02

  Thank you.

• 30:57Chuck Nice?

  And that is, that is put a beer bottle on top of the curling stone. And have it delivered to the people at the end of the run.

• 31:12Neil deGrasse Tyson?

  All right. Right. So Laurie, typically, a hockey is the same season as the Icecapades.

• 31:20Speaker 02

  Yeah.

• 31:20Neil deGrasse Tyson?

  The literal Icecapades or whatever is that version today. That we all grew up with going to arenas. And are you suggesting that when they do their figure skating in the ice capades, they might change the temperature of the ice to serve their needs relative to the hockey game that's going to play that evening?

• 31:40Speaker 02

  Yeah, they will do. So you, you, for figure skating, what you want is a kind of a softer ice, to be honest. Because if you think about what a figure skater is doing, they're having to kind of dig into the ice so that they can launch upwards, you know? So they actually need to get the blades into the ice. So they need, the stats of the Winter Olympic Games, figure skating is the softest, warmest ice. It's like minus five degrees C, I'm sorry, minus three degrees C is figure skating. But ice hockey needs something a bit harder because they have to, they need that combination of grip and glide, you know, they're changing direction a lot. So ice hockey ice tends to be about minus five degrees C. So you can switch between the two.

• 32:23Speaker 02

  You tend to need to flood, you tend to go, I think, from memory, I think you go ice hockey to figure skating, I think that's right. But you, you can kind of add more water, you flood the ice, they literally flood it with water and let it freeze and then add more water and let it freeze. And they can change the underlying temperature of the, what's underneath, the compressors and stuff underneath. So they, they, they do, you know, in an ideal world and in a competition, they would absolutely want to change temperatures for, between sports.

• 32:51Neil deGrasse Tyson?

  And so, but isn't that laying a layer of water, isn't that what the Zamboni does?

• 32:54Speaker 02

  Yeah, yeah, it is.

• 32:55Neil deGrasse Tyson?

  Right, right.

• 32:56Speaker 02

  Yeah.

• 32:57Neil deGrasse Tyson?

  Yeah.

• 32:57Speaker 02

  That's exactly that.

• 32:58Neil deGrasse Tyson?

  So Gary, what else you have for her in this segment?

• 33:00Gary O'Reilly?

  So do we, do we need to consider these brushes that curlers use? And we didn't, didn't we go through a phase where they had something known as the Frankenbroom?

• 33:10Speaker 02

  Yes, broom gate.

• 33:11Gary O'Reilly?

  Broom gate.

• 33:13Neil deGrasse Tyson?

  Broom gate, broom gate.

• 33:14Gary O'Reilly?

  Got to have, got to have one of those.

• 33:17Chuck Nice?

  Let me, let me guess, the, the broom actually was more abrasive and scratched the ice to create more pebble-like surface so that the curl could increase.

• 33:33Speaker 02

  Bingo, Chuck.

• 33:33Chuck Nice?

  There you go.

• 33:35Speaker 02

  Yeah, so the, the broom, it's pretty much bang on, yeah.

• 33:40Neil deGrasse Tyson?

  You've been, you holding out on us, Chuck. You, you, you're a total curling fan.

• 33:45Gary O'Reilly?

  Chuck's read, Chuck's read Laurie's book.

• 33:50Neil deGrasse Tyson?

  Chuck, you cheated.

• 33:50Speaker 02

  Yeah. It's all right. It's just research, Chuck. It's okay. No, you're right. So there was a period. So the brooms, the brooms that they use now are pretty like a nylon. They're not abrasive. And the job of the sweeper, the people who are sweeping the brooms in front of the curling stone, they are actually trying to melt the ice. So what they are trying to do is reduce how much the curling stone curls. So they want to straighten out the path of the curling stones. They sweep furiously, create this liquid layer, and that kind of minimizes how much the curling stone curls, depending on where you want it.

• 34:24Neil deGrasse Tyson?

  So they're using friction?

• 34:25Speaker 02

  Yeah.

• 34:26Neil deGrasse Tyson?

  That's why they rub it real fast.

• 34:27Speaker 02

  They rub it real fast. Yeah, exactly. Yeah.

• 34:29Neil deGrasse Tyson?

  Okay. We gotta, we gotta take a break. When we come back, we'll finish out the curling controversy here. We're gonna learn whether Chuck really did write a book on curling and performs in the dark of night. And we're gonna find out Ice on Earth, what's it all about with glaciers, when StarTalk Sports Edition, all about ice, return.

• 35:02Neil deGrasse Tyson?

  We're back. StarTalk Sports Edition with our number one ice expert, Laurie Winklitz. Laurie, coming to us from New Zealand. Thanks for coming in this far for this episode, Laurie.

• 35:14Speaker 02

  Oh, my pleasure.

• 35:14Neil deGrasse Tyson?

  Yeah. So I got some, some leftover questions for you. I think we saw Chuck, single-handedly solved the broom gate problem.

• 35:23Speaker 02

  He did.

• 35:24Neil deGrasse Tyson?

  With, with curling. And so what I wonder is, if we move this whole exercise to Earth's surface, all right, and we get things like snow on the sides of mountains.

• 35:42Neil deGrasse Tyson?

  Skiers care greatly about what the texture of the snow is. Could you briefly just tell me what they prefer? And do they prefer it because they have more friction or because they have less friction?

• 35:53Speaker 02

  So I don't ski, but like a good scientist, I talk to people who ski. And they prefer natural snow. But something we saw in, and we are increasingly seeing in the Winter Olympics is a kind of a reliance on manufactured snow. Because we aren't getting enough snow in these regions to actually host the Olympic Games. So skiers definitely prefer the softer, natural snow, mostly because it is softer. And the manufactured snow is, when you look at it under a microscope, is kind of solid little icy balls more like than snowflakes. And so it's harder.

• 36:29Neil deGrasse Tyson?

  Why can't we make snowflakes?

• 36:31Speaker 02

  Yeah.

• 36:31Neil deGrasse Tyson?

  Why can't we make snowflakes? It's the 21st century.

• 36:35Speaker 02

  Yeah, we've, I don't know if anyone's tried, if I'm honest.

• 36:38Gary O'Reilly?

  We did have a, we did have a couple of guys, remember? They made artificial snow, but they couldn't, they couldn't scale it.

• 36:45Speaker 02

  Right.

• 36:46Neil deGrasse Tyson?

  I remember that.

• 36:47Chuck Nice?

  Yes.

• 36:48Neil deGrasse Tyson?

  We have a whole episode on that.

• 36:49Chuck Nice?

  We did, yes.

• 36:50Neil deGrasse Tyson?

  Right now, or after the show, everybody go to the archives and dig out. We have a whole episode. Gary, I forgot all about that.

• 36:56Chuck Nice?

  Yeah.

• 36:57Neil deGrasse Tyson?

  They had perfected it. And the question was, did they make enough of it to be useful on an entire mountainside?

• 37:03Chuck Nice?

  Yeah.

• 37:03Neil deGrasse Tyson?

  Is what that was, but okay, so.

• 37:06Chuck Nice?

  And we need to check back with those guys, because if they've conquered that scale issue, that's an investment opportunity.

• 37:17Neil deGrasse Tyson?

  All right. So, so Lori, let me hand you some low hanging fruit. You ready? So what happens if it snows and the snow never goes away?

• 37:29Speaker 02

  As in formation of a glacier?

• 37:32Neil deGrasse Tyson?

  Yeah.

• 37:33Speaker 02

  Ding, ding.

• 37:39Gary O'Reilly?

  It's so funny.

• 37:41Chuck Nice?

  See, this is, these are trick, see people, you just found out what a trick question is to a scientist. You know, when you ask a question that is so simple, they're like, what the hell is happening?

• 37:55Speaker 02

  Small amount of panic just rising up in my, in my chest there.

• 38:00Neil deGrasse Tyson?

  So, so what's the difference between the era of the growth of glaciers and the era of the loss of glaciers? Like what's, what's going on? Why?

• 38:11Neil deGrasse Tyson?

  Why does it happen one way at one time and the other way the other time?

• 38:14Chuck Nice?

  Hmm.

• 38:15Speaker 02

  Because we need snow to form glaciers. We need low temperatures and that sounds really simplistic, but a lot of our freshwater systems, especially in mountainous areas, they actually rely on glaciers to get fresh water. So when they have less snow because of climate change, the glaciers are melting or and or not forming, so both of those. And and their freshwater supplies are are in are, you know, damaged by that. So climate change is is the answer, unfortunately.

• 38:47Chuck Nice?

  Exactly. Yeah. And while you're on that subject, just let me just say this. Uh, because people may be thinking, so what glaciers don't affect me. However, drinking water does affect you. So no matter where you are, most likely, a lot of your uh places, your drinking water comes from elevation. It comes from mountainous areas where we get what's called a snowpack. That snowpack slowly melts uh in the spring and feeds uh, you know, arteries that feed tributaries. And that brings you your fresh drinking water. When we don't have the snow because of the lower temperatures, I mean, sorry, the warmer temperatures. We don't have the drinking water and that actually leads to a depletion of aquifers.

• 39:32Chuck Nice?

  And it also leads to drought. So this is why, one of the reasons why climate change is so terribly important. Because um you like drinking water. So.

• 39:44Neil deGrasse Tyson?

  This public service announcement brought to you by.

• 39:47Gary O'Reilly?

  No, Chuck. Chuck's absolutely spot on and don't and add to that, Chuck. Immigration for crops and for farming.

• 39:55Chuck Nice?

  Absolutely.

• 39:56Neil deGrasse Tyson?

  Wait, wait, Chuck, you missed you you missed something in that.

• 39:58Chuck Nice?

  What did I miss?

• 39:59Neil deGrasse Tyson?

  PSA was that PSA was beautiful. Let me just start out by that. But it's not whether or not it's cold enough to snow. Okay, because if it rains, that'll also fill the aquifer. Right? So what the snow does is it allows the water accumulation of the winter to return. To you in times when it melts.

• 40:21Chuck Nice?

  Exactly.

• 40:22Neil deGrasse Tyson?

  So and replenish the aquifer in the spring or whenever the the rotation of seasons uh uh brings it. So so what the problem is you don't have the storage of water as glaciers had.

• 40:35Chuck Nice?

  And that is.

• 40:36Neil deGrasse Tyson?

  Ever since the ice.

• 40:37Chuck Nice?

  Really the key. That is the key is point too that I did that I did kind of gloss over is is that the snow itself is the storage of the water. Mm hmm.

• 40:46Neil deGrasse Tyson?

  Yes, yes.

• 40:47Chuck Nice?

  Which is which is nature's incredible mechanism because when it rains, people say, so what? So it rains. Rain is then runoff. So think of it that way.

• 40:56Neil deGrasse Tyson?

  Right, right, right. Good point. Good point.

• 40:58Chuck Nice?

  Yeah.

• 40:59Neil deGrasse Tyson?

  And at the bottom of every glacier, there's a river coming out the bottom, right?

• 41:02Chuck Nice?

  Yeah. So.

• 41:03Gary O'Reilly?

  But is it? Is it always a river? Is is it not that cold that it actually freezes to the the bedrock?

• 41:09Speaker 02

  It depends. It depends on the glacier, to be honest. Like the glaciologists who I've interviewed over the last while have said that no two glaciers are the same. You know, so some some parts of a glacier will stick to the bedrock, whereas you might also get these kind of streams like Neil mentioned that form underneath the glacier too. So you have a combination of kind of sticking ice and slippery water and you also the weight of the glacier. It's kind of as if it's on a hill, if it's in a mountainous area, it's kind of constantly moving forward because of internal deformation. So you have all of these forces acting together to to cause the movement of of glaciers.

• 41:47Neil deGrasse Tyson?

  Well, wait, explain to me. Wait, wait. So my the ice I make in my freezer isn't rolling out of the freezer, comes on the floor. So is why would froze? Why would frozen water or or packed ice move at all? I mean, who? Why? I mean, it's just sitting there. I don't care if it's on a hill. It's frozen there.

• 42:07Chuck Nice?

  Yeah.

• 42:08Neil deGrasse Tyson?

  What? Why? Why is it gonna flow? I don't get it. How deep does? How? How? How much? How? I don't get it.

• 42:18Neil deGrasse Tyson?

  All right. Okay. Calm down.

• 42:21Speaker 02

  Okay, I challenge. Challenge accepted. So you have a combination of sliding at the base, like we mentioned. So you have some ice that's sticking on the surface. And you will have this formation probably due to kind of pressure melting type activities. And where you have these streams of of liquid water that lubricate the movement. But you also just have, if you think about ice, it's not a, it's not an eternally solid material, right? It is, there's always slight movement. And this is true for most materials. On a long enough time scale, a lot of things flow, even things that we think of as solid. And I, these glaciers are massive. They are absolutely enormous. And that weight, the weight of the ice, combined with it being, you know, on a slope,

• 43:06Speaker 02

  will mean that the front part of it is moving ever so slightly more. And internally, you have this constant kind of movement of ice molecules within the glacier. And that, that.

• 43:17Neil deGrasse Tyson?

  What's the difference between ice and compacted snow?

• 43:21Speaker 02

  Yeah.

• 43:22Neil deGrasse Tyson?

  Because a glacier is compacted snow.

• 43:23Speaker 02

  Yeah.

• 43:24Neil deGrasse Tyson?

  So what's the difference?

• 43:24Speaker 02

  Very, very good point. So when you have, so the way, the way a glacier forms is you have the snow, it densifies over time. You get these, the ice molecules, the water molecules get tighter and tighter and tighter together. And in that process, air gets squeezed out. So you start to lose the kind of white fluffiness aspect of snow, which has lots and lots of air involved in it. And it starts to turn into something that looks a lot more like ice. So it's much, much, much denser. So the ice, the snowflakes effectively lose their structure and and they turn into this kind of granular ice surface. And that, at the first stage of that, I think is called fern. So it's a particular type of ice that has been created from snowfall.

• 44:06Speaker 02

  And then after decades of this kind of cycle of, you know, snowfall, melting, compaction, all of that stuff, you will actually get types, you will get ice deep in a glacier. And you may have seen this in images that looks blue. It has so little air in there that it's almost completely transparent. And and that, so that's, one of the glaciologists I talked to, she described glacier ice as a type of metamorphic rock. Because it is formed so specifically on this geological scale over long periods of time, just like other metamorphic rock.

• 44:40Neil deGrasse Tyson?

  You still didn't say why it's blue.

• 44:43Speaker 02

  Okay, so my.

• 44:44Chuck Nice?

  I know, because it's sad. It's very, very sad.

• 44:49Neil deGrasse Tyson?

  I didn't ask you, Chuck.

• 44:53Speaker 02

  I know, well, my understanding of it, which could be wrong, right? My understanding of it is it's the way that light is scattered through large columns of of solid water. And this is kind of similar way to the oceans looking blue to us. It's how light scatters.

• 45:09Chuck Nice?

  Oh, okay.

• 45:10Neil deGrasse Tyson?

  That's cool. Or like the sky.

• 45:12Speaker 02

  Yeah.

• 45:12Neil deGrasse Tyson?

  It's like light scatters across into the sky.

• 45:15Gary O'Reilly?

  So Laurie, do we do we look at glaciers as kind of like you talked about them being like meta metamorphic rock?

• 45:23Speaker 02

  Hmm.

• 45:23Gary O'Reilly?

  Are they not like a little bit more like plastic with the deformation and the way that they'll crevasse?

• 45:28Neil deGrasse Tyson?

  Oh, I like that, yeah.

• 45:29Gary O'Reilly?

  They'll crevasse and then they'll then they'll start to move. They'll be a

• 45:32Speaker 02

  Yeah.

• 45:32Gary O'Reilly?

  They'll be a free. Yeah. Okay, yes.

• 45:34Speaker 02

  That's a that's a great observation, Gary. It is especially deep down in the glacier where, you know, the deformation is kind of constant. Whereas, you know, on the surface of glaciers, you'll sometimes see these big crevasses. And that's because the the ice or snow at that level is is a lot more brittle. But down in the in the base of the glacier, it's much more like a plastic than anything else, really.

• 45:54Neil deGrasse Tyson?

  Yeah. And you need those crevasses so we can dig out the dead cavemen, okay? They're looking for food. It was Louis. Oh, he didn't he didn't come back since for a week. All right, let's keep going.

• 46:06Gary O'Reilly?

  So so.

• 46:07Neil deGrasse Tyson?

  No, that's it's true, right? It's some of our best DNA are the retreat of glaciers.

• 46:12Speaker 02

  Yeah.

• 46:12Neil deGrasse Tyson?

  And we had prehistoric creatures, including humans.

• 46:16Speaker 02

  Yeah, because there's no air and, you know, they're so it's so condensed that it is actually quite good at preserving stuff. Yeah.

• 46:23Chuck Nice?

  That's why they find woolly mammoths in the permafrost.

• 46:27Neil deGrasse Tyson?

  Yeah.

• 46:28Gary O'Reilly?

  Laurie, let's go back to what Neil's point about those ice streams that are

• 46:32Speaker 02

  Yeah.

• 46:33Gary O'Reilly?

  very rapid and come through on the base of glaciers. Now, did we not have something recently where there was what they called an underwater tsunami created by one of these or a whole load of these ice streams that come through out of the ice sheet?

• 46:51Speaker 02

  Yeah, that does sound familiar. I'm not, I don't think I know enough about that in particular to mention it, but I do, I do remember seeing something a few years ago now. And it was, there was a particular glacier, I'm going to say Greenland, I apologize if that's wrong. But it was moving, it was found to be moving like something like 40 meters a day, which was as much faster than it really should be moving.

• 47:17Chuck Nice?

  Yeah, that's no longer a glacial pace.

• 47:20Neil deGrasse Tyson?

  No, no, it's an ice tsunami, right?

• 47:23Chuck Nice?

  Right.

• 47:24Neil deGrasse Tyson?

  But you can run away from that one. That's true, yeah.

• 47:28Gary O'Reilly?

  See, the thing is, everybody, everybody looks at glaciers and rising sea levels, and they see the face of a glacier or the ice sheet just collapse into the ocean. But this is now the double whammy of ice streams coming through and the collapse

• 47:44Speaker 02

  Yeah.

• 47:44Gary O'Reilly?

  of an ice sheet's face.

• 47:45Speaker 02

  It is, it's speeding up.

• 47:47Gary O'Reilly?

  I mean, particularly in the western Atlantic.

• 47:48Neil deGrasse Tyson?

  Laurie, isn't it true that this water lubricates the flow of the glacier?

• 47:53Speaker 02

  Yeah, it really, it really does.

• 47:55Chuck Nice?

  It does, right? And not only that, it weakens the structure beneath so that it's collapsing. So think of it as like when you're making a, if you have a little, a tunnel, but then the water itself is the drill that made the tunnel. And you have more water coming through the tunnel. So it's, it's a self-exacerbating problem.

• 48:19Gary O'Reilly?

  Yeah, and if it's moving, then it's not going to, it's not going to freeze as well.

• 48:22Speaker 02

  No.

• 48:23Chuck Nice?

  Right, and you, and you need refreeze as, as a part of the process, which, you know, listen, this is serious stuff, we're screwed, people.

• 48:35Gary O'Reilly?

  I must ask you this Laurie, when it's cold enough for water to freeze or a frost to occur, it doesn't always. And there must be some reasons as to why, if it's minus something, there's no frost. Is it, what is it? Air pressure? Is it, what is it?

• 48:54Speaker 02

  It's a, it's a combination of different things. Like you do, you do need cold temperatures. That's kind of obvious, I suppose, like you said, but you also need things like um nucleation point. So something for a water molecule to cling on to for long enough um to form a crystal, you know, to form an ice molecule. You do need that as well. Um, and you, temperature wise, there's also this thing called the dew temperature. Um, so you, and, and that, in, in most aspects of normal life, the dew temperature, the dew point, I should say, and the freezing point are, are pretty similar. Um, but you do also need that, that nucleation point. So like Chuck mentioned earlier, you can have liquid water at temperatures well below freezing if you don't have something

• 49:37Speaker 02

  for, for those water molecules to cling on to, to become ice.

• 49:41Gary O'Reilly?

  All right. Thank you.

• 49:42Neil deGrasse Tyson?

  By the way, I would add to that, that there's more than one source of thermal energy reaching the surface of a pond. If you want to call it, let's say we're thinking of a puddle, right? Well, the puddle freeze overnight. And so you have whatever retained temperature the ground is from having heated during the day. So even if the air above it drops below freezing, the pond might delay against that because it's got heat from the ground. But also there are layers of the atmosphere that if there's a pocket of warmth, it can radiate to the puddle. And that's a second source of energy

• 50:24Neil deGrasse Tyson?

  that could prevent it from freezing at a freezing point. So I'm saying it's, there's more thermal physics going on. And um only when all the rest of that gets, gets used up, all that other heat sources get used up, then the air temperature will, will, will win for sure. But Laurie, give us some parting thoughts here. What should we think about going forward? And I'm afraid to go to Chuck because he'll give us another public service announcement and we don't have time for that. So

• 50:54Neil deGrasse Tyson?

  what's the future of ice research, Laurie? What can we look forward to?

• 50:59Speaker 02

  What I'm kind of hoping to see is some interesting work around. Can we design surfaces so that they, you know, change how ice forms on them? You know, maybe, maybe we could, not that we want to seed glaciers necessarily, but if we could design surfaces that would allow ice to form very efficiently, that could be interesting for lots of reasons. The other end of that scale is there are lots of industries who don't want ice to form on surfaces like the aviation sector, right? You don't want ice forming on your plane. And so that's kind of the other end of the same question. So I definitely like to see more around that space. And whether it's scalable or not, I have, I have no real sense. I think probably not at this point, but.

• 51:40Neil deGrasse Tyson?

  Laurie, where do we find you on social media?

• 51:41Speaker 02

  I'm on Twitter, Laurie underscore Winkless. And I'm on Mastodon as well with the same handle.

• 51:47Neil deGrasse Tyson?

  Wow, Mastodon, okay. Mastodon. And your most recent book?

• 51:52Speaker 02

  And my most recent book is Sticky and there's a whole chapter on ice in there. And lots of curling controversies as well.

• 51:58Neil deGrasse Tyson?

  So there it is. We'll look for it. Sticky. Love that title. All right, we got to call it quits there. Laurie, delight to have you back on StarTalk and this surely won't be our last invitation to you.

• 52:11Speaker 02

  Thank you.

• 52:11Neil deGrasse Tyson?

  The Winter Olympics is, is surely just around the corner. And no better time to get you back on than that. Chuck, Gary, always good to have you there, man.

• 52:20Chuck Nice?

  Pleasure.

• 52:20Neil deGrasse Tyson?

  Always a pleasure. All right, Neil deGrasse Tyson here, your personal astrophysicist, as always. Keep looking up.