Speaker 1: Welcome to Stuff to Blow Your Mind production of iHeartRadio.
Speaker 2: Hey you welcome to Stuff to Blow your Mind. My
Speaker 2: name is Robert Lamb, and I am Joe McCormick, and
Speaker 2: we're back with another Invention themed episode. Some of you
Speaker 2: may notice Joe and I were just chatting about this.
Speaker 2: We were doing an episode here on ice skating. It is,
Speaker 2: of course the very beginning of summer.
Speaker 3: Most of the articles you find about this come out
Speaker 3: in December, so actually you might be much more familiar
Speaker 3: with the seasonal mismatch if you live in the Southern Hemisphere.
Speaker 3: But yeah, I guess for the majority of readers in
Speaker 3: the Northern hemisphere reading, I guess they're only going to
Speaker 3: click on an article about ice skating in December. I
Speaker 3: don't know. I'm against that kind of thing. I believe
Speaker 3: in anti seasonal topicality.
Speaker 2: Yeah, I mean, plus, people are ice skating somewhere year around.
Speaker 2: There are of course indoor ice skating rinks. And I
Speaker 2: should also mention that the way we're getting to ice
Speaker 2: skating is because my initial inspiration here was to do
Speaker 2: an episode on roller skating. This is of course, the
Speaker 2: past time that initially boomed during the so called Golden
Speaker 2: Age of roller skating, This is roughly nineteen thirty seven
Speaker 2: through nineteen fifty nine. I think there's a lot of
Speaker 2: you know, escaping from the darkness of the world in
Speaker 2: that period and finding a little lightheartedness on the roller
Speaker 2: skates in the skating rink. But you know, it's something
Speaker 2: that's never completely gone out of fashion either, and it's
Speaker 2: experienced sustained popularity in various parts of the world and
Speaker 2: saw a major boost during the global pandemic.
Speaker 3: Can I ask a question to older listeners if you
Speaker 3: watch movies about the fifties, you often see people roller
Speaker 3: skating down the hallway in high school or in another
Speaker 3: setting that's not a dedicated roller skating environment like a
Speaker 3: rink or something, and people just roller skating on the
Speaker 3: sidewalk at school going from class to class. Is that
Speaker 3: a thing people?
Speaker 2: Actually, I don't know they're doing it now because roller
Speaker 2: skating is not only going strong, but it's I think
Speaker 2: it's getting stronger. We may get into this in a
Speaker 2: in another episode, but there are a lot of like
Speaker 2: financial I saw some financial papers talking about how the
Speaker 2: roller skating industry is just going to continue to grow
Speaker 2: over the next decade or.
Speaker 3: So I do think we should bring back the roller
Speaker 3: skate mounted server at the drive in restaurants, because that's interesting.
Speaker 3: It adds an element of danger and theatrical athleticism to
Speaker 3: the dining out experience that you don't usually get.
Speaker 2: Well, I don't know how dangerous it is, but yes
Speaker 2: it is. There is kind of a neat charm to it.
Speaker 2: But yeah, I've been seeing a lot of roller skaters recently.
Speaker 2: My kid is involved in a local vibrant skating club,
Speaker 2: and it really made me reconsider what I thought I
Speaker 2: knew about skating and skating culture. So I figured, hey,
Speaker 2: well let's let's do a nice summer episode about roller skating.
Speaker 2: But the thing is, before you can even begin to
Speaker 2: cover the invention of roller skates, you have to explore
Speaker 2: their cold weather predecessor. You have to talk about ice skates.
Speaker 3: I assume there's no disputing this at all, which came first.
Speaker 3: The ice skate is definitely older than the roller.
Speaker 2: Skate, definitely, definitely by a considerable margin. Yeah, nobody's even
Speaker 2: making the case, even if you were getting into potential
Speaker 2: possible examples of somebody designing something like a roller skate
Speaker 2: that just wasn't usable. Anywhere, because maybe you lacked the
Speaker 2: places for I've I've seen no arguments that this is
Speaker 2: the case. If anyone out there is aware of even
Speaker 2: any just unhinged theories about the roller skate coming before
Speaker 2: the ice skate, send it our way and we will evaluate.
Speaker 2: But as far as I can tell, nobody's making this case,
Speaker 2: and so we're going to stick to what seems to
Speaker 2: be the established lower here. We're going to talk about
Speaker 2: ice skating now, and then I think maybe an episode
Speaker 2: later in June, we'll come back and discuss roller skating
Speaker 2: in more detail. Fair enough, Okay, So, as is generally
Speaker 2: the case when we're talking about an invention, we like
Speaker 2: to talk about what comes before, so we can appreciate
Speaker 2: the invention. What came before skating on the ice using
Speaker 2: some sort of an ice skate. Well to properly consider
Speaker 2: ice skates. Oh wait, you already have an answer. Let's
Speaker 2: have it.
Speaker 3: No, I was going to slipping on the ice, slipping
Speaker 3: and falling game first.
Speaker 2: Well, it always does in ice skating, doesn't it. You
Speaker 2: could and you could make an argument that skating on
Speaker 2: the ice one way or another is slipping in style.
Speaker 2: It is a controlled slip.
Speaker 3: Exactly controlled slipping.
Speaker 2: Yeah, I think the most important thing that I quickly
Speaker 2: realized looking at the history of the ice skate is
Speaker 2: we think of ice skating more as novelty, or perhaps
Speaker 2: you think of it as part of sport, but we
Speaker 2: really have to view ice skates not as an item
Speaker 2: of recreation, but as a mean of conveyance, of moving
Speaker 2: the human body from one point to another. And so
Speaker 2: before humans skated across ice as a means of conserving
Speaker 2: energy and maximizing speed, they did a few different varied
Speaker 2: things on ice, including slipping and falling down. Of course,
Speaker 2: walking across the ice is of course the oldest forerunner,
Speaker 2: obviously requiring no technology, but certainly benefiting from a variety
Speaker 2: of innovations that would occur over human history, including the
Speaker 2: leather shoe I believe, the oldest surviving example being a
Speaker 2: some five five hundred year old arny one shoe from
Speaker 2: Armenia or what is now Armenia. But obviously such footwear
Speaker 2: was biodegradable by its very nature, so who knows what
Speaker 2: we lost though?
Speaker 3: Of course, when we think about ice skates, these are
Speaker 3: obviously tools designed to decrease friction on the ice and
Speaker 3: allow you to glide more easily. I would tend to
Speaker 3: think that the earliest ice traversal technologies were exactly the opposite.
Speaker 3: They would be things disa to help you better grip
Speaker 3: the ice to avoid slipping and falling while you walked.
Speaker 2: Yeah, which brings our mind to things like spiked cleats.
Speaker 2: I was looking around. Let's say there's some examples that
Speaker 2: survive from the first and second millennium CE, But again
Speaker 2: there's no telling what was lost as well in our
Speaker 2: ability to figure out how to make grippier footwear for
Speaker 2: walking around on the ice. And then, on top of this,
Speaker 2: we should also point out that a certain understanding of
Speaker 2: the different types of ice and how it responds to
Speaker 2: your weight would also have been important for moving across
Speaker 2: the ice. The examples of the oldest surviving cleats that
Speaker 2: I was finding my research were things from the Viking era,
Speaker 2: So it's very possible there are older examples of this
Speaker 2: that didn't survive, and possibly something that didn't come up
Speaker 2: with my research. So as always, if anyone knows of
Speaker 2: an earlier example of some sort of grippy footwear technology,
Speaker 2: send it our way. Furthermore, before humans turn to ice skating,
Speaker 2: proper they make use of sleds, a variation of the sledge,
Speaker 2: which itself is a predecessor to the cart. And these
Speaker 2: of course are ancient and widespread innovations which, depending on
Speaker 2: the environment and you know where they were constructed, they
Speaker 2: might have entailed bone, ivory or wood. So we can
Speaker 2: easily imagine that the idea for the ice skate perhaps
Speaker 2: comes together from ruminations on existing sled technology, you know,
Speaker 2: like what if ice strapped a sled to my foot,
Speaker 2: as well as experiences walking, sliding, slipping on ice covered lakes, rivers,
Speaker 2: and so forth. Couple that with a need for such
Speaker 2: skates for a conveyance, such as areas where human communities
Speaker 2: are separated by expansive frozen over bodies of water. And
Speaker 2: it's only a matter of time till someone tries to
Speaker 2: miniaturize the whole affair and place it on a boot.
Speaker 2: Those will discuss the physicality and indeed physics of ice
Speaker 2: skating differs significantly from either of these pre existing technologies.
Speaker 2: So here in a bit we're going to go back
Speaker 2: and look at the most ancient known examples of ice skates,
Speaker 2: how they worked and didn't work, and how they evolved.
Speaker 2: But let's go ahead and move towards our current understanding
Speaker 2: of the ice skate and just talk about how it works.
Speaker 3: As in, what physics principles does the ice skate take
Speaker 3: advantage of?
Speaker 2: Yeah, because we can all sort of have innate understanding
Speaker 2: of out works. But yeah, let's get into the physics. Yeah.
Speaker 3: So this is one of those things that seems like
Speaker 3: a question that would have a fairly simple, well understood,
Speaker 3: well agreed upon answer, But surprisingly, no, the physics of
Speaker 3: ice skating are quite complicated. The issue is still being investigated.
Speaker 3: Some explanations that you see all over the place and appearing,
Speaker 3: I think even in fairly recent physics textbooks are actually
Speaker 3: disputed by experts, and from what I can see, new
Speaker 3: papers on the physics of ice skating still appear regularly
Speaker 3: in scientific journals, at least as of a couple of
Speaker 3: years ago.
Speaker 2: That's crazy. It's not settled science yet.
Speaker 3: Yeah, there is a lot we do know now, but
Speaker 3: a lot of that was established rather recently, and then
Speaker 3: there are still a bunch of questions that we don't
Speaker 3: have answers to yet. But I always think it's interesting
Speaker 3: when you come across something like this, one of those
Speaker 3: things that you assume would have a short, simple, non controversial,
Speaker 3: one paragraph answer in the physics textbook, and actually it's
Speaker 3: like a super complicated unsolved question. But anyway, so the
Speaker 3: main thing that we need to explain when looking at
Speaker 3: the physics of ice skating is why can an ice
Speaker 3: skater glide with such low friction? That's the main physics question.
Speaker 3: To illustrate this, you can quite well imagine the scenario.
Speaker 3: You don't really need to do the experiment. We know
Speaker 3: well enough from walking on various services how this would work.
Speaker 3: Imagine you put on a pair of ice skates, you
Speaker 3: stand on a flat stretch of parking lot, and you
Speaker 3: get somebody to stand behind you and give you a push.
Speaker 3: Is that gonna work? Are you going to glide? No,
Speaker 3: that's all right. The blades will not glide smoothly over
Speaker 3: the surface of the pavement the way they would over
Speaker 3: the ice. They will know, I wrote here on my
Speaker 3: notes that they will I was gonna say, grind to
Speaker 3: a stop, but they probably won't even grind to a stop.
Speaker 3: They're just not going to move at all. They will
Speaker 3: be clamped to the ground where you are standing, and
Speaker 3: any forward momentum you had from the push somebody gave
Speaker 3: you will cause you to fall in your face because
Speaker 3: the blades are not going to go anywhere. They will
Speaker 3: grip the ground and the top half of your body
Speaker 3: will go forward. The friction defeats the momentum, so the
Speaker 3: friction is the problem. The physical principles that make low
Speaker 3: friction skating possible on ice are still under investigation. That said,
Speaker 3: the best and most up to date core research that
Speaker 3: I could find on this was summarized in a December
Speaker 3: twenty nineteen there's December again. December twenty nineteen review article
Speaker 3: in the journal Nature by Daniel Bond called the Physics
Speaker 3: of Ice Skating and a bit of background on the
Speaker 3: author here. Daniel Bond is a physicist affiliated with the
Speaker 3: Institute of Physics at the University of Amsterdam. Bond specializes
Speaker 3: in fluid mechanics, among other things, so you'll see him
Speaker 3: writing articles on these kinds of topics, sometimes aimed at
Speaker 3: a more popular audience. But a couple of notable achievements
Speaker 3: that I wanted to mention of his because they're kind
Speaker 3: of indirectly connected to this topic. This will take us
Speaker 3: a little bit of field, but I think it's an
Speaker 3: interesting parallel. Bond was involved in research you might remember
Speaker 3: from roughly a decade ago, building on some earlier research
Speaker 3: about how the massive stone blocks that were used to
Speaker 3: build the pyramids were probably transported across the ground to
Speaker 3: the building site. Of course, this was a serious question
Speaker 3: because each stone piece is enormous. The amount of force
Speaker 3: required to move it across the ground, it's hard to
Speaker 3: imagine you would have had tons and tons of workers pulling.
Speaker 3: They were probably mounted on these sledges and moved along
Speaker 3: with great difficulty. But Bond and colleagues discovered that you
Speaker 3: could greatly decrease the friction between the sandy ground and
Speaker 3: a sledge used to transport a stone block by slightly
Speaker 3: wetting the sand in front of the sledge. They found
Speaker 3: that you want to add something like two to five
Speaker 3: percent water per unit of sand by volume, and this
Speaker 3: can reduce roughly by half the amount of force and
Speaker 3: thus the number of workers needed to pull the stone
Speaker 3: along the ground. Now why would the water do that? Essentially,
Speaker 3: the water here helps the sand grains stick together rather
Speaker 3: than flow, so the sand functions more like a solid,
Speaker 3: flat surface when you wet it this way dry sand
Speaker 3: when you're pushing something really heavy through it, it tends
Speaker 3: to get kind of pushed out in front of the load,
Speaker 3: forming this mound that then takes more force to pull past.
Speaker 3: You can kind of imagine this. It's like as you're dragging,
Speaker 3: you're constantly like building a little mountain in front of
Speaker 3: where you're trying to go.
Speaker 2: Yeah, yeah, that makes sense.
Speaker 3: But when you wet the sand, it doesn't do that
Speaker 3: as much. It forms more of a solid flat surface
Speaker 3: and you can drag it over the top more easily.
Speaker 3: Bond compared the benefits of wet sand here to the
Speaker 3: reason that you want to use wet sand to build
Speaker 3: a sand castle. It sticks together and holds its shape better.
Speaker 3: Another cool at side about that discovery about the wet
Speaker 3: sand is that this process of pouring out water on
Speaker 3: the sand in front of a stone work during transport
Speaker 3: was actually depicted in ancient Egyptian art. So this is
Speaker 3: not really even a hypothetical process. It was instead investigating
Speaker 3: the physics principles of a process that ancient Egyptians depicted
Speaker 3: themselves doing. So there's like one example here is there's
Speaker 3: a tomb from the Middle Kingdom twelfth dynasty about nineteen
Speaker 3: hundred BCE. Belonging to a governor called Jehudi Hotap. That
Speaker 3: shows teams of workers sporting this big statue and they're
Speaker 3: pulling it with ropes as it's mounted on a sledge,
Speaker 3: and then it shows workers pouring water out of jars
Speaker 3: on the ground right in front of the load. This
Speaker 3: was previously interpreted as a libation, like a ceremonial pouring
Speaker 3: out of liquid as an offering to the gods, but
Speaker 3: this discovery completely reframes that pouring out of liquid as
Speaker 3: something that was very likely functional in nature, whether or
Speaker 3: not it had ritual significance, which it might also have had.
Speaker 2: Yeah, you can very well imagine it having both, and yeah,
Speaker 2: then it makes the ritual even more potent by knowing
Speaker 2: that you can see the results right away.
Speaker 3: Yes, so Bond was involved in that research. But one
Speaker 3: more funny thing about him. He was part of the
Speaker 3: team that won the twenty twenty four Igno Bell Prize
Speaker 3: for chemistry. We didn't talk about the chemistry prize in
Speaker 3: our in our last episodes.
Speaker 2: Did we?
Speaker 3: But this was quote for using chromatography to separate drunk
Speaker 3: and sober worms. I feel kind of sad we didn't
Speaker 3: cover this anyway. I looked it up to figure out
Speaker 3: what this was about. The issue is it was not
Speaker 3: really about worms. Instead, the worms were being used as
Speaker 3: a model to test different methods, different methods of sorting
Speaker 3: different kinds of polymers. So the sober worms represented what
Speaker 3: are called active polymers that can move around, and the
Speaker 3: drunk worms were non active polymers because they just kind
Speaker 3: of chill anyway. All that was an aside on Bond's
Speaker 3: previous work. Here Bond is writing an article reviewing recent
Speaker 3: ice skating research. It's a short review in the journal Nature,
Speaker 3: summarizing both the previous state of research on ice skating,
Speaker 3: as well as especially a new paper published in the
Speaker 3: journal Physical Review X by Canali at All from that
Speaker 3: same year, from twenty nineteen. So Bond begins by talking
Speaker 3: about the explanation that has long been given sort of
Speaker 3: the older textbook explanation for why ice skating works, and
Speaker 3: that is that at the interface between the blade and
Speaker 3: the surface of the ice, there is a thin layer
Speaker 3: not of ice, but of liquid water, and this thin
Speaker 3: layer of water lubricates the contact between the two solid objects,
Speaker 3: between the blade and the ice. Now, why would that happen,
Speaker 3: Why would that liquid water be there. There are several
Speaker 3: different explanations that have been offered throughout the years. One
Speaker 3: is the idea of surface melting. This is the concept
Speaker 3: that there's sort of a quasi liquid layer of water
Speaker 3: that exists on the surface of ice, generally primarily at
Speaker 3: higher temperatures, though still below freezing, and this is sometimes
Speaker 3: called pre melt. Another idea, this is commonly sighted but
Speaker 3: now disputed by Bond and by many others. And I'll
Speaker 3: get to the reason why in a second. But this
Speaker 3: idea is pressure melting at the contact point. So under
Speaker 3: this hypothesis, like the weight of a human body distributed
Speaker 3: over the small surface area of the bottom edge of
Speaker 3: a skate blade creates so much pressure at that contact
Speaker 3: point that it causes the ice crystals to melt and
Speaker 3: become water. And thus you get your lubricating layer of water.
Speaker 3: And then the final possible explanation for that layer is
Speaker 3: frictional heating. So we know what frictional heating is. When
Speaker 3: you rub things together, the friction generates heat. This idea
Speaker 3: here says that this kind of frictional heating happens between
Speaker 3: the skate and the ice. The heat melts the ice
Speaker 3: and the thin layer of slippery melt water is formed.
Speaker 3: I've come across sources, especially older ones, that favor the
Speaker 3: explanation based on pressure melt melting, but Bond says this
Speaker 3: is now widely thought to be incorrect because apparently this
Speaker 3: would not work at temperatures below negative twenty degrees celsius.
Speaker 3: And we can see that ice skating regularly works well
Speaker 3: at temperatures lower than that, So just the observation of
Speaker 3: ice skating does not match that explanation. So then maybe
Speaker 3: is it surface melting that pre melt the quasi liquid
Speaker 3: layer on the outside, or is it frictional melting leading
Speaker 3: to a liquid layer on top of the ice. Strangely,
Speaker 3: Bond says, neither of those seem to fully explain what's
Speaker 3: going on either, especially not in the idea that they
Speaker 3: could just create a layer of liquid water, because, for
Speaker 3: one thing, these mechanisms would be equally present at the
Speaker 3: surface of other various solids that you cannot skate on.
Speaker 3: So there must be something else at place, something special
Speaker 3: about water ice compared to other solids. Another interesting question,
Speaker 3: what exactly are the mechanical properties of this lubricating layer
Speaker 3: of water. Bond points out some things that are not
Speaker 3: really consistent with the idea that water lubricates the interface
Speaker 3: between the skate and the solid surface. For one thing,
Speaker 3: you can't skate on a flat, solid surface covered in water.
Speaker 3: You think about this like imagine a flat basketball cort
Speaker 3: or something. You drench the floor with a thin layer
Speaker 3: of water, put on some ice skates and try to
Speaker 3: skate on it. That does not work.
Speaker 2: Yeah, yeah. Your only hope is if the heat the
Speaker 2: floor that is being covered by the water is ice. Yeah.
Speaker 3: Yeah, so there's something special about ice. It's not enough
Speaker 3: to just have liquid water underneath your skate blade. Another
Speaker 3: interesting thing he mentions water is generally not a great lubricant,
Speaker 3: in part because it is too thin. When it gets
Speaker 3: pressed between two solids, water is easily squeezed out of
Speaker 3: the space between them like a grippier. Stickier fluid like
Speaker 3: oil or grease, makes a better lubricant because it clings
Speaker 3: to the space between the solids and doesn't get pressed
Speaker 3: out as easily. So curious questions confounding observations here.
Speaker 2: So you would see oil skating would be more likely
Speaker 2: to take off than this water skating.
Speaker 3: I mean, I would imagine if you coat a floor
Speaker 3: with oil. You can probably do some good slipping and
Speaker 3: sliding on it. I don't know exactly what the skate
Speaker 3: blade but maybe but anyway, so whatever the mechanism, the
Speaker 3: idea has long been that ice skating is possible because
Speaker 3: instead of skating on solid ice crystals, you are actually
Speaker 3: gliding over a microscopic, invisible layer of liquid. What Kanali
Speaker 3: and co authors found in their paper is that this
Speaker 3: is half true. When you skate over the ice, there
Speaker 3: is a lubricating layer of something, but it's not simply
Speaker 3: liquid water. It's actually a unique water based substance that
Speaker 3: has some properties of liquid water and some properties of
Speaker 3: solid ice. So to show this, the authors of this paper,
Speaker 3: Canali and co authors created an experiment where they were
Speaker 3: able to measure the coefficient of friction of both the
Speaker 3: ice and the lubricating layer on top of the ice
Speaker 3: at the same time. And they did this with a
Speaker 3: device that Bond compares to a tuning fork. Here I'm
Speaker 3: going to quote from Bond's description of their experiment. Quote.
Speaker 3: The fork was made to vibrate so that a millimeter
Speaker 3: scale glass bead attached to one of its prongs oscillated
Speaker 3: across an ice surface. The bead thus functioned as a
Speaker 3: tiny ice skate, gliding for distances of the order of
Speaker 3: tens of micrometers across the same region of ice. An
Speaker 3: accelerometer attached to the same prong of the fork as
Speaker 3: the bead measured the amplitude of the bead's oscillations parallel
Speaker 3: to the surface and compared them with the amplitude of
Speaker 3: the driving force. Canali at all use the difference in
Speaker 3: amplitude to calculate the friction force between the bead and
Speaker 3: the ice, So they did that, and then at the
Speaker 3: same time also they were measuring the oscillation of the
Speaker 3: bead perpendicular to the ice surface. Essentially that would be
Speaker 3: sort of how it was bouncing up and down to
Speaker 3: learn things about the lubricating layer underneath the bead. And
Speaker 3: then by comparing these two different measurements based on the
Speaker 3: parallel oscillations and the perpendicular oscillations, the authors could figure
Speaker 3: out the friction coefficient between the bead and the ice
Speaker 3: and could figure out flow properties of the lubricating layer
Speaker 3: in between them. And what they found was weird and interesting.
Speaker 3: The lubricating layer has some viscous properties, so like a thicker,
Speaker 3: stickier fluid compared to regular water, and it also had
Speaker 3: elastic behavior, meaning it can have its shape squeezed or
Speaker 3: stretched and then bounce back to its original shape like
Speaker 3: a rubber ball. It behaved neither like water nor like ice,
Speaker 3: but like a hybrid of the two.
Speaker 2: Quote.
Speaker 3: The author suggests that repeated sliding over the same spot
Speaker 3: generates a mixture of ice and water, which displays both
Speaker 3: elastic behavior from the ice and viscous behavior from the water.
Speaker 3: In response to a load. The resulting layer of material
Speaker 3: would be more difficult to squeeze out of gaps than
Speaker 3: ordinary water. This could, at least in part explain the
Speaker 3: layer's excellent lubrication properties. So it has something to do
Speaker 3: with the special characteristics of the outer layers of water. Ice.
Speaker 3: In particular, other melting solids would not necessarily behave this way,
Speaker 3: and as we observe, many other melting solids do not
Speaker 3: behave this way. There's something special about H two zero
Speaker 3: bond rights quote. Few materials can form a viscoelastic liquid
Speaker 3: solid third body in response to friction and wear. That's
Speaker 3: something that makes water special. Also, Bond mentions at the
Speaker 3: end of this review that there are plenty of questions
Speaker 3: about the physics of ice skating that remain. The lots
Speaker 3: of things we still don't know, For example, like why
Speaker 3: does the ideal temperature for reduced friction on the ice
Speaker 3: seem to be like negative seven degrees celsius. That that's
Speaker 3: a finding, but we don't know why that temperature. And
Speaker 3: another thing he points out which I hadn't quite considered,
Speaker 3: but I think is worth the certainly worth understanding. Having
Speaker 3: a complete science of lubrication is not just trivia. This
Speaker 3: is not just like, you know, somebody goes ice skating
Speaker 3: and wonder how does this work. It's not just to
Speaker 3: satisfy our curiosity. Understanding lubrication is hugely important to human
Speaker 3: economics and technology. Bond Site's an estimate that something like
Speaker 3: twenty percent of the world's total energy consumption is lost
Speaker 3: to friction, meaning it's turned into heat and wear on
Speaker 3: components from things rubbing together. Generally that that is not
Speaker 3: useful to us as a type of energy. Thus, better
Speaker 3: lubrication technologies could represent big improvements in energy efficiency and
Speaker 3: in the performance and durability of our machines.
Speaker 2: Yeah, that's a great point, I thought so too.
Speaker 3: So let no one, Let no one snicker at the
Speaker 3: idea of lubrication science is it is serious business. But
Speaker 3: anyway to bring it back around, I would summarize what
Speaker 3: I've read on this subject by saying that it seems
Speaker 3: ice skating works because the surface of regular ice, regular
Speaker 3: hexagonal crystal and ice can and usually does, become coated
Speaker 3: in a quasi liquid layer of H two oz made
Speaker 3: of some interesting mixture of liquid melt and tiny ice crystals.
Speaker 3: And this quasi liquid layer does not act like regular
Speaker 3: liquid water, but instead has a sticky bouncy quality or
Speaker 3: what are called in the paper visco elastic qualities, and
Speaker 3: these qualities make it an amazing lubricant between solids. This
Speaker 3: lubricating layer is not primarily created by pressure from the
Speaker 3: skater's body weight as physics as people used to say,
Speaker 3: especially a long time ago, though pressure could play some
Speaker 3: small role, it seems frictional heating between the blade and
Speaker 3: the ice probably does play some role, maybe a major one,
Speaker 3: though some of this quasi liquid layer is already naturally
Speaker 3: there on the ice within the normal temperature range for
Speaker 3: ice skating, and then beyond that, of course, you have
Speaker 3: to think about the physical characteristics of the blades themselves.
Speaker 3: The smooth blades of the skates allow the skater to
Speaker 3: further decrease friction, more so than say the relatively rough
Speaker 3: and grippy soles of shoes or of the bottoms of
Speaker 3: your bare feet, and the blades also allow the skater
Speaker 3: to control movement. There's greater control because they allow you
Speaker 3: to both do a pushing motion when applied to the
Speaker 3: ice one way, and a gliding motion when applied in
Speaker 3: a different way.
Speaker 2: Which of course is the great that's part of the
Speaker 2: great fun of ice skating, this gliding sensation, the pumping
Speaker 2: your legs side to side. I don't get out and
Speaker 2: ice skate all that often. Generally, like once a year,
Speaker 2: I'll go ice skating. Oh and it's cold enough here
Speaker 2: in Atlanta, and they have some outdoor ice skating rinks.
Speaker 2: But generally I spend at least half the time i'm
Speaker 2: there relearning how to ice skate and getting my balance,
Speaker 2: and then it gets pretty fun. You know.
Speaker 3: I haven't done it since I was a kid. There
Speaker 3: was an ice skating rink in town when I was
Speaker 3: a kid, and we would go a number of times.
Speaker 3: It's one of those things where I think I only
Speaker 3: ever did it enough to just get to the edge
Speaker 3: of not being terrible at it, and then never proceeded
Speaker 3: to go into like being able to do it.
Speaker 2: Yeah. Yeah, I mean, like I say, I always have
Speaker 2: to relearn. At least half the time, I'm just getting
Speaker 2: my balance right and figuring out how I'm supposed to
Speaker 2: do this, allowing my confidence to build up enough, and
Speaker 2: then I'm finally in a place where I can dodge
Speaker 2: all the children out there on the rink and make
Speaker 2: a few laps that feel pretty satisfied.
Speaker 3: This is a tangent, but this makes me think I
Speaker 3: don't know if there's a name for this phenomenon, but
Speaker 3: I would be interested in doing something on the show
Speaker 3: about these kinds of endeavors where you get stuck in
Speaker 3: the perpetual beginner zone, where you're always just like retreading
Speaker 3: or reviewing the beginner material and you never break out
Speaker 3: into actual competence of it.
Speaker 2: Yeah, there are probably a lot of things like that, though,
Speaker 2: of course, one of the great things about hobbies is
Speaker 2: you don't actually have to be good or even competent
Speaker 2: at them. They are your hobbies, after all. But yeah,
Speaker 2: I think there are a lot of things like this
Speaker 2: where we can look to our own experiences and say, well,
Speaker 2: I almost did that, I almost served once.
Speaker 3: Well, I feel like there are some hobbies that are
Speaker 3: more fun to spend time in the beginner zone in
Speaker 3: than others. Like with ice skating, you know, you can
Speaker 3: imagine that you'd be having more fun once you were
Speaker 3: able to feel some amount of mastery over it, whereas
Speaker 3: other things you can just be messing around in the
Speaker 3: you know, total beginner zone and it's already pretty fun
Speaker 3: to be right there.
Speaker 2: All right, well, let's get back into the history of
Speaker 2: ice skating, and again we'll stress the caveat that the
Speaker 2: earliest examples of any given technology don't always survive or
Speaker 2: have yet to be found, especially if their biodegradable materials
Speaker 2: bound up in their production. But the oldest ice skates
Speaker 2: that I think we know of date back to roughly
Speaker 2: eighteen hundred BCE in Scandinavia, where the ancient Scandinavians seemingly
Speaker 2: invented the technology. Some three thousand years ago, I was
Speaker 2: reading a paper by Frederico Formenti and Alberto E. Minetti.
Speaker 2: Formenti in particular has written numerous papers dealing with recreating
Speaker 2: old examples of ice skates and comparing them to other models.
Speaker 2: This particular two thousand and seven paper was titled human
Speaker 2: locomotion on ice and it was published in the Journal
Speaker 2: of Experimental Biology, and he mentioned that there's also a
Speaker 2: case to be made for Bronze Age invention of skates
Speaker 2: in what is now Northern Russia. And I also am
Speaker 2: going to come back around to some arguments here in
Speaker 2: a bit that also point to parts of modern day
Speaker 2: China where we have some evidence of ice skating, and
Speaker 2: then also some things like ice skating I'll get into,
Speaker 2: but it seems like universally, the earliest skates that we
Speaker 2: know of they were not made of metal. They were
Speaker 2: not even made of wood entirely. They were made of bone,
Speaker 2: which makes a lot of sense. Bone is a dense,
Speaker 2: dependable construction material for human tool use. And yeah, you
Speaker 2: can look up some images of this. In particular, I
Speaker 2: would say that Science Friday has a really good article
Speaker 2: about the paper in question here that I'm referencing, and
Speaker 2: it has some nice color images of for Minty's reconstructed
Speaker 2: ancient skates that you can look at. They're the same
Speaker 2: images in the original paper, except in this case they're
Speaker 2: in color, and so I included one here for you, Joe,
Speaker 2: of reconstruction of an ancient bone ice skate, and it's
Speaker 2: pretty simple.
Speaker 3: It looks like a bone with two belts looped through it.
Speaker 2: That's right. Yeah, this would be a bone from a
Speaker 2: horse or a cow. Generally the metatarsal bone strapped to
Speaker 2: a boot via leather straps that are worked through slits
Speaker 2: in the bone. Oh, I meant to mention that. Formenti
Speaker 2: also notes that the ancient Scandinavian sagas suggest that the
Speaker 2: first ice skates were made of wood, but this is
Speaker 2: something that is present in textual evidence, but there's no
Speaker 2: archaeological findings to support this currently, so as far as
Speaker 2: we can tell, it was bone all the way back.
Speaker 3: This reminds me of our Bone Punk episodes where we
Speaker 3: were talking about those Ice age dwellings with the huts
Speaker 3: made out of mammoth bones.
Speaker 2: Yeah.
Speaker 3: Yeah, I believe part of the idea there was that
Speaker 3: those were in places where wood was actually in quite
Speaker 3: short supply or would have been precious for other reasons,
Speaker 3: and thus the bone was like it made sense economic
Speaker 3: sense to use mammoth bones as a building material. I
Speaker 3: don't know if there was a similar thing in here.
Speaker 3: It might just be that the bone had properties that
Speaker 3: you would prefer for skating.
Speaker 2: I think a lot of it comes down to those properties. Yeah,
Speaker 2: So it's thought that these would have been the first
Speaker 2: variety of ice skates that humans used. And the crazy
Speaker 2: thing is these remained in use up into the eighteenth
Speaker 2: century CE, so until fairly recently folks were still known
Speaker 2: to strap some bones to their feet and hit the ice. Now,
Speaker 2: the authors here note that these ice skates lacked the
Speaker 2: edge that you find on modern metal skates, so you
Speaker 2: couldn't just pump along on these with your legs. That
Speaker 2: kind of that sliding and gliding motion that we were
Speaker 2: just talking about being so fulfilling. You would not be
Speaker 2: doing that on these ice skates. You wouldn't be doing
Speaker 2: a lot of tricks I'm guessing either, and whirls and
Speaker 2: whirls and so forth, because your locomotion depended pretty much
Speaker 2: entirely on your upper limbs working a pair of poles
Speaker 2: to push you along. Oh interesting, Okay, So in that
Speaker 2: it has more in common I would imagine with skiing,
Speaker 2: which we're not really getting into today. It's going to
Speaker 2: be a separate episode at some point. Now. From and
Speaker 2: his co author point out that skates such as these
Speaker 2: would have been used for accompanying animal driven sleds or sledges.
Speaker 2: They would have been used in ice fishing or fishing
Speaker 2: from positions further out on the ice, but especially among
Speaker 2: the Dutch people, the technology soon became essential for winter
Speaker 2: transportation via frozen rivers, lakes, and eventually canals. So think
Speaker 2: of a region where you know, where you have a
Speaker 2: bunch of frozen over rivers and or canals that are
Speaker 2: ultimately connecting different human populations, or situations where you have
Speaker 2: a completely frozen lake and you have human populations at
Speaker 2: different points across from each other across said lake. It's
Speaker 2: ultimately faster and more energy efficient to use some sort
Speaker 2: of skating technology. And yeah, for Menty stresses that it
Speaker 2: was highly efficient. This was no mere novelty. They weren't
Speaker 2: doing this. You know, maybe it was fun, but they
Speaker 2: weren't doing it because it was fun, He writes, quote
Speaker 2: from its very conception, skating on ice was a form
Speaker 2: of human powered locomotion that was simple and effective, very cheap,
Speaker 2: and thus accessible to a large part of the population,
Speaker 2: and allowed people to reach more distant destinations than they
Speaker 2: could do by walking or running. In fact, unless more
Speaker 2: expensive means of transport such as horses or later trains
Speaker 2: were used, ice skates were probably the most convenient locomotion
Speaker 2: tool until bicycles were built. That would have been the
Speaker 2: nineteenth century, the latter probably not being very safe on
Speaker 2: slippery roads in winter.
Speaker 3: That's interesting, Well, I would not have thought about it
Speaker 3: that way.
Speaker 2: Yeah, so not everywhere and certainly not year round, but
Speaker 2: that there would be places where this was just highly efficient.
Speaker 2: It was just the most the most sensible way to
Speaker 2: move from point A to point B if conditions were
Speaker 2: just right. Now, while again bone skates were ultimately a
Speaker 2: long lasting technology against superior to mere wood, it would
Speaker 2: seem by the thirteenth century CE in the Netherlands, skaters
Speaker 2: returned to wood to make use of metal in their skating,
Speaker 2: constructing wooden skates that had metal blades. Now, these were
Speaker 2: still things that you would strap to the bottom of
Speaker 2: your shoes, and I included an image of one of
Speaker 2: these for you here, Joe. It is also not very fancy.
Speaker 2: If you didn't know you were looking at an ice skate,
Speaker 2: you might not know you were looking at an ice skate.
Speaker 2: It's like a imagine a wooden skate but with a
Speaker 2: thin metal blade, and then it is strapped or tied
Speaker 2: to your shoes.
Speaker 3: Yeah, yeah, it looks It looks like the wooden bottom
Speaker 3: of a boat, or like a boat keel with a
Speaker 3: tiny little strip of metal blades sticking out of the bottom.
Speaker 2: Yeah. And so for Mantiene's co author point out that
Speaker 2: the wood here would have been easy to work, the
Speaker 2: metal that they use was very durable. An interesting thing
Speaker 2: here is that these skates would apparently according to their
Speaker 2: reconstructions and their tests, would have suffered from greater friction
Speaker 2: compared to bone skates. But their big advantage was that
Speaker 2: they allowed the user to finally propel themselves with their
Speaker 2: lower limbs, so you could seemingly throw away the poles,
Speaker 2: free up your arms, and depend almost entirely on leg power.
Speaker 2: And as such, this is really when we begin to
Speaker 2: see skating as we know it today entering the world,
Speaker 2: Because if you go to any ice skating rink, and
Speaker 2: certainly if you go to a roller skating rink, you're
Speaker 2: not going to see people pushing around on poles. I mean,
Speaker 2: maybe there's some sort of scenario where you use poles
Speaker 2: to get your feet underneath you. But I've never seen
Speaker 2: anything like that.
Speaker 3: Right, So I imagine it's like the thinness of the
Speaker 3: blade that allows you to just use your legs because
Speaker 3: of the way that you can angle the foot to
Speaker 3: push versus gliding, and you can't really do that with
Speaker 3: the more rounded edge of a bone.
Speaker 2: Yes, that's my understanding. So at this point, yeah, we're
Speaker 2: kind of off to the races. We're really not purely
Speaker 2: inventing something new, but we've innovated to a very interesting
Speaker 2: place in the development of the ice skate. And during
Speaker 2: the fifteenth and eighteenth century ice skates they retain their
Speaker 2: metal wood construction, but they became about thirty percent lighter.
Speaker 2: According for Mente, Dutch skates of the time were shorter
Speaker 2: compared to modern skates and therefore more difficult to balance
Speaker 2: on compared to what we have today, but they would
Speaker 2: have proven especially useful to them during the Little Ice
Speaker 2: Age of the sixteenth through nineteenth centuries, during which the
Speaker 2: system of rivers and canals would have proven ideal skate
Speaker 2: routes connecting different populations and different different destinations. And then
Speaker 2: during the eighteenth century, skates on the whole became longer
Speaker 2: and enabled easier balance and resulted in lower resistance the
Speaker 2: weight spread out across longer blades. And I've included another
Speaker 2: photo Formenti's work here reconstruction. This is still something you
Speaker 2: strapped your existing footwear, but it is even more identifiable,
Speaker 2: I think as an ice skate.
Speaker 3: Oh yeah, totally.
Speaker 2: And then during the nineteenth century we finally ended up
Speaker 2: with specialized ice skates, with the skates permanently affixed to
Speaker 2: a boot of some sort screwed into place, an ice
Speaker 2: skate that has shoe ices so forth, like you would
Speaker 2: identify now when you go in like rent ice skates
Speaker 2: to go ice skating. And the blades were even longer,
Speaker 2: apparently up to twice the length of the old thirteenth
Speaker 2: century skates, enabling even greater balance and maneuverability. And then
Speaker 2: a whole host of additional innovations have been made and
Speaker 2: continue to be made, producing skates that are ever more ergonomic, speedy,
Speaker 2: and effective. Different breaking mechanics were added, blades that ultimately
Speaker 2: like have a mechanical aspect to them and can shift
Speaker 2: and so forth. Saw a Fermente quoted in an article
Speaker 2: I believe it's the Science Friday, where he basically says
Speaker 2: that we probably haven't seen as long of a skate
Speaker 2: as is ideal, like, skates are probably going to keep
Speaker 2: They're going to keep evolving. They're still evolving, They're becoming
Speaker 2: more and more efficient, and they may get longer. We
Speaker 2: have not reached peak ice skate length yet.
Speaker 3: Wait, does he have a specific peak length in mind?
Speaker 2: Now he's just saying that we're still like fine tuning everything.
Speaker 2: And I guess the other interesting thing here is that
Speaker 2: there's not just one purpose for ice skates. There are
Speaker 2: a lot of highly specialized purposes for ice skates. So
Speaker 2: you know, we have a whole host of skate based
Speaker 2: sporting activities and they range from figure skating to ice hockey.
Speaker 3: Yeah, I was reading about that too, And an interesting
Speaker 3: thing there is that apparently different ice temperatures are preferred
Speaker 3: for the different sports. I think the way I was
Speaker 3: reading it is that usually they want the temperature a
Speaker 3: little bit higher for figure skating because figure skaters, I
Speaker 3: think a softer ice gives them more control over precise movements,
Speaker 3: whereas with ice hockey, I think they like a slightly
Speaker 3: colder ice because that allows them to achieve like a
Speaker 3: higher top.
Speaker 2: Speed okay, interesting, Okay, So with hockey it's more about speed,
Speaker 2: and with figure skating it's maneuverability, which makes it now
Speaker 2: Fomenty and his co author in the aforementioned paper, they
Speaker 2: compare the effectiveness of the four main eras of ice skates,
Speaker 2: and the results illustrate this continual improvement process that we're
Speaker 2: looking at here. I'm not going to roll through the
Speaker 2: entire chart. You can find it in the original paper,
Speaker 2: but you can see here he breaks things out by speed,
Speaker 2: stride frequency, stride length, and so forth, and Fermenty points
Speaker 2: out that with the same metabolic power, skaters today have
Speaker 2: a speed four times that of our ancestors, and again
Speaker 2: it's only increasing as we find tune our skate design.
Speaker 3: This might not actually be an issue, but I just
Speaker 3: had the thought. Do skaters on rink ice have higher
Speaker 3: speeds as well, just because they can feel safe to
Speaker 3: go at higher speeds, whereas if you're on a natural
Speaker 3: body of water you might be more I don't know,
Speaker 3: cautious about like straying into an area of thin ice
Speaker 3: or something like that.
Speaker 2: That's a good point. I mean, I guess the other
Speaker 2: number of factors that might come into play, right, if
Speaker 2: you're dealing with like natural ice versus zambonid ice, right.
Speaker 3: Yeah, And I know that the zambonid ice, like the
Speaker 3: rink ice, is laid down one layer at a time
Speaker 3: to give it special properties, to kind of make it
Speaker 3: perfect for skating, whereas, of course natural ice on a
Speaker 3: body of water, I mean, it might be great for skating,
Speaker 3: but it doesn't have whatever refined quality they're looking for
Speaker 3: on that rink ice.
Speaker 2: Now, I want to come back to ice skating in
Speaker 2: China because as I was hitting like the core data here,
Speaker 2: I kept finding various references to Chinese ice skating, and
Speaker 2: I'd read that ice skating in China might date back
Speaker 2: to the Song dynasty, so nine sixty to twelve seventy nine.
Speaker 2: See that is, of course in addition to possibly connected
Speaker 2: or independent developments in the north of Russia as I
Speaker 2: referenced earlier. But certainly I looked into this a little
Speaker 2: bit more, and you have these ice festivals the Bingshe,
Speaker 2: which I think means ice amusement festivals that seem to
Speaker 2: date back to the Song dynasty in China and consisted
Speaker 2: of various winter sports and performances. Among the many festivities
Speaker 2: there was a downhill skating event that involved kind of
Speaker 2: a leather ice skate. I wasn't able to find any
Speaker 2: images of reproduction of this, but I found some various
Speaker 2: modern illustrations of what these might have consisted of. And
Speaker 2: these these are kind of like curved leather shoes that
Speaker 2: seem to have been made expressly for sliding across the
Speaker 2: ice and or snow.
Speaker 3: If this is what's depicted in the illustration you put
Speaker 3: in our outline that kind of curled up at the
Speaker 3: toe like elf shoes.
Speaker 2: Yes, yes, think like leather elf shoes designed for sliding
Speaker 2: around on ice. It's not skating in the sense that
Speaker 2: we've been talking about skating, I think from the physics standpoint,
Speaker 2: But these would have been things that would have been
Speaker 2: you would have worn for like this downhill skating competition
Speaker 2: or something that I've seen translated as ice football, in
Speaker 2: which people were skating around on the ice in these
Speaker 2: leather shoes throwing some sort of a ball back and forth.
Speaker 2: The illustration here that I found is from the Beijing
Speaker 2: based World of the World of Chinese website, So my
Speaker 2: understanding is like these are similar but a little bit different.
Speaker 2: These would have also the examples we're looking at here
Speaker 2: would have definitely been novelty based skates. These were not
Speaker 2: about locomotion, These were about amusement. However, in other parts
Speaker 2: of modern China you do find ancient examples of bone skates.
Speaker 2: I was reading that in twenty twenty three, Chinese archaeologists
Speaker 2: found an example of a bone ice skate in a
Speaker 2: Bronze Age tomb from roughly three thy five hundred years ago,
Speaker 2: possibly of the Andronova culture of cattle herders that lived
Speaker 2: in China's western Shijang Weaker Autonomous Region. These would have
Speaker 2: been very much akin to what we were talking about,
Speaker 2: like the bones scrapped to a boot or to a
Speaker 2: shoe that enabled one to move across naturally frozen bodies
Speaker 2: of water. But again, it does seem to come back
Speaker 2: to bones. It comes back to horse and cow bones
Speaker 2: strapped to the bottom of your feet, enabling you to
Speaker 2: at least push yourself across the ice with a big
Speaker 2: with a pair of poles or sticks.
Speaker 3: Well, Rob, you've talked me into it. If I if
Speaker 3: I take my child ice skating this year, I'm gonna
Speaker 3: I'm gonna have to get some bone skating to try
Speaker 3: out see how they do.
Speaker 2: You know, I don't think it would be a good idea.
Speaker 2: I think this would not in the long run, this
Speaker 2: would be a failure. But I could imagine someone trying
Speaker 2: to market this. You know, why settle for ice skating
Speaker 2: when this year when you could do primal ice skating,
Speaker 2: bone ice skating, and people would be like, yeah, you know,
Speaker 2: I'm kind of a little over three own axes at
Speaker 2: the local acts throwing range. I want to try something
Speaker 2: else that has this kind of like, you know, ancient
Speaker 2: vibe to it. Let's strap on some bones and see
Speaker 2: how it goes. I think you would find it. Would
Speaker 2: it would? It would be harder. It sounds like every
Speaker 2: everything I've read about it, it would have been a
Speaker 2: much harder and clumsier thing to do. We're much better
Speaker 2: off with modern ice skates, but for.
Speaker 3: The metal of it, maybe you use the non metal.
Speaker 2: Yes, bone ice skates are very metal. We'll definitely say that.
Speaker 3: All right.
Speaker 2: Should we wrap up there, Yeah, We're going to go
Speaker 2: ahead and close out this episode. However, again, definitely tune
Speaker 2: in later in June when we come back and talk
Speaker 2: about roller skating on its own again directly connected to
Speaker 2: the invention of ice skating, but very much its own
Speaker 2: thing as well. In the meantime, would of course love
Speaker 2: to hear from everyone out there. Do you have experiences
Speaker 2: or thoughts related to ice skating? Is there anyone out
Speaker 2: there who has tried a more archaic version of the
Speaker 2: ice skate? If so, definitely right into it because we
Speaker 2: would love to have your feedback. As always, we'd like
Speaker 2: to remind you that Stuff to Blow Your Mind is
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