Friction's Role in the Everyday World

In this episode of Perfecting Motion, our host, Marc Ingram, dives into the "hidden science" of tribology with Jennifer Vail, author of Friction – A Biography, to uncover how this often-overlooked force shapes the modern world. The conversation journeys from the fundamental physics that allow us to walk and drive to the historical milestones where engineering hurdles sparked scientific breakthroughs. We explore the ways humans instinctively "tinker" with friction in daily life, the fascinating presence of tribology in the natural world, and the critical role of lubrication and wear-control in today's most vital industries. Finally, the episode looks toward the future of material science, discussing whether we can ever achieve near-zero friction and why understanding this invisible force is key to solving the next generation of global engineering challenges.

Our guest:

Dr. Jennifer Vail studied tribology at the University of Florida before moving to England as a researcher at the University of Sheffield and Imperial College London. She returned to the United States to start the first dedicated R&D tribology lab for DuPont and then produced educational content for the Khan Academy. Her TED talk on tribology has reached more than 2.5 million people and her book Friction: A Biography was released in early 2026.

For more information on STLE, please visit https://www.stle.org/ If you have an idea for our podcast, or interested in being a guest, please Email STLE Director of Professional Development Robert Morowczynski at rmorowczynski@stle.org . Also, we love your feedback, please take a minute to provide us with your thoughts at Perfecting Motion Podcast Feedback or Email us at rmorowczynski@stle.org.

For more information on STLE, please visit https://www.stle.org/ If you have an idea for our podcast, or interested in being a guest, please Email STLE Director of Professional Development Robert Morowczynski at rmorowczynski@stle.org .   Also, we love your feedback, please take a minute to provide us with your thoughts at Perfecting Motion Podcast Feedback or Email us at rmorowczynski@stle.org.  

Transcript

Welcome to Perfecting Motion, an STLE podcast series that talks with members and industry
professionals about current issues and trends impacting the global tribology and lubricants
community. Hello, and welcome to our STLE podcast, Perfecting Motion. I am Bob Morizynski,
STLE's Director of Professional Development. And today we have with us Dr. Jennifer Vale from TA
Instruments, and who just published her first book titled Friction, a Biography. and our guest host
today and back for another episode is Mark Ingram from Ingram Technology. Today, Mark and Jen will
be talking about friction and its role in our industry. Mark, our host, I'll hand it over to you.
Okay, thank you very much, Bob. Yeah, welcome to Perfect in Motion podcast. Today, we are stepping
back a little bit to look at the bigger story of friction and tribology. I'm joined by science
writer Jennifer Vale. author of Friction, a biography. And we are going to explore the hidden
science that helps us walk, drive, and build the modern world. Hi, Jennifer. How are you doing?
Hi, Mark. I'm doing great. Thank you for having me. Our pleasure. Our pleasure. So what inspired
you to write Friction, a biography? Well, I guess when you think about it,
friction really is ubiquitous, right? It's impacting you, me, everyone, every day.
And so its reach is pretty amazing. Working with it can take us from machinery,
to cells, to things moving through space. And so it just became apparent with that kind of impact
and reach, friction had a story to tell, and I decided to give it a go. I believe it stemmed from
your TED Talk. Is that how you kind of got out there as a kind of publicist in this area?
How did that kind of come about? Yeah, so I did a TED Talk a few years back,
and it was unexpectedly popular. And the response to it is really what prompted this.
A lot of people were interested. It caught the eye of the editor that I now work with. And we just
decided, let's tell this story of Friction because it is resonating with so many people. And it
does because once you've realized it's everywhere around you, you become pretty interested in it.
So the editor got in touch and you kind of started writing. And did you kind of agree like an
overview or, you know, what's the kind of next step, I suppose? Yeah, so she reached out to me.
And after I thought maybe it was phishing or something suspicious, I just replied back with thank
you for the kind feedback on my TED Talk. I'm not really interested in writing a textbook. And she
was of the, that's great. I'm not interested in editing a textbook. Let's chat. And so I really
went from not having thought about writing a book to really thinking what is Friction's story and
mapping out a proposal. presenting it to the publisher and going from there. And that is how this
book came to fruition. Yes, I've read most of it.
And it's a lovely historical context of the change of friction and tribology,
as we know today, with loads of lovely anecdotes and stuff. Okay, so why do you think friction is
such an overlooked part of science and technology?
Oh, man, I mean, I think friction really is probably one of the most underappreciated forces in our
lives. And I think it's, Back to what we were just saying about how it's everywhere. So we've just
gotten to a point where we either take it for granted or we forget about it just because we're so
used to it. And we tend to only remember friction when it's suddenly in our way. Ignoring it isn't
possible. Either there's too much of it and we can't move what we're trying to move or there's not
enough of it and we're slipping and sliding all over the place. That tends to be when we remember
friction. Otherwise, we're just coexisting with it and forget about it. Exactly.
And I think we'll come on to it later, but a lot of the developments you describe in the book,
it was clear to me that the development of the science of friction was solving problems,
wasn't it? It was us as humans coming across certain problems, investigating them and trying to
overcome that. the art of tribology, if I can quote an art, came out of those problems we've come
across. Yeah, every advance we've had in friction has really been born out of necessity, which is
kind of funny because I was thinking about this yesterday. When we first learn about it, you learn
it in school and then you sort of forget it. And everything beyond that is, we're going to ignore
friction. We're going to ignore friction. So that's kind of what we're taught as students. But
throughout history, We have not been allowed to ignore friction because if you do ignore friction,
you're not going to succeed. You're not going to get that engine to give enough power to overcome
the friction. It's a necessity that we've been forced to contend with. And that's why we've sort of
stepped along throughout history, advancing our understanding of it. I really like one of the
sentences you use in your book. I think you say, yeah, you two have adapted to and tinkered with
friction your whole life. Can we expand on that? How do you see people kind of tinkering and
adapting to friction? Yeah, so I think adapting to friction,
we've done it in ways that we are not even aware that we're doing it. So we have been having some
crazy weather, right? And we will change the way we walk when it's rainy or if it's icy.
We change our footwear. That's much more intentional. But if you... of think a little bit about how
you walk. You sometimes take those smaller steps. There's just different things you're doing to
adapt to the change in friction. And then in other cases, we are very intentional and we're
actually tinkering with it. When a screw is jammed up, we go straight to WD-40 to put it in there
and loosen up the screw. When we have those icy conditions, we'll put sand or salt or grit or
something down so that we can change the friction. And even something like your favorite pen.
You're picking that because of how it feels when you're writing it. And that's really coming down
to the friction that is being experienced as you write on the paper. So lots of different ways that
we are constantly adapting and tinkering with friction. I was just thinking is, if we bring it back
to the modern day as well, right up to the kind of cutting edge of tribology research, you know,
and obviously we're biased, both me and you here, is... In biotribology now, we're really
interested in the friction of foods and skin creams. And I was wondering when you're cooking and
making recipes, whether you're inadvertently changing the mouthfeel and the friction in the food,
you know, with different kind of mixtures or cakes and, you know, different kind of things in
baking. Have you got any comments around that? I think you're spot on. I think it is 100% part of
what goes into recipes. Sometimes, again, unintentionally but sometimes very intentionally if we
substitute an ingredient we want to make sure it feels the same like you don't want to substitute
ingredient and all of a sudden the texture's not quite right so it is something that we are doing
with intention now but in some cases not so much and then there's the whole other side of friction
there's the huge story of friction throughout history of trying to make sure we can cook without
things sticking and friction and so sometimes We're also trying to mitigate the friction in the pan
or the pot without impacting flavor. That's a huge part of it. You don't want things to stick, but
you don't want to get a greasy texture on the cake you're baking, right? So the way around that is
to use grease-proof paper or PTFE or something on the surface. Yeah, although obviously PTFE is a
little bit controversial right now as that. But that's the whole story of PTFE, right? That was one
of its biggest uses. But because we've learned more... ptfe now we're we're phasing that out of
cookware and again being forced to evolve our technology adapting friction and developing new non
-stick coatings or different papers or cooking sprays that don't impact the taste or the texture
but help with that non-stick issue where do you think people come across friction in their
everyday lives but not realize Oh, you could probably be here all day identifying where friction's
impacting us. One that just jumps out to me right now is actually blinking, right? I don't think
anyone's really thinking about the fact that there's friction involved every time you blink because
you're blinking how often throughout the day. And you would only really maybe think about it when
that friction's changing, when you have dry or irritated eyes. But that to me is definitely an area
where friction's impacting you all the time and you just don't realize it. I suppose like day-to
-day as well, you'd have... Yeah, footwear and your tires on your car, I guess the obvious ones and
conditioner in your hair and skin creams and yeah. Yeah, we could go through a whole morning
routine, right? You get out of bed, your feet on the ground, friction is there. You know, if you
put your slippers on and they don't have the sticky pads at the bottom, you might slip. Brushing
your teeth, your tires, your windshield wipers, your shoes, every interaction that you have
throughout the day that's involving something moving, friction's there and you just don't
necessarily realize it. If we take it back to the introduction then, as engineers,
we're frequently taught to assume a friction coefficient or to ignore it. So if we take our day-to
-day lives now and use that assumption, what would be the results? You know,
if the friction on your shoe is 0.1 instead of 0.5 or something, and you know, what would happen
then if we follow the textbooks, I guess? Oh dear. Oh, the physical world would just,
our interactions would be so different, right? a coefficient of friction of 0.1 in our footwear,
that would be great for something like curling, where you want to be able to slide across the ice
when you're throwing the stone, right? But if it's that low when it's raining outside,
then you're probably going to be slipping and sliding. So assuming... or trying to design to one
specific coefficient of friction is not how the physical world is going to work. And if you assume
the coefficient of friction of 0.1 when actually it's going to be 0.5 in that shoe or higher,
then you're going to have big problems because nothing is going to work the way you think. And this
is huge with machinery design, right? If you were to assume that those moving components all have a
coefficient of friction of 0.2. But that's not at all what the reality is. Your actuator is not
going to provide the right force to even make anything move in the first place. So you have major
problems. You're going to slip everywhere and things aren't going to move. I think in the book,
you had this lovely way of describing your time dancing. I think, was it tap dancing?
And you wanted like a certain level of slip, but also a certain level of stick as well.
So I suppose, you know, the way you've... with the friction of the tap shoe designer or i suppose
you you yourself buying it the shoes would be to get a certain level of that characteristic and i
think you describe really well as as well the um the slip of the tennis shoes i didn't realize you
know how important when you can see it now once you know but when when you're playing tennis The
sliding of a tennis player, I guess, to keep their body square to the ball and return the ball is
difficult. And then you brought up a very important point in Wimbledon where it's grass courts.
That must play havoc with the players trying to control that because grass has a huge change in
coefficient of friction depending on the moisture and how wet it is. And thankfully in the UK,
we have lots of variability. All those kind of things. Yeah. Yeah.
I mean, the grass in Wimbledon changes throughout the two weeks too, right? So the shoes that you
wear at the start of the tournament are going to be experiencing very different friction than
toward the end. And I mean, how do you design for that? That's a very difficult challenge with
friction. And then when you're buying your kind of tap shoes, and I assume it's the same kind of
thought process and buying... tennis shoes if you're playing wimbledon and i've never played
wimbledon so so would you do you know how the people would design those shoes or what's the kind of
process there of getting the friction characteristics just right the really challenging thing with
dancing as you could be on various surfaces right so professional dancers the stage will probably i
mean hopefully be a bit more controlled but i was amateur and doing this on Different stages with
different textures. So you never actually knew fully what the friction was going to be between your
shoe and wherever you were performing. So often what I'd have to do is I'd always get the same tap
shoe. You basically will get the shoe that works best for your foot because there's also the
complicated dynamics of the shape and everything of your foot. And depending where the performance
was, I would... how the taps were doing on that floor. And if I knew I needed a little bit more
traction, we'd actually take not the part of the tap itself, but just next to it and scuff it up
until it had the right feeling. Obviously, if you scuffed it too much, you'd have the problem of
giving yourself stick slip, which you didn't want to do. But it literally would change. And I just
you go through a lot of shoes as a dancer because of this, but I would adapt the scuffing to it.
And it was the same similar thing with pointe shoes. really important to have the right friction
there to go up on point. And so in that case, you use rosin. You literally dip the shoes into the
powder rosin and clap it off. And again, you figure out the right amount of rosin for how you dance
to get the friction you need on whatever stage you're dancing on so that you can look graceful and
not like someone who's fighting friction while trying to look graceful. Yeah. So I guess the rosin
is to increase friction on the toe part. Okay. So as you go up, you have control then.
Okay, cool. Yeah, so I guess we'll move on to discussing your book is a lovely kind of continuum of
the history of tribology. And I suppose we'll talk a bit about that. When did scientists first
begin studying friction seriously?
Technically, I believe the first person to do it was da Vinci. You know, if we look in his
notebooks, it's very clear he took a very scientific approach of trying to understand friction. He
sketched out tripometers and he even did the, oh, the coefficient of friction might be 0.20 for
everything and that he backtracked that. But the problem was he didn't share this information. And
so this was really lost in his notebooks really until the last century. So we'd have to fast
forward. I think it was about 150 years later into the 17th century with Guillaume Amantans.
And that is really where. the science of friction, I would say, kickstarted because Amitans found
the exact same things da Vinci found, but he fortunately did share it publicly and documented it.
And so that was really when we were off to the races with scientifically approaching friction.
But what timescales are we talking now between da Vinci and Amitans? Oh,
so da Vinci would have been the turn of the... 15th century, and then I think Guillaume Amantans
was 150 years later. Okay, so a big gap there. Yes, there was a pretty big gap with that.
Yeah, so you see some of the diagrams of da Vinci's kind of tribometers, I guess,
the weight pulling on a slider and how we'd measure it. And, you know, they haven't changed a lot,
have they? No, he was spot on. He had sketches of ball bearings in raceways, right,
which is literally when you search for a ball bearing, it looks exactly the same. So it is a bit of
a... that he didn't share it and his notebooks if you read about them he had a an interesting way
of writing so even if people he had had his notebooks kept safe with a trusted friend and then they
just got stored away but even if you or i had sort of come across them the way he wrote i believe
it was like mirrored and they think that might have been because he was left-handed so it wasn't
even something where you could quickly glance down and immediately decipher what he was doing it
took a little bit of effort to understand his notes so it's just a Interesting little side tidbit
about da Vinci there. Yeah, great. And if we kind of fast forward then to close to the modern era,
we get to who's the next kind of person to take up the mantle, I suppose. I think a few of them are
in the UK as well. But who was the kind of next group to take it up? Let's see.
So after Amantons, we have Coulomb. And Amantons and Coulomb are really credited largely with the
first three laws of friction. When we start fast forwarding from that and start looking also at
fluid friction, you get to Osborne Reynolds, which is he is in the UK. And then we get a bunch of
names in the UK with looking at how contacts behave with Greenwood Williamson and Tabor.
And then we also have we eventually get over to the United States with a mechanical engineer named
Robert Thurston, who I believe he is. 18th century,
1800s, was on record basically saying friction's the enemy of engineering and wanted to reduce
friction in factories and plants. And I think that takes us pretty close to the modernish era.
And then we get obviously into the 20th century. We had the committee that was formed in the UK to
really look at this, at the bigger picture of what was happening with these moving surfaces. And
that, of course, was the... Jost report that gave us the word tribology actually almost exactly 60
years ago. Of course, yeah.
Thorsten, is that how you say his name? Thorsten. Thorsten, sorry. He's the chap who he quoted as
saying about 50% of the energy in a factory can be lost to friction. And that was like a huge
takeaway I took from your book because I didn't realize it could be that high. Yeah,
the Jost report came along. And then I suppose, yeah, if we really push forward now, who are the
kind of modern day scientists? Where does it go to next?
I guess you get to the Greenwood kind of people, I guess. And then your old prof,
I guess, like as well. Yeah, I think you start getting, there's Greenwood and Williamson, there's
Johnson, Kendall and Roberts who looked at different types of contacts. And then we start getting
into Duncan Dowson was in there as well. And we start getting into tribologists who are practicing
today. And in academia, there's great labs worldwide now. And I think the most exciting thing is
actually the fact of how prevalent it now is in industry. I don't know if you've sort of seen this
as well throughout your career, but when I first started... was the person starting up the
tribology lab in the industry I was working in. And now all of the companies in that industry have
a dedicated tribology lab, which had not been the case previously. So we're starting to see a lot
of different people moving into the field of tribology just because friction's everywhere. So you
have to figure it out. Yeah, I suppose through my career, a few observations I've seen is...
A lot of companies work in this space, but maybe it could just be one person. You'd be surprised
that a lot of the Formula One teams in the UK, they may only just have one person working on
specialist tribology. It may be wrapped up in a materials department, or it could be wrapped up in
described as energy efficiency or company efficiency or something like that. You'd have these type
of people. I find people move through it quickly. That's one thing I always take away.
I think if you become quite a good... tribologists, if you're good at the chemistry of lubricants,
good at material scientists, good at quantum mechanics, measuring friction, you generally become
quite valuable in an organization. And then you move into different parts of that organization.
Yeah, that's one of my biggest observations is how people move through quickly. Yeah,
that's a great point. And on the flip side and sort of related to that is the fact that there's
also people who are more generalists. Having to contend with friction. So they'll have,
you know, the mechanical engineering role that their projects are changing all the time. And
depending on what the project is, all of a sudden then they have to really focus on dealing with
friction and they will. And then the project will close and then they switch over to something
else. So it's like friction is creeping in everywhere. But then, yes, on the other side of it,
when you have the specialist, I've seen the same. are able, they move up and around quite a bit.
And it's valuable, but that's also, oh, they were so valuable they moved into something else. So
who's focused on it now type thing. Yeah, and it's amazing, you know, some of the problems we've
kind of seen over the past years. And like following on from one of the points we had from your
book is the development of tribology with problems. And we're certainly seeing problems coming from
all over kind of different parts of industry, from anything from, you know, monitor arms being an
interest in new winter. to chocolate to snacks to you know all formula one cars parts you know can
it stretches across like a huge continuum and and yeah usually comes from a problem you know
there's a problem with alternative proteins now people don't like the taste or the feel of pea
protein when they eat it they prefer beef or sausages or whatever You know, and so it's a tribology
problem, isn't it? So now there's this whole development that's going to happen around biotribology
of mouthfeel. It's already happening now, isn't it? It follows on from the history of your book and
you can see it happening now where there's going to be a huge amount of research on these niches
based on the problems we're facing as a society.
Yeah, it's a great point. And it's just, it's going to be more of the same but different, right?
We don't necessarily know where friction is going to take us until suddenly it's taken us there.
And even though we've been studying friction now for hundreds of years, we're still having to learn
an awful lot to be able to move forward. Because I think if you'd asked people even 50 years ago to
think about friction with eating, it would not have been on anyone's mind. And now it's a top of
mind problem. What is the role of friction in our experience with? eating and foods and what can we
do to optimize that would not have been on you know any conversation about friction 50 years ago it
all would have been machinery parts really exactly and then we've got to adapt we have to adapt
quickly because it's a big problem i suppose it's a big problem but it's also a huge market isn't
it so that's why it's it's becoming popular because if if you can make these processed foods more
tasty that they have like a big um profit margin and you know companies want to look at that,
obviously. I suppose with your kind of 40,000 feet view now of the history of tribology and you've
worked as a professional tribologist for a long time before your career, where do you think we're
kind of going? You know, what's your, I guess another way to ask, what's your favorite bits you're
working on and where do you think we're moving as an industry and where do you think the kind of
problem spots are? Well, that's a loaded question. We just touched on some of it there.
I think biotribology is probably among the most fascinating and how we can really quantify what is
often a subjective experience right it's i don't like the way this feels my mouth how can we
scientifically quantify that oh look friction is there it's something that we can do so I think
that that is really fascinating and as well as using friction as one of these tools as we try to
make things more sustainable by substituting out some of the more hazardous materials or things
that we can produce more sustainably friction is a good lever to use to compare from A to B to make
sure it's the same but I also think there's A lot we still are learning about friction inside our
own bodies, the roles that it's playing in different biological processes. And as we understand
that more, how we can maybe use that for therapeutics or understanding how that one variable plays
into the larger picture. And so we can also model things more accurately because the more you can
understand every variable, obviously you model. So things like protein folding. That to me is an
aspect that I find very fascinating and we're making leaps and bounds with it, but there's just
still so much we don't know. I'm interested in seeing where it goes. Yes,
on the bio side especially, isn't it? I think we spoke before where when you start looking at the
biological... kind of tribology systems in the human body or in nature you realize how clever they
are having evolved for how many millions of years and there we are putting a base oil between two
gears you know we're pretty prehistoric so yeah there's lots lots to learn i agree there's
fascinating some of the work you you see by the different groups you know when they're looking at
all these different like synovial fluids or different ways of wetting and hydrogels and proteins i
think it's it's fascinating it's going to be a huge there's biomimics i think people use as well
when they try and mimic the natural world for surfaces or lubrication or whatever.
How much of modern technology do you think depends on controlling friction?
Well, is the modern technology moving? Because if it's moving, it depends on it.
So I don't know how to quantify how much is moving, but I'd say it's an awful lot of things moving.
And so most modern technology is depending. on controlling friction. And the bigger question to me
is if we've recognized that in all the opportunities it's there. In some cases, I think we have,
you know, the car and automobile transportation industry is, you know, a great success story in
starting to identify ways we can control friction. But with other technology out there,
have we looked at it yet to figure out how to optimize it? And if not, what kind of energy savings
are available to us by doing that? But yeah, if it's moving, there's friction and there's a lot of
movement in modern technology. Indeed. And I suppose our challenge is to keep it moving as
efficiently as possible. I suppose we haven't talked about failures, but maybe we'll keep that for
another day. But, you know, it's like keeping the thing moving, stopping it from breaking, I
suppose, is the first challenge. And then to optimize and reduce energy efficiency. And that was
the whole thing. When you have to have a plant go down, it goes back to thirst. And that's why he
was saying it's an enemy. very expensive when you have machines that aren't working anymore and
friction can play into that yeah and it's still true of modern factories maybe even more so they
run so for such long hours and any kind of downtime is huge loss revenue isn't it yeah we demand
more and more and the more we fix it the more we want from it if we look look to the future a bit
more then we've talked a little bit about the developments what do you think are the most kind of
exciting developments that are happening that you see happening now? I think one of the things that
excites me is the fact that we have reached a point where, yes, we still have a lot to understand
about friction, but in many cases, we understand enough to actually use it as a tool to get things
done and perhaps done in a different way. So if we look at recycling lithium-ion batteries,
friction is being used as a process to try to do this more sustainably. The whole process of making
lithium ion batteries is just, it's not nice. It is not sustainable. It is something we have to
improve because these batteries are used in everything now. So if we can recycle the lithium being
used, that can help with the natural resource and extraction. And so they've developed a process
that is deliberately using friction to do this. And by doing so,
they can run the recycling at lower temperatures, so there's less emissions and toxic emissions
coming out. The acids that they can use to help with the process are actually much weaker, so
they're less hazardous. And overall, it is actually a lower energy process, even though we always
think of friction as wasting energy. But to me, this is exciting because we are now looking at
friction as a tool to help us and to solve some challenges like...
the lithium-ion batteries and making them more sustainable in any way we possibly can. Yeah,
it's a really interesting point that we've gone from, I guess, being reactive and trying to solve
problems as it comes to using it as a tool to some kind of development,
like you say, the lithium batteries. Yeah, it's a really interesting. Yeah, I suppose it's becoming
more of a well-established science that people can pick off the shelf and use in their processes.
Another challenging question for you, but you know, you're the one that wrote the book, so I'm
going to keep going. Could we ever create machines with super low friction that never wear out?
I mean, in my own defense, I don't think I'd go anywhere near trying to touch that subject.
I think we will continue moving towards making things as efficient as we possibly can and always
trying to lower the friction and lower the wear. Personally, maintain a healthy skepticism if we
could ever have something that never wears out. And I also, I appreciate that you said,
really low friction rather than frictionless. I get very annoyed every time I hear people say
frictionless and they're saying it all the time now. It's like a buzzword being used and I'm just
like, there's always going to be friction. So that is my personal view. I'm happy to be proven
wrong in the future though. What's your favorite factoid you came across?
when you're writing a book that is full of interesting ones that I haven't heard of. But, you know,
what's your favorite? Jessica, give us a few, if you like. Yeah, there is. I was surprised with
some of the interesting tidbits I stumbled across on this, you know, because it's funny. We're
tribologists. We think we're pretty familiar with this stuff. But then just random, interesting
bits of history came up with this. I think I'll go with one that was really baffling,
actually, and kind of funny. And it comes from... of Romans using ball bearings in a very
unexpected way. So there was this, these legends of sunken ships in Lake Nemi,
which, and we're not talking about, you know, sunken rowboats. It was, they were supposed to be
really large ships. And it was just like, why would there be large ships in this? Because, oh, it's
a landlocked lake and it's, you know, it's very pretty, but why would you have a big ship in there?
And so actually Mussolini had the lakes temporarily drained and on earth.
two very large shipwrecks. I mean, you can look up pictures of them compared to people. They're
huge. And it turns out they're believed to have been party boats for Emperor Caligula,
which is really kind of a waste of Roman engineering. But on these ships,
they demonstrated pretty impressive friction mastery because they had really large rotating
platforms. I don't know if this was the first rotating club dance floor. Not sure. But they used...
eight really large bronze balls to rotate it so essentially the bronze you know the ball bearing
raceway in this completely unexpected application and at a time where actually I think historians
weren't even sure if Romans could build such large ships. So that to me was one of my favorites
because I was just, I stumbled on that one just going through the history of ball bearings and I
was not expecting Roman ball bearings at that time and especially not from a party boat for Emperor
Caligula in a landlocked lake. That's hilarious. If you're going to use tribology, you may as well
be on a party boat in a landlocked lake. You know, there's really fun applications of it. Did they
actually pull up the actual moving component or is it from drawing?
So how did they kind of put it back together? It was from when they drained the lake and they could
actually see the ships themselves and they were exploring them. Yeah, they found the platforms and
the balls. And we don't, like I said, we don't know exactly what these large rotating platforms
were for. But I'm just going to go with, you know, Roman club dance floor because that's fun.
Yes, that's for a big toga party.
I really like this. There's another one as well is with the chariot wheels catching fire,
you know, and I should do the sums and see if it's actually possible or whether it's a myth, you
know, but I remember you say that, you know, the friction can get so high in these plane bearings
and they were lubricated by, it was like an animal fat or something, wasn't it? Yeah, and I'm sure
I'm going to say it wrong. I think they called it axongia and I'm 100% sure I'm butchering that,
but. Yeah, it was in a Roman text, and I can't remember off the top of my head.
It was a very famous Roman writer who wrote it, but literally described the chariot races with
glowing red under the driver's feet. And so that made me think, I was like, oh,
yeah, because, you know, in modern tribology, we're always worried about the flashpoint, right? So
was the friction high enough that we could have gotten there with the glowing red? And they know
that the Romans for chariot races, after a certain amount of time, people were standing on the
sidelines with large jugs of water to just throw on the chariots to cool them off. So we know that
this was definitely a thing. And I'm just thinking if it's glowing red, even with a sandal between
me and feet, like that's pretty hot on your feet. So I like to say that was when the pit stop was
invented, was, you know, throwing water on these chariots to keep things from getting a little too
warm there. I was thinking this must be such like, you must look very cool, you know,
a big flex as you're racing around as a Roman person with your chariot wheels on fire.
That's a great visual. Okay, any other factites you kind of enjoyed in the book?
Well, I think on the opposite end of the spectrum, I think it is very cool that really recently
researchers were using a type of friction called dynamical friction.
to possibly detect dark matter around black holes. That sort of blew my mind a little bit.
That was a type of friction I'd never heard about because it's really a gravitational drag between
objects moving through space. So as an Earth-bound tribologist, I had no need to come across it.
But in my book, I ran across it and then came across a study published in the past few years,
so very recent, where they were looking at the decaying orbits of two separate stars.
that were believed to be orbiting around black holes, which is why the orbit's decaying, because
they're being pulled into the black hole. And with gravitational lensing and our detection methods,
they could really accurately measure the orbital decay, but their modeling was coming up different.
So they knew something was missing in their modeling. So they were like, all right,
it's theorized that there's a lot of dark matter. outside and around black holes, that would be
causing some of this dynamical friction, the interactions coming. And if we add that factor into
it, what happens? And when they did, the orbital decay rates were pretty much exactly what they
were measuring. And so it was one of these first indirect proof of dark matter around black holes.
And I thought it was really, really fascinating that a type of friction was helping give us clues
about that. I guess this is the type of force we can't measure in our canon disk rigs.
Nope. I mean, maybe there's a way. We haven't figured it out yet, but no. And it was a friction
that was introduced to us from an astrophysicist, as opposed to up until now, it was mostly a lot
of engineers, right, who in these very practical applications. But in this case, it was a very
famous astrophysicist, Mr. Brahman Chandrasekhar, who did it. Please tell me the dynamical friction
was about 0.1. Yeah, he does not even pretend to predict what the dynamical friction will be.
But if you ever want to look, it's very complicated equations that get you there. Okay. This was on
that vein of solving problems then. What problem would you yourself most like to solve or you'd
like to see being solved in the space of tribology? Yeah,
I don't work anywhere near that. that field right now, but I would love to be trying to understand
the role of friction in some of those fundamental biological processes we're talking about, either
with bacterial viral infection and the way friction impacts the DNA as it moves and is trying to
infect for good or bad purposes of the infection. I think that would be a super fascinating thing
to work on, as well as really digging into the friction involved in protein folding.
very far away from anything I've done before. But, you know, if I had like dream projects to work
on, that would be one far more practical standpoint. I'm still not entirely convinced that we have
perfected the friction of windscreen wipers. So I'd really like to solve that.
I've been having a bit of a battle with mine in the past week. And I feel like that's just always
going to be an evolving problem that we keep making improvements on because we keep advancing a
little bit on the technology. But yeah, that's... Two opposite ends of the spectrum there. No,
I hear you. Sometimes the simple problems are the most annoying to your day-to-day life, like a
squeaking windscreen wiper can ruin your day, I guess. Ah, yep.
Well, maybe a complaint to the people in Bosch or someone who make them go quite a long way.
And I feel bad saying it because I know they do a lot of engineering and design and science behind
it. So I know that it's not for a lack of doing a lot of work and they've come a long way. But
yeah, it's just when it starts to do the little chatter and the stick slip. And I mean, I know why,
I know what's happening with the friction, but I understand with the temperature ranges, it's
actually a really hard problem to solve. So I imagine it's quite satisfying to be working on it.
And then you kind of can get the instant impact of it, right? Like, oh, I made a bit of this
improvement. Look at my windscreen riper. It'd be great. Yeah, like rubber formulations are, you
know, I think lubricant formulations are difficult, but rubber is a complete.
Yeah. I do feel for them. And like you said, it's out there under all different types of
conditions, hot, cold, you know, probably stick there with ice and get ripped apart and all kinds
of things going on probably. So yeah, they probably do have a challenge. I guess one of the
arguments would be, you know, they're fairly cheap to change. Right. Yeah. It's, I mean, right.
You said they're, they're easy to change. They're cheap to change. And, but you know, we have. in
certain climates, summer tires and winter tires, because obviously the way rubber is, why don't we
have summer and winter windscreen ripers? I feel like that should be a thing. There you go. You've
got your one million pound, no, one million dollar company right there. Heard it here first,
folks.
What's the one thing you'd like people to remember about friction? You know, as we start signing
off now, what's the... It's hard to make it one because if there's one thing, it's just to remember
that friction's there. I think that's been the theme of our whole conversation. It's overlooked.
But really, I want it to be that friction. isn't the enemy. I think friction has really developed a
bad reputation, and Thurston didn't help us with that by pointing out how much energy we can waste.
But really, just because something is there resisting doesn't make it bad.
And look at how much progress we've had because of that force resisting us. So friction's not the
enemy, and its resistance is really leading us to a lot of progress. It is indeed.
And I suppose I'd like to say, you know, I really appreciate the book. And I learned a lot by
reading it. You know, I've been working in this field for a while. And it's really interesting to
just put it all in perspective, having a nice kind of fun format. And it's a real pleasure to read
it. And I think I want to say thanks on behalf of everyone, I guess, who reads it. Thanks for
putting it together and taking the time.
It probably took you several years and a lot of work. And thank you for doing that, you know, and
giving us like a little bit of, you know, a nice popular science book that we can recommend to
people and enjoy ourselves. Thank you so much. I'm glad this is audio only because Mark can see
I've turned very pink. Definitely blushing with that kind of view. It means a lot coming from the
tribology community. I've been very nervous about having this book get out there. So thank you. for
the kind words. And I hope I've been a good ambassador for friction and the field of tribology.
Jennifer, you've been a brilliant ambassador. Thank you so much. And thank you so much for coming
on the podcast and hopefully see you again very soon. Yeah, thanks, Lars. Great to see you. Okay,
cheers. Mark and Jen, we would like to thank you for taking the time to talk with us today and
share your thoughts on friction that I'm sure we can all relate to. And for your support of STLE,
we appreciate you sharing your expertise with us here. We would like to hear your ideas for future
episodes, and we would love some feedback in the comments or the link survey in the description.
For those interested in learning more about STLE, please visit our website at www.stle.org.
Thank you for joining us, and remember, keep your gears turning, keep your creativity flowing, and
keep our world in motion. Bye. Thank you for joining us on this episode of Perfecting Motion,
brought to you by the Society of Tribologists and Lubrication Engineers, the premier technical
society serving the tribology and lubrication industry. STLE's mission is to advance the science of
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