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Hey, everybody. Thank you for joining me on the unsupervised learning podcast. Today I have a returning guest, Dr. Chad Orzel, a physics professor at Union College in Schenectady, New York. And last year, you know, I talked to Chad about his earlier books, which were about about physics. He's a physicist, right? I think your most popular book is how to teach quantum physics to your dog. Right, Chad?
Yeah, the talking dog is still the most popular by a good margin. Okay, so
you guys can check out that book. And there's a bunch of others, like breakfast with Einstein, Eureka. And then I think Teach relativity to your dog. Your dog's learning a lot. This is a smart dog. All right
She was the best.
So I have to say you got a new book out, I knew you were I knew you were working on this book, we've talked about this. It is a brief history of timekeeping. And it says the science of making of marking time from Stonehenge to atomic clocks. So one thing that I mentioned before we got on is, this is a, a different book in I don't know about stylistic, but I mean, you're kind of going into a topic outside of your- your bailiwick, and kind of touching a lot of different things. This is not just a, I mean, physics books that are written for the popular audience always have to have people and kind of talk about things besides physics to anchor people. But you know, there's a lot in here. That's beyond physics, like we're talking 2012 We're talking, you know, water clocks and all this stuff. So, you know, I will mention that. I mean, this is a history book, as well as a physics, you know, engineering history. I mean, it's pretty different.
Yeah, I mean, this, this comes out of a class that I taught here at Union. So we're a liberal arts college, right. So everybody has to take a bit of everything. And we have this in our general education curriculum, we have this course the sophomore research seminars, which is supposed to be interdisciplinary cover a wide range of topics. And this is a topic that I did for one of those. So you know, I've taught this to classes that were mostly STEM majors, students have also taught this to classes that are almost entirely not STEM students. So you kind of have to, you have to have a balance of of, you know, some some stuff that has a little bit of math in so that the future engineers are happy, and some and some stuff that has absolutely no math for the the future arts majors and it works out pretty nicely. So this, this book kind of grew out of out of that. And they're the starting point for all of it is recognizing that that obsession with time and timekeeping is something that that crosses pretty much every culture that we have decent records of, over a span of 1000s of years, people have always been trying to tell what time it is.
Yeah, I mean, I just want to mention, I really like the cover, obviously, I know, I know, this is superficial thing. And I actually don't judge books by their covers. I hope I hope listeners know that. But I mean, I'm predicting good things from the book, just by the cover. I've heard that that's that makes a difference.
They did a really great job. I'm really happy with the way the interlocking the brass gears on the blue, it really pops and yeah, and it stands out. So yeah, I hope it's I hope that's eye catching. And yeah, it does really give people a pretty good idea of what what you're looking at.
Yeah, so um, you know, you touch a lot of topics. And I do have to say, sometimes when authors go outside of their not saying 'comfort zone', but their core specialty in academia, you know, they can kind of lose control. You know, I talked to Armand Leroi last year, and he wrote a book called The lagoon about Aristotle, it was a really long book. And he admitted that it was because he was going into history of science. He's a developmental geneticists, a biologists. And when you're talking about biology, we talk about developmental genetics. He knows what to include and what to not include. And he can kind of defend himself as a area specialist, right. So when he wrote the lagoon, well, he's not a historian of science. He's a big fan of Aristotle. But he's not historian of science. And so he just really, really went everywhere to like, cover his bases. And the book is, I think, almost 500 pages, it's a pretty long book. And that was obviously, he said, like, you know, the feedback, it was just an enormous problem of people getting through a popular book, you did not have that problem. I feel like you stayed within the 300 page. I mean, that that seems to be like, the high end, but not like incredibly high. Did you have to cut a lot of stuff, like, I'm actually curious about your process here.
Um, so for me, the the focus is more, I'm covering a lot of history and have a lot of the historical topics there. But my primary goal is I want people to come away with with us knowing a little more about the science of clocks, right, knowing more about, you know, why is it that a swinging pendulum is something that makes a sensible clock? And, you know, why is it that people spent all this time, you know, working on predicting the orbits of planets and that sort of thing. Because, you know, at the end of the day, that's my real goal is to get people to know more about science and have a greater appreciation for what's going on there. So the the really the hardest part was like, cutting that stuff, like not going into huge detail about stuff that I know really well, because I get enthusiastic about that. And then, you know, we're talking about Fineman diagrams or something. You know, there's no need for that.
Yeah. Yeah, I know what you're saying there. I mean, you know, we both went to substack. And I forgot to mention that I'll link in the show notes. Chad's gonna substack I gotta substack. And, you know, my editors, like, no one cares about this. And I'm like, but like, Don't people care about this minor detail? She's just like, you just said minor? Yeah. Yeah, go on.
We had a couple of we had a couple of points. There. There was one point where in my editor was, like, had a comment at one point that was like, Oh, God, more astronomy. And I'm like, No, this matters. This is important! like this, itself. That is the whole point, though. So
when I get that comment, what I've learned from this is, this is my fifth book, I've learned that when I get that comment, it doesn't mean that the Astronomy Part is necessarily bad. It means that I haven't done enough of a job of making the case for why this matters, so that somebody who isn't already interested in it will care about about what we're doing. And so, you know, so I had to go back and, and reconfigure some sections and put some more material in there to say, like, look, this is why this doesn't seem like it's leading to a clock, or something that you would recognize as a timekeeping device. But in fact, it's really critically important to sort of that, you know, the millennia long enterprise of being able to understand the world in terms of how time is marching forward, and, and what's predictable and what's not.
Yeah, I mean, so, yeah, you began. I mean, the beginning of the book is basically ancient astronomers stuff like I mean, and I think people of our generation, the Time Life books, you know, ancient astronomers on TV, you'd see these commercials. And so you start out with Stonehenge and new Grange. Can you talk a little bit about that? Because this is this is archaeology slash history of science. And I think, you know, much, much respect to you. I think that's a really good place to actually hook people in because it kind of starts at the beginning. And people know what Stonehenge is right? They kind of have an intuition. So can you talk about that?
Yeah, I actually, I probably talk a little bit more about Newgrange than Stonehenge because it's actually older but it has the downside, like Stonehenge is on the cover in the subtitle because Stonehenge is the one everybody knows, right? Everybody knows the, the Spinal Tap song and all of that. So. But yeah, that's, that's really the place to start, because that makes it clear, most clear that that we're talking about something that's really a fundamental human preoccupation, right, that, you know, 5000 years ago, people went to the effort to drag you know, tons of stones over long distances and pile them up in particular ways. So they could mark the passage of the year and you know, a calendar is really just a very slow clock, right? It's a clock that ticks once a year as you come back to the Winter Solstice. That's what that's what Newgrange is. Newgrange is a passage tomb in Ireland. It's right outside of Dublin. And it says massive artificial hill with a passageway that goes into the center. And for just a couple of days a year right around the winter solstice. The rising sun will cast a beam of light all the way down this 20 meter long passage into the central chamber and the only time that sees light here. So this is a device that marks you know, here's the short, here's sunrise on the shortest day of the year. So you can check that. Okay, we know that now it's been a full year, right. And now it's time to start getting ready for, you know, we're at the darkest point of winter, like the days are going to start getting longer. And it's time to start, you know, thinking about what are we going to do in the spring? Right? What are we how are we going to get prepared to plant things? How are we going to, you know, get ready to, to hunt animals as they come out of hibernation and that, and then that sort of thing. So, so this is, you know, something is critically important. I mean, it's a massive effort. It's like 100,000 tonnes of, of rocks and dirt that are heaped up to make this this monument and its fundamental purpose is timekeeping.
Yeah. So, you know, you talked about how we don't know much about the people who, you know, made Newgrang and stuff like that. I do want to jump in here. Have you read Dr. Lara Cassidy's ancient genomic works on the demand buried in new Grange? Oh, no, I haven't. Okay, so this is within the last year. So I'm gonna like tell the listener here. I'm gonna take a short digression because we actually do know a lot more since I think I think this is since you started writing the book.
Almost certainly. It's been a couple years.
Yeah. And so basically, what's going on with Newgrange here is there's a man buried at Newgrange, he was sequenced, his parents seem to be siblings. And his genetic sequence indicates that he is descended from Neolithic farmers from Spain. And there have been other passage tombs in Ireland, where they got sequences, and most of the men at these tombs share the same Y chromosome, which indicates that they were part of an elite paternal lineage that probably had a lot of power in Ireland at that time. So just to add a little color to what Newgrange was, and you know, why they invested so much. I mean, who's, who's investing the effort to create these, like, you know, Cyclopean, like, you know, stone works and stuff like that. It's not just like some bottom up, like, you know, communist utopia. It was like, it seems like some really powerful people were like, we're gonna get this done. You know?
Yeah, no, it had to be a massive, coordinated effort. And it's also, you know, like, you could go to the monument now and take a tour. And, like I can, I'm a big guy, I can barely fit through the passage. But you can go go into the center, and they have it rigged up with light bulbs. So they simulate what it looks like at sunrise on the on the solstice. But, but you know, you're not putting, you're not putting a lot of people in there, right? Like the this is elite knowledge, this is going to be...
Only the most important - only the most important, right?
Yeah, there's gonna be, you know, three, four people in their tops watching for this. And so this is this tells you something that, you know, this is knowledge that's incredibly important to them, but also tightly controlled by, you know, somebody who's in charge who was able to muster this massive effort to put this together. Stonehenge is a little more - and that's a little more debatable as to exactly which thing that's meant to mark. But Stonehenge like, that's wide open. Right. You know, you could, yeah, they do it today. Right. I think they're, I think the evidence suggests they're doing it on the wrong Solstice, but you get, you know, 1000s of Neo pagans showing up in the summer to watch the, the sunrise, when I think the evidence suggests it's probably actually aligned with the sunset on the winter solstice.
Yeah, that makes sense. So I mean, so, you know, with with time, I think, you know, you know, so, you know, you're a physicist, you know, we talk about science and objectivity, and these, like, universal realities that transcend space and time, right. That's a big deal. But, um, I mean, one of the aspects of your book, you know, of your scholarship here, that I think I want to emphasize to people is, how integrated a sense of time was into the lives of early humans? And how you know, so I think in terms of evolutionary - human evolutionary context, right. Okay, so you need to know when the harvest starts if you're an agriculturalist, or if you're a forager, or maybe your migratory patterns are due to time due to the sun, this sort of stuff. And like, yeah, sometimes it gets warm, early, or warm late, but really, you can't always just follow the weather because it could be like, it could be like a false spring and then there's like cold again. So you have to like have these regular cycles. And so this is why time is important. And now you know, with Newgrange and you know, I do have to say I wish Newgrange was more well known, it's very beautiful. Just just the stonework is very beautiful. It's very awe inspiring. And the other aspect is you know, humans we bring religion into many things and so Father Time and you know, time related gods and so you have this functional need for time, and then you have kind of this spiritual dimension, and then integrated into all of that is this like material, physical, scientific dimension of like, okay, you create an instrument that measures this abstraction. So I think with this book, I just want to make it clear to people, you're touching on a lot of different dimensions of human experience and perception. And I think that's kind of the goal of your original class. And, and like what you're doing here, right?
Absolutely. Yeah, the the idea is to point at this is something that that sort of permeates, you know, every aspect of people's lives and, you know, for 1000s of years, and, you know, and across cultures, and, you know, there's like, that's, you mentioned, the 2012 stuff, like I have a section in there about the the Mayans, and you know, that's, that's a culture that did something radically different, as far as their timekeeping, because they had this intricate system of cycles, that would give one one way of looking at, they gave a four character name to every individual day through a combination of a 365 day calendar and a 260 day cycle that, you know, gives you this, this set of cycles that repeats after about 52 years, which is kind of a very human span, right? That's, that's long enough that you know, someone who makes it out of childhood, even in a Stone Age culture, someone who's making it out of childhood, can expect to see 50 years ish, right. So, you know, you might see days that you remember, repeat again, and that's kind of a there's a kind of, you know, poetic element to that. And they also had this, the thing that led to all the 2012 Nonsense, a decade ago, was this system for sort of deep time, right? They have these very long cycles that are hundreds of years, that supposedly, you know, were coming to an end in 2012. And that, that's another way of looking at it. That's a that's a thing where they probably were backdating themselves. They were probably if you look at the the nominal start date for that calendar. It's so far in the past that they almost certainly didn't really, you know, start it, then they probably started it, you know, 5000 years later, and said, we're starting at 5000.
Yeah. So you jumped to the Maya, I want to like actually, like, roll it back, or like in terms of like the chronology your book, but also I think real chronology. Egyptians and you know, the lunar calendars, I think the Babylonians were doing lunar calendars, they're really common. A lot of Americans, you know, we're busy people, whatever. We don't encounter ideas like the lunar calendar, unless we're maybe like Jewish or Muslim or something like that. Or Chinese. I don't know, lunar calendars are really common. Solar calendars, though, are really useful is the way I would say it. So can you talk about the lunar and the solar differentiation? Also, the beginning of the Egyptian calendar, you pinpointed how specific it was - talk about that? I think that's an interesting fact, we have like a really specific date this early.
Yeah, there's, there's an interesting thing that goes on, right, because the moon is is screamingly obvious, right? Like, if you're someone who's outside at night ever, right? You You're aware of the changing cycle of the moon. And so counting full moons and days from the full moon is a very natural thing to do. So everybody tries to make a calendar out of that. But it's not an integer number, right? There's there's not an integer number of full moons in a year. It's 12. And a bit. So if you're just counting full moons, you come up a bit short of you know, 12 full moons is a bit less than a year. And so if you're trying to track the seasons, that way, it starts to go wrong pretty quickly. So you got to do something else every few years, you've got to have 13 full moons in a year. And so there are the systems for interpolation and adding a adding an extra month here and there. But because you know, the moon is really convenient, and that it's it's a 28-29 days cycle to complete. And it changes fast enough that you could look at it and say okay, you know, it's been like four days since the last time we checked - checked in with the moon. But it throws you off what really matters for agricultural purposes is the solar year, right. That's how long it takes to complete an orbit and come back to the solstice or the or the equinox. And those are incommensurate. With the Egyptians. The Egyptians make this break where they go to mostly solar calendar. And it happens because they have a really convenient agricultural cycle and also a really convenient astronomical marker, which is the most important event of the agricultural year in ancient Egypt is the flooding of the Nile. which happens every year in late summer. And just before the Nile floods the star Sirius, which is the brightest star in the sky other than the sun, the star Sirius will rise just before sunrise, right? It's for a period, it's behind the sun. And so we don't see it in the night sky at all. And then you know, just before sunrise Sirius starts to appear above the horizon. And that's a really screamingly obvious marker in the sky that hey, the flood is coming real soon. So the Egyptian calendar is nominally anchored to that, right, the start date is supposed to be the helical rising of Sirius and, and that marks, you know, that comes just before the flood, which is the start of their agricultural year, and everything flows from there. So they set up a calendar that did their, they did their best to just match that, right and forget about the moon, or they kept track of the moon for some ritual purposes. But they didn't keep time by the moon, they were going by a more solar calendar that's checked against the this rising of Sirius. And they got really close, they got they had a 365 day calendar, they had 12 months of 30 days each, right, which is very much like our calendar. And then they had this five extra days that were tacked on at the end that were, you know, holidays, basically, and, and that comes really close to a solar year, which is 365, and a bit less than a quarter. But it's off by a quarter of a day. And so every four days that that rising of Sirius, which shifts relative to their calendar by a day, you know, it takes, you know, 20 30 40 years before you really know that that's what's happening, at which point they kind of made the decision to just track that. And but the Egyptian civilization lasted so long that, you know, it takes 1400 years for.. if you start with serious rises on day, one of the calendar, it takes 1400 years to come around to Sirius rising on that day again. And they lasted through two cycles of that. So that's how we know approximately when they implemented the calendar. Because, you know, they came around the second time in the Roman era. And the the Romans made a note of, you know, the Egyptians have this cool solar calendar, it's 365 days, you know, it drifts by a little but you know, it happened to come around just a few decades ago, it hit, you know, on this day Isn't that cool? And so we've got this record of that. And so we can say, with some reasonable certainty about when that was implemented, and the span is just incredible.
Yeah, yeah. I mean, it's, it's, it is pretty incredible. And so the Egyptians like, you know, they have this like solar calendar, that's what we're familiar with. And, you know, we know about leap years and, you know, this, like, fudging like we got it, like, you know, because basically, astronomy doesn't, you know, it doesn't align with what's convenient for us. And so we have to figure out these these workarounds. But like a lot of other societies, they use the lunar calendar. Right? And so I can you talk about why that was popular, and then why it was less popular. And, I mean, my understanding is mostly lunar calendars are around for either religious reasons, or astrological reasons today. But,
Yeah, no, I mean, the the Muslim calendar, right is strictly lunar. I mean, if you are really, you know, the certain sects, right, don't even go on, you know, astronomy says that the moon, you know, the New Moon is this day, right, like, somebody's got to see it. Right for it to be declared the start of the new month, right, that this was a case that came through the courts a while ago in New York, that somebody's saying that now like, No, you know, you can't tell me that Ramadan ends on this day, it ends when you know, somebody sees the crescent moon, right. So. So, you know, that's still in use. And that's primarily for ritual purposes. The Jewish calendar is much more complicated. It's, it's again of a lunar base calendar, and it's synced very well with the moon. And they do this thing where you know, every few years, it's seven times every 19 years. They have a year that has a 13th month. And so they add in these extra months every now and then to keep in time with the keeping time with the seasons, but also have months that are strictly tied to the moon. The China, the Chinese traditional system does something similar. They every few years, you're adding an extra month, so that that the moons you know, a new month always starts at the new moon, but you aren't drifting relative to the solstices and equinoxes. The calendar We have today is really in some sense, you know, you hate to attribute special things to Western cultures in particular, but it really comes out of in some sense, like the peculiar obsession of the Romans and the Jews, right is that that, you know, you've got, the Romans were extremely religious and had rituals that had to happen at certain seasons. And it was critically important to them that those happen that particular points in the astronomical year, right, so they wanted a calendar that was going to do that, and but they're also trying to keep this, you know, as Christianity grows out of Judaism, we're trying to keep Easter synced with Passover, without referring it to the, you know, the local synagogue, to find out when the dates gonna be. So they're trying to tie those two things together, is what ends up leading to the Gregorian calendar, which was, again, you know, that you implement leap years with the Caesars, you know, and I think eight AD is the final tweakIt was 8 BC, maybe, yeah, they do the final tweak to the leap year rule. And that's still off by about 10 or 11 minutes a year. And so by the, you know, by the 1500s, they've slipped several days. And, you know, having these rituals happen at exactly the right time in the seasons. And the right phase of the moon is critically important to Christianity inherited from Judaism. And so they're they're trying to match match this up with the Roman calendar, and you get this Gregorian reform that that, you know, is our current calendar system. And that's gonna, that's going to take 3300 years to lose a day. So. So we have this, this obsession with time that's kind of inherited from those from those cultures. Which I think is fascinating.
Well, I mean, yeah, it is. And it's interesting, because we have, you know, I don't want it I'll jump forward later and talk about like, time in the modern day, but like, you know, like, look, I got a calendar, like we've been talking about the schedule, like we have stuff to do at a specific time. So time is really important to us, but like, it's very practical and functional. Whereas for ancient people, it was very sacred. So they might not have, you know, Google calendars or whatever running to like, monitor, like, you know, regiment their whole day. They're relaxed in certain ways. When they started to work. I mean, it was like, it was a sun, right, like agriculture. But when it comes to the religious stuff, like they got to get the right day. And you know, astrology is also based on kinda like the seasons. And so your book is about timekeeping. It's interesting, because you know what I initially heard about this, when you initially mentioned it, I just thought clocks. But this is way, way bigger than clocks. And so we have basically, like, you're talking about Stonehenge and Newgrange. Okay, so those are human material constructions made out of stone, but they're calibrated and oriented towards the sky. So we have a clock in the sky, you know, we have we have a time piece in the sky. And then you talk about water clocks in the book. And then you fast forward to the future. We have nuclear clocks and quantum clocks like so. I mean, it's just like, this is abstract concept. That's a lot of things are feeding into it. I can you talk about water clocks a little bit? Because I think a lot of us know about water clock from like, period pieces. I don't think we've ever seen. I don't know if I've, I might have a science museum. I've sure I've seen a water clock. But can you talk about water clocks? And how they work?
Yeah, so the idea of a water clock is really, you know, as simple as it gets, right? You take a container with a hole in it, you fill it with water, and then, you know, you measure you measure time by how long does it take to drain? Right? How long does it take for all the water to run out of this. And that gives you a thing that you can repeat, right? It's a cycle, you can repeat the same as the sun rising and setting, you can refill it and let it drain again, refill it, let it drain again, and, and keep track of time in that way. Or you can track the level of the water as it as it falls, you know, and that that works very well as well. These are again, things that are 1000s of years old. There's a tomb and I'm blanking on the guy's name is like, you know, Amenemhet or something. There's a tomb from around 1500 BC where some court official brags that he had perfected a water clock that kept time at different months of the year. Right. And so And all it is, is it's basically shaped like a flower pot, it's tapered a little so that the rate of the water dropping remains constant. And then he's got the markings for different times. You know, there's a column for each month in the Egyptian calendar. And it says, you know, in this month that you know, this is midnight, this is you know, one in the morning, two in the morning, three more and so on. So this is yeah, that's that's 1500 BC right that people were doing this. So this is again, we're pretty sure has a ritual purpose, right there are there are things that needed to be done at a particular time of night. You need to know what time it is when the sun isn't up, or you know, if you're indoors and can't see the the stars. So, you know, people have these develop these devices, though, allow them to do that. And that's the state of the art and timekeeping up into the up into the Renaissance. Really?
Yeah, I feel like I feel like it's like a renaissance, you know, like the Medici, you know, TV shows or something like that. I remember seeing water clocks just in the background. So, you know, you know, we're talking about like, basically, okay, these are physical, physical phenomenon. And now I'm thinking about undergrad and 9.8 meters per second squared. I think a lot of listeners will immediately remember what that is. That's like, rate of acceleration, you know, the Earth's gravity well, for so, you know, I haven't like thought about it concretely. Okay. So it's under second squared. There's the time right there. You know, there are all these graphs that do like temporal, you know, like T, like time is the x axis, right? So it's just, it's just part of one of our assumptions of how we understand physics and physical processes. So naturally, we're gonna come at it through a bunch of different directions. And you know, as I was, I said, it's important to astrology to agriculture, engineering. And so I think one of the interesting things that maybe people don't know about is the importance of timekeeping and time to navigation. Can you talk about that a little bit? l
Yeah, the the fundamenta problem there is, right? If you're starting 1000s of years ago, right, you're keeping time by the sun, right? You say? Well, you know, noon is when the sun is at its highest point in the sky. And, you know, that's a thing that you can measure locally. But you know, that happens at different times in different places, right, so different points on the earth. So if you move east or west some substantial distance, then, you know, the sun is rising, you know, an hour later, two hours later, than it is where you are. So you know, the time of day, as measured by the Sun is different in different locations. That gives you a way to navigate east and west, right? North South navigation is really easy, because all you have to measure is, you know, how high is the sun when it's at its highest point in the sky? Or how high is the north star above the northern horizon? Those are easy measurements. But east west, it's hard to do, actually.
Actually - Chad, I want you to cuz I know a lot of listeners do not think about this a lot. Can you talk about the north south thing really quickly? I know. It's not like... but just I just want them to actually know what you're talking about here. I know what you're talking about. But,
Oh, yeah. So if you're, if you imagine, you know, the earth is a sphere, right? We're on it going around, right? The sun is at its highest point when it's closest to being straight overhead. So let's say you're standing on the equator at the equinox, the noonday sun will be directly over your head. As you move north, right? The sun will necessarily appear a bit south of you because they're curved. Right? And you know, straight up as you move north, that direction that that corresponds to straight up changes. And so so there's some angle between straight up and where the sun is at its highest point in the sky. And that difference tells you the longitude, or it tells you your latitude.
Yeah, it tells you a latitude. And like this is why when you watch movies about Scandinavia, there's this like beautiful light because the sun is always low in the sky.
Yeah, it's always low in the sky.
Like if you look at like tropical pictures from tropical areas, notice how bright everything is. And it's because the sun is like straight down. I think people don't realize that it's not like stuff is actually brighter in Kenya it's that the sun is overhead
Yeah, the angle makes lighting,
but but but longitude longitudes and latitudes, right? Like, this is like this is one of those like history of science things but longitudes are different.
Yeah, latitudes north south one and that's easy to measure, you're just measuring an angle that's really obvious. longitude is hard to do, to know how far you've gone east or west from your starting position, you really need to know what time it is, you need to have a way of knowing, you know, when did... the sun supposed to come up at you know, eight o'clock. At my starting location, it came up at nine o'clock where I am now that means I've gone 15 degrees to the to the west. Right. So you know, you and I are separated by you know, a timezone. Right.
We are?
So, you know, the time is about an hour earlier for you than it is for me.
Yes.
So, um, so measuring that is a really hard thing to do. And there's there's kind of two approaches to it. One is to just build a really good clock, and that's kind of the most famous of them because it has that that element of technological innovation and genius that that people really like, it's a super hard problem, particularly if you want it to work on a ship, right? If you're going to, you know, you need this information for sailing from Europe to the Americas, right, you need to know what your longitude is, you want to keep that on on board, a ship where it's rocking, and there's salt water spray, and the temperatures are going through these wild swings, that's really hard to do make a clock that keeps time well enough. The other thing you could do is you can predict events that are visible from everywhere on Earth at the same time. So something like an eclipse of the moon, right happens at a particular instant, when the moon is in, moves into the Earth's shadow. And everybody on the night side of the Earth can see that, yeah, that you can see that, you know, okay, now I know when that Eclipse is going to happen. Now I know what time it is, those are a little too rare to be that's one of the ways that people end up setting clocks in, you know, sort of the age of, you know, where the European empires are starting to get get big, but those don't happen that often. So, so it's not as useful. So what you end up with is this program that that spans years of making extremely careful measurements of the orbit of the moon, to allow you to predict what you know, where is the moon going to be in the sky at a particular time on a particular night, and then you matching that to particular stars. So, you know, the moon is closest to, you know, this star at, you know, three in the morning on January 14. And then you know, if you see that it's, you know, okay, it's, you know, at its closest approach to that star, you know, it's three in the morning, January 14, and then you can compare.. us that, you know, it's three in the morning, January 14, in London, right, and you can compare that to then your, the time as measured by the sun where you are, and that lets you determine the longitude. So this is this lunar distance method. And that's largely the work of I mean, comes Newtonian physics needs to be developed before you can predict the orbit well enough, and then the measurements to get that orbit and do the calculations come from a guy named Tobias Meyer, who was a German is from a poor family. And he, you know, got into this this map making business and, you know, took on this problem and ended up making the pivotal contributions.
Yeah, it's, uh, you know, we're talking about like, geography, archaeology, astrology, astronomy, you know, you know, these, they say, times the fourth dimension, you know, it's just, it just pervades everything. Right. So I mean, it's, it's a topic that you could just go on and on about, can you actually I do want to mention this one thing. You know, we're talking about, you know, we take time for granted, my computer automatically updates, everything automatically updates. And I think it's, I don't know what it's synced with. But it's synced with some atomic clock somewhere, I'm assuming. We are old enough. Where this was actually not totally trivial to get the right time. There's all sorts of ad hoc ways that people would like set time pieces and clocks and how they would calibrate and kind of follow that. And I just remember, as a kid, you know, during like, daylight savings time, stuff like that, you know, you'd be like, so for example, I think I remember, like a particular TV show, I would, you know, I would just make sure like, I know, this is eight o'clock. So if it's five minutes earlier, or five minutes later, that sort of thing.
Yeah, yeah. No, like, you know, we're both old enough to remember, like, you know, if you really wanted to know exactly what time it was, right, there was a number you could call on your phone, you know, with a rotary dial and, you know, in a recorded voice would tell you what, what, what time it is, those still exist, by the way, the National services in the US and the UK, both both still maintain, there's a number you can call and a voice will tell you what time it is. Because I think it's mostly for lonely people at this point. Because, you know, if you've got a if you've got a smartphone, right, you just pull it out and, and take a look. And you see a time that is that is synced with the global telecommunications network. That is, you know, everybody knows exactly what time it is all the time. Right. And so that's, that's a revolutionary change in a in a small and subtle way.
Yeah, yeah. I mean, we take it for granted, that smartphones and computers and smart things do all of this for us. But, you know, as you said, you know, we're old enough to remember a time where things were just way more manually, and then we're going back 1000s of years. And what is time, I mean, you know what noon? You know what this afternoon? Like, there's these like vague analog perception.
It's only right. It's only in the 1880s. Right? Ish, that, that we decouple time from the, the specific position of the sun. Right, this system of time zones that we use now is installed in, you know, around 1880 ish in the US, because basically, it was more convenient for the railroads to have this system where, okay, we're just going to say that everywhere in the eastern time zone, it is, you know, 1:45. And, you know, even though by the sun, you know, in eastern Maine, it's a, it's a little later than that. And by the sun, it's a little earlier that than that, in Ohio, we're just going to say, like, look, for convenience. Everybody say it's the same time through this whole wide swath of the country, that breaking us up into four time zones happens, you know, it's only 150 years ago. So, so it's changed a lot. In modern times,
Well so, a lot of us do remote work, and we work with people in other parts of the world. And I myself have started to think like, okay, you know, we should just all go by Greenwich Mean Time, and like, you know, if it's like, if noon is actually 1 AM or whatever, that's fine. Yeah, I mean, I understand that I'm not typical, collaborating with people all across the world, but it's a pain in the butt. And a lot of times, we just say, we're just gonna go by Pacific Standard Time, and everyone will just go by that. And sometimes I just wish, like, okay, you know what, let's just do GMT. And then nobody will have to have calendar sync issues and all these complications.
Yeah, you know, one of the ways that we ended up with Greenwich as the standard is actually, the guy who put this together is a guy named Alan, for the work for the railroads. He noticed that, you know, the center of the the Eastern Time Zone is just about an even number of hours from from the meridian in London. So well, let's just say that, you know, it's it's exactly five hours from London, for this whole time, which has the brilliant effect of , it doesn't fall, that line, that's exactly five hours doesn't fall exactly through any major American cities. So every city had to change their clocks by a couple of minutes. And then nobody's ox was getting gored by like, you know, it wasn't like, it wasn't like, we're adopting Philadelphia time. And then everybody in New York is like, Well, fuck them. Right? It's, you know, we're adopting something that's based on London time, and everybody's gonna change their clocks by, you know, plus five minutes minus two minutes, whatever. And that made it go much more smoothly than it otherwise might have.
Yeah, so I mean, there's so all these historically contingent things that are that are that are shaping something that's, you know, time is kind of objective, and it's fixed, but it's really not. So let's, I mean, that's kind of like a segue. Relativity. I mean, you know, we all know about relativity, but like, talk to us about, I mean, we don't know relativity. It's like, it's like random people know about the spike protein. Like, I'm dating myself with this podcast, but you know, all about the spike protein, don't you Chad?
Everybody knows what mRNA is. I can't even say it/
So tell us about relativity, and how, you know, time dilation, all the cool stuff that we know about as kids.
Yeah, that's weird. So it's kind of starts like, fuzzy and I don't wanna say subjective but subjective, that we have these ideas, I guess, like Newtonian clockwork universe, where there's like a common framework of objectivity. And now, you know, you're talking about like relativity, simultaneity, all these other things that just kind of like scramble it. I mean, I still think it's subjective, but it's obviously like, pretty weird and counterintuitive.
Yeah, it's, you know, you get people as, as I've said, in a couple of books, you get people who are - start denouncing relativity, either denouncing or praising relativity as, as sort of a they mix it up with relativism, right, with the idea that it's just kind of anything goes and everybody gets to make up their own thing. Right? Right. Relativity is a very rigorous theory that tells you, you know, how to convert, right, so if there, there's a very precisely defined difference between how fast my watch ticks, and how fast the watch of somebody moving at three quarters the speed of light Ticks, right, I can tell you exactly. If I know what time it is, according to my watch, I can tell you what time it's going to be, according to their watch. Yeah. So you know, so there's this element of subjective experience to it, that, you know, it's how much time has elapsed on your watch depends on your history, and your location and all of these other factors. And thus, is kind of a very individual thing. But at the same time, you know, if you know your history and you know, your altitude and where, you know, the path you took from point A to point B, you know, you can say with absolute certainty, what time it is, you know, for this person and this person, they can they can reconcile their their measurements perfectly. Given the equations of relativity, it's just kind of a pain in the ass.
Well, so, you know, you you explored a lot of different topics here in this book. And again, just for the listener, "A Brief History of timekeeping", great title, by the way.
Surprisingly, I've used it before.
But, uh, what's the most surprising thing that you encountered doing research for this book?
You know, weirdly the I think the thing that I found most surprising is that the mechanical clock, the earliest mechanical clocks, and the earliest hourglasses like, you know, to two chambers, one full of sand that drains drains into the other. Those show up at almost the same time, historically speaking, the the the earliest unambiguous representation we have of an hourglass is in a fresco from the early 1300s. And the earliest mechanical clocks are in like, you know, the 1200s. They're within their within 100 years of one another. And you would think that, you know, you look at it and say this, like the sand timer, you know, this is incredibly ancient, right, they must have been doing this in Egypt. And, you know, before they before they built the pyramids, but no, that didn't happen until, until, you know, 1200 ish in Europe. So it was kind of amazing. Yeah, no,
I that. Yeah. That's, that's what that is weird. So, you know, obviously, this book has like, a lot of different topics are a you know, a lot of different. I mean, you go in a lot of different directions again, like you kept it 300 pages. I mean, that's impressive. And it's a good fast read. It's a quick read. I don't think it's like, I don't know, I don't think it's super technical. But I'm a nerdy person, but I don't think it is, I think this is actually a very accessible book, I really recommend it. I do want to say though, Chad, you have a substack "counting atoms", right? So people should check that out. It's super interesting. I am a paid subscriber, just so everyone knows out there. That's a social proof endorsement.
Thank you Appreciate that.
It's a social movement. But yeah, it's been great talking to you. I hope you have all the success with this book. Last question, though, what book are you going to work on in the future? Do you know,
ah, you know, the tail end of this one there because this was finished during the pandemic. So that was kind of a slog. So I haven't really made a concrete start on the next one, I'm thinking of a thing that's come up like three or four times, you know, I talk about atomic clocks. Modern atomic clocks use laser cooled atoms, and that's my home area of physics is laser cooling. And every time I need to mention that in a book, I'm like, oh, there's got to be a good popular discussion of this somewhere. And there isn't like, nobody has written a book that explains it. That's, that's readily available. So I think probably something, something talking about that area of physics, again, introducing laser cooling, and Bose Einstein condensation, all these ultra cold atom stuff. But probably, I'm thinking that the way to do that is maybe to do also bring in some like, life in the lab stuff, you know. So, you know, here's, here's the theory behind this. And here's sort of, you know, gory, the gory details of what it's like when you're in the lab, and it floods because you did something stupid when you hooked up your laser, and the kinds of issues that show up through it making this stuff practical.
Yeah, and like, you know, we didn't get... have time to talk about it. There's, there's a lot of topics in the book, you know, I wanted like, there's laser stuff in there a lot of stuff in there that I obviously did not get to, you're not gonna get all that in a podcast. So again, you touch on a lot of this stuff, I think, you know, in the book, and you know, I probably, you know, there's a lot of celestial mechanics. I mean, look, time is a big a big subject. It's a big subject. So you touched on other things, but um, thank you for your time Chad. Maybe in a year or two ou got another book you know, just keep this regular man.
Yeah, this is this is fun. I appreciate you having me on and yeah, it's good talking to you.
