A new type of clock might require a new definition of what a second is. Is time about to turn upside down?
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Brought to you by Toyota Let's go places. Welcome to Forward Thinking. Hei there, and welcome to Horrid Thinking, the podcast that looks at the future and says underneath the big clock. At the corner of Fifth Avenue and twenty two Street, I stuta and waited for a girl I knew at the spot where we agreed to meet. It was four minutes of two. I'm Jonathan Strickland and I'm Lauren Folk. Bob and our third co host, Joe McCormick is not with us today in his place as an extraordinarily long quote. Yes, I I figured, since we would save time, would Joe not introducing himself, I would take that time and repurpose it for an even longer quote from one of my favorite bands of all time. Fair Enough. You know, some day we should really put together a playlist of all of the songs that would have mentioned. Some of them are not safe for work. Like I try to, I try to avoid those, but sometimes when I I get a little, I get a little rambunctious, punch, a little bungee. At the end of the week, Vim and Vinegar, and especially when it's like two minutes before we're supposed to start recording, and I realized, hey, I don't have a song lyric to go at the front of the show. I have to admit that every single time Joe and I are are podcasting alone with without you and what you will be doing very soon, we will because you are going on vacations. I will. I'll be cruising around. That is I believe where Joe is right now, although he could be following my footsteps to Europa. Every time that Joe and I are in the studio alone, like we we always it's like knol hits record, Null are super producer, and then one or the other of us goes, we haven't chosen a quote yet? Why did Jonathan start that? As like a standard way of opening the show. What I should do is also go back and find the first episode where I did that and just start writing down, like how many times has have you used the same four songs? Right? I know that I know that there are certain songs I've used more than once, and in fact, I almost started this one with a song I'm pretty sure I've used before. But all of that put aside, we're wasting time and time is precious. Time is so precious. Every second counts in every millisecond, every nanosecond counts, and we were learning that what we think of as a second may not actually be a second. No, well kind of okay. So so news broke at the end of May, the year which we are recording this, in that researchers had created a new clock so much more precise than existing clocks that were like maybe going to have to change the definition of a second. And that got us thinking about the history and the future of time keeping, right, And this also means, by the way that we have to redefine what a second is, by its very nature, we're eventually gonna have to readefine one, a New York minute really mass fair enough. It's not that our idea of what a New York minute or or a second is wrong. A second is a second. It's the machines that we used to tell time that are that are wrong or at the very least imprecise. So okay, you know how like how like digital clocks that aren't connected to the internet, like like the clock in your car, or an analog risk to watcher a wall clock, you know, analog meaning like has hands and gears, like like it's the kind of clock where you look at it and then you think, I remember, I used to know how to tell time this way. When I was first writing these notes, I I originally started to type old fashioned and then stopped myself because where I felt so anxious and where you could at least say, like when Mickey's big hand is on the two and his little hand is on the three. But but so these clocks that aren't connected to the interwebs slowly go off time, right, And that's because the mechanisms that drive them aren't white measuring seconds correctly, and the difference slowly adds up until it's noticeable to even our very slow brains. Right. And we could be talking about fractions of a second of an error, but eventually those fractions of a second add up to a second, and eventually those seconds add up to a minute. Now, this takes a lot of time, depending on how precise that clock happens to be, But even even if you're talking super small errors, it does add up over time, oh absolutely. And while it may not be terribly important to us, there are mechanical applications or digital applications rather, in which it becomes very very important. Yes, and uh, clocks these days are are even even old fashioned analog clocks are really pretty good at doing what they do. But that has not always been as precise the case. Yeah, As it turns out, if we want to talk about the way we are now being able to to find a second and keep that time as precisely as we currently know how to do it, behoods us to look back into our distant past and learn about the history of time keeping. Ah. Yeah, because the concept of a second is, like in the Grand scheme of humanity, relatively new. Yeah, yeah, especially when it comes to time. In fact, the original version of a second had more to do with geography than with time passing. So you know, I was gonna bust out the way Back Machine, but I don't know. Do you think I could handle a trip all the way back to ancient Egypt? I mean, we haven't taken it that far back in a long time. We I don't think I've ever taken it that far back. Do you think it's safe to be in the way Back machine and talk about time that much? Do you think it's going to get mad at you could get a little time you want? You know what? You only live once into the way back machine. You go, okay, all right, now we just have to here's the problem. The all the digits are hieroglyphs when you want to go to ancient Egypt. So it's let's see it's this is ticked off kitty cat uh uh, snakehead person and block. All right, I got it right in the first try. Okay, So here we are back in ancient Egypt. Now, to be fair, we believe that timekeeping may go back further than the ancient Egyptians, but it's so uncertain that I don't even trust the way back machine. Yeah, there are there's a possibility that the Sumerians had this covered pretty much right, but we don't have any evidence of the Sumerians actually building any sort of time keeping device of any sort. Also, my cuneiform is really rusty. Yeah, I I I'm barely hanging on with the hieroglyphs as it is. So one thing that we should mention though about those Sumerians. They had something that will later on factor in importantly in the timekeeping discussion. They loved the number sixty a lot, like a whole bunch. Yeah, the Egyptians loved the number twelve and the Sumerians loved the number sixty, and sixty is kind of a cool number. It makes it really easy to deal with certain fractions because there's so many numbers that are uh that sixty is divisible by so one through six all of those are divisible, or sixties divisible by all those uh ten, twelve, fifteen, twenty, and thirty, which starts to sound familiar when you start thinking about clocks. And so this, this this base of six kind of concept is something that was adopted by a lot of civilizations from that time and and and location. Right, the Babylonians, they said, hey, you know, we didn't dig everything you Sumerians did, but we like this sexygesimal base system. Uh So we're gonna use that for our astronomy. Astronomical calculations. We're gonna when we're exploring stuff in the sky and we're describing how it moves and the relationship of different stars to one another. This is the bass system we're gonna use because it makes it very easy to to divide by all these different numbers. Sharing kind of based on that. The Greeks also picked it up, yes, and so that ended up being very important further down the line. But we'll rejoin that, because that's like medieval Europe, y'all. When we have to get to the point we're applying it to time. So if they weren't using it to describe time, what were they using it for. Well, besides the astronomical calculations, they were starting to talk about using it to describe geometric features and also the describing geography itself. Yeah, not not just space geography, but geography right here on Earth. Yes, yes, so that you could be able to say things like where one place is in relation to this other place, other than just all right, you're gonna go down this road away for about five minutes, and then you're going to take a rat turn the yield crisp crane. If you see a guy playing a banjo, you gone too far, turn around, come back. Yeah, that's that. I wish that I knew the ancient Greek for crispy cream, yeah, or banjo at any rate. Uh. The sexogasmal system was used to help define these things and arrest knees. Use the system to divide a circle into sixty parts to create a geographic system of latitude. Um Hipparchus normalized these lines, making them parallel because before they were kind of wavy. The essentially well arrest the knees used them to connect places that he thought were particularly interesting, which didn't necessarily mean they went in a straight line. They might lean a little to the right, like, hey, this place is kind of cool, you might want to check that out. D Yeah. So Hipparcus was like, no, we're gonna normalize this stuff, make it a lot easier. And he also developed a system of longitude, which had three hundred sixty degrees. Then you have Claudius Ptolemy, who expanded on this and subdivided the three sixty degrees of latitude and longitude into smaller segments. So he divided each degree into sixty parts, and each of those sixty parts he's subdivided into sixty smaller parts. Okay, so so so that's where you get that's where you get minutes and seconds, right. The first the larger subdivisions were known as the partists minute prima, or the minutes, and then you had the second ones, known as the partisan minute secunda or second minute, or later just second. But it would take more than a thousand years for that stuff to be actually applied towards timekeeping. It was really applied toward map making and geography. Okay, but so I mean around the same time ish stuff was happening with early forms of clocks, Yes, sort of the Egyptians. You know, if we look around right here, you just look a little bit over to the right. Okay, you notice there's that big tall obelisk over there, all right, So that obelisk, it's for a real important reason. It's there to tell you when it's in the early part of the day versus the later part of the day. Yeah, in case you're not aware that it's now later than it was earlier. You can look at the shadow. I've taken naps where I've gotten up really confused. So actually that that could be very helpful that moment where you wake up and you aren't even aware of which pyramids you're sleeping, like what time of day it is. So yeah, these are were very basic clocks. They essentially divided the day up into before noon and afternoon, but they also would show when the longest or shortest day of the year happened to be. If it was the longest day of the year, the shadow would be shorter. It was the shortest day of the the year, the shadow would be longer, so you could tell kind of the time of year. Yeah, so you'd be like, wow, it's really cold out. Also, shortest day of the year. Interesting. Um, So the sun dial itself would show up in fred BC. So this is like two thousand years after those obelisks were the early stages of timekeeping. Now these this is also courtesy of the Egyptians. So we're just gonna stay here then chat about it. The device, the sun dials, had multiple divisions on it to help divide up the day a little bit better. Also, once you got to noon, you had to turn the sun dial a hundred eighty degrees around so it would continue to keep time properly. So this is the first instance of having to wind a clock so that it keeps time. Um. So the Egyptians divide the daylight hours into twelve segments. They were really big on that number twelve, remember, which is fortunate since again sixty is divisible by twelve, so that will come in hand you later. So they thought, let's divide up the day into twelve, the daylight hours into twelve segments. So there became twelve periods or hours of daylight in a day. But since the amount of daylight changes throughout the year, then the the length of an hour changed throughout the year. Okay, So so light time was was twelve hours to twelve periods, and then nighttime was night. Nighttime at first was nothing. Nighttime was just not the day was just go go home. It's just like there's nothing to do. Go to sleep. You know, there's no you don't have Netflix, we have only so much oil to burn. Go to sleep. So yeah, and at first nighttime was nothing. But then the astronomers in Egypt, they began to develop tools where they were studying the movement of stars, and they divided up the night hour nighttime hours into twelve as well. So you had twelve nighttime hours twelve daytime hours for a total of twenty four periods in a day. Right, And they again were not fixed length, right, It all depended on what time of year. So literally, in the summer you had longer hours than you did in the winter. So time did not pass the same way from a from the perspective of counting the hours, it passed the same way in a different sense. If you're not concerned about what quote unquote time is it, uh, that's trying to think about going about your day like that is very confounding to me. Well, as it turned out, most people back then really just need to know is it early enough for me to do work? Is it getting to the point where it's going to be too hot to do work? Is it the time to eat? Is it the time to not be awake anymore? Really was pretty you know, there weren't a whole lot of evites that people had to respond to with yes, no, or maybe. They were really kind of simple in that way. Now, the Greeks were the first to introduce the idea of fixed length hours, but they did this so that they could make astronomical calculations. They didn't do it so that people would keep regular time. In fact, most people didn't bother with that. They stuck with the more casual variable our system, and in fact that would hold true until the Middle Ages. Um, but that's not the only type of clock that was around at this time. Oh yeah. Also right here in ancient Egypt, where we absolutely are, were water clocks that were probably developed here. Again, you know, like it's basically whatever you dig up is your evidence for what was developed when and if it didn't survive then you Yeah, but so one was water clock was definitely found in a Menhotep, the first tomb, dating from around five b C. And uh, they water clocks covered a few of sundials or or astronomy clocks pitfalls because you could use them when it was cloudy, crazy um, and you could also use them as stop watches. The Greeks would later pick up on them too, though not until around like three b C we think, and they called them clip sidras, which I love, which basically means water thieves. And it's interesting they're called water thieves. It's specifically because of the physical way the clock keeps time, right, yeah, yeah, So so the idea here is that you've got a stone bowl with a very small hole near the bottom through which water would flow hypothetically a kind of sort of more or less constant rate. You put this, You put this bowl with a hole in it inside a larger basin that's filled with water, and the water will slowly fill the bowl if if, if the inside of the bowl is then marked with lines, you can tell the rough passage of hours by watching the water mark. Yeah, I've seen a similar one where it was again going back to the Egyptian times, where you had a container with a very small hole in it, and it would allow water to flow through one container into a second container. And the second container have a bobber in it. Oh, sure that had a water mark that could tell you, Yeah, you look at the bobber and you'd say, all right, so, uh, three marks have gone by. We're going to call those hours. But keep in mind that these devices also weren't precise time keeping devices. A rough idea. Yeah, and and I'm sure that I mean, you know, as water war would change the shape of the whole of the given device, your your concept of a pure it of time would would also change. But okay, so, uh supposedly devices very much like this. We're used to time speeches in courts of law circa four thirty BC in Athens, so even and ancient Greece we told our politicians, yo, hey, shut up for serious, come on, man, sit down, John They and okay, I think I think we're going to finally have to leap ahead a little bit. Or do I mean, I mean, do you want do you want to save it for medieval times or do you want to you know what? We we can save it for medieval times. I'm a little partial to medieval times, Okay, fair enough, fair enough, so so I'll just mention that that these water clocks went mechanical after a few hundred years by by letting water the Grecian water clocks, I should say, by letting water drip measuredly into a chamber like you were just talking about, you can you can raise not just a little bobbin, but like a floating piston, and therefore do simple work like like pushing a marker or even a gear to turn a pointer. And so between like one d b c E and five hundred CE, Greeks and Romans both we're trying to make the flow more constant by regulating the water pressure. And as a result of that, some of the devices that they were making could like ring a bell or a gong when the water would hit a certain point, or they would even like push a mechanism to open little decorative hatches containing small figurines that would dance around or or move astronaut astrological models. Yeah. Um, And And meanwhile in China, mechanical water clocks were also in use from around two hundred through around thirt hundred CE, including at least one that used this big old water wheel like story and a half tall water wheel to power dozens of elaborate sounds and mechanisms that would dance around and do weird little stuff. Man, and I thought the uh, the church near my neighborhood, whenever it's noon or six pm, it goes pretty much bonkers with its chimes. I imagine it had to be even more spectacular with something along those lines, although maybe not necessarily quite as regular, Yeah, I would imagine not, but still still a party. Yeah. Yeah, So let's get back in the way back machine. We're gonna actually jump ahead to medieval Europe and we'll we'll get out there. So did you bring your nose? Come on, I worked the Renaissance Festival. I've been to dragon Con. I can handle medieval Europe. Here we go, Here we go. Welcome to medieval Europe. Huzzah. Where food is on a stick. And this doesn't look like the Resaissance festival and all. This is kind of awful. Yeah, I don't see any chicken fried bacon. There's actually awful in the street in Soul. That's the kind of awful this is anyway, So it's worse than our pus Field trip. Yeah, that was man. You never thought you'd look back on that with like nostalgia. But here we are in fourteenth century medieval Europe. This is about the time where mechanical clocks began to become a thing. And at those in those early clocks, they had our markings. Uh, some had minute markings, but none of them had second markets. And uh. So it would actually take about a couple hundred years really sixteenth century medieval Europe where you started seeing minutes as a standard marking of time. And this is where we take that concept we talked about with the geography, and it was converted into a time keeping concept. The idea of well, we've got these these twelve periods of daylight and twelve periods of nighttime that the uh, the Egyptians had proposed. The Greeks had formalized that into actual fixed length hours, uh for their calculations. We're gonna do that for the purposes of keeping time. Then we're going to subdivide that. And because they were working with twelves and twenty fours, they said, how about we look at sixty. We're looking at, you know, a division of sixty smaller increments that make up one full hour, and then eventually you think about that long enough and you realize, all right, well we can subdivide that even further. A minute is still a pretty long amount of time depending on what you need to do. Right, some things, a minute's no time at all, right, If if it's something really fun that you love to do. Maybe you're riding on a horse, jousting your Henry the eighth, a minute is like no time at all. But maybe you're being accused of witchcraft, being dunked under the water. A minute's a really long time. At that point you're going like, can we break this period up a little bit? And maybe we and look at like a fifteen second interval if you're gonna be you know, slowly like drowning me, like i'd like to can we negotiate this at all? So they looked at the round face of the clock that they had designed, and the division of the day into really twelve segments. You can think of twenty four, but really most clocks are twelve segments, right, And then we just amend either a M or p M in our brains to denote whether it's in the morning or it's in the evening UH, and they adopted that sexic asimal system, and each hour was divided by sixty and two minutes and dividenes again in sixty into seconds. And this was the first time we really had a definition of a second in terms of timekeeping. UH and and all of this, I imagine was also partially driven by just the mechanical complexity of clocks in the capacity. But because a mechanical clock, if if you guys aren't familiar with the inner workings of a of your basic wall clock or watch or something like that, is based on a coiled spring that you apply tension to buy either winding it or exposing into some kind of electricity like electrical pulses. And and then UH in the case of these these earlier clocks, the capacity of gears that you attached to the spring to to react in in regular movements. Yeah, it's kind of like a transmission, you know. You use smaller gears and larger gears to dictate exactly how frequently a gear will turn within a given amount of time, assuming that in fact the clock is wound, and then you get the mechanical UH performance where it rotates once an hour. For that you know, for the uh, the the little the little mickey arm, yes, and and so so. As as the spring making and gear making techniques became more complex, I'm sure that people started going like, surely we can make this more complicated, let's put some seconds in there. And in fact, you know, for a lot of people's seconds weren't really that important, not yet anyway. As much as I joked about the whole dunking of people to see if they're witches or not, that was not really on the forefront of people's minds in that particular scenario. Yeah, but the second was really um thought of as important for making those astronomical calculations, and in fact, we attempted to standardize it with the International System of Units and the The definition for a very long time was that a second is a fraction of a mean solar day in a tropical year. But all of that changed in nineteen sixty seven. So I think we should probably just jump the way back machine, go back to the studio. Okay, Okay, that's that's fair. I don't I I'm pretty much done with history for the day. Yeah, I think we can talk a little bit about the the nineteen sixties, but um, you know, we don't need to go there. That's not that long ago, all right, and the smells will be barely exciting. Yeah, okay, we're back, man. I just realized we've seen the Beatles another time. Yeah, yeah, sure, sure we can. We can always rev it up again. Uh okay. Actually, before we talk about the nineteen sixties, I need to talk for a second about for a second about the nineteen forties, because there was a physics professor at Columbia University by the name of Isidor Rabbi. I think I'm saying that right. Uh. And anyway, he proposed that a very precise clock could be constructed by measuring the vibration of atoms, and as far back as the ninetties had been experimenting with with this discovery that when some atoms are exposed to some wavelengths of electro magnetic energy, those atoms vibrate very, very consistently, So you can measure the oscillations and then use those to build a standard for the passage of time. And what is actually happening here is that if you have the right frequency of energy hitting a particular type of atom, it excites the electrons in that atom to higher energy bands and then those electrons will come back down to their normal energy band. That's the vibration there. But if you're talking about a resonant frequency, that in that we talked about resonance before resonance is this idea that you have found a frequency that resonates with a particular material. In this case we're talking about atoms, and it makes them vibrate themselves. So, for example, we see this in the macro level with the opera singer singing that note that is resonant with a particular crystal glass, and it causes the glass to shatter. Uh same sort of thing. Instead of shattering atoms, you're just making them wiggle on wiggle, very precisely, and very quickly, very very quickly, as it turns out. So, based on all of this, in nineteen sixty seven, the International System of Units wound up changing their definition of a second to the vibe to a particular vibration of the ces um atom or a scum atom a given sazon atom at any given time um and these suckers vibrate so consistently at when exposed a certain wavelengths of light, and uh so a second was defined as nine billion, one ninety two million, six hundred thirty one thousand, seven hundred and seventy cycles of those vibrations. Well, there's your problem. I lose track right around four billion. I just lose interest. But now that's amazing. The thought of being able to to define a second as something that is more than nine billion vibrations of a particular atom. Now you might wonder, how the heck can you turn that into an atomic clock? Yeah, how do you measure that? That's pretty weird. So I'm gonna do my best to describe this. Please keep in mind I was a liberal arts major. So here we go. First, the thing that these are the earlier atomic clocks I'm going to talk about. Now we have a different type of atomic clock will be chatting about shortly, and then and even more advanced type of clock to talk about the future of the second. But first, you would heat caesium so that atoms would boil off of the gas typically, and you would pass that down a tube that's maintained at a high vacuum. So then you would use magnetic fields to sort through the caesium atoms and passing the ones with the right energy state to the next level. So in other words, you're separating out ions from from regular caesium atoms, and you want just the specific ones that are going to react to the microwave radiation you're going to pass through it. So once you've sorted them and all the ones that you want are going the right pathway, the atoms will then pass through a microwave field that has a varying frequency within an extremely narrow range of frequencies. One of the frequencies within that range is that magic nine billion, million, six seven seventy hurts that corresponds with the vibrations of the caesium atom. So when a caesium atom encounters a microwave at that frequency, it changes its energy state. It wiggles, and the atoms continue on, and another magnetic field separates out those that had their energy state altered by the microwaves and the ones that did not have their energy state altered, so the wigglers versus the non wigglers exactly, and a detector picks up those atoms the wigglers, and that output is data that is proportional to the number of caesium atoms striking it. In other words, the output says how many atoms were wigglers. And then that way you can actually start to tune your device so it is closer to the proper frequency, and you'll see that number go up. That that number goes because you'll hit more ces um adams with the right frequency. You start to narrow it down until you get just the right tuning, and once you're there, you're you stop. You have you have reached the point where you are creating the pulse that is a second each time um and then you So what you would do is you take your frequency number that you had arrived at and the number of uh that that really big number we've said a few times already, and when you divide the two, it should end up being one. That means one second. Right, So it's it's a little weird to think about, but yes, it all comes down to how many of those wigglers are you picking up? And as you pick up more and more, you get these pulses that end up being exactly or at least mostly exactly one second. It turns out that as we get better at measuring things, our definition of what exactly is changes. Now. I love that. So atomic time keeping created a new approach called coordinated universal time, which, despite the fact that would usually make the acronym cut cut, it's actually U t C. That's what's universal time coordinated. I guess. In the United States, we depend upon the U. S. Naval Observatories, master Clock, and the National Institutes of Standards and Technology in Boulder, Colorado to regulate our time. They're the ones telling us what time it is. In other words, so interesting fact U t C and astronomical time don't quite match up. So we've got a second that is very precise. But when you change it to the real world and the way that the Earth rotates, it doesn't. The Earth does not rotate according to our beautiful math. In other words, so once in a while, I can't trust it for anything. I know it's I mean, i'd leave, but it's where I've got all my stuff. So it turns out like every now and again, we have to throw in a leap second, leap second, leap second every ten years or so, You've got about eight minutes out of that entire decade where you where some of those minutes, those eight minutes they actually have sixty one seconds as opposed to sixty seconds. Okay, So is so is this because are these clocks aren't quite precise enough. Even though we've gotten this precision down to the vibration of an atom, they're they're just not as precise as they could be. Well, that's that's definitely part of the problem, because as time goes on, the slight imprecision of these clocks becomes more and more noticeable, and you have to correct for that. And it's really interesting that such a thing could, even like it's so hard to imagine something so small we're talking about the difference of nanoseconds here could actually matter that much. It's almost like if you were to look at, say, an aunt, and you've said that little any ant couldn't do anything to me, and then you saw ten million ants and you thought, so when there are ten million of them, they actually do matter. It's sort of the same with these name seconds. Uh. But let's talk a little bit about a slightly newer version of atomic clock, the microwave fountain clock, which does not involve putting one of those little fountains from like a uh, like a bookstore or something inside a microwave. Don't do that. That's not how you're gonna get a microwave fountain clock. That's how you're gonna get a broken microwave. So they use a slightly different method, but they still depend upon caesium atoms and microwaves. So you take caesium gas and you introduce it into a chamber that has six lasers, all mounted at right angles to each other. So you've got like up and down and uh and like some on the on the actual walls point and inwards. It looks like a James Bond trap, but instead of saying no misr caes um, I expect you to die, the lasers are actually slowing down the movement of those caesium atoms. Okay, so it's an atom trap, not at James Bond trap exactly. And we also know that movement and heat are essentially the same thing. Right as adams move, there are there warm. When you start to slow them down, they cool down. So the goal is to cool them down to close to absolute zero. Once they're at that point, they are forming into kind of balls of atoms. So you've got these little caesium gas balls that are suspended because they've been slowed down so much, and then you use a couple of lasers to push them up into a microwave chamber. This is the fountain action. So if you imagine a fountain, that's that's just shooting straight up, the water shoot straight up. In this case, lasers are pushing that caesium ball up into the microwave chamber. And then those particular lasers, the ones that are pushing the caesium atoms, turn off. Then you've got microwaves within that chamber. Some of the microwaves are at the proper frequency to make caesium vibrate, and when they do encounter the caesium atoms, the atoms will change energy states. And as those caesium atoms leave the microwave chamber, they encounter yet another laser. We love our lasers. Caesium atoms that have been altered by the proper resonant frequency fluoresce. They light up and a detector makes note of that, and then the system is dialed in. So it sounds very similar to the old atomic clock, right. They dial it in until that maximum fluorescence is achieved, and that defines the natural resonance frequency of the caesium atoms and can be used to define a second But they these also as accurate as they are, they do not keep time perfectly forever. Yeah, they do lose time over time. And uh, and we're talking about like a nanosecond a month, which seems nothing. I mean, I was going to waste it anyway. I was probably spending that playing bulled. I was probably playing Overwatch. Okay, uh, but but but it does but it does that up eventually and and especially digitally, so nonetheless, Okay, we should say that the atomic clocks are are really cool for a number of reasons. I think a number one because they are what keeps our our geo syncritous orbiting satellites basically not running into each other. Right. Yeah, when you're talking about things like satellites, like communication satellites, or you're talking about GPS satellites, you need to have extremely precise time keeping in order for those operations to to work properly. And in fact, this comes with a whole host of problems and challenges. Um, but you're looking at an accuracy that needs to be down to billionths of a second. So when you have like a nanosecond error in there, that's actually a big deal. So each GPS satellite actually has four atomic clocks on board, and there are twenty four GPS satellites in orbit, and uh a GPS receiver on the ground can determine its location by triangulating broadcast signals sent from multiple GPS satellites. And then what does is it looks at the time stamp on each of those factors in how long would it take the signal to travel from that time stamp and where you would be. You actually have two answers to that, but one of them happens to be inside the Earth, So your GPS usually ignores that answer. Generally, Yeah, it's like, all right, obviously can't be that one, so you have to be here. But knowing that you have these potentials for errors, you actually that that translates into a less precise positioning. When you're getting your read out, it may be accurate to just a few meters, which is fine if you're traveling around and you're driving and you know, generally speaking, you're not gonna have an issue where you're suddenly realizing need to turn a mile back. Share it, but it does explain why. For example, if you have your WiFi off, your GPS may think that you're on the other side of a bridge that you haven't crossed yet, or something like that or yeah, or I'll read you the same instruction off twice because it's just glitching as to where precisely your your car is. Or if you're using something like a car service app and you see where you are and you know where you are based like you see where you are on the map and you see where you are in real life, and you realize that if you pen the point that it shows you on the map, you're gonna have to walk another block to get to that car. You're like, no, I want to be right. Those apps are particularly bad at that. I don't know what the issue is. I don't know if it's on the app side or if it's my phone's GPS. But anyway, So, one of the cool things about space and satellites in time is that you have to take into account both special and general relativity. That's always sighting because it messes with dime. So right, okay, because because satellites are are are moving relative to a single point on the ground. Yes, well, and if you're talking about a geosynchronous satellite, it's moving. It's moving like if you were looking up you would always see it, right if you were directly below it, which means it actually has to travel faster. It's going a further distance in the same amount of time, so it's traveling faster than the air's rotation share the same way that a track runner on the outer side of the track is going to have to run a little bit faster than the inner truck crowder to keep up. Exactly. So you start to think, all right, we're talking about time dilation here, how does that? How big a problem is that? It's pretty huge. So we just talked about how a nanosecond a month was a big deal. First of all, you have to look at special relativity. That's the one with the time dilation effect. That's when you're talking about the speed that ends up about seven micro seconds of difference. That means the clocks aboard the satellite, due to special relativity, we'll move seven micro seconds slower than a clock on the ground. Kay, So that means you have to figure that out factor that in except you also have to remember about general relativity. The general relativity tells us that the satellite is orbiting high above the Earth, where the curvature of space time is less than what we experience here on the Earth's surface. Exactly the Earth is a giant mass. For us, it's a giant mass. For the Sun, it's nothing, but for us it's for us, it's pretty big. Again, it's where we keep all our stuff. So there's a pretty big mass. Uh. And so that it so. So a clock here on on on the ground, the clock on my on my wrist, if I had such a thing, would be it would actually be going faster. It would be going faster because of the curvature of spacetime, so it would actually be going your wristwatch clock would be going slower than the one that's aboard the satellite. So special relativity says that the clock aboard the satellite is gonna go a little slower than ours. Right, that's the whole idea that if you were to travel it near the speed of light and came back, time would have passed less. Time would have seemed to have passed to you than to everybody on Earth. But according to general relativity, it's the clock and the satellite is going faster exactly, so microseconds, so you have to, yes, exactly, You've got to take the seven microseconds where it would have been going slower, and the forty five microseconds where it would be going faster, and you come up with thirty eight microseconds distance difference, and so GPS systems take this into account. I know, I just had GPS systems and I'm like saying, a t M machine and pin number, But it doesn't matter. That's not what I was cringing at. Just the math caught up with me. Yeah, thirty eight microseconds difference, so you have to account for that. And we're looking for an accuracy down to twenty to thirty nanoseconds. So nanoseconds are much smaller than microseconds. It's a big deal. And and and real errors would pile up due to these due to these mistakes exactly. So if we did not correct for us, on the first day, we'd be thinking, uh, all right, well this isn't great, but it's you know, it's it's it's usable. And then as the day goes on would be thinking, wow, this is this is getting less cool. And then the next day we'd be thinking this is completely inaccurate, because the errors would be enough to account for a ten kilometer error per day. Yeah, so these little bits of time really make a big difference, which is why you want to have a really precise timekeeping device. Um. So, one way that they correct for this is they actually make sure that the clocks aboard the satellites tick at a slightly slower rate before putting them up in orbit, because then general relativity will take care of the rest and they'll start ticking at the rate that they should be taking at, which is kind of like you know that sort of thing where you've already planned for the thing to go wrong, Like you're not trying to stop the thing from going wrong. You're just like, well, yeah, well this is gonna happen, so here you go. This is what my life is now. It's just how the that's just how physics work, y'all. Yeah, uh okay, but that's not even atomic. Clocks are not even the most precise type of clock that human people have created. I know where you're going, and I'm already crying. I know what. I'm sorry you and you got to the notes faster than I could, so it's your fault. Really. Yeah, alright, So the clock that inspired us to do this episode is a type of optical clock. Optical clocks, and I looking at the clock on my wrist, hypothetically, if I had such a using optics right now. Uh, these use these depend very heavily on lasers, and again with the lasers. So we had in our notes how they work. And I almost just put a frowny face sticks to it because I started reading how this works, and it's so complicated that, first of all, I gotta be upfront, I do not understand it. All right, that's just me being I'm being straight with you guy. Yeah, yeah, neither of us are laser physicists. Yeah, I'm not a laser scientist. Okay, I'm not a second scientist either. But they're very, very complicated, and as I was reading it, I just realized that it would take me probably weeks of study to really get a basic understanding what's going on here. But uh, they work with lasers and adams and specific frequencies. And here's the problem. It's so technical. Uh there are phrases like optical frequency standards, forbidden transitions. I didn't know there were such things Doppler broadening and optical clockwork. And I'm pretty sure I don't understand any of it. Oh yeah, forbidden transition sounds like something out of Welcome to night Vale more than exactly so okay, but but can you can you give us like the very very very basic yes. So optical clocks they don't necessarily rely on Just let me put it this way. There are different types of optical clocks, and they work on different types of particles. Right, So, with atomic clocks, were typically talking about either caesium or rubidium. Uh, yeah, I think it's rubidium. But at any rate, we're only talking about those. The optical clocks there are a lot more options, so you can talk about certain atoms or ions or even molecules depending upon the type of optical clock you've got set up. And the optical clocks can correct for caesium clock drift, which is good. So they are more precise. They can divide time up into ever smaller amounts um, and they are really I mean that's really important because the more precise you get, the more accurate your timekeeping is. But what they're essentially doing is slowing these atoms and ions and molecules down to microwave frequency standards, which is similar to what the caesium atomic clock us. Uh So the idea being that light frequencies are way too fast. Uh, they're much faster than the micro Even with that nine billion number, that's slow compared to what the light frequencies are. UM, so it's it's important to use it to slow it down to these microwave amounts. But it means that you can actually create what's kind of called like an optical comb frequency, and you are able to subdivide those frequencies further and further and further, which is what allows us to look at smaller and smaller fractions of a second and make more and more precise clocks. And we have literally reached the limit of my understanding. Okay, okay, but part of my understanding of them is more top level than that. You just went way deeper than I did. Um but uh but but I'm but I'm aware of the idea that they're not considered as dependable as atomic clocks, and that's why they have not been been used to switch over the definition of a second as of yet. Yeah, they're incredibly complicated machines and there are a lot of potential points of failure, so if something goes wrong, the whole system doesn't work right, and things go wrong. Technology doesn't always work, especially young technology where you're you know, this is still relatively young technology where you're trying to develop something. And because it's a delicate system and it's very complicated, and downtime is a factor. Uh. That means you have to actually account for time required to fix the clock, which means that like like like like hours or even days. Yeah. And so while it's offline, you you aren't you don't have time, yeah, unless unless you pair to this type of system with another type of system, which is what essentially is up with this new clock that we mentioned at the very top of the podcast years and years ago. It seems like it seems like another lifetime Lauren. Yeah. So this, uh, the story came from a research team out of the National a Trology Institute of Germany and metrology that's a science of measurement and and and while there are branches of this institute all around the world, I think there's something so fitting was the Germans, especially for time. It's just again it's stereotypical, but you just think, like you know, piseyah. So the specific type of clock that they were working with is a strontium optical lattice clock. By the way, there are research institutes in the United States that also are working on this same technology, and that's the actual optical clock. The optical lattice is pretty much what sounds like. It's an arrangement of lasers that are meant to manipulate those atoms of strontium. So again back to the James Bond slash mission impossible kind of trap. Uh. They use a second device to help account for time whenever the lattice clock goes off line, and that is a maser. Yeah, it sounds like it, but in fact, maser's predate lasers, mazers were Masers were discovered or created in the lab before lasers were. They're similar to a laser. It is a microwave amplification by stimulated emission of radiation. So it used to be an acronym. Now it's just a word, just like laser. Uh. Masers operate at microwave frequencies, which again are not as high as laser frequencies and little light frequencies, which means that because their frequencies are are are lower. I keep saying slower, but I really should just say lower. I know all the physicists out there, I've been cringing. I apologize to you guys, but it means that because you have a lower frequency, you have a lower level of precision. It's kind of like, you know again, Like the way I would think of it is, imagine that you have um a measuring cup, and uh and I you have a measuring cup, I've got a bucket, and we each have to say how much water is in a pool. And so it's gonna take us a long time to figure this out. But you're gonna be a lot more precise with your answer than I will, although you'll get to your answer quicker than I will, relatively. So I didn't say how big the pool was. If it's a big enough pool, then both of us have just wasted our lives at any rate. The same idea with the mazer. With the lower frequency, it can take less precise measurements. So what the team did was they used the maser to cover for the downtime when the optical clock was offline. And the way they did this was they then they applied an optical frequency comb to divide the maser's measurements into smaller units, similar to that to the optical clocks. So while the optical clock was still working, they tuned the mazer's frequency so that the output most closely resembled that of the optical clock once fed through this comb. Yeah. So they're like, well, the mazer, while we know it cannot take as precise measurements as the optical clock, if we apply this optical comb to it, we can kind of fake it, sort of. And as long as we have attuned the two together, then we can at least depend on this until we can get the other one working. Sure. Yeah, and then when the optical clock comes back online, then you re a tune everything, make sure it's all flowing together and kind of cut the difference. Yeah. Yeah, and then you might call people. I'm like, hey, I'm going to need that six nanoseconds back. Sorry, sorry, sorry, David, We're gonna have to docu six nano seconds for it. You took too long for your lunch now. But so so, in in this experiment that this team published about recently, they ran a test of the system for twenty five days, and the optical clock did indeed experience downtime up to two days at a go. But at the end of the trial their system was just under zero point to nanoseconds off. And there's a kind of flashy number that the press has latched onto and and it's an extrapolation of that, which is that. Okay, So assuming that the system wouldn't like degrade over a longer lane of time, and assuming that we could have somehow started running it at the beginning of the universe as we know it a k a. Like fourteen billion years ago, when time became a thing. Yes, um it, this clock would have lost only about a hundred seconds over those fourteen billions years. So, so less than two minutes billion billion, pretty precise. Yeah. And and and at tom the clocks are pretty good at that thing too, like relatively but but they but but it beats him out by a factor of like a hundred. Yeah. So ultimately, does this mean about the future of time keeping, the future of seconds themselves? Well, well, okay, the definition of the SI unit isn't just going to change overnight. Yeah. In fact, the researchers on this project said that it would be at least a decade out for that to change, partially because the technology, right, it's so young. And we talked about all the fact that they're all these different style of optical clocks. They don't all use strontium. They may use something else, and we haven't figured out yet which one is quote unquote the best one to go with, as in, the most reliable, the most precise, that has yet to be decided. This is still a very early form of research, so it may turn out that it will take a decade for that to shake out and for us to say, all right, this is the optical clock that is best to use that we're going with, and this is what a second is now. And okay, so so when we do accomplish that, we'll we'll have more accurate clocks. Yeah, but practically what will that do for us? Lots of stuff. Well, first of all, we hear it forward thinking. We always stress that pure research ultimately benefits us in ways that we cannot anticipate. Oh absolutely, I mean, and you know, like like hurrah for the spirit of scientific inquiry and in the advancement of physics and all that rad stuff. But but okay, like like really, technically, we're not doing all of us, all of this for us, right, human beings don't miss the nanoseconds that the current you know, gold standard atomic clocks are accidentally shaving off. That means that yes, in the spirit of Joe being and not being here, but in his spirit we're doing this for a robotic overlords. Yeah. Yeah, So it turns out like the besides the satellite systems that we depend upon, we have a lot of systems here on Earth that are really important to coordinate with timekeeping, including things like our electric grid. But obviously, if we're going to have more and more technology interacting with one another, talking to one another, uh, causing things to happen within our world, timekeeping becomes incredibly important. Obviously, Like if I if I am walking into a room and I want a specific outcome to happen through my technology, I want that to happen while I'm walking into the room, not five minutes after I walked into the room, or five minutes after I walked out of the room. Sure, if you if you have a GPS system that's controlling your autonomous vehicle and another person's autonomous vehicle, you want those GPS satellites to be able to hone in on you well enough to to to not crash them together. Right, If you have a system that is and like an external system that's controlling a lot of vehicles, you could in theory, reduce traffic to nothing, right, because you could you could have the cars moving impossibly close to one another incredibly safely. But if your timekeepings off, that suddenly becomes a lot of bumping and rubbing on the road. Time and distance are still linked and uh or or for another example. So back in February, we did an episode about how machines run the stock market. Computers are very precisely running the stock market these days, making these trades at fractions of fractions of a second. The episode is called show me the zero zero one zero zero one zero zero if you'd like to go look for it. I believe that code actually stands for the dollar sign. That's adorable. Yeah, I think I actually looked that up. That's how much of a dork I am. But but so obviously this kind of precision and timekeeping will will totally matter to to these computers and to to others like them. You know, just think, Jonathan, how many interactions and transactions you could complete in a few extra nano seconds every day? Man, my Amazon wish list is gonna be sick. Yeah, so we're we've been joking around a lot and talking kind of about this. This somewhat odd idea of a second secon time is such a weird thing right to talk about in a objective, definitive way when we also are aware that it is relative. It makes it really kind of mind bindy to to go on about this. And uh, ultimately, if we get to a future where people are zooming around the galaxy at ridiculous speeds, this kind of precise timekeeping will also be important so that we can have any form of communication that might be possible as long as they're still you know, with reachable distances, um and Yeah, if they're going to be the speed of light, then you're you're never going to catch up to them, Like the message will always be behind them until they stop. And then what will happen is they'll travel at the speed of light and they'll be like twenty seven light years away and then they'll stop and then they'll say you forgot your underwear. I'm like, dude, no, I'm just thinking of how have that bump in your inbox when you finally right down and then all of a sudden it's like, oh my gosh, and it's all adds. So this was fun to talk about something like this, and we really look forward to tackling other interesting topics like this in the future. If you guys have any suggestions for future topics, maybe there's something you've always wondered. How is that going to be? What? What will that be like in the future? Let us know. Send us an email. The address is FW thinking at how Stuff Works dot com, or you can drop us a line on social media. On Twitter, we are FW thinking. If you search f w thinking over on Facebook, our profile will pop right up. You can leave us a message there. We'll be happy to hear from you, and we will talk to you again really soon. For more on this topic in the future of technology, visit forward thinking dot com, brought to you by Toyota. Let's Go Places,