What Day Is It, Really?

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1:20Welcome to The Rest is Science. I'm Professor Hannah Fry. And I am Michael Stevens, creator of Vsauce on YouTube. Hey, happy new year, Michael. Okay. Are you teasing me? Why? Is it really a new year? Is it really 2026? Like, are we sure people have been counting without missing, you know, a day or a year here or there? We may have been lied to about what time it is. And that is what we're going to be talking about on this episode. We are going to look at days that never happened, centuries that disappeared, and whether or not we have been keeping count. All right, so let's begin by talking about what day everyone says it is.

2:00Like, we pretty much all agree it's the 2020s, according to the Gregorian calendar. And that was decided for us in 1582 by Pope Gregory XIII. Unlucky 13, if you ask me. It's quite a lot of Gregory to have happened since the year zero. Or I guess the year one, because the number zero really wasn't in regular usage until Shakespeare was walking on the earth. That's true, but not even then, because in the year one, Jesus hadn't made Peter the first pope yet. So, like, the Greggs are busy. The Greggs are busy. Okay, so why did Pope Gregory decide that this was the calendar that everybody should have?

2:39Okay, let's do the long and short of it, and please pop in and help me, because I'm not completely up to snuff on my Greggs. But before the Gregorian calendar, a lot of Europe was using the Julian calendar. And this calendar had started in the year 45 BC. Okay. And it was pretty good. I'm sure you've got a lot of criticisms and it shows. Okay. The Julian calendar assumed that there were 365 and a quarter days in the year. You're absolutely right. I've got criticisms because that is out. That is out. for how long it takes for the Earth to actually rotate around the sun by 11 minutes and 14 seconds every single year.

3:22Burned. Oh, Julius, you idiot. You idiot. 11 minutes off. And yeah, what was really relevant to them at the time wasn't exactly the astronomical year, but the tropical year, the time between the equinoxes. That was something that you could measure very easily from Earth. When is the day and the night the same length? Okay, and that would happen twice in a year. And they tried to make the organization system work. But because in reality, a tropical year is 365.2422 days, it wasn't quite right. And the Julian calendar was off by a little bit of time. I think it added in too many leap days as well.

4:07And so by the year 1582, the equinox was not happening on the day that it should. Should? Who says should? Well, the astronomers care quite a lot because the equinox, depending on which side of the Atlantic you happen to be from, it's the moment when the sun crosses the equator, right? So it's that moment where the tilt of the earth and so on, it's that moment. And I mean, maybe if you're not an astronomer, you wouldn't care that much. But the Catholic Church themselves, they also really cared about this because Easter is set as the first Sunday after the first full moon after the spring equinox which they which they said was the 21st of May but there kind of came a point I mean hundreds of years before Pope Gregory came along where you know this day was slipping further and further backwards in time because okay it doesn't sound like very much if you're only 11 minutes 14 seconds or whatever it was out every single year.

5:07But if you are, you know, if you're doing that every single year, it means that by two years in, you're 22 minutes behind, you know, three years in, you're 33 minutes behind. It starts to compound these errors. So even by the 1200s, the astronomers were like, guys, you know, this equinox is like, it's getting further and further away. And then there was one guy called Roger Bacon who wrote this big document, sending it to the Pope, begging them to change the calendar and was like, eventually Easter is going to be a summer holiday. You need to sort of do something about this. Yeah. And that might not have been a problem.

5:46You know, I think people like Bacon were upset with Easter shifting throughout the year. But also in the year 325 AD, the Council of Nicaea got together to try to figure out some of this stuff. I mean, they got together to figure out what Christianity was. And determining when Easter should be was one of the problems. And there was a lot of fights about whether they should continue to follow the Jewish lunar calendar or not. And they never decided when Easter should be. I mean, they didn't even decide it should be on a Sunday back then. All they did is that they said, it is hereby decreed that the vernal equinox, the spring equinox, must happen on the 21st of March.

6:28So they started dictating to the stars and the moon, basically. They dictated that, and they also set this really important rule for all Christians, which was that Easter had to be celebrated simultaneously worldwide by all Christians. So they needed to standardize how they named and numbered the days, because they all had to choose the same date. and by the time of Pope Gregory in 1582, Gregory the 13th, want to respect the Greggs, by his time, the vernal equinox was happening not on the 21st of March as decreed by the Council of Nicaea, but instead on March 10th. So something had to be done.

7:05What did he do then? Well, he decided, screw it. We're going to just jump 10 days forward and we're going to rejigger the algorithm of the calendar. Name it after myself. It's going to be better. We're going to do leap days every four years unless the year is divisible by four and a hundred. I mean, it's kind of a whole complicated system. We still use this today because it's okay. It's better than the Julian calendar. And this is how they get around those 11 minutes, right? It's that we have leap years every four years, but with a twist. So if a year is divisible by a hundred, it's not a leap year unless it's also divisible by 400.

7:39So 1900 wasn't a leap year, but 2000 was. And that's essentially how they do the maths, how they managed to keep the calendar in sync with the Earth's orbit. That's right. And so on the 4th of October, 1582, the next day should have been the 5th of October. Pope Greg was like, nope, it's the 15th of October. Psych. And... Unlucky if your birthday's on the 10th. Isn't that unlucky? So I always love to, if I don't know a historical answer, I always say, oh, I think that happened on October 7th, 1582. And everyone's like, really? And they look it up and they go, there never was a 7th of October, 1582.

8:19He's a wizard. And I'm like, guilty. He also didn't change the actual days though, right? Didn't he? He said, okay, the date is changing, but even though it was a, I don't know, a Tuesday, tomorrow is still going to be a Wednesday. Yeah, it was a Thursday. October 4th, 1582 was a Thursday. And the next day was Friday, October 15th. And so if you're ever like feeling bad on a Monday, just think that if it hadn't been for the Pope, it would be Friday. And this is why I'm late all the time, right? Because it's like, it's actually Tuesday right now. Exactly. Whatever day of the week you're listening to this.

8:55We are still living in a world reverberating with the consequences of this 13th Greg. The thing is, this old Greg, old Greg XIII, I mean, this is the Catholic Church, right? This is a point where they are extremely powerful, but not everybody in Europe in particular is underneath the Catholic Church. And the Protestants in particular were very suspicious of this. They thought that actually this was a trick that the Catholic Church were pulling to make it so that the Protestants celebrated Easter on the wrong day and therefore would damn their souls to hell. It was just a mean trick. and the astronomer Jonas Kepler he said that Protestants would rather disagree with the sun than agree with the Pope I think it's probably fair to say that Catholics and Protestants, not the best of friends Michael, but maybe we'll leave that one to the rest of his history, shall we?

9:42As far as I can understand There were some other people who were really worried that Catholics were trying to steal time so that they could live longer and different countries adopted it at different times So Poland, they were like, okay, we're going to do whatever Pope Greg says. We're happy with this. They adopted it almost immediately. But their neighbor, Prussia at the time, they took another 30 years to decide that they were going to adopt it. Which meant that if you lived on the border, you could send a letter from Poland on October the 15th and it could arrive in Prussia on October the 6th.

10:21Yeah. I mean, all of this confusion is funny, but it makes sense. I mean, imagine if tomorrow Donald Trump said, that's it. I'm changing the calendar. Year zero is now my birth date. It's actually the year 79. Like, I can't wait for the year 80. Happy New Year. Not everyone would go along. There would be all kinds of resistance. And yeah, it took the Gregorian calendar centuries to finally get adopted. I mean, technically, Saudi Arabia didn't even accept it until 2016. Well, I think the Ethiopian Orthodox Church still hasn't. Their calendar uses one that's about seven to eight years behind the Gregorian calendar.

11:00Yeah, and good for them. They think it's 2018 at the moment, which means someone should really warn them about what's coming in 2020. Yeah, right. So, I mean, that joke actually gets at two very different kinds of time. There's physical time, the tapestry on which events occur in. And then there's also organized human standardized time that is a series of languages and words that describe and name them. And so, you know, I've always joked that if like Jesus had been born 25 years later, NSYNC would have been the hottest band of the 70s. And that also toys with the fact that there's time, which is the order, the chronology of events.

11:44And then there's what number we give them. And yeah, we're still all kind of like using multiple calendars. I don't want to date this episode really specifically, but it is what, the 10th of December. But if you're still using the Julian calendar, it's only November 26th. I do often wonder also whether our perspective on the year would be very different if we had decided instead of tying it to the birth of Jesus, but had tied it to the beginning of human civilization or the agricultural revolution or whatever it might be. I think that if we were living in the year 125 ,782, looking back to, say, the Second World War or even things that happened in the Middle Ages, it would feel like much more present than they do at the moment.

12:37Well, I like the Holocene calendar proposal, which is that we just add 10 ,000 years. So right now it's actually the year 12 ,025. And that one, instead of starting at the birth of Jesus for the positive integer years, we start at the end of the last glacial recession, which is really when humanity started to kind of be the dominant force of life changing earth. I think it makes you feel more connected to your ancestors in a lot of way, actually. Just that tiny, subtle change of adding a one to the beginning of the year. Yeah. And the change of not putting BC on years so that it seems like an alien world.

13:20If instead Aristotle was doing stuff in the year 8000 and we were in 10 ,000, it would still feel like we were more contemporaneous. Right? Yeah. Yeah. Which in a lot of ways we are. We are. Yeah. I mean, not to get too far off field, but like we're still living in the Stone Age. I mean, our world is still made out of things that we find in rocks, concrete, steel, like we have not actually moved on. Oh, silicon? That's still a stone. It's sand, you guys. It's sand. We are still Stone Age people. We were never modern. Like, let's get over it. I mean, lucky for us that it turns out you can do quite so much with sand.

14:00We probably wouldn't go as far if you needed gold in order to build computers. Oh, man, imagine that. Only squillionaires wouldn't be allowed to have them. It's actually almost weirdly lucky that... It is weirdly lucky, isn't it? It's so easy to make computers out of the dirt all around us. Maybe even suspiciously lucky. Suspiciously. Suspiciously lucky. We'll do that one for another episode, shall we? Here's something else that's suspicious. We need to talk about Pope Gregory XIII again. He added 10 days to the calendar. He jumped 10 days forward because that's how far the Julian calendar had drifted off of the actual motions of the earth and the sun.

14:39But if you do the math from 45 BC until his time, 1582, it all should have been off by not 10 days, but 13. So what happened? Well, in the 90s, this guy named Heribert Illig, great name by the way, started to put together a hypothesis that he called the Phantom Time Hypothesis. And the idea is that the Pope was off because the Popes had lied to us about what year it was. That there were three missing centuries, which accounts for those three days that they didn't have to add on. Isn't thou shalt not lie one of the Ten Commandments? Yeah, right. Or maybe not right, because we need to investigate this phantom time hypothesis a bit more.

15:30I'll tell you some more of the details. So according to Illig's theory, the years 614 to 911 never happened. OK, they were completely fabricated because at the time, Pope Sylvester II not only wanted that putty cat, but also wanted to reign during the year 1000. So they said, let's just fudge the numbers. It's not we're not in the 600s. Oh, my gosh, you guys, it's almost the year 1000. Ha ha. And they fabricated all of the history that today we are taught happened in those three centuries. That means Charlemagne never existed. That means that the Carolinian period was a complete fabrication. They just made it all up to trick everyone into thinking that it was the year 1000.

16:15Hold on though. So is the idea that the Catholic Church went and created all of these original sources, I mean, Charlemagne's essentially fan fiction. Is that what we're saying? Constructed, put in place. Wow. Okay. I mean, that's quite a bold statement. Are they doing that on the basis of just thinking that Pope Sylvester was really into branding of like wanting to hit the year 1000? Yes. Yes. And I think also just a suspicion of authorities that like if they could do something dastardly like this, they would. And Illig's only evidence really was the aforementioned 10 days jumping forward when it should have been 13.

16:58and also the kind of vague, like hand wavy. I mean, can you even name something that happened in the year 700? There aren't a lot of historical records from that time period. And he was like, well, that's because it's all been made up. So the idea then is that the Dark Ages are kind of like dark matter. It's just sort of a bit of a kind of shady, unknown region. You just give it a name and move on. That's a really good analogy because it's like, I mean, it happened in that the events they say happened matter. It has an effect on us, but you can't see it. You can't interact with it because it never physically happened.

17:34Now, unfortunately, because it would be very funny if it was the case, it'd be like the greatest lie ever told. Illig's theory never got very popular for a few reasons. First of all, the Gregorian calendars 10 day jump forward instead of 13 is easily explained by the fact that the Julian calendar had not remained untouched since 45 BC. The Council of Nicaea adjusted it a little bit, and that completely answers that problem. Well, there's other ways too. I mean, like science steps in to really help us out on this one, because there's an area of research which is called dendocrinology. This is like super fascinating.

18:14So the idea is that you you chop down a tree, it has tree rings, you get one tree ring a year. And the reason for that is because of the seasons, right? So the way that as a tree grows, it grows faster and slower, depending on the conditions that are surrounding it. So if it is warmer, you get more growth, you'll sort of get a faster growth, you get a wider ring. If it's colder, you'll get it kind of narrowing, which is what happens over winter. But it also changes depending on whether there's a lot of rain for one year, also how much sunlight there might be. And what you can do is you can take two trees that have existed in a similar place and when you cut them down there is a way to uh to to cross compare those tree rings and see the same pattern of growth appear in both of them so maybe one tree is born 50 years after the other um but you can work out sort of daisy chain them as it were work out where the overlap is and uh where one tree out survived another so what scientists have done is they they've managed to do this really successfully um in with with trees all across europe also in america as well um german pine is amazing at this you get really really old german pines um but also in the the bog lands of ireland which is where my family are from the bog people that's that's who we are i didn't know that we are absolutely the the right in the center of ireland and the heart where the peat bogs are um you get this sort of like semi fossilized Irish oaks in there, which can go thousands of years old.

19:42And using this exact same technique with modern oaks that are around now and then all the way back, you can daisy chain this so that we have basically an unending record of the sort of climate of a particular region that goes back over 10 ,000 years. Now, that on its own doesn't tell you anything about what year the church were calling it. But what you can do is you can go into a building that is, say, built in the year 800 AD or 1000 AD, whatever it might be. And if there is oak timbers in there, they can be analysed and slotted into this timeline that we have about what was happening in the climate of the world.

20:26And every time you do that, they slot in exactly without those 300 years that are missing. There's kind of more evidence for this because in 536 AD, there was this gigantic volcanic eruption in Iceland. It was so bad that across Scandinavia, crops failed, people abandoned villages. You find all of these sort of hidden gold in parts of Scandinavia, which around that time, they think that people were sort of making offerings to bring the sun back because the volcanic ash was so dramatic. But you see this scar effectively inside of the rings of trees all across the region. But you also, of course, if the sun gets blacked out by volcanic ash, there's also this written record of it.

21:12Monks are writing about this. People are writing about the villages being abandoned. And it all ties up exactly. I mean, if these 300 years really were missing, then the tree records and the written records would be out by 300 years. But we know that they're not. I didn't know about that. That's beautiful. I love that the Earth can hold us accountable. I had heard about the problems of solar eclipses, that there have been all these reports of solar eclipses at certain times, and they all line up exactly when they should with this, specifically, this 297-year gap that the phantom time hypothesis says didn't happen.

21:53Unfortunately, it looks like it did. Because you could wind back the clock with the simulations that we have of the solar system now and work out precisely the day the solar eclipse has happened in the past. And I love to imagine, I mean, this is one of my hobbies, basically, is to imagine when you had an event like that, before we really understood what was going on in the sky, how unimaginably terrifying it must have been to be like, OK, everybody, today the sun disappeared for like a few minutes and then it came back. What on earth does it mean? I know. And you better believe that people were writing about that.

22:33In between all the plagues and the murder and stuff, there was lots of people writing about those solar eclipses. It must have been so terrifying. Because when a solar eclipse happens now, it terrifies me. It's just such a big event that I cannot stop. Like I'm very much a person who's grown up in a society where I can press pause and I can decide when I do what. And yet the eclipse is going to happen whether I want it to or not, whether I'm ready or not. And I've been visiting like every eclipse that I can. And I get so anxious just before it happens. It's a very scary thing that these two things that are bigger than I can even imagine are about to do something.

23:12And it's going to happen when it happens. But imagine not even knowing that it was going to happen or how long it would go on or what it meant. Yeah. And that then being used as proof that the Catholic Church were telling the truth all along. Imagine that on top. Imagine that cherry on top. Maybe the sun and the moon and the trees are actually in cahoots with the Catholic Church. I like how you're thinking. The tree of knowledge, more like the tree of ignorance and lies. Okay, I'll tell you what, we'll agree for now on what day it is. That's fine. But as for what time it is, I mean, that's where stuff gets messy.

23:51Join us after the break.

23:59Welcome back. We are today asking, when is today? Is it today? When is it really? What time even is it, Michael? That's where we're at today. Think about New Year's, right? There's sort of nothing cosmological, nothing agricultural, nothing seasonal about the reason why it's got to be the 1st of January. It's just sort of, it's kind of a collective lie that we've all bought in on. But why? I actually have no idea why January 1st was chosen to be the beginning of the year. It comes back to the Romans. So the original Roman calendar, they actually only had 10 months. They started in March. Decimal month system.

24:40I like that. Right. But this is still there, right? So October, the eighth month, November, the ninth month, December, the 10th month. And then they just never bothered with January, February because they were like, it's dark. There's no crops. Don't worry about it. It's just, you know, get through it. Get through it. That makes sense. they also this is the reason why you've got 31 and 30 days because odd numbers were lucky that they preferred odd numbers think of sort of roman numerals you kind of wanted a little stick in the end so they were sort of like oh yeah let's just sprinkle some odd numbers through through these 10 months then in um about 713 bc they were like okay maybe we'll count these extra ones this extra bit of time we'll add in we'll add in january and february and then in 153 bce I agree with you about the calendar not liking it let's call it in the year 9000 thank you Holocene calendar I love it 9847 that's the one it would have been wow you should be a math professor at Cambridge you know what I might just consider it thank you anyway so this is the Roman Empire this is the days that we're in it's all kicking off in Spain.

25:53Spain are revolting. There's all of this stuff going on. And the Romans need to appoint two new consuls. These are the people who order the army what to do. But they've got this rule that they're only allowed to do that at the beginning of the year. Now, up until this point, the first day of the year was the 1st of March, the beginning of spring, the beginning of their calendar. But now they're stuck, right? Because it's all going off in Spain. And they've got to wait a couple of months before it's the beginning of the year when they're allowed to appoint new consoles. So rather than changing the rule, they decided let's just change when the year begins.

26:32So basically, the reason why it's the 1st of January, it's admin. Admin is the father of this modern holiday. So that's how it happened. Yeah, that's how it happened. Wow. And just like the Gregorian calendar, I mean, not everyone was happy. Again, it was all over the place. In England, it was the 25th of March. In France, it was Easter was the beginning of the year. In Scotland, it was January. In Russia, it was September. It wasn't until sort of the 1750s that everyone sort of started to slot into place with this idea that the Gregorian calendar and the 1st of January was the correct date. It takes a long time, especially back then.

27:10I think as the world becomes more connected, you have to confront the importance of standardization. No one really cared. until people were moving around enough that they needed to sort of cross-reference it. I mean, it's the same as time. You know, for most of human history, I mean, it didn't matter what time it was. You get up when you get up, you go to sleep when you go to sleep. Yeah, if you didn't have to coordinate what the year was or what the time was with people in a different country, then you didn't need to think too much about it. As long as it worked locally, it was fine. I think that that idea about coordinating with another location, we didn't actually have to worry about what time it was at all until we had ships and trains.

27:56When it comes to ships in particular, there's a strange truth, which is that if you want to know where you are, you need to know when it is. so north and south is easy you just look at the angle that the sun makes in the sky uh at midday so of course if you're if you're if you're you know really at the north pole the sky the sun will be very low in the sky if you're at the equator the sun will be very high in the sky so you can work out how far north you are right but how far east and west you are is much much much much, much harder. It relies on knowing what time it is relative to a fixed position.