WEBVTT - Is the Earth round? 0:00:09.280 --> 0:00:12.480 Hey, Daniel, how do you feel about skepticism. I don't know, 0:00:12.520 --> 0:00:14.600 I'm a little skeptical of it. Well, I mean, do 0:00:14.640 --> 0:00:17.480 you think it's always a good thing to be asking questions? 0:00:17.600 --> 0:00:20.200 I'm always in favor of questions. I mean, that's definitely 0:00:20.200 --> 0:00:21.840 how we got where we are, and that's how we 0:00:21.960 --> 0:00:24.960 learned so much about this incredible universe. But you know 0:00:25.120 --> 0:00:27.160 there are caveats. Okay, so I got a good one 0:00:27.200 --> 0:00:31.040 for you. Do you believe the Earth is round? Actually 0:00:31.120 --> 0:00:34.080 know that Earth is not round? What? Are you one 0:00:34.080 --> 0:00:37.519 of those flat earthers? No? No, No, those people are crazy. 0:00:38.600 --> 0:00:40.199 There are a lot of them out there. I know 0:00:40.240 --> 0:00:42.960 there are flat earthers all around the globe, all around 0:00:42.960 --> 0:00:46.400 the globe, not on top or below the globe exactly. Well, 0:00:46.440 --> 0:00:50.040 what's your take from a physicist? The official answer is 0:00:50.159 --> 0:00:53.320 Earth round or flat? It's a false choice. The answer 0:00:53.440 --> 0:01:13.880 is neither. Stay tuned and find out. Hi. I'm Jorge, 0:01:13.920 --> 0:01:17.000 I'm a cartoonists and the creator of PhD Comics. Hi, 0:01:17.120 --> 0:01:20.160 I'm Daniel Whiteson. I'm a particle physicist by day and 0:01:20.200 --> 0:01:23.520 a podcaster by any other time. And welcome to our podcast. 0:01:23.600 --> 0:01:27.200 Daniel and Jorge explain the Universe, a production of I 0:01:27.400 --> 0:01:30.039 Heart Radio, in which we try to explain crazy things 0:01:30.080 --> 0:01:33.600 about the universe, sometimes things really far away, sometimes things 0:01:33.600 --> 0:01:37.040 in our neighborhood, sometimes things right under our feet. I'm sorry. 0:01:37.040 --> 0:01:40.080 We try to tackle big questions, small questions, Questions you 0:01:40.160 --> 0:01:43.480 think you know the answer to, but maybe the universe 0:01:43.520 --> 0:01:46.240 has a way to surprise you. That's right. Round questions, 0:01:46.240 --> 0:01:50.640 flat questions, square questions, squiggly questions, and squishy questions. We 0:01:50.720 --> 0:01:53.920 love all the questions. Questions are our business. Who I 0:01:53.920 --> 0:01:57.040 like that as our company? Mottel, that's right. Do we 0:01:57.080 --> 0:01:59.640 have a company, Daniel, Um, we should make one. Yes, 0:02:00.080 --> 0:02:01.960 We're in a good company. All right. Well, so today 0:02:02.000 --> 0:02:05.960 we're tackling a question that obviously humans have been um 0:02:06.520 --> 0:02:09.240 had been struggling with for a long time, and I 0:02:09.240 --> 0:02:12.120 think for pretty much the last couple of centuries, people 0:02:12.200 --> 0:02:14.240 think we know that the answer to right. That's right. 0:02:14.520 --> 0:02:17.240 This is the kind of question people ask, and it's 0:02:17.240 --> 0:02:19.560 a kind of question it can be hard to answer 0:02:19.720 --> 0:02:22.840 immediately just by looking at what's around you. But it's 0:02:22.840 --> 0:02:25.160 a fun question because it's the kind of question that 0:02:25.880 --> 0:02:28.320 you know, sort of the beginning of cosmology. It's like, 0:02:28.400 --> 0:02:31.320 let's try to get a larger scale understanding. Let's try 0:02:31.360 --> 0:02:33.720 to understand not just the world I live in every 0:02:33.800 --> 0:02:36.200 day when I walk to my friend's house or go 0:02:36.520 --> 0:02:39.200 to the river and wash my food, but like the 0:02:39.280 --> 0:02:42.280 larger context where we find ourselves and how it all works. 0:02:42.320 --> 0:02:45.639 So the beginning of that intellectual struggle, yeah, kind of 0:02:45.680 --> 0:02:49.960 asking like what's beyond what we can see and touch? Right? 0:02:50.040 --> 0:02:51.960 That's right? How does it all fit in? Right? Like, 0:02:52.440 --> 0:02:54.680 you know the picture frame that my life lives in. 0:02:55.080 --> 0:02:57.480 Am I a tiny little dust mode in the corner? 0:02:57.520 --> 0:03:00.000 Am I in the center of it? Um? How big 0:03:00.080 --> 0:03:02.720 is that picture frame? You know? This? These are interesting questions, 0:03:02.720 --> 0:03:04.840 and I wonder sometimes like who were the first people 0:03:04.919 --> 0:03:07.880 to think of those questions? You know, as humanity emerge 0:03:08.000 --> 0:03:12.320 from you know, pre humans into an intelligence, Like when 0:03:12.320 --> 0:03:16.480 did people post humans? When did people first start to 0:03:16.520 --> 0:03:19.040 ask these kinds of questions? You know, how big is 0:03:19.080 --> 0:03:22.240 the earth? What is its shape? Um? You know, where 0:03:22.320 --> 0:03:24.280 is the sun? All these kind of questions about our 0:03:24.280 --> 0:03:27.320 basic cosmology? Yeah, Like who do you think was the 0:03:27.360 --> 0:03:30.720 first sentient being? That just kind of wondered, like if 0:03:30.760 --> 0:03:33.440 I keep going in that direction, what's going to happen? 0:03:34.240 --> 0:03:36.640 Or if I shoot straight up, what's going to happen? 0:03:36.880 --> 0:03:39.000 Or straight down? I don't know, but I think the 0:03:39.040 --> 0:03:41.880 answer would probably um make you happy, because I think 0:03:41.920 --> 0:03:46.120 that a lot of anthropologists imagine that humans have been 0:03:46.160 --> 0:03:49.240 intelligent for tens of thousands of years, and the major 0:03:49.320 --> 0:03:54.040 evidence of that is basically cartoons. Oh yeah, that's I 0:03:54.080 --> 0:03:58.240 always say, that's a sure sign of intelligence to draw them, 0:03:58.280 --> 0:04:00.480 to be able to draw them, or the sign of 0:04:00.480 --> 0:04:03.840 the society is about to crumble, that's right, and good 0:04:03.920 --> 0:04:08.240 extinct like those ancient civilizations. No, but it's cave paintings, right, 0:04:08.280 --> 0:04:10.680 I mean we can see which are basically cartoons like 0:04:10.800 --> 0:04:15.480 people doing symbolic thinking and describing dogs and buffalo and 0:04:15.520 --> 0:04:17.960 all sorts of things on the walls of caves describing them. 0:04:17.960 --> 0:04:20.040 I think that's the first sign of intelligence. So probably 0:04:20.080 --> 0:04:22.800 around then people started to have thoughts about, you know, 0:04:22.839 --> 0:04:25.520 their situation and how it works and what's the bigger 0:04:25.600 --> 0:04:28.200 what's the bigger situation that their life is in, and 0:04:28.240 --> 0:04:30.640 so I think that's what led them to ask this question. 0:04:31.080 --> 0:04:33.280 So yeah, that's kind of the question is, uh, you know, 0:04:33.360 --> 0:04:36.240 what did humans think about when they asked themselves? What 0:04:36.240 --> 0:04:38.159 happens if I keep going in one direction. And so 0:04:38.240 --> 0:04:46.080 today on the program, we'll be taggling the question is 0:04:46.120 --> 0:04:50.000 the Earth round? That's right? What shape is this crazy 0:04:50.160 --> 0:04:52.840 rock that we're living on? And you know, you can 0:04:52.920 --> 0:04:55.400 look at a lot of things that people describe early on, 0:04:55.520 --> 0:04:58.039 you know, drawings from hundreds or thousands of years ago, 0:04:58.320 --> 0:05:01.120 people trying to draw maps and what the Earth looked like, 0:05:01.200 --> 0:05:03.760 and there's some pretty crazy ideas out there. But if 0:05:03.760 --> 0:05:05.800 you just sort of look around you, or if you're 0:05:05.839 --> 0:05:08.200 just like born in the world and you look around, 0:05:08.400 --> 0:05:11.280 the world looks pretty flat, right, Like, as far as 0:05:11.279 --> 0:05:13.920 you can see, the ground is pretty flat. You think 0:05:13.960 --> 0:05:16.599 that we're sort of on a on a flat surface, right, 0:05:16.680 --> 0:05:20.080 because you your immediate surface around you is flat, and 0:05:20.240 --> 0:05:21.840 kind of you look out a little bit further, it's 0:05:21.880 --> 0:05:24.599 still flat. Yeah, And it seems simple, right, And if 0:05:24.640 --> 0:05:27.599 you're the goal is to understand around you, well, what's 0:05:27.600 --> 0:05:29.120 around you, then the first thing you're gonna do is 0:05:29.160 --> 0:05:31.280 think of the simplest thing. And the world looks kind 0:05:31.279 --> 0:05:33.400 of flat, and you can't see that far away, and 0:05:33.839 --> 0:05:36.680 you know, many surfaces, if you're only looking a small 0:05:36.720 --> 0:05:39.080 portion of them, look flat. I mean, the Earth could 0:05:39.120 --> 0:05:41.360 be all sorts of crazy shapes, and if you only 0:05:41.360 --> 0:05:44.760 look in your neighborhood, it might look flat in the vicinity. Yeah. So, 0:05:44.839 --> 0:05:48.080 and I imagine most of our listeners, um probably think 0:05:48.839 --> 0:05:52.279 or know that the Earth is not flat. But we're 0:05:52.320 --> 0:05:56.000 wondering if people actually know the real answer to the question, 0:05:56.120 --> 0:05:58.839 is the Earth round? Yeah? Or what is the shape 0:05:58.839 --> 0:06:01.120 of the Earth? That's a different Russian What shape is 0:06:01.160 --> 0:06:05.440 it in? That's right? What shape it is it? Politically 0:06:05.960 --> 0:06:09.120 fitness wise, I think we should not be judgmental the Earth. 0:06:09.160 --> 0:06:11.839 I think we should be Earth positive, you know, I think, um, 0:06:11.880 --> 0:06:13.440 this is the one only one we have. And he 0:06:13.480 --> 0:06:15.960 gets depressed and you know, decides to end itself and 0:06:16.000 --> 0:06:18.880 plumbing into the sun. You'll be sorry. That's right, the 0:06:18.920 --> 0:06:22.960 Earth is round and proud? That's right? Exactly. Who wants 0:06:22.960 --> 0:06:28.160 to be on a slender planet anyway? You know? All right? So, 0:06:28.360 --> 0:06:30.760 as usual, Dad, we were wondering what people how people 0:06:30.800 --> 0:06:32.680 out there in the street would answer this question. And 0:06:32.680 --> 0:06:36.360 so Daniel went out there into the street and accosted 0:06:36.640 --> 0:06:40.880 innocent bystanders and asked them a very basic question. That's right. 0:06:40.920 --> 0:06:43.520 And not only did I ask them if they believe 0:06:43.560 --> 0:06:46.200 the Earth was round, but I asked them how they knew, 0:06:46.480 --> 0:06:49.320 which I thought. Let's some of the more fascinating answers. Well, 0:06:49.400 --> 0:06:51.480 let's see what people had to say. Do you believe 0:06:51.520 --> 0:06:54.680 the Earth is round? Yes? Why what evidence do you 0:06:54.680 --> 0:06:57.000 have that the Earth is round? I think it is 0:06:57.200 --> 0:07:02.640 best answered by astronomy is like, of the Earth is round, 0:07:03.240 --> 0:07:06.360 we go. If the Earth is not round, you go. 0:07:06.520 --> 0:07:09.039 You start from a point and you keep going and 0:07:09.080 --> 0:07:12.800 you learn reach to this to your first place. Do 0:07:12.840 --> 0:07:16.640 you agree with me? Says one reason? And there are 0:07:16.680 --> 0:07:19.880 I'm pretty sure there are like lots of proofs about it. Yes. 0:07:20.240 --> 0:07:23.080 Why whateverence do you have the Earth is round? Because 0:07:25.160 --> 0:07:28.440 the idea that satellites are free fall and that they 0:07:28.480 --> 0:07:30.320 free fall around the Earth. So if you throw a ball, 0:07:30.400 --> 0:07:32.680 it goes, it has a curve, and so that kind 0:07:32.680 --> 0:07:35.920 of goes ahead improves that like we're falling innocence, and 0:07:35.960 --> 0:07:38.240 so that can go ahead and explain how satellites can 0:07:38.280 --> 0:07:42.320 fall around the Earth constantly cool orbits. Okay, good answers around, Yes, 0:07:42.440 --> 0:07:45.280 why what everything is do you found? Well, based on 0:07:45.320 --> 0:07:49.200 what everyone else has said, I don't know, there's some evidence, 0:07:49.240 --> 0:07:51.080 but I do believe the Earth is around. Do you 0:07:51.120 --> 0:07:53.760 believe that the Earth is round. What evidence do you 0:07:53.760 --> 0:07:58.800 have inund airplanes? I don't know, pictures of like from 0:07:58.840 --> 0:08:01.880 the I like that, all right, pictures from space other 0:08:02.080 --> 0:08:06.720 other astronomical objects are also around, so good point other 0:08:06.720 --> 0:08:09.200 points around. I do believe there is around. Why is that? 0:08:09.240 --> 0:08:11.760 Whatever you want? I believe this is around because just 0:08:11.920 --> 0:08:14.840 what I've learned in my education growing up middle school 0:08:14.840 --> 0:08:17.600 to high school to college, it's just what I'm familiar with. 0:08:17.800 --> 0:08:24.040 So yes, why whatever pictures NASA? Al right, pretty no 0:08:24.200 --> 0:08:26.640 flat earther is you couldn't find any flat earthers out 0:08:26.640 --> 0:08:30.120 there in Irvine. That's right, good job you see, irline. 0:08:30.680 --> 0:08:33.600 I was really relieved to not run into any flat earthers. 0:08:33.600 --> 0:08:35.760 I mean I was a tiny bit curious, like, what 0:08:35.800 --> 0:08:37.760 would I do if I met a flat earther, Would 0:08:37.760 --> 0:08:39.839 I like engage them in debate on the spot and 0:08:40.120 --> 0:08:42.559 be able to persuade them. Anybody who believes the Earth 0:08:42.679 --> 0:08:45.760 is flat is probably not really open to actual scientific 0:08:45.800 --> 0:08:48.320 dialogue on the subject um. But I was also sort 0:08:48.320 --> 0:08:51.800 of relieved that, like in this educational community, at least 0:08:51.840 --> 0:08:55.199 we've succeeded at that level that everybody understands the basics 0:08:55.440 --> 0:08:57.720 of the world around them. I think the flat earthers 0:08:57.800 --> 0:09:02.520 only exist on the Internet. Sometimes I wonder if the 0:09:02.520 --> 0:09:04.840 flat earthers are all just trolls, you know, if they're 0:09:04.920 --> 0:09:08.400 just being ridiculous to make everybody mad because they get 0:09:08.440 --> 0:09:11.800 their kicks by pissing people off. But I did some research, 0:09:11.840 --> 0:09:13.959 and there's a pretty hardcore group of people out there 0:09:13.960 --> 0:09:17.240 that really, honestly, sincerely believe the Earth is flat. So 0:09:17.280 --> 0:09:19.679 you got pretty much everyone said yes, uh, and they 0:09:19.720 --> 0:09:22.280 all had all pretty good reasons for believing that the 0:09:22.280 --> 0:09:24.080 Earth is around. Yeah, I'll be great. Some of the 0:09:24.120 --> 0:09:26.320 reasons as excellent, and some of the reasons is a 0:09:26.320 --> 0:09:29.960 little weak, like the weaker ones are like, well, everybody 0:09:30.000 --> 0:09:34.000 says so, you know, and that's okay. Like you, you know, 0:09:34.080 --> 0:09:36.040 you should be a skeptical person. You should try to 0:09:36.080 --> 0:09:38.480 think about these things for yourself. On the other hand, 0:09:38.559 --> 0:09:42.720 like if there's something that everybody is believing, probably it's true. 0:09:42.800 --> 0:09:45.160 I mean, there's probably a good reason why, you know, 0:09:45.240 --> 0:09:48.320 scientists and experts and everybody are saying X, y Z 0:09:48.480 --> 0:09:51.559 is true. So while you should be skeptical, you shouldn't 0:09:51.559 --> 0:09:54.840 just toss out everything that experts are saying just because 0:09:54.880 --> 0:09:57.080 you can't prove it yourself. Well, it gets a little 0:09:57.080 --> 0:10:01.040 bit philosophical, because I mean, it's impossible to know everything 0:10:01.200 --> 0:10:05.040 and to be aware of all the evidence for every 0:10:05.080 --> 0:10:07.600 single thing out there in the world, and so at 0:10:07.600 --> 0:10:09.200 some point you do sort of have to be like, 0:10:09.240 --> 0:10:12.080 all right, most scientists believe this. I guess it's probably true. 0:10:12.160 --> 0:10:14.439 That's right. Yes, sometimes you have to talk to an expert. 0:10:14.760 --> 0:10:16.600 And you know, what's the point of talking to experts 0:10:16.640 --> 0:10:18.600 if you're not going to believe what they say? Right? 0:10:18.640 --> 0:10:20.719 Like you ask me physics questions. You don't go off 0:10:20.720 --> 0:10:23.520 and double check every single thing I say? Or do 0:10:23.600 --> 0:10:27.480 you a triple check it? Daniel? Does that mean you 0:10:27.480 --> 0:10:29.400 have to other physicists on the line who are like 0:10:29.679 --> 0:10:31.679 giving the thumbs up of the thumbs down in your 0:10:32.000 --> 0:10:36.160 secret Daniels in my pocket? Man, I'd like some secret 0:10:36.200 --> 0:10:38.640 Daniels in my pocket. Do some of that work for me? 0:10:38.720 --> 0:10:41.080 That'd be awesome. I have a Daniel Grayson and a 0:10:41.160 --> 0:10:47.440 Daniel and defeat green Sun, different shades of Daniel, all 0:10:47.480 --> 0:10:51.160 the colors of Daniel, different fifty shades of Daniel. You 0:10:51.200 --> 0:10:55.120 know there's a fascilating book. I don't know what that 0:10:55.160 --> 0:10:57.640 book is about. I have to be the fan fiction 0:10:57.760 --> 0:11:01.120 version of this podcast, they're not safe for persion. Um. 0:11:01.280 --> 0:11:03.240 The other answer is that I really liked were the 0:11:03.280 --> 0:11:05.560 one people who have their own reasons, you know, who 0:11:05.600 --> 0:11:07.679 had thought about it. They're like, well, that's impossible, and 0:11:07.760 --> 0:11:11.280 here's why they could actually make an argument, you know, like, um, 0:11:11.320 --> 0:11:13.880 everything else out there is round, or we know that 0:11:13.960 --> 0:11:17.080 things are in orbit, right, these are good reasons, um. 0:11:17.280 --> 0:11:19.480 Or you know, people who don't think that the government 0:11:19.520 --> 0:11:22.760 is lying to them about everything. They believe the pictures. 0:11:22.800 --> 0:11:27.000 They believe that, they believe the you know, they believe 0:11:27.040 --> 0:11:28.719 the pictures of other I mean, and I guess you 0:11:28.720 --> 0:11:30.520 can see other planets, right, you can see the moon, 0:11:30.600 --> 0:11:33.520 and with the telescope you can see other planets. Yeah, 0:11:33.559 --> 0:11:35.600 you certainly can. You can see other planets, and they're 0:11:35.640 --> 0:11:38.079 all around. Pretty much everything out there in space above 0:11:38.120 --> 0:11:40.960 a certain size is round, and for good reason, right, 0:11:41.559 --> 0:11:44.079 it's or round dish at least. And the reason is 0:11:44.160 --> 0:11:47.240 just gravity. You know. Any if if you have a 0:11:47.280 --> 0:11:49.320 big enough object, it's gonna have a lot of gravity. 0:11:49.679 --> 0:11:52.760 And then if it's not around, that means that some 0:11:52.880 --> 0:11:55.480 part is further from the center than another part, and 0:11:55.480 --> 0:11:57.800 eventually it's just going to break and roll downhill like 0:11:57.800 --> 0:11:59.960 all mountains on Earth. All mountains on Earth will event 0:12:00.000 --> 0:12:04.560 actually crumble, right due to rain and gravity and other forces. Now, 0:12:04.640 --> 0:12:19.599 a quick word from our sponsor if we're going to 0:12:19.679 --> 0:12:21.800 answer this question, is the Earth round? Let's let's start 0:12:21.960 --> 0:12:24.400 kind of where humans started, right, And so let's start 0:12:24.400 --> 0:12:26.319 first of all with how do we know the Earth 0:12:26.600 --> 0:12:30.320 is not flat? Because that's kind of what your intuition 0:12:30.360 --> 0:12:32.440 would tell you if you never traveled or seen pictures 0:12:32.480 --> 0:12:34.720 from space. Right. Okay, so if you haven't seen pictures 0:12:34.760 --> 0:12:37.880 from space and you're like, you know, natural science kind 0:12:37.880 --> 0:12:40.560 of person a few thousand years ago, how might you 0:12:40.640 --> 0:12:43.439 figure out that the Earth is not flat? Well, the 0:12:43.640 --> 0:12:45.960 you know, the history of it is that people did 0:12:45.960 --> 0:12:49.280 things like they did experiments where they stuck sticks in 0:12:49.320 --> 0:12:52.400 the ground and they look to the shadows. Now, if 0:12:52.400 --> 0:12:54.600 the Earth is flat and the sun is just like 0:12:54.760 --> 0:12:57.120 above us, then every stick is going to have a 0:12:57.120 --> 0:13:00.760 shadow the same length. But if the Earth is round, 0:13:01.080 --> 0:13:03.120 then those shadows is going to be different lengths at 0:13:03.160 --> 0:13:06.040 different places. And so this is like what a Greek 0:13:06.080 --> 0:13:09.480 guy did. He put tall sticks in different towns in Greece, 0:13:09.800 --> 0:13:11.880 and he knew how far away those towns were from 0:13:11.880 --> 0:13:14.520 each other, and he measured the angles of those sticks 0:13:14.559 --> 0:13:17.280 and the length of the shadows, and from that he 0:13:17.320 --> 0:13:19.720 could estimate he could prove that the Earth was round 0:13:19.960 --> 0:13:24.720 and estimated size to pretty good accuracy. What is this 0:13:24.840 --> 0:13:29.240 a like a apocryphal story or for real? Hey? You 0:13:29.240 --> 0:13:31.480 know everything about ancient Greece could be apocryphal, right, The 0:13:31.520 --> 0:13:34.160 whole thing could just be invented as far as as 0:13:34.160 --> 0:13:36.640 far as we know. Um, But you know this is 0:13:36.800 --> 0:13:38.959 um as far as we understand it, This really happened, 0:13:41.800 --> 0:13:46.920 you agree, Greece. Let's talk about whether Greece really happened? Right? 0:13:46.960 --> 0:13:54.440 Is Grease just a conspiracy man? No? But you know, 0:13:54.840 --> 0:13:56.839 the thing about ancient Greece is that we know so 0:13:57.040 --> 0:14:00.040 little of what happened because the Dark Ages and so 0:14:00.240 --> 0:14:02.440 much of what they did was destroyed. And you know, 0:14:02.480 --> 0:14:06.080 we have like a tiny trickle of the vibrant intellectual 0:14:06.120 --> 0:14:08.760 product of that civilization. So we really don't know what 0:14:08.840 --> 0:14:10.600 was going on in ancient Greece. We know a tiny 0:14:10.640 --> 0:14:13.480 little slipper, which is such a tragedy. It breaks my 0:14:13.559 --> 0:14:15.959 heart to think about all those great ideas that were 0:14:15.960 --> 0:14:19.440 just like lost, you know. Um. But anyway, all those 0:14:19.480 --> 0:14:23.280 big wine parties. No, it's just to me. It's it 0:14:23.360 --> 0:14:26.760 breaks my heart when I when I think about you know, um, 0:14:26.760 --> 0:14:30.400 progress that's been made, Things have been figured out, mathematics 0:14:30.400 --> 0:14:34.120 has been developed, and then just just discarded or lost, 0:14:34.160 --> 0:14:37.080 you know, like in huge fires of ancient libraries and 0:14:37.120 --> 0:14:41.640 destructions of civilization. Anyway, we do have some clues about 0:14:41.680 --> 0:14:43.680 what happened in ancient Greece, and there are stories about 0:14:43.680 --> 0:14:47.360 the about folks measuring the size of the Earth using 0:14:47.400 --> 0:14:49.680 basically just two sticks in the ground. Okay, and so 0:14:49.800 --> 0:14:52.360 the ideas that he planted a stick in one town 0:14:53.520 --> 0:14:55.840 and then it's kind of like if you plant the 0:14:55.880 --> 0:14:59.920 stick in California and then you run over to Florida 0:15:00.120 --> 0:15:03.560 and plant another stick there. At any given time of 0:15:03.640 --> 0:15:07.480 the day, the shadows are might be different. Yeah, there 0:15:07.480 --> 0:15:10.480 will be different lengths, right, because those two sticks have 0:15:10.520 --> 0:15:13.240 a different angle with respect to the sun. They're seeing 0:15:13.280 --> 0:15:16.080 the sun at different points in the sky. Yeah, exactly. 0:15:16.680 --> 0:15:18.560 And if the earth, but if the Earth was flat, 0:15:18.800 --> 0:15:22.120 the shadows would be identical. That's right, that's right, Yeah, 0:15:22.320 --> 0:15:25.680 that's that's the point. Yeah. Um No, they wouldn't be 0:15:25.720 --> 0:15:27.640 the same, would they, But there would be the same 0:15:27.720 --> 0:15:29.240 length there might be a different angle, but there would 0:15:29.240 --> 0:15:31.720 be the same length. Pretty sure, Pretty sure. I mean 0:15:31.720 --> 0:15:35.080 it depends on your particular flat earth model, right, But 0:15:35.200 --> 0:15:38.320 on a sphere, it's definitely true that there are different 0:15:38.400 --> 0:15:41.320 lengths and angles and that you can use that to 0:15:41.360 --> 0:15:44.120 measure the size of the sphere. And another key element, 0:15:44.120 --> 0:15:46.560 of course, is knowing that the Sun is really really 0:15:46.600 --> 0:15:49.000 far away, so that the light that comes from it 0:15:49.040 --> 0:15:52.640 is basically always parallel, because otherwise you could try to 0:15:52.760 --> 0:15:55.360 explain the different angles that you get from sticks to 0:15:55.400 --> 0:15:58.120 different places and make it consistent with a flat earth. 0:15:58.360 --> 0:16:00.440 You could try to do that by saying, oh, well, 0:16:00.480 --> 0:16:02.720 maybe the Sun is really close to the Earth and 0:16:02.800 --> 0:16:05.320 that's why we get different angles right over a flat earth. 0:16:05.520 --> 0:16:07.880 But that's silly. We know the Sun is far away. 0:16:08.000 --> 0:16:09.840 If the Sun was that close to the Earth, you 0:16:09.840 --> 0:16:12.440 could see it's apparent size like change as you move 0:16:12.480 --> 0:16:14.680 around the Earth, and we don't see that. So that's 0:16:14.720 --> 0:16:18.480 an important part of the argument. Interesting, but wouldn't that 0:16:19.400 --> 0:16:22.480 require you to have like a walkie talkie between the 0:16:22.520 --> 0:16:25.920 two places, you know, to say, all right, right now, 0:16:26.400 --> 0:16:28.320 measure the length of the shadow. But if you don't 0:16:28.360 --> 0:16:30.800 have that instant communication, how would you like coordinated and 0:16:30.880 --> 0:16:32.920 know that it was measured at the same time. That's 0:16:32.960 --> 0:16:35.160 a good question. I don't know how they managed it. 0:16:35.760 --> 0:16:40.680 Maybe they had walkie talkies in ancient Greece increase, They 0:16:40.680 --> 0:16:42.600 definitely didn't. We don't know anything they could have burned 0:16:42.640 --> 0:16:44.960 with the labrary. I mean that the power of the 0:16:45.040 --> 0:16:48.360 test is greater the further the sticks are apart. But 0:16:48.440 --> 0:16:50.160 I don't know how far apart they have to be 0:16:50.280 --> 0:16:52.320 for you to have a measurable effect. It might not 0:16:52.360 --> 0:16:54.480 have to be very far, you know, so you might 0:16:54.480 --> 0:16:56.480 be able to say, like, all right, we'll both walk 0:16:56.520 --> 0:16:58.680 for an hour and then plant a stick and then 0:16:58.720 --> 0:17:01.440 measure the length, and it might be enough, Oh I see, 0:17:01.520 --> 0:17:03.880 or maybe like a smoke signals or something like if 0:17:03.880 --> 0:17:06.600 it's several miles and you can still do it, yeah, 0:17:06.600 --> 0:17:10.000 smoke signals exactly. Um, you'd be good at inventing physics 0:17:10.000 --> 0:17:13.480 experiments in ancient Greece. Yeah, I definitely want to around. Um. 0:17:13.600 --> 0:17:15.199 But there are also other ways. You don't have to 0:17:15.200 --> 0:17:17.200 do two sticks in the ground, Like, there are other 0:17:17.200 --> 0:17:20.480 ways to figure out that the Earth is round, even 0:17:20.560 --> 0:17:23.440 even without technology. All right, what are those ways? Well, 0:17:23.480 --> 0:17:25.800 you can just look at the stars. Right, travel the 0:17:25.800 --> 0:17:28.400 Earth and look at the stars. You see different stars 0:17:28.640 --> 0:17:31.480 from different parts of the Earth. Right. If the Earth 0:17:31.560 --> 0:17:34.480 is flat, then everybody should be seeing the same sky. 0:17:34.520 --> 0:17:36.320 I mean, you'll be seeing it from a slightly different 0:17:36.320 --> 0:17:38.080 point of view if you're in a different spot on 0:17:38.160 --> 0:17:42.359 the Earth. But some stars are blocked by the earth. 0:17:42.600 --> 0:17:45.000 Right you walk from you walk from North America to 0:17:45.040 --> 0:17:48.600 South America, you're gonna see different stars in the sky. Right, 0:17:48.680 --> 0:17:51.000 the northern stars you can't see them because the Earth's 0:17:51.040 --> 0:17:54.760 curvatures in the way. Oh I see. So if you 0:17:55.600 --> 0:17:58.280 assuming you can remember the sky right, or you can 0:17:58.359 --> 0:18:02.720 draw it for example, Yeah, you heard of that drawing 0:18:03.480 --> 0:18:06.280 only in caves. I only know that kind. And you 0:18:06.320 --> 0:18:07.879 can't see the stars when you're in a cave, so 0:18:08.160 --> 0:18:09.960 you can sort of you chisel along the side of 0:18:09.960 --> 0:18:11.680 you join on the side of the cave. You walk 0:18:11.760 --> 0:18:14.240 to South America, you draw another cave, and they're like, hmmmm, 0:18:15.320 --> 0:18:17.359 I should have brought my cave with me. That's how 0:18:17.400 --> 0:18:26.439 they invented the portable cave, probably otherwise known as the tent. Okay. 0:18:26.440 --> 0:18:28.479 So that's another way you would tell, right, is you 0:18:28.520 --> 0:18:31.959 would uh notice that the stars are different in different 0:18:32.000 --> 0:18:36.320 parts of the Earth, which means that the Earth can't 0:18:36.320 --> 0:18:39.919 be flat. That's right, that's another reason. Another way you 0:18:39.960 --> 0:18:43.520 can tell, again without really much technology, is just seasons. 0:18:43.560 --> 0:18:46.960 Like how do you get seasons on a flat earth? Right? 0:18:47.119 --> 0:18:49.200 I mean different parts of the earth have difference. You 0:18:49.280 --> 0:18:51.240 might say, okay, we can get north, we can get 0:18:51.240 --> 0:18:53.879 winter the sun goes further away, we can get summer 0:18:53.920 --> 0:18:56.240 when the sun gets closer. But we have different seasons 0:18:56.280 --> 0:18:58.320 and different part of the earth. Right, we have summer 0:18:58.480 --> 0:19:01.280 in the northern hemisphere when we have during the southern hemisphere. 0:19:01.560 --> 0:19:03.320 How do you account for that? Well, I mean if 0:19:03.359 --> 0:19:05.360 I if I live thousands of years ago, I mean 0:19:05.359 --> 0:19:07.520 I wouldn't know. I wouldn't know anything, right for all? 0:19:07.560 --> 0:19:10.639 For all I know there are gods and weird you know, 0:19:11.000 --> 0:19:15.359 magical beings that make it winter here, and some are there, yes, absolutely, 0:19:15.640 --> 0:19:20.480 And there is always another explanation that's like ridiculously complicated, 0:19:20.560 --> 0:19:24.400 involves magic and gods are like crazy trajectories that can 0:19:24.440 --> 0:19:27.080 explain all the data. But we prefer the simplest, right, 0:19:27.560 --> 0:19:29.919 If the simplest explanation is that the Earth is a 0:19:30.000 --> 0:19:32.560 body just like all the other ones we see, and 0:19:32.600 --> 0:19:35.320 it looks just like them, and it's also circular. It's 0:19:35.320 --> 0:19:39.719 also basically spherical, and that explains everything we see. And 0:19:39.760 --> 0:19:43.240 so it's like, by far the explanation we prefer to, 0:19:43.720 --> 0:19:47.480 there's some crazy magic aliens out there doing some crazy 0:19:47.480 --> 0:19:50.040 tricks on us, or here on Earth? Are you here 0:19:50.119 --> 0:19:52.480 on Earth? Exactly? Okay? Cool? And then what's the last 0:19:52.680 --> 0:19:56.120 last experiment you as a Greek scientist can do. Well? 0:19:56.200 --> 0:19:58.800 The simplest one is that you can see hints of 0:19:58.840 --> 0:20:01.840 the curvature. I mean you can look at ships, for example, 0:20:02.200 --> 0:20:08.159 coming over the horizon from far away, like what's blocking them? Right? Ships? Um? 0:20:08.359 --> 0:20:10.760 Coming over the horizon, You're seeing them come over the 0:20:10.800 --> 0:20:14.760 curvature of the Earth. Right, that's pretty direct right there. Um. 0:20:14.800 --> 0:20:18.280 And in a similar way, you can see further when 0:20:18.280 --> 0:20:20.960 you get higher up, Like if the Earth was flat, 0:20:21.480 --> 0:20:24.159 then you couldn't see any further by getting any higher up, 0:20:24.200 --> 0:20:26.320 or you can see at a different angle, right, but 0:20:26.359 --> 0:20:29.160 you couldn't see any further. But on a spherical Earth 0:20:29.240 --> 0:20:32.080 or nearly spherical earth, the higher you go, the less 0:20:32.160 --> 0:20:35.400 the Earth's curvature blocks you, the larger your field of view. 0:20:35.720 --> 0:20:38.480 And that's exactly what you experience. You go to a skyscraper. 0:20:38.520 --> 0:20:41.040 At the top of a mountain, you can see much further. Okay, 0:20:41.040 --> 0:20:42.640 so I guess the idea is that is that if 0:20:42.680 --> 0:20:46.399 the Earth was flat and you were standing at the 0:20:46.440 --> 0:20:49.280 beach and you saw a ship go off and away 0:20:49.320 --> 0:20:52.040