WEBVTT - Listener Questions 36 0:00:08.520 --> 0:00:11.039 Hey, or hey, do you ever wish you had more 0:00:11.119 --> 0:00:14.560 than two arms? That would be weird, but sometimes it 0:00:14.600 --> 0:00:16.480 would be useful. You know, if you're a parent, you're 0:00:16.520 --> 0:00:19.520 carrying around a couple of kids, would be great to 0:00:19.600 --> 0:00:22.079 have extra arms. Well, is it more arms do you 0:00:22.120 --> 0:00:24.480 want or more hands? I think what I want is 0:00:24.480 --> 0:00:27.680 maybe more brains. That would be handy. Then I can 0:00:27.760 --> 0:00:30.520 have twice a number of thoughts, or one of them 0:00:30.520 --> 0:00:32.479 could think while the other one naps, and then they 0:00:32.479 --> 0:00:34.720 can take turns. I think I already have more ideas 0:00:34.760 --> 0:00:37.000 than my arms and hands can handle. It. Sounds like 0:00:37.000 --> 0:00:39.440 you need less brains then, or more arms, like a 0:00:39.479 --> 0:00:42.839 whole army of arms. That would be pretty handy. It 0:00:42.880 --> 0:01:00.880 would be quite a handful. I am hand with cartoonists 0:01:00.880 --> 0:01:03.600 and the creator of PhD comics. Hi, I'm Daniel. I'm 0:01:03.640 --> 0:01:06.560 a particle physicist and a professor at UC Irvine, and 0:01:06.680 --> 0:01:08.960 I'm pretty sure I could make use of a third 0:01:09.080 --> 0:01:11.880 arm if it had a hand attached to it. Where 0:01:11.880 --> 0:01:14.119 would you put it? Though? In your body? Like at 0:01:14.120 --> 0:01:16.480 the top of your head, that would be useful. I 0:01:16.560 --> 0:01:18.800 was just gonna say it top of my head, yeah, exactly. 0:01:19.080 --> 0:01:21.600 You could like scratch your nose or scratch your back. 0:01:21.720 --> 0:01:23.960 Even that would be pretty handy. Yeah, but how would 0:01:24.000 --> 0:01:27.240 you scratch your arm? I'd have two other arms for 0:01:27.319 --> 0:01:30.320 that job, but would they reach I think the more 0:01:30.319 --> 0:01:32.800 interesting question is how you would call them, Like is 0:01:32.840 --> 0:01:35.000 it your right arm, your left arm, and your top arm, 0:01:35.360 --> 0:01:38.240 or you're like your dominant arm, your subdominant arm, and 0:01:38.280 --> 0:01:42.000 your sub subdominant arm. Maybe you could call it like 0:01:42.040 --> 0:01:47.000 your color arm or your weak heart. What if it's 0:01:47.040 --> 0:01:49.840 extra strong though, on the top of my head anyway, 0:01:49.960 --> 0:01:52.360 lots of fun things to think about, Yeah, because it 0:01:52.440 --> 0:01:54.440 is a fun universe with a lot to think about. 0:01:54.680 --> 0:01:57.360 There are a lot of stars and galaxies and amazing 0:01:57.400 --> 0:02:01.120 objects and invisible matter and will energy out there for 0:02:01.200 --> 0:02:04.040 us to wonder about and to have questions about. No 0:02:04.120 --> 0:02:06.400 matter which arm you'd like to use to scratch your head. 0:02:06.680 --> 0:02:09.520 Welcome to our podcast Daniel and Jorge Explain the Universe, 0:02:09.560 --> 0:02:12.880 a production of iHeartRadio in which we dig into all 0:02:12.880 --> 0:02:16.200 of the heads scratching mysteries about the universe, Why it 0:02:16.240 --> 0:02:18.720 looks the way it does, what color it is, if 0:02:18.760 --> 0:02:22.000 we can even possibly understand it, Why everything out there 0:02:22.080 --> 0:02:25.280 seems to be spinning, and why they spin in such beautiful, 0:02:25.480 --> 0:02:28.920 worly patterns. We dig into all of the mysteries of 0:02:28.960 --> 0:02:32.120 the universe, from the tiny quantum particle to the inside 0:02:32.120 --> 0:02:34.400 of black holes, to the edge of the universe, to 0:02:34.480 --> 0:02:37.680 its very beginning and its very end, because we love 0:02:37.720 --> 0:02:40.920 these mysteries, and we love marinating in our understanding and 0:02:41.200 --> 0:02:44.519 our ignorance. Yeah, because there are beautiful patterns out there 0:02:44.560 --> 0:02:48.520 in the universe. Patterns in color, patterns, in shape patterns, 0:02:48.600 --> 0:02:51.600 also in mysteries. It seems like the universe has sort 0:02:51.639 --> 0:02:54.720 of a recurring pattern of always having things that are 0:02:55.000 --> 0:02:57.760 difficult to explain or that don't reveal how they work 0:02:57.840 --> 0:03:01.480 right away. It is interesting that the universe is mysterious, 0:03:01.760 --> 0:03:04.880 but not so mysterious that we can't make progress. It's 0:03:04.919 --> 0:03:07.960 like we are just smart enough to understand like the 0:03:08.000 --> 0:03:10.520 next chunk of physics, but not so smart that we 0:03:10.560 --> 0:03:13.400 figure it all out right away, but also not so 0:03:13.480 --> 0:03:16.440 dumb that it's totally a mystery to us. We seem 0:03:16.480 --> 0:03:19.080 to be sort of like fine tuned to be entertained 0:03:19.120 --> 0:03:21.640 by the mysteries of this universe. You're saying, we're like 0:03:21.639 --> 0:03:26.040 the goldilocks of all species in the universe, But how 0:03:26.040 --> 0:03:27.720 do you know this, Daniel, how do you know we're 0:03:27.720 --> 0:03:30.240 not behind? How do you know we're not actually like 0:03:30.280 --> 0:03:33.560 at the back of the class roster. Yeah, we could be. 0:03:33.680 --> 0:03:35.720 There might be aliens out there that I figured out 0:03:35.720 --> 0:03:38.280 the physics of the universe and about ten seconds. But 0:03:38.360 --> 0:03:40.440 what I'm saying is that maybe this is more fun. 0:03:40.840 --> 0:03:43.200 Maybe it's more fun to be a little confused for 0:03:43.240 --> 0:03:46.200 a while and then figure something out, rather than just 0:03:46.280 --> 0:03:48.880 have the entire theory of everything come to you in 0:03:48.920 --> 0:03:51.440 a single flash of insight. That sounds like something a 0:03:51.520 --> 0:03:54.160 student who's not doing well in school might say, like, Hey, 0:03:54.320 --> 0:03:57.680 I got an F because it's it's fun. It's more 0:03:57.760 --> 0:04:00.640 like somebody who wants to keep the mysteries on because 0:04:00.680 --> 0:04:03.000 it's part of my job. I mean, if we like 0:04:03.080 --> 0:04:06.480 solved physics tomorrow, then what would I do the rest 0:04:06.480 --> 0:04:08.200 of my life? Is that what you tell the funding 0:04:08.200 --> 0:04:10.520 Agency's like, Hey, you paid me all this money and 0:04:10.560 --> 0:04:13.520 I haven't figured anything out, but I'm having a lot 0:04:13.520 --> 0:04:16.880 of fun. And really what's more important than that. It's 0:04:16.960 --> 0:04:19.160 the friends you make along the way to figuring out 0:04:19.200 --> 0:04:21.640 the universe. That's right, I got an F on my 0:04:21.839 --> 0:04:25.719 research paper, but F stands for friends and fun. Not funding. 0:04:26.040 --> 0:04:28.400 And it's not just people like me who are wondering 0:04:28.440 --> 0:04:31.599 about the nature of the universe and enjoying thinking about it. 0:04:31.600 --> 0:04:34.919 It's everybody sciences of the people, by the people, and 0:04:35.120 --> 0:04:38.520 for the people, and that includes me and you. It 0:04:38.600 --> 0:04:41.800 includes anybody who thinks about the universe, wonders why it 0:04:41.839 --> 0:04:44.480 works the way that does, and tries to figure it out. 0:04:44.680 --> 0:04:48.000 That's right. Everybody has questions, and sometimes we even answer 0:04:48.080 --> 0:04:51.040 those questions on this podcast, although sometimes the answer is 0:04:51.160 --> 0:04:53.880 we don't know. All too often the answer is we 0:04:53.880 --> 0:04:56.080 don't know, so give us some money to figure it out. 0:04:56.279 --> 0:05:00.720 Stay tuned. But we encourage everybody out there to engage 0:05:00.760 --> 0:05:03.400 with their curiosity, to look out the universe and connect 0:05:03.400 --> 0:05:06.839 with their personal questions. You know, something that I think 0:05:06.839 --> 0:05:10.160 maybe people don't appreciate is how science is driven by 0:05:10.279 --> 0:05:15.120 individual people's curiosity. The reason we study this and not that, 0:05:15.320 --> 0:05:19.440 the reason people investigate the mating patterns of South American bats, 0:05:19.600 --> 0:05:23.080 is because somebody has decided that that's the most important question, 0:05:23.120 --> 0:05:25.880 the one to dedicate their life too. So I like 0:05:25.960 --> 0:05:28.400 to encourage people to think about what is your most 0:05:28.440 --> 0:05:30.880 important question? If you could ask a single question of 0:05:30.920 --> 0:05:33.520 the universe and get an answer what would it be? 0:05:33.800 --> 0:05:36.040 And so we encourage our listener to think about the 0:05:36.120 --> 0:05:39.039 universe and to write to us with their questions. Yeah, 0:05:39.080 --> 0:05:41.159 we get questions all the time, and sometimes we even 0:05:41.200 --> 0:05:43.960 answer them on the podcast. We will pull up a 0:05:44.120 --> 0:05:46.279 question that we get and we'll try to give you 0:05:46.320 --> 0:05:49.080 our best answer on the air. Answer Right. We answer 0:05:49.320 --> 0:05:52.279 all of our questions that listeners send us to questions 0:05:52.360 --> 0:05:55.640 at Daniel and Jorge dot com. But sometimes there's one 0:05:55.680 --> 0:05:58.480 that I think is especially intriguing or requires a little 0:05:58.520 --> 0:06:01.120 bit of background research, so we answer it here on 0:06:01.160 --> 0:06:03.719 the podcast. And so today on the program, we'll be 0:06:03.760 --> 0:06:13.520 tackling listening our questions episode number thirty six of our 0:06:13.560 --> 0:06:17.000 listener question series That's Right, which puts us well above 0:06:17.000 --> 0:06:20.440 a hundred in terms of questions answered on air. And 0:06:20.640 --> 0:06:22.720 do we have a theme for this set of questions? 0:06:23.120 --> 0:06:26.600 This one's sort of like big questions about the big Universe. 0:06:27.000 --> 0:06:34.200 I see the usual then everything exactly. Today we have 0:06:34.279 --> 0:06:39.960 questions about questions exactly. Let's fall into the big questions category. 0:06:40.080 --> 0:06:42.520 All right, big questions here today we have three awesome 0:06:42.600 --> 0:06:46.480 questions about the shape of our galaxy, about the color 0:06:46.640 --> 0:06:49.359 of the universe, and also about whether the universe is 0:06:49.400 --> 0:06:53.680 maybe tearing itself apart. You mean emotionally or like physically. 0:06:54.080 --> 0:06:56.479 I think first physically and then emotionally. If you tear 0:06:56.520 --> 0:06:58.760 yourself apart physically, then if you want to really be 0:06:58.880 --> 0:07:01.800 able to tear yourself a part emotionally, Yeah, that's true. 0:07:01.839 --> 0:07:04.120 Depending on how the universe collapses, you might not have 0:07:04.200 --> 0:07:07.480 time for an emotional response. Well, let's dig into these 0:07:07.560 --> 0:07:10.320 questions because they're pretty interesting. The first one comes from 0:07:10.320 --> 0:07:13.240 Matt from Indiana. Hey, Daniel and Horey. This is Matt 0:07:13.280 --> 0:07:15.520 from Indiana. I was just reading an article which has 0:07:15.600 --> 0:07:17.560 some of the most recent Hubble pictures now that it's 0:07:17.520 --> 0:07:20.320 successfully returned to prime time. The question I have is 0:07:20.360 --> 0:07:24.040 about the galaxy aarp m adri zero zero zero two 0:07:24.080 --> 0:07:27.120 D five H three. NASA is saying it's noteworthy as 0:07:27.160 --> 0:07:29.360 it only has three arms to it and most spiral 0:07:29.400 --> 0:07:32.320 galaxies have even numbers. Why wouldn't we find an equal 0:07:32.360 --> 0:07:35.360 amount of even an odd armed disc galaxies symmetry. I'm 0:07:35.400 --> 0:07:38.200 perplexed on this. Thanks for your time, cheers, Matt. All right. 0:07:38.280 --> 0:07:41.760 Awesome question from Matt. He's asking not about the milk Away, 0:07:41.840 --> 0:07:44.840 but a different galaxy that the Hubble Telescope has found. Yeah, 0:07:44.880 --> 0:07:47.480 we have imaged so many galaxies. You know, when you 0:07:47.480 --> 0:07:49.560 look up in the night sky, you mostly see stars, 0:07:49.640 --> 0:07:53.240 but behind those are tiny little smudges which are galaxies. 0:07:53.840 --> 0:07:55.960 And as we saw from the recent James Webb Space 0:07:56.000 --> 0:07:59.840 Telescope images, every tiny little dot of sky is filled 0:08:00.040 --> 0:08:02.760 with galaxies, and they have lots of really interesting shapes 0:08:02.800 --> 0:08:05.640 and characteristics. And so now we have lots and lots 0:08:05.640 --> 0:08:08.320 of examples of what other galaxies look like. And Matt 0:08:08.400 --> 0:08:11.080 is asking about one particular one that NASA said was 0:08:11.120 --> 0:08:13.560 a little weird. Yeah, and he spelled out the name 0:08:13.600 --> 0:08:15.400 of it. Maybe we should spill it out again in 0:08:15.400 --> 0:08:17.760 case anyone wants to look it up. Yeah, that's galaxy 0:08:17.880 --> 0:08:22.400 AARP DASH M A D O R E. Then the 0:08:22.480 --> 0:08:25.960 number is two one one five dash two seven three 0:08:26.000 --> 0:08:28.000 And we'll put a link to NASA's page about this 0:08:28.240 --> 0:08:30.440 in the show notes. They just got a catchy name, 0:08:30.520 --> 0:08:32.800 my daughter. It sounds like I love you or something. Well, 0:08:32.800 --> 0:08:34.679 if you look up the image and the link on 0:08:34.720 --> 0:08:37.720 our website, you'll see basically a picture of our galaxy. 0:08:37.960 --> 0:08:40.520 But it looks kind of interesting because it's got two 0:08:40.559 --> 0:08:43.920 short arms, but then a one long arm on the bottom. Yeah, 0:08:43.960 --> 0:08:46.360 lots of these spiral galaxies have the same basic features 0:08:46.360 --> 0:08:48.600 you have, like a central bar and then some arms 0:08:48.720 --> 0:08:51.720 swirling around them. And this one is a little weird because, 0:08:52.000 --> 0:08:53.800 as you say, it has two sort of shorter arms 0:08:53.800 --> 0:08:56.760 and one longer arm. And that's the thing that Matt 0:08:56.800 --> 0:09:00.000 picked up on that the fact that this has three arms, 0:09:00.000 --> 0:09:02.720 according to this press release, having an odd number of arms, 0:09:02.720 --> 0:09:05.480 like not two or four or six is a little weird. 0:09:05.640 --> 0:09:07.800 You mean, it's a little odd you have an odd 0:09:07.880 --> 0:09:10.560 number of arms, because I think we're kind of used 0:09:10.559 --> 0:09:14.040 to arms coming in pairs, right, I certainly have two arms, 0:09:14.040 --> 0:09:17.120 though i'd like a third. But if we're talking about galaxies, 0:09:17.520 --> 0:09:20.200 then it sort of makes conceptual sense to imagine them 0:09:20.280 --> 0:09:23.160 being even numbers, like or basically there's just two arms 0:09:23.160 --> 0:09:25.240 because you have the central bar and then the arms 0:09:25.320 --> 0:09:28.040 swirling off around it. But it turns out that galaxy 0:09:28.120 --> 0:09:30.679 arms are a lot more complicated than you might imagine. 0:09:30.920 --> 0:09:33.800 M Well, let's dig into it. First of all, why 0:09:33.880 --> 0:09:36.520 do galaxies even have arms? And I guess maybe we 0:09:36.559 --> 0:09:38.720 should define what we mean by arms. It's kind of 0:09:38.760 --> 0:09:40.640 like a you look at a picture of a galaxy 0:09:40.679 --> 0:09:42.760 you see a cluster of stars, but then you see 0:09:42.760 --> 0:09:46.240 these kind of like tendrils, these rows of stars kind 0:09:46.280 --> 0:09:48.400 of swirling from the center of it. That's what an 0:09:48.480 --> 0:09:50.880 arm is. Yeah, and so we tend to call these 0:09:50.880 --> 0:09:54.440 things spiral arms. And there's really two things going on there, 0:09:54.520 --> 0:09:57.600 the spiral nature of them and the arms. Right, So 0:09:57.679 --> 0:10:00.800 let's first talk about like why are these things spiraling 0:10:01.000 --> 0:10:04.199 at all? Why is there a spiral pattern in the galaxy. 0:10:04.280 --> 0:10:06.160 And that just comes from the fact that the galaxy 0:10:06.400 --> 0:10:09.040 is spinning. So everything in space is spinning, and as 0:10:09.080 --> 0:10:11.719 it collapses, it spins faster and faster. The things a 0:10:11.800 --> 0:10:14.680 different distance from the center of the galaxy don't always 0:10:14.760 --> 0:10:18.680 rotate at the same like number of angles per second. Instead, 0:10:18.679 --> 0:10:22.520 they tend to move through space at the same linear speed. 0:10:22.760 --> 0:10:26.880 So galaxies don't rotate like a DVD or a compact disc, 0:10:27.280 --> 0:10:29.960 where like every point along some line rotates with the 0:10:29.960 --> 0:10:33.840 same angular speed. It's more like they rotate like runners 0:10:33.920 --> 0:10:36.600 going around a track, where people on the outside tend 0:10:36.640 --> 0:10:40.280 to fall behind even if they're running at the same speed. Well, 0:10:40.320 --> 0:10:43.120 maybe let's take it a step back. Because you mentioned 0:10:43.240 --> 0:10:46.160 everything is always spinning. What does that mean? Wh are 0:10:46.160 --> 0:10:48.440 things in space necessarily spinning or do you mean, like 0:10:48.520 --> 0:10:52.520 everything's moving but relative to like the center of gravity 0:10:52.679 --> 0:10:56.280 or the center of a cluster of stuff, you're sort 0:10:56.320 --> 0:10:58.719 of spinning around that. So everything in space is sort 0:10:58.760 --> 0:11:03.160 of whizzing around. And remember that spinning is relative to 0:11:03.320 --> 0:11:06.640 an axis. You like, draw a line through space and say, 0:11:06.760 --> 0:11:09.760 are things moving around this point? And so you can 0:11:09.800 --> 0:11:12.080 pick any axis you like. You know, pick like the 0:11:12.080 --> 0:11:14.280 center of the sun. That makes sense to think about 0:11:14.280 --> 0:11:16.240 the motion of the Solar system, or you know, the 0:11:16.240 --> 0:11:18.440 north south axis of the Earth. But you really could 0:11:18.480 --> 0:11:20.680 pick anything, but it makes most sense to pick like 0:11:20.840 --> 0:11:23.360 the center of mass of a big blob of stuff 0:11:23.400 --> 0:11:26.400 and ask are things moving around this center of mass? 0:11:26.720 --> 0:11:29.520 And because everything is sort of flying around through space, 0:11:29.520 --> 0:11:32.400 it's not stationary with respect to like the center, then 0:11:32.440 --> 0:11:34.920 all that stuff tends to add up to some spinning. 0:11:35.360 --> 0:11:37.800 Like it's possible for a huge blob of stuff to 0:11:37.960 --> 0:11:41.080 not be spinning, but that would require everything inside of 0:11:41.080 --> 0:11:44.360 it to like exactly balance all of its motion. It's 0:11:44.360 --> 0:11:47.760 sort of unlikely, like flipping a million coins and having 0:11:47.840 --> 0:11:51.520 exactly fifty percent of them land up heads. So any 0:11:51.559 --> 0:11:54.840 big blob of stuff tends to have some spin around 0:11:54.840 --> 0:11:57.200 its center. Yeah, so I guess you know, things tend 0:11:57.240 --> 0:11:59.320 to fly in a straight line in space. But once 0:11:59.320 --> 0:12:01.280 you get a bunch of sort of in the same area, 0:12:01.440 --> 0:12:03.719 it's going to have some gravity and it's going to 0:12:03.880 --> 0:12:07.880 start pulling stuff inwards towards the center of massive that blob, 0:12:07.920 --> 0:12:10.280 and that's where the kind of the spinning happens, right, 0:12:10.320 --> 0:12:12.920 That's where the circular emotion happens. And so that's why 0:12:12.920 --> 0:12:16.800 everything's kind of spinning around a galaxy cluster m exactly. 0:12:16.920 --> 0:12:19.400 And as that's been happens, it very naturally forms a 0:12:19.480 --> 0:12:22.760 spiral pattern, right, because things that the outside get left behind. 0:12:22.800 --> 0:12:26.360 They're not spinning as fast as things closer in. Like 0:12:26.400 --> 0:12:28.640 if you're really close to the center, it doesn't take 0:12:28.679 --> 0:12:30.720 you as long to go all the way around the galaxy. 0:12:30.760 --> 0:12:33.280 For example, if you're really far out and you're moving 0:12:33.280 --> 0:12:35.800 at the same speed, takes you a lot longer to 0:12:35.840 --> 0:12:38.199 go all the way around the galaxy. So things and 0:12:38.240 --> 0:12:40.559 the outside tend to get left behind, and that's why 0:12:40.600 --> 0:12:43.440 you end up with spiral patterns in the galaxy. But 0:12:43.520 --> 0:12:46.440 that doesn't explain why you get arms, right, if you 0:12:46.520 --> 0:12:48.520 just have like a big blob of stuff and it 0:12:48.559 --> 0:12:50.920 was spinning and collapsing, it would tend to sort of 0:12:50.960 --> 0:12:54.680 like wind itself up. You wouldn't necessarily get blobs like arms. 0:12:55.000 --> 0:12:58.640 So the spinning explains the spiral nature, but not the arms. Right, 0:12:58.679 --> 0:13:00.840 Like if you had a big blob of out there 0:13:00.840 --> 0:13:03.680 in space and that was evenly distributed, like a hazy cloud, 0:13:03.800 --> 0:13:06.000 and then you just got it going, you would think 0:13:06.000 --> 0:13:08.319 it would just kind of like swirl towards the center, 0:13:08.480 --> 0:13:11.000 kind of like a toilet, right, there'd be no clustering. 0:13:11.000 --> 0:13:13.400 It's just like a like a tornado, like an even 0:13:13.559 --> 0:13:15.679 swirl down to the center. Yeah, Like if you put 0:13:15.679 --> 0:13:18.160 a fork in spaghetti and spin it, you're gonna end 0:13:18.200 --> 0:13:20.000 up with lots and lots and lots of strands, not 0:13:20.120 --> 0:13:22.640 like a few big clumps. But what we see in 0:13:22.760 --> 0:13:25.320 galaxies is it we've got like really big chunks. We 0:13:25.400 --> 0:13:28.120 got like two or four or three in this case, 0:13:28.480 --> 0:13:31.400 chunks of stuff flying out in this spiral pattern, or 0:13:31.480 --> 0:13:34.480 more like the three giant or three or four giant 0:13:34.760 --> 0:13:37.200 spaghetti noodles, right, instead of like a bunch of little 0:13:37.200 --> 0:13:41.880 spaghetti noodles. Somehow, the spaghetti's kind of clustering to giant 0:13:42.400 --> 0:13:48.080 strands of spaghetti. Yeah, exactly like metapasta or something megapasta formations. 0:13:48.280 --> 0:13:50.360 And so a lot of people think that when you're 0:13:50.400 --> 0:13:53.160 looking at a galaxy and you're looking at these spiral arms, 0:13:53.200 --> 0:13:55.800 that you're looking at structures of matter, that like, the 0:13:56.000 --> 0:13:59.560 arms are a blob of stars like a blob of spaghetti, 0:13:59.600 --> 0:14:01.880 and that whole arm is sort of rotating, that the 0:14:02.000 --> 0:14:05.280 stars are moving with the arm. But that's actually not 0:14:05.480 --> 0:14:09.960 the case. The arms are not structures of matter. They're 0:14:10.000 --> 0:14:14.120 just density waves. They're more like traffic patterns in cars, 0:14:14.760 --> 0:14:18.120 you know, like a traffic wave can move along the highway, 0:14:18.320 --> 0:14:20.760 making some cars slow down and some cars speed up 0:14:20.840 --> 0:14:23.600 or clump together, But the cars don't necessarily move with 0:14:23.640 --> 0:14:26.120 those waves in the same way the arms in the 0:14:26.200 --> 0:14:30.760 galaxy are rotating. But stars don't necessarily rotate with the arms. 0:14:31.000 --> 0:14:32.920 They can be left behind by the arm, the arm 0:14:32.960 --> 0:14:36.080 can catch up with them. The stars don't move with 0:14:36.240 --> 0:14:38.120 the arms. Well, first of all, what do you mean, 0:14:38.160 --> 0:14:40.360 because there aren't the arms made of stars? Like, if 0:14:40.360 --> 0:14:42.360 we can see them in the night sky in space, 0:14:42.640 --> 0:14:44.960 that means it's bright, and so that means we're seeing 0:14:45.280 --> 0:14:47.920 the stars in them. Yeah, they are made of stars. 0:14:47.920 --> 0:14:49.920 For sure, the same with the like traffic patterns are 0:14:49.960 --> 0:14:52.720 made of cars. But the things that make the arm 0:14:52.760 --> 0:14:55.360 the arm is that there's a denser spot of stars. 0:14:55.400 --> 0:14:59.040 There's more stars there than somewhere else. But as the 0:14:59.280 --> 0:15:03.120 arm moves, sort of moves through the stars the same 0:15:03.160 --> 0:15:06.600 way that like waves move through water, but the individual 0:15:06.680 --> 0:15:10.200 particles of water don't necessarily move with the wave. Right, 0:15:10.440 --> 0:15:12.760 the wave is motion of the water. Oh, I see 0:15:12.760 --> 0:15:14.240 what you're saying. You're saying, like if I looked at 0:15:14.320 --> 0:15:17.760 a sped up or fast forwarded movie of a galaxy, 0:15:18.000 --> 0:15:20.400 I would see it looking like it's a squirrel, like 0:15:20.400 --> 0:15:23.160 it's spinning, But it's not actually spinning, you're saying. It 0:15:23.480 --> 0:15:26.760 just has these waves running through it that go around. 0:15:26.960 --> 0:15:29.120 The waves are spinning, But if you tracked a wave 0:15:29.280 --> 0:15:31.680 and you also tracked an individual star, you would not 0:15:31.800 --> 0:15:35.560 necessarily see them move together, like a star can be 0:15:35.680 --> 0:15:37.920 part of an arm and then later not part of 0:15:37.920 --> 0:15:41.040 an arm, and then part of another arm. Whoa, and 0:15:41.400 --> 0:15:43.040 so how do we know this because we haven't been 0:15:43.120 --> 0:15:45.440 looking long enough for us to see that. Yeah, it's 0:15:45.440 --> 0:15:48.040 a really interesting idea. It's only been around for a 0:15:48.080 --> 0:15:51.680 few decades, and it's not one hundred percent certain, though 0:15:51.680 --> 0:15:53.920 in the last few years we've got some evidence that 0:15:53.960 --> 0:15:56.640 this is true because we've looked at the color of 0:15:56.760 --> 0:15:59.600 light in these stars. Because the galactic arms tend to 0:15:59.600 --> 0:16:03.040 be aligned with star formation, these galactic arms are places 0:16:03.080 --> 0:16:06.160 of greater density, which means you get more stars being 0:16:06.200 --> 0:16:08.960 made because you're compressing the gas. So you tend to 0:16:08.960 --> 0:16:11.760 have younger stars in the arms as they are forming, 0:16:12.040 --> 0:16:15.040 and younger stars tend to be bluer because bluer stars 0:16:15.080 --> 0:16:17.680 don't live as long. So anyway, the long story short, 0:16:17.720 --> 0:16:19.960 you can look at the pattern of color in these 0:16:20.080 --> 0:16:22.680 arms and you can see how sort of how old 0:16:22.680 --> 0:16:25.200 they are and the age of stars within the arms, 0:16:25.480 --> 0:16:28.200 and so you can sort of confirm this hypothesis, though 0:16:28.400 --> 0:16:31.320 I should say it's not a one hundred percent totally established. 0:16:31.760 --> 0:16:34.200 So you're saying the arms of a galaxy are actually 0:16:34.400 --> 0:16:38.200 kind of like waves that are going through the huge 0:16:38.240 --> 0:16:42.480 cloud of stars in the galaxy. But what's causing these waves? 0:16:42.760 --> 0:16:45.440 So these are density waves, So they're just caused by 0:16:45.440 --> 0:16:48.440 things not being totally smooth, the same way like all 0:16:48.520 --> 0:16:52.000 gravitational effects are. If you have a little perburbation, things 0:16:52.000 --> 0:16:54.600 aren't totally smooth. Then gravity tends to pull on that 0:16:54.640 --> 0:16:58.240 and exaggerated, so gravity will take a little perburbation in 0:16:58.320 --> 0:17:01.360 like a totally smooth clump and turn it into larger 0:17:01.400 --> 0:17:05.160 and larger perturbations. So it's not again totally understood where 0:17:05.200 --> 0:17:08.320 these come from and why they last so long. But 0:17:08.400 --> 0:17:11.480 they think they come from original density perturbations and like 0:17:11.560 --> 0:17:15.080 the central clump of the galaxy. So they are structures. 0:17:15.080 --> 0:17:17.960 Then you said earlier that they weren't structures. So it 0:17:18.119 --> 0:17:20.560 is there because the stuff in it is kind of 0:17:20.560 --> 0:17:23.840 holding together gravitationally. Yeah, but it's a density structure. It's 0:17:23.840 --> 0:17:26.280 not like a matter structure. It's not like the same 0:17:26.359 --> 0:17:29.840 stars are sweeping around and staying in the arm. There 0:17:29.920 --> 0:17:32.680 is a structure there at the density structure, right, and 0:17:32.720 --> 0:17:35.080 that you're saying the density is caused by the gravity 0:17:35.119 --> 0:17:39.199 between them. So let's see, I'm a planet or I'm 0:17:39.240 --> 0:17:42.359 a star around a galaxy. What's going to make me 0:17:42.400 --> 0:17:44.320 want to join one of these waves. Well, it's sort 0:17:44.320 --> 0:17:47.040 of sweeping through the galaxy and it creates regions with 0:17:47.200 --> 0:17:49.760 higher gravity and regions with lesser gravity, and so some 0:17:49.800 --> 0:17:52.720 stars are like getting pulled towards these things, and some 0:17:52.720 --> 0:17:55.959 stars are getting left behind right, And so that's how 0:17:56.000 --> 0:17:59.920 a density wave propagates. Right, it creates regions of great 0:18:00.160 --> 0:18:04.000 and lesser force, which tends to apply differential forces on 0:18:04.040 --> 0:18:07.719 the stars. Right. But unlike a wave and water, you 0:18:07.720 --> 0:18:12.240 have forces that pull and push, right, like something behind 0:18:12.280 --> 0:18:14.359 you pushes you forward, but then some in front of 0:18:14.400 --> 0:18:16.320 you pushes you back, and that's kind of how the 0:18:16.400 --> 0:18:19.639 wave occurs. But in gravity, gravity only attracts. So what 0:18:20.040 --> 0:18:22.679 moves the wave forward? Well, what's moving the wave forward, 0:18:22.960 --> 0:18:25.760 Like at the forefront of the wave, it's density, So 0:18:25.800 --> 0:18:29.560 it's pulling those stars towards it. Right, So the density 0:18:29.600 --> 0:18:32.399 of the arm creates a denser region in front of it. 0:18:32.640 --> 0:18:34.720 Oh I see, So the wave in front of it 0:18:34.760 --> 0:18:38.359 eats up more stars, which moves the center of gravity 0:18:38.440 --> 0:18:42.280 of the arm forward, which then leaves behind the stars 0:18:42.320 --> 0:18:46.240 behind it exactly. And so that's how a density wave propagates. 0:18:46.320 --> 0:18:48.560 And what's really interesting to me is that you know, 0:18:48.600 --> 0:18:51.000 the velocity of the arms is not the same as 0:18:51.000 --> 0:18:53.880 the velocity of the stars. That means where your star 0:18:54.080 --> 0:18:57.040 is in the galaxy determines whether these density waves are 0:18:57.080 --> 0:19:00.960 passing you or whether you're passing them, like for example, 0:19:01.040 --> 0:19:03.359 our sun moves around the center of the galaxy at 0:19:03.359 --> 0:19:05.760 a certain speed, which is basically determined by where it 0:19:06.000 --> 0:19:08.719 is a distance from the center, And so it's actually 0:19:08.720 --> 0:19:12.160 moving around the galaxy about twice as fast as the arms. 0:19:12.200 --> 0:19:14.960 So we are catching up to arms and passing them by. 0:19:15.119 --> 0:19:17.399 But if we were further out, then the density waves 0:19:17.400 --> 0:19:20.000 would be passing us by, and so that's where arms 0:19:20.040 --> 0:19:23.800 come from. Now. Matt's question was, why is it weird 0:19:23.920 --> 0:19:26.720 that this one galaxy that we saw has three arms? 0:19:26.760 --> 0:19:28.800 Why is it weird to have an odd number of arms? 0:19:28.840 --> 0:19:31.680 So they make this comment on the page describing this galaxy. 0:19:31.800 --> 0:19:35.080 So I chatted with a couple of experts about galaxy formation, 0:19:35.240 --> 0:19:37.439 and they quibbled a little bit with this claim that 0:19:37.480 --> 0:19:40.040 it is unusual. First of all, they say, it's not 0:19:40.080 --> 0:19:43.119 even really easy to define, like how many arms a 0:19:43.160 --> 0:19:47.120 galaxy has, you know, because it's basically just visual inspection. 0:19:47.160 --> 0:19:49.720 You're just sort of like looking at it and seeing sorrels. 0:19:50.280 --> 0:19:52.959 But you know, galaxies have more complex structure than just 0:19:53.000 --> 0:19:55.240 like here's an arm. There's an arm. Like if you 0:19:55.240 --> 0:19:58.080 look at the Milky Way our galaxy, it has sort 0:19:58.119 --> 0:20:01.200 of two major arms, but lots of like little spurs 0:20:01.359 --> 0:20:05.119 off of it. For example, we live in the Orion spur, 0:20:05.440 --> 0:20:09.960 which is like a little offshoot from the major Sagittarius arm. 0:20:10.480 --> 0:20:13.359 So is that really another arm or not. It's not 0:20:13.440 --> 0:20:15.960 like a well defined way to count these arms. It's 0:20:15.960 --> 0:20:18.520 just sort of like by looking at it, M I 0:20:18.600 --> 0:20:21.920 see so's it's it's hard to define what makes an arm. 0:20:21.960 --> 0:20:25.280 It's hard to define what makes an arm exactly. And 0:20:25.359 --> 0:20:28.080 so you look at this particular galaxy and you're like, yeah, 0:20:28.080 --> 0:20:29.840 I could call that three or I could call that 0:20:30.000 --> 0:20:33.320 four maybe. And so the short answer is that I 0:20:33.359 --> 0:20:36.879 don't think there's broad agreement on how to define arms 0:20:37.200 --> 0:20:41.320 or how many arms it makes sense for galaxies to have. M. 0:20:41.800 --> 0:20:43.640 I guess my question would be, if you look at 0:20:43.680 --> 0:20:46.280 all the galaxies that we can see out they're in space, 0:20:47.280 --> 0:20:49.560 what is more common? Is it more common to have 0:20:49.720 --> 0:20:52.920 an even ish number of arms or an odd ish 0:20:53.040 --> 0:20:55.640 number of arms. Yeah, it's a great question, and it's 0:20:55.640 --> 0:20:58.840 a hard question to answer without like a systematic way 0:20:58.880 --> 0:21:01.360 to analyze these things. Basically, a human has to look 0:21:01.400 --> 0:21:03.520 at it and say, I think it has three, But 0:21:03.640 --> 0:21:05.960 another human might look at the same galaxy and say, no, 0:21:06.040 --> 0:21:08.560 I think this one has four. So to get like 0:21:08.840 --> 0:21:12.400 enough statistics to do some analysis of that, you need 0:21:12.520 --> 0:21:15.800 some like really rigorous way to analyze these things. And 0:21:15.840 --> 0:21:18.119 people have done like for any analysis or the distribution 0:21:18.200 --> 0:21:21.199 of density waves through galaxies, But that's really just a 0:21:21.200 --> 0:21:23.920 way of counting like the strength of these things. Again, 0:21:23.960 --> 0:21:26.119 you have the problem of deciding when to call it 0:21:26.200 --> 0:21:29.520 another arm. So right now is really just mostly anecdotal. 0:21:29.800 --> 0:21:32.000 People have seen a bunch of galaxies and they haven't 0:21:32.000 --> 0:21:34.560 seen ones that look like this to them, And there 0:21:34.600 --> 0:21:36.159 are ways to explain it. Like if you look at 0:21:36.160 --> 0:21:37.879 a galaxy like this and you say, how did this 0:21:37.960 --> 0:21:41.720 galaxy get this way? Well, one possible explanation is that 0:21:41.800 --> 0:21:45.280 it recently had a strong gravitational interaction with another galaxy 0:21:45.440 --> 0:21:47.600 that sort of messed it up. Because this one also 0:21:47.600 --> 0:21:50.800 seems sort of asymmetric, right It's got like one long 0:21:50.960 --> 0:21:52.879 arm on one side and two shorter arms on the 0:21:52.920 --> 0:21:55.159 other side. So it may just be that like a 0:21:55.200 --> 0:21:58.000 passing galaxy sort of pulled on it in a way 0:21:58.000 --> 0:22:01.840 it separated those density waves. M But I mean, I 0:22:01.880 --> 0:22:05.160 guess is it easy to pull up pictures of galaxies 0:22:05.200 --> 0:22:07.800 that look like they have three arms? Is it maybe 0:22:07.840 --> 0:22:10.919 harder or easier or the same as pulling up pictures 0:22:10.920 --> 0:22:13.520 that looked like they have four arms or two. I 0:22:13.560 --> 0:22:16.280 think it's probably true that most of the galaxies you 0:22:16.400 --> 0:22:18.720 look at, if you've just counted them, you would probably 0:22:18.760 --> 0:22:20.560 get an even number of arms. A lot of them 0:22:20.640 --> 0:22:22.639 just look like they have two, though they're sort of 0:22:22.680 --> 0:22:25.240 like tightly wrapped around. But look at the Milky Way, 0:22:25.240 --> 0:22:27.600 for example, it's not easy to say, like how many 0:22:27.680 --> 0:22:30.520 are there? Like I count one, two big ones and 0:22:30.600 --> 0:22:33.840 at least two maybe four little ones. Although we don't 0:22:33.840 --> 0:22:35.440 really have a picture of the Milky Way, do we. 0:22:35.880 --> 0:22:38.399 We certainly don't have an actual image of the Milky 0:22:38.400 --> 0:22:41.960 Way from the outside, though we can reconstruct the density 0:22:42.000 --> 0:22:44.240 of stars in the Milky Way using a lot of 0:22:44.240 --> 0:22:47.920 our observations. Right, well, could there be maybe some effects 0:22:48.000 --> 0:22:50.480 we are talking about waves right around sort of a 0:22:50.560 --> 0:22:54.160 fixed medium. Is it possible that, you know, given the 0:22:54.160 --> 0:22:57.800 typical size of a galaxy with the typical number of stars, 0:22:57.840 --> 0:23:02.120 maybe like a standing way of four arms is more 0:23:02.200 --> 0:23:04.800 likely than a standing wave of three arms, you know, 0:23:05.000 --> 0:23:08.800 like waves around the spiral of the galaxy. I read 0:23:08.840 --> 0:23:11.879 some papers about these things, and there's are some arguments 0:23:12.000 --> 0:23:15.200 for why you might get two or four if these 0:23:15.240 --> 0:23:18.199 things really do come from like density perturbations in the 0:23:18.200 --> 0:23:20.399 center of the galaxy, because you would expect that to 0:23:20.440 --> 0:23:24.119 be somewhat symmetric, right, that it would cause similar effects 0:23:24.119 --> 0:23:26.600 in one direction and in the other. And so it 0:23:26.640 --> 0:23:28.840 makes some sort of sense for this thing that collapse 0:23:28.880 --> 0:23:31.800 into a bar that then generates two arms, and that 0:23:31.880 --> 0:23:35.040 those might split, but that splitting would always give you 0:23:35.080 --> 0:23:38.760 an even number. So there are some papers suggesting that 0:23:38.800 --> 0:23:41.439 you would expect, on average to get an even number 0:23:41.440 --> 0:23:43.800 of arms, and I think that makes some sense, but 0:23:43.880 --> 0:23:47.200 it's not very well established. Well, so then the picture 0:23:47.240 --> 0:23:49.119 that Matt saw, he saw I did an article that 0:23:49.160 --> 0:23:52.000 said that NASA think is weird to have an odd 0:23:52.080 --> 0:23:55.119 number of arms? What was NASA saying there? So the 0:23:55.200 --> 0:23:58.000 quote the article says, while most disc galaxies have an 0:23:58.040 --> 0:24:01.440 even number of spiral arms, this one has three. But 0:24:01.480 --> 0:24:03.680 you know, the astronomers I talked too, quibbled with that 0:24:03.800 --> 0:24:05.639 a little bit. They didn't think it was so weird. 0:24:05.920 --> 0:24:09.440 They've seen galaxies with three arms before. M I guess 0:24:09.480 --> 0:24:11.679 we'll have to ask NASA. I mean, what do they know. 0:24:12.560 --> 0:24:14.600 Let's have them on the podcast. All right, Well, I 0:24:14.640 --> 0:24:17.400 think that answers Matt's question, which is like, maybe it's 0:24:17.600 --> 0:24:20.040 maybe it's not that weird, right, It seems like some 0:24:20.160 --> 0:24:22.800 astronomers don't think it's as weird to have three arms. 0:24:23.119 --> 0:24:25.320 It seems like it's kind of a fuzzy thing. Anyways, 0:24:25.520 --> 0:24:28.000 it is. But what is weird is that arms exist 0:24:28.119 --> 0:24:31.359 at all. It's really fascinating in the dynamics of galaxies. 0:24:31.760 --> 0:24:34.480 They have these things slashing and swirling around, and it 0:24:34.560 --> 0:24:38.399 just reminds you that galaxies are dynamical objects. They're not 0:24:38.520 --> 0:24:41.120 fixed things that have been formed millions of years ago 0:24:41.200 --> 0:24:45.080 and unchanged. Right, they are swirling, they're crashing into each other, 0:24:45.400 --> 0:24:49.800 they're constantly changing, just on these vast, vast time scales 0:24:49.840 --> 0:24:52.199 that we can hardly even imagine. Yeah, and they're not 0:24:52.240 --> 0:24:54.960 just dynamic, they're like wavy, right, They're rippling. That's what 0:24:55.000 --> 0:24:57.919 these arms are. They're ripples in their structure. All right, Well, 0:24:58.000 --> 0:25:00.800 let's get into some of our other questions. One is 0:25:00.840 --> 0:25:03.359 about the color of the universe and the other is 0:25:03.400 --> 0:25:07.160 about the fate of the universe. So let's get into those. 0:25:07.200 --> 0:25:21.760 But first let's take a quick break. All right. We're 0:25:21.760 --> 0:25:26.160 answering listener questions here about everything is usual, the whole 0:25:26.160 --> 0:25:29.879 she bang, the whole universe. And our second question comes 0:25:29.920 --> 0:25:33.120 from Genie, Hi, Daniel and Hagee. The question I would 0:25:33.119 --> 0:25:35.639 really like to ask is did the universe have a 0:25:35.680 --> 0:25:38.679 color after the Big Bang? If there was no color, 0:25:39.200 --> 0:25:41.600 when was there first a color? And what was it? 0:25:42.119 --> 0:25:45.720 Thank you have all the questions we've gotten, this is 0:25:45.720 --> 0:25:48.000 the one that really threw me for a loop, Like, Wow, 0:25:48.040 --> 0:25:50.920 a question I've never even thought of before, never heard 0:25:50.920 --> 0:25:54.080 of before. What a super fun question. Yeah, it's a 0:25:54.160 --> 0:25:57.240 very colorful question. Jennie asked, did the universe have a 0:25:57.359 --> 0:26:00.320 color after the Big Bang? So I guess a big 0:26:00.359 --> 0:26:03.800 bang happened, and I guess her maybe her question is like, 0:26:03.840 --> 0:26:06.879 if there was a human present there, what would it 0:26:06.920 --> 0:26:10.800 look like? Would it look red, purple, green, polka? Or 0:26:10.800 --> 0:26:13.320 would it just fry your eyes? Yeah? It really is 0:26:13.320 --> 0:26:16.080 one question what would you see if you were there? Right? 0:26:16.280 --> 0:26:18.840 Really love this question and I think it's really fun 0:26:18.880 --> 0:26:21.720 because it makes us think about like what is color? Anyway? Yeah, 0:26:21.840 --> 0:26:24.600 let's dig into that. What is color? How would you 0:26:24.640 --> 0:26:27.080 define it? I know it's related to the wavelength of 0:26:27.119 --> 0:26:29.920 the light. It is related to the wavelength of light, 0:26:30.240 --> 0:26:33.600 But I think it's important to distinguish, right, Like, photons 0:26:33.720 --> 0:26:36.240 have a wavelength, which means like how long it takes 0:26:36.280 --> 0:26:38.200 for them to go up and down. It's related to 0:26:38.200 --> 0:26:40.919 their frequency, right, how many times they wiggle per second. 0:26:41.200 --> 0:26:44.560 But the color is not a property of the photon, 0:26:44.760 --> 0:26:48.560 like photons themselves don't have color. Color is something inside 0:26:48.560 --> 0:26:51.960 your head. It's like how your brain responds to a 0:26:52.080 --> 0:26:56.040 signal of a photon of a specific color, So it's 0:26:56.080 --> 0:26:58.959 not part of the photon itself. It's like the taste 0:26:58.960 --> 0:27:01.840 of salt itself. Doesn't have a taste your tongue as 0:27:01.880 --> 0:27:05.040 a response to sensing salt. Right, I guess you're sort 0:27:05.040 --> 0:27:07.320 of quivaling about the definition of things. But I mean 0:27:07.440 --> 0:27:10.600 light does have different wavelengths, right, it does. But there 0:27:10.600 --> 0:27:13.280 are lots of wavelengths of light that we can't see 0:27:13.400 --> 0:27:16.440 and our brain doesn't respond to. So photons above the 0:27:16.520 --> 0:27:20.640 visible spectrum like have no color to them. Early, they 0:27:20.680 --> 0:27:24.480 have no color. So far, we could panically start naming 0:27:24.480 --> 0:27:29.320 other colors, right, Yeah, absolutely, you could even imagine creating 0:27:29.440 --> 0:27:33.040 a new internal response that's a different color than anybody 0:27:33.080 --> 0:27:35.840 has ever imagined before. Right, If colors are really just 0:27:36.000 --> 0:27:39.000 part of your mind, If there are a response to 0:27:39.600 --> 0:27:42.680 signals from your optic nerve that in principle there's no 0:27:42.760 --> 0:27:47.159 limitation on experiencing new colors, not just combinations of existing colors, 0:27:47.160 --> 0:27:50.959 but like brand new colors, and so in principle that's possible, 0:27:51.040 --> 0:27:53.720 and you could assign those to very high frequency light. 0:27:53.760 --> 0:27:57.240 You could imagine like building a technological eyeball that sends 0:27:57.280 --> 0:27:59.960 messages to your brain. Your brain would learn to interpret 0:28:00.080 --> 0:28:02.880 those responses by giving you some new experience that would 0:28:02.880 --> 0:28:05.000 be like a new color. Yeah. I think what you're 0:28:05.040 --> 0:28:06.920 talking about is that you know, light has a certain 0:28:06.960 --> 0:28:09.640 frequency that can come in certain frequencies, and let's say 0:28:09.720 --> 0:28:13.040 like seven gig gigga hurts or something, or like seven 0:28:13.480 --> 0:28:18.040 hurts might be a frequency. And when I see that 0:28:18.119 --> 0:28:20.920 frequency of light, I think the color green, for example, 0:28:22.000 --> 0:28:24.400 And you and I agree that if we see light 0:28:24.440 --> 0:28:26.200 at this frequency, if we're going to call it green. 0:28:26.280 --> 0:28:27.760 But I think what you're saying is like, maybe what 0:28:27.880 --> 0:28:30.199 I experienced this green is different with them what you 0:28:30.280 --> 0:28:33.040 experience is green. That's certainly true. And there's only also 0:28:33.119 --> 0:28:36.199 a narrow band of photon frequencies that we even have 0:28:36.359 --> 0:28:39.400 colors assigned to, and sort of the long history of 0:28:39.400 --> 0:28:42.320 the universe is that it started out really really hot 0:28:42.360 --> 0:28:45.560 and dense, and photons created in the very very beginning 0:28:45.640 --> 0:28:47.960 of the universe after the Big Bang had very very 0:28:48.080 --> 0:28:51.840 high energies, very high frequencies. Then the universe is cooling down, 0:28:51.920 --> 0:28:55.600 and so the photons created get longer and longer, right, 0:28:55.800 --> 0:28:58.480 lower frequencies, and so the universe sort of starts out 0:28:58.520 --> 0:29:02.000 invisible and then passes through the visible spectrum. And so 0:29:02.080 --> 0:29:05.840 like Genie's asking, what color was the universe when it started? Right, 0:29:05.880 --> 0:29:07.880 And the problem is that the energy of the photons 0:29:07.880 --> 0:29:10.120 at the very beginning of the universe don't really have 0:29:10.160 --> 0:29:13.640 a color. They're too high frequency for us to fc right, 0:29:13.680 --> 0:29:16.959 because the energy of a photon is related directly related 0:29:17.000 --> 0:29:20.120 to its frequency, right, Like the higher the energy, the 0:29:20.200 --> 0:29:24.200 higher the exactly, and hot stuff tends to make higher 0:29:24.280 --> 0:29:26.600 energy photons. We've talked about this on the podcast a 0:29:26.600 --> 0:29:30.720 few times. Everything generates photons. Everything that has charged particles 0:29:30.720 --> 0:29:34.040 inside of it generates photons, and it generates photons based 0:29:34.080 --> 0:29:37.240 on its temperature. So the Sun generates photons as some 0:29:37.360 --> 0:29:40.880 temperature because of its thousands of degrees kelvin, the Earth 0:29:40.920 --> 0:29:44.600 glows and generates photons at some temperature because it's much cooler, 0:29:44.640 --> 0:29:47.440 and you generates photons at some wavelength. Your eyes can't 0:29:47.520 --> 0:29:50.520 see the photons generated by yourself or by the Earth. 0:29:50.720 --> 0:29:53.160 They can see the ones from the sun. So some 0:29:53.200 --> 0:29:55.760 of these photons are visible and some of them are invisible. 0:29:55.960 --> 0:29:58.360 But the hot or something is the higher energy the 0:29:58.400 --> 0:30:01.320 photons it generates. Right. So are you're saying maybe at 0:30:01.360 --> 0:30:04.880 the Big Bang everything all the photons that were there 0:30:05.400 --> 0:30:09.080 were super high frequency or low wavelength. What are you 0:30:09.080 --> 0:30:11.840 saying that? Initially at the Big Bank things were so crazy. 0:30:12.360 --> 0:30:15.800 All the photons were super duper high energy. They were 0:30:15.840 --> 0:30:19.280 super high energy, which means very short wavelength, which means 0:30:19.360 --> 0:30:22.800 very high frequency, right, And so these photons were zipping 0:30:22.800 --> 0:30:24.960 around the universe. And if your eyeball was there just 0:30:25.000 --> 0:30:27.120 after this moment, when the universe was like at the 0:30:27.160 --> 0:30:30.040 Plank temperature, then not only would it be cooked instantly, 0:30:30.240 --> 0:30:32.080 but the photons that hit it it wouldn't know how 0:30:32.080 --> 0:30:35.080 to interpret. Your eye wouldn't see them, So the universe 0:30:35.120 --> 0:30:37.680 would just be black, even though it'd be super duper 0:30:37.720 --> 0:30:40.360 hot and filled with photons. Yeah, Like, if your eye 0:30:40.360 --> 0:30:42.760 could somehow survive being in a Big Bang, it wouldn't 0:30:42.800 --> 0:30:45.120 you would see total darkness, right, because all the light 0:30:45.160 --> 0:30:47.000 would be sort of like X rays, they just passed 0:30:47.040 --> 0:30:49.320 through your eyeball. One question is would they interact with 0:30:49.360 --> 0:30:52.320 your eyeball or they passed through like X rays, right. 0:30:52.480 --> 0:30:54.480 X rays do interact with some parts of your body, 0:30:54.520 --> 0:30:57.120 but not others. And as a frequency of photons change, 0:30:57.160 --> 0:30:59.840 there are chances of interacting with you changes. But you're right, 0:30:59.840 --> 0:31:02.160 a lot of these photons might just fly right through you, 0:31:02.400 --> 0:31:05.320 like X rays, which are higher energy photons than our 0:31:05.360 --> 0:31:08.760 eyeballs can see. But then the universe temperature changes. But 0:31:08.840 --> 0:31:12.360 then eventually, after the Big Bang, the universe started cooling down, right, 0:31:12.400 --> 0:31:16.920 and so you started seeing photons with a lower energy, yes, exactly. 0:31:16.960 --> 0:31:19.400 So as the universe cools and it's really dense, plasma 0:31:19.440 --> 0:31:22.000 gets more and more dilute, it cools down, and so 0:31:22.040 --> 0:31:26.160 it starts generating photons with longer wavelengths. So as time 0:31:26.200 --> 0:31:29.680 goes on, the temperature of the universe is dropping and 0:31:29.720 --> 0:31:32.560 the energy those photons is dropping, and so the wavelength 0:31:32.680 --> 0:31:36.440 is increasing. So they're like the general light of the 0:31:36.520 --> 0:31:39.560 universe started off way too high for our eyes, but 0:31:39.640 --> 0:31:42.720 then it gradually as it cools starts to approach the 0:31:42.840 --> 0:31:46.400 visible spectrum. Yeah, and there's a really fascinating moment around 0:31:46.440 --> 0:31:49.280 three hundred and eighty thousand years after the Big Bang 0:31:49.840 --> 0:31:53.800 when the universe cooled so much that atoms could now form. 0:31:54.160 --> 0:31:56.800 So you have protons and electrons whizzing around with so 0:31:56.880 --> 0:31:59.440 much energy that they couldn't be bothered to bond together. 0:31:59.680 --> 0:32:02.520 But after a certain time things cool down those electrons 0:32:02.520 --> 0:32:05.240 that it no longer had enough energy to escape the 0:32:05.280 --> 0:32:08.000 pull of those protons which have a positive charge and 0:32:08.360 --> 0:32:12.280 pull on the electrons, and so you get neutral hydrogen forms. 0:32:12.600 --> 0:32:15.280 And in this moment, the universe goes from being opaque 0:32:15.560 --> 0:32:17.800 like a really hot plasma like the center of the Sun, 0:32:18.120 --> 0:32:21.560 to being transparent, just like clouds of gas in space 0:32:21.800 --> 0:32:24.760 that light could mostly pass through. So all the light 0:32:24.840 --> 0:32:28.280 generated before this moment was just reabsorbed by the hot plasma. 0:32:28.440 --> 0:32:32.000 Light generated after this moment can fly through the universe, 0:32:32.040 --> 0:32:34.760 and like hit your eyeball, and this light is still 0:32:34.840 --> 0:32:37.920 flying through the universe. It's the cosmic microwave background light. 0:32:38.240 --> 0:32:40.640 We can see it with our telescopes. When it was 0:32:40.720 --> 0:32:43.880 generated at that moment in time, the universe was still 0:32:43.880 --> 0:32:46.200 filled with a pretty hot plasma. It was like several 0:32:46.280 --> 0:32:48.840 thousand degrees So that was the moment when the universe 0:32:48.920 --> 0:32:52.520 first became transparent and the light that were created sort 0:32:52.520 --> 0:32:56.160 of becomes persistent. Right, But still that light is too 0:32:56.560 --> 0:32:59.040 high energy for eyeballs to capture. Right, Like when I 0:32:59.040 --> 0:33:01.280 look up at the night sky, I can't see the 0:33:01.320 --> 0:33:04.120 cosmic microwave background with my eyes, can I You cannot 0:33:04.160 --> 0:33:07.800 see the cosmic microwave background with your eyes currently. But 0:33:07.840 --> 0:33:10.880 when it was created, it actually was in the visible 0:33:10.920 --> 0:33:13.920 spectrum because remember that the wavelength depends on the energy, 0:33:13.920 --> 0:33:17.040 on the temperature, and when that light was created, the 0:33:17.160 --> 0:33:20.760 universe was still pretty hot. It was several thousand degrees kelvin, 0:33:21.040 --> 0:33:23.600 which is about the same temperature as the surface of 0:33:23.640 --> 0:33:27.680 the Sun, which produces visible light. So when the CMB 0:33:27.800 --> 0:33:30.600 light was created, it was in the visible spectrum. You 0:33:30.640 --> 0:33:33.040 could have seen it if Jeanie had her eyeballs back 0:33:33.080 --> 0:33:35.720 in the early universe. Back then, she could have seen 0:33:35.800 --> 0:33:38.120 the CMB with her eyeballs. Now, you're right, when you 0:33:38.160 --> 0:33:39.800 look up in the night sky, you don't see it. 0:33:40.080 --> 0:33:43.080 That's because it's no longer at that frequency. It's been 0:33:43.120 --> 0:33:46.600 stretched by the expansion of the universe. Down to much 0:33:46.680 --> 0:33:50.000 much longer wavelengths, right, and that's why you need like 0:33:50.560 --> 0:33:55.040 infrared telescopes, right exactly. But it's too low frequency for 0:33:55.120 --> 0:33:56.840 us to see, right. It started out in the visible 0:33:56.880 --> 0:34:00.360 spectrum and got stretched out below the visible spectrum very 0:34:00.440 --> 0:34:03.920 very long wavelengths infrared, and so that's why we need 0:34:03.960 --> 0:34:06.440 really sensitive telescopes in order to see it, because it's 0:34:06.440 --> 0:34:09.440 now super duper infrared. And people say the temperature of 0:34:09.480 --> 0:34:12.680 the universe is two point seven three degrees kelvin. What 0:34:12.760 --> 0:34:16.520 they're talking about is the temperature a plasma would have 0:34:16.560 --> 0:34:19.920 to be to generate the photons that we see in 0:34:19.960 --> 0:34:23.960 the CMB. The plasma that actually generated those photons much 0:34:24.040 --> 0:34:27.040 much earlier, was much hotter, but then it's light got 0:34:27.160 --> 0:34:30.200 stretched out, so now it looks like a plasma that's 0:34:30.280 --> 0:34:34.280 much cooler generated this light. Right. So that's a cosmic 0:34:34.320 --> 0:34:37.440 microwave background radiation which comes from the moment when the 0:34:37.520 --> 0:34:41.480 universe became transparent and not hazy. But that's I wonder 0:34:41.520 --> 0:34:44.760 if that's really what would fit into her definition of 0:34:45.080 --> 0:34:47.959 the first light, Like, you know that the light still 0:34:47.960 --> 0:34:51.200 existed when the universe was hazy and opaque, right, yeah, exactly, 0:34:51.239 --> 0:34:54.720 So backing up again, the universe started out really really hot, 0:34:54.760 --> 0:34:58.120 and then as it cools, it passes into the visible spectrum. 0:34:58.320 --> 0:35:02.040 That happened before this moment when the universe became transparent, 0:35:02.080 --> 0:35:04.600 but just about the same time. It's like an interesting 0:35:04.640 --> 0:35:08.120 overlap here that the universe became transparent around the same 0:35:08.160 --> 0:35:12.200 time as it became visible. The temperature for hydrogen become 0:35:12.320 --> 0:35:15.000 neutral is about the same as the temperature of the 0:35:15.000 --> 0:35:19.080 surface of the sun where visible light is generated. Right, So, 0:35:19.120 --> 0:35:22.279 then as the universe moved into the visible spectrum, what 0:35:22.400 --> 0:35:24.799 would have been the first color that you would have 0:35:24.800 --> 0:35:27.560 seen if you were there and was able to survive, Like, 0:35:27.680 --> 0:35:30.840 what's the highest frequency color that we can see with 0:35:30.880 --> 0:35:34.480 our eyes? Yeah, it'd be like the most violet violet, right, 0:35:34.480 --> 0:35:37.320 it'd be like super duper purply blue is the highest 0:35:37.360 --> 0:35:40.480 frequency light that we can seem. So then the first 0:35:40.520 --> 0:35:46.480 color was blue, That was right. I don't know if 0:35:46.520 --> 0:35:48.239 purple and blue are the same, but yeah, it was 0:35:48.320 --> 0:35:52.440 definitely very very bluey, very purply blue, ultra violet, he said, 0:35:52.560 --> 0:35:55.640 violet blue. All right, we'll go with purple. The first 0:35:55.640 --> 0:35:59.279 color in the universe was purple, basically, Yeah, I think 0:35:59.320 --> 0:36:01.879 that's true. It was purple. All right, Well, Genie, thank 0:36:01.880 --> 0:36:04.280 you for that question. I hope purple is your favorite 0:36:04.280 --> 0:36:08.400 color as well, because it is apparently the universe first color. 0:36:08.640 --> 0:36:10.400 But you know, if there are aliens out there and 0:36:10.440 --> 0:36:13.839 they have eyeballs and their brains interpret things differently, if 0:36:13.840 --> 0:36:16.120 they brains give them like a red experience for that 0:36:16.160 --> 0:36:19.239 same frequency and a purple experience for very low frequencies, 0:36:19.520 --> 0:36:23.000 then aliens would say a different color was the first color. 0:36:23.200 --> 0:36:25.120 And that's just because again, color is not part of 0:36:25.120 --> 0:36:27.719 the universe, it's part of our brains. So it's a 0:36:27.800 --> 0:36:30.439 very human thing to say that violet was the first 0:36:30.440 --> 0:36:32.760 color in the universe. It was the first human color 0:36:32.800 --> 0:36:35.319 in the universe, I suppose. Well, it's the first name 0:36:35.360 --> 0:36:37.440 that the human would give it. But the frequency was 0:36:37.480 --> 0:36:39.680 still the same, so we would all agree. I mean, 0:36:39.880 --> 0:36:41.640 the experience I have a violet might not be the 0:36:41.640 --> 0:36:44.000 same experience you have a violet, but we can all 0:36:44.000 --> 0:36:48.280 agree that about that frequency. That's true. Yeah, though aliens 0:36:48.360 --> 0:36:50.719 might be able to see much higher frequencies, and they 0:36:50.840 --> 0:36:54.840 might say an even higher frequency was visible before our violet. 0:36:55.520 --> 0:36:58.239 M I see, they might have a different first color, 0:36:58.520 --> 0:37:01.279 assuming they call it color. Maybe they spell over the 0:37:01.360 --> 0:37:05.480 K or something, but they put a U after the second. Oh, 0:37:08.560 --> 0:37:10.879 I think you went too far there, Yeah, who would 0:37:10.920 --> 0:37:13.680 do that? All right, well, I think then answers Jeannie's question. 0:37:13.960 --> 0:37:16.320 Thank you, Jeanie. And so we'll get to our last question. 0:37:16.440 --> 0:37:20.160 This one is about the universe tearing itself apart. So 0:37:20.239 --> 0:37:23.560 let's take that apart. But first let's take another quick break. 0:37:36.120 --> 0:37:38.839 All right, we're answering questions about the universe and our 0:37:38.920 --> 0:37:43.520 last question. It's a bit dramatic, a bit drastic, it 0:37:43.640 --> 0:37:45.760 certainly is, which is why we saved it from last. 0:37:46.040 --> 0:37:48.640 All right, our last question comes from Courtney, and she 0:37:48.680 --> 0:37:52.800 has a question about the universe. Hey, Daniel and Jorge, 0:37:53.000 --> 0:37:55.520 I have a question for y'all. Is our universe tearing 0:37:55.560 --> 0:37:58.400 itself apart? Is physics as we know and measure it 0:37:58.719 --> 0:38:01.400 stable enough to be really light upon? If so, for 0:38:01.520 --> 0:38:04.200 how long? If at the beginning of the universe the 0:38:04.239 --> 0:38:08.280 electro week force broke in one moment, everything was whizzing 0:38:08.360 --> 0:38:12.040 around at the speed of light, then suddenly the next 0:38:12.160 --> 0:38:17.960 some particles experienced mass, fundamentally altering the trajectory of our universe. 0:38:18.320 --> 0:38:20.920 Could we be looking forward to another dramatic change in 0:38:21.000 --> 0:38:24.440 how our physical forces manifest themselves? Could we measure that 0:38:25.760 --> 0:38:29.240 looking forward to hearing back? Thanks? All right, awesome question 0:38:29.280 --> 0:38:31.440 for Corney. I think really what she's asking is does 0:38:31.480 --> 0:38:34.200 she have to do her homework for tomorrow or do 0:38:34.280 --> 0:38:36.640 that errente she needs to do? Or if the universe 0:38:36.719 --> 0:38:40.239 just totally going to flip on itself or maybe she 0:38:40.640 --> 0:38:42.879 could be doing other things today. Yeah. I did get 0:38:42.880 --> 0:38:44.840 the sense that she was trying to make plans and 0:38:44.920 --> 0:38:47.279 she wanted to know how far in the future she 0:38:47.400 --> 0:38:49.759 needed to think, Like, if I buy this house, is 0:38:49.800 --> 0:38:51.520 it going to be for sale in twenty years or 0:38:51.600 --> 0:38:54.520 is the whole universe going to get shredded before that? Yeah? 0:38:54.600 --> 0:38:56.520 Do I still have to pay my mortgage? Or can 0:38:56.600 --> 0:39:00.239 I just buy the biggest mansion I can now because 0:39:00.239 --> 0:39:02.479 the universe is going to end? That's right, real estate 0:39:02.480 --> 0:39:05.120 investment advice from people you shouldn't be listening to about 0:39:05.160 --> 0:39:07.680 real estate. Well, she's going to ask a multipart question. 0:39:07.760 --> 0:39:10.839 She asked whether the universe is tearing itself apart, which 0:39:10.880 --> 0:39:12.959 I guess maybe is related to her second question, which 0:39:13.000 --> 0:39:15.680 is like how stable do we think the universe is? Like? 0:39:15.840 --> 0:39:18.000 Is it going to stay like this? Forever. Can we 0:39:18.320 --> 0:39:21.680 invest in real estate? Or is it possible for the 0:39:21.760 --> 0:39:25.479 universe to suddenly change tomorrow or today or right now 0:39:25.600 --> 0:39:28.160 and make it a whole different universe, And it maybe 0:39:28.160 --> 0:39:31.160 that happened, we would we notice even I really love 0:39:31.239 --> 0:39:32.920 this question because the touch is on one of the 0:39:32.960 --> 0:39:36.000 most interesting ideas in physics that I think is not 0:39:36.239 --> 0:39:40.160 very widely appreciated, And it's actually connected to Genie's question 0:39:40.200 --> 0:39:42.920 about like the temperature of the universe. You know, we 0:39:43.000 --> 0:39:46.080 think about the universe and how it works, but we're 0:39:46.080 --> 0:39:49.759 really just describing the universe in one phase. When I 0:39:49.800 --> 0:39:51.680 say phase, I don't mean like, you know, a toddler 0:39:51.719 --> 0:39:54.120 throwing a tantrum. More like a phase is in the 0:39:54.160 --> 0:39:56.560 state of matter. Like if you're a scientist and you're 0:39:56.560 --> 0:39:59.759 trying to understand water, then you might have one understanding 0:39:59.760 --> 0:40:02.360 of how works when it's a vapor, and another understanding 0:40:02.360 --> 0:40:04.400 of how it works when it's a liquid, and another 0:40:04.480 --> 0:40:06.799 understanding of how it works when it's a solid. Right, 0:40:06.840 --> 0:40:10.800 we notice these phase transitions when water changes its behavior 0:40:10.880 --> 0:40:13.919 pretty dramatically as it heats up or as it cools down, 0:40:14.200 --> 0:40:16.600 and we can have a law that describes each of 0:40:16.600 --> 0:40:19.600 those phases and in principle, if you had like the 0:40:19.719 --> 0:40:22.560 ultimate theory of physics, you could have a single law 0:40:22.600 --> 0:40:24.920 that describes all of them. But typically what we do 0:40:25.000 --> 0:40:27.839 is we have effective laws to describe one phase at 0:40:27.880 --> 0:40:31.960 a time. And so the universe, the whole universe is 0:40:32.000 --> 0:40:34.440 cooling down, as we talked about a minute ago, and 0:40:34.480 --> 0:40:38.080 so we think it's passing through different phases, and so 0:40:38.160 --> 0:40:41.440 our current understanding of physics, a standard model of quarks, 0:40:41.440 --> 0:40:43.799 the photons, the weak force, the Higgs boson, all that 0:40:43.840 --> 0:40:48.239 stuff just describes the current phase of the universe in 0:40:48.280 --> 0:40:51.160 the sense of like having an effective theory that describes 0:40:51.200 --> 0:40:54.680 how things work right now, right because as we kind 0:40:54.680 --> 0:40:57.440 of talked about a minute ago with Genie's question, the 0:40:57.560 --> 0:41:00.760 universe kind of went through a pretty significant a change 0:41:00.960 --> 0:41:05.000 early soon after the Big Bang, Like before this event, 0:41:05.600 --> 0:41:07.880 everything all the matter, what's had so much energy, so 0:41:08.000 --> 0:41:11.640 much velocity, so much going on that like not even 0:41:11.760 --> 0:41:14.880 protons and electrons could hold together or come together and 0:41:14.960 --> 0:41:17.920 stick into atoms and matter things that are just kind 0:41:17.920 --> 0:41:20.120 of like a giant plasma. And then when things cooled, 0:41:20.200 --> 0:41:24.400 when space expanded, things cool suddenly, like things clicked into 0:41:24.560 --> 0:41:26.920 atoms and the stuff we see today, which is I 0:41:27.239 --> 0:41:28.799 think what you're trying to say is similar to like 0:41:28.920 --> 0:41:32.560 what happens to vapor or ice. It's like the molecules 0:41:32.600 --> 0:41:34.440 are flying around, but at some point they lose so 0:41:34.520 --> 0:41:36.600 much energy that some of the other forces in plate 0:41:36.800 --> 0:41:39.680 start to click them together or to bring them together 0:41:39.719 --> 0:41:42.919 as a liquid exactly. And what Cordy is bringing up 0:41:43.040 --> 0:41:46.400 is another kind of phase transition, even deeper phase transition 0:41:46.440 --> 0:41:49.800 than just like how do protons and electrons click together? 0:41:50.320 --> 0:41:53.160 She was talking about the moment when things got mass. 0:41:53.560 --> 0:41:55.800 All right, we've described the nature of the universes. We 0:41:55.880 --> 0:41:58.319 understand it in terms of all these quantum fields that 0:41:58.360 --> 0:42:00.800 are slashing around, and we talk about how the Higgs 0:42:00.800 --> 0:42:04.239 field is there and it's giving mass to particles by 0:42:04.360 --> 0:42:06.880 interacting with them and changing how they moved through the 0:42:07.000 --> 0:42:08.759 universe and all of this stuff. But if you go 0:42:08.800 --> 0:42:10.480 back to one of our podcasts where we talk about 0:42:10.520 --> 0:42:13.319 the very early history of the universe, you know that 0:42:13.360 --> 0:42:16.080 there was a moment before this happened, before the Higgs 0:42:16.080 --> 0:42:18.960 field was giving mass to particles, when we still had 0:42:19.000 --> 0:42:21.680 this description of everything in terms of quantum fields, but 0:42:21.719 --> 0:42:25.320 effectively the universe was very different. Everything was basically mass 0:42:25.480 --> 0:42:28.360 less electrons and quarks and all this stuff. We're flying 0:42:28.360 --> 0:42:30.760 to the universe all at the speed of light before 0:42:30.800 --> 0:42:34.400 the Higgs boson sort of kicked in and gave everything mass. 0:42:34.640 --> 0:42:37.760 So that was another big phase transition in our universe. 0:42:38.280 --> 0:42:41.359 Now that one's pretty fundamental, like the universe went from 0:42:41.400 --> 0:42:45.400 not having mass to having mass. Things having mass, and 0:42:45.440 --> 0:42:49.440 you said, something clicked, but like the laws of physics change, 0:42:49.640 --> 0:42:53.479 or within our laws just some sort of potential change, 0:42:53.600 --> 0:42:56.800 or we reached the threshold where suddenly the laws preferred 0:42:56.840 --> 0:42:59.680 to be this way rather than having no mass, so 0:43:00.120 --> 0:43:02.960 that the laws we have now describe the universe now. 0:43:03.040 --> 0:43:06.400 And also before this transition, so same laws of physics, 0:43:06.560 --> 0:43:09.120 but you have different temperature. And so as the Higgs 0:43:09.160 --> 0:43:12.160 field was cooling down, it got stuck in sort of 0:43:12.160 --> 0:43:14.680 a local minimum, and that's what she referred to as 0:43:14.719 --> 0:43:18.360 electroweak symmetry breaking. It's got stuck in this sort of 0:43:18.400 --> 0:43:21.839 weird spot where it treats w's and z's differently from 0:43:21.840 --> 0:43:24.720 how it treats photons, and it gave those particles mass, 0:43:24.840 --> 0:43:26.920 and it gives mass to the other particles sort of 0:43:26.920 --> 0:43:29.880 because where it got stuck as the universe was cooling, 0:43:30.040 --> 0:43:32.560 So it's the same basic laws of physics, but as 0:43:32.560 --> 0:43:35.480 the universe cools down, the effect of those laws changes, 0:43:35.760 --> 0:43:37.720 and one of the effects is that the Higgs field 0:43:37.719 --> 0:43:40.040 got stuck in this weird spot and that's why these 0:43:40.080 --> 0:43:42.920 particles have mass. And so really, I think her question 0:43:43.040 --> 0:43:46.400 is like, do we expect further similar phase transitions in 0:43:46.440 --> 0:43:49.680 the future or the universe that could fundamentally change what 0:43:49.800 --> 0:43:53.080 we experience. Yeah, I guess she's not asking like can 0:43:53.120 --> 0:43:56.320 the laws change? He's more asking like, is the universe, 0:43:56.360 --> 0:43:58.719 like you said, is the universe stable? Are we like 0:43:58.880 --> 0:44:01.360 in a spot where the basic configuration of the universe 0:44:01.440 --> 0:44:03.160 is going to be the same, or can it change 0:44:03.200 --> 0:44:05.759 like it did once before? Though, you know, it is 0:44:05.800 --> 0:44:09.040 possible that the laws could change, because even though we 0:44:09.080 --> 0:44:12.200 can describe the history of the universe pretty far back 0:44:12.320 --> 0:44:15.240 using our laws and quantum fields, there's a moment beyond 0:44:15.239 --> 0:44:17.799 which we can't right at the very very beginning of 0:44:17.840 --> 0:44:20.080 the universe, just after inflation with things where at the 0:44:20.080 --> 0:44:23.080 plank temperature. We think our laws break down there, and 0:44:23.120 --> 0:44:25.920 before that we need something else, some theory of quantum 0:44:25.960 --> 0:44:29.719 gravity that's deeper. We think that even our laws of 0:44:29.760 --> 0:44:32.280 physics that do a great job of describing the universe 0:44:32.320 --> 0:44:34.799 today and very very far back in time. They are 0:44:34.920 --> 0:44:37.840 just effective laws. They're like understanding water when it's a 0:44:37.840 --> 0:44:40.960 liquid and how it flows, but not deeply understanding the 0:44:40.960 --> 0:44:44.240 true theory of water that would explain all of its phases. 0:44:44.719 --> 0:44:47.160 So there is a sense in which the actual effective 0:44:47.200 --> 0:44:50.520 laws of physics do change over time, though we don't 0:44:50.520 --> 0:44:52.000 know what's going to happen in the future. We think 0:44:52.000 --> 0:44:54.520 the universe is just going to keep cooling and probably 0:44:54.840 --> 0:44:57.920 this current effective set of laws are going to hold fast. 0:44:58.120 --> 0:45:00.600 But even if these laws hold fast, there might be 0:45:00.640 --> 0:45:03.759 phase transition still in our future. Right. We talked on 0:45:03.800 --> 0:45:06.000 the podcast once about how the Higgs field is sort 0:45:06.000 --> 0:45:08.640 of stuck in this one spot, but it's not that stable. 0:45:08.920 --> 0:45:11.080 We don't know if it's going to stay stuck in 0:45:11.080 --> 0:45:14.600 that spot or if it's going to collapse and change 0:45:14.640 --> 0:45:17.200 the masses of everything, and that would be like another 0:45:17.239 --> 0:45:20.840 effective phase transition. So it might be that sometime in 0:45:20.880 --> 0:45:24.200 the future, you know, maybe spurred on by particle collisions, 0:45:24.239 --> 0:45:26.719 that some super collider could spark a change in the 0:45:26.800 --> 0:45:29.719 Higgs field which creates an effective phase transition in the 0:45:29.760 --> 0:45:32.279 basic laws of physics. Yeah, I think we talked about 0:45:32.320 --> 0:45:34.680 this in our book. Frequently ask questions about the universe, 0:45:34.760 --> 0:45:36.920 But you know, is the universe is going to end 0:45:36.960 --> 0:45:38.680 at some point? Or how is the universe going to end? 0:45:38.680 --> 0:45:42.400 And one possibility is for this Higgs field to collapse, 0:45:42.560 --> 0:45:45.120 because it can collapse right like, it's sitting at a 0:45:45.160 --> 0:45:49.680 place where it can still fall down in terms of energy. Yeah, 0:45:49.719 --> 0:45:51.920 the reason the Higgs field does what it does is 0:45:51.920 --> 0:45:54.600 because it has a lot of energy still stored in it. 0:45:54.600 --> 0:45:56.759 It's like the whole universe is cooling down, but the 0:45:56.840 --> 0:45:59.400 Higgs field got stuck and sort of staying hot. But 0:45:59.400 --> 0:46:01.560 it's kind of like ball that's stuck on a shelf 0:46:01.600 --> 0:46:04.000 and it could roll off that shelf and fall further 0:46:04.160 --> 0:46:07.640 down in temperature. We don't really understand very well how 0:46:07.800 --> 0:46:11.040 stable the spot it's stuck in is and what it 0:46:11.040 --> 0:46:13.000 would take to sort of nudge it out of that, 0:46:13.280 --> 0:46:16.320 and so there's a possibility that it could collapse even further, 0:46:16.719 --> 0:46:18.400 and that would mean a change in the masses of 0:46:18.400 --> 0:46:21.680 all the particles, which would mean like chemistry out the window, 0:46:21.960 --> 0:46:24.760 need totally new chemistry, and you know, everything that relies 0:46:24.800 --> 0:46:28.480 on chemistry, like life and podcasts also out the window, 0:46:28.840 --> 0:46:31.480 and I guess buying a house also along with that. 0:46:32.040 --> 0:46:34.520 But I think you describe it as sort of like 0:46:34.520 --> 0:46:37.440 a spark and a spark propagating. I know we've covered 0:46:37.440 --> 0:46:39.919 this in the book, but it's almost like if something 0:46:40.000 --> 0:46:42.480 happens and does cause a Higgs boson to kind of 0:46:42.520 --> 0:46:45.000 fall over or give up its energy in one spot, 0:46:45.280 --> 0:46:48.239 it would basically cause the entire universe to do the same, 0:46:48.280 --> 0:46:51.640 Like it would spread out like a wave. Right, if 0:46:51.640 --> 0:46:54.120 it happened anywhere, it would spread out like a wave 0:46:54.200 --> 0:46:56.600 propagating at the speed of light. So it may have 0:46:56.719 --> 0:47:00.719 already happened somewhere else in the universe, and that wavefront 0:47:00.760 --> 0:47:04.200 of phase transitions is heading for us or maybe not, 0:47:04.280 --> 0:47:06.879 and maybe it'll be stable forever, right, And you're saying 0:47:06.880 --> 0:47:09.160 that one thing that could trigger it maybe is building 0:47:09.200 --> 0:47:13.600 a large particle collider, maybe under Geneva or something, yeah, 0:47:13.719 --> 0:47:16.160 or around the surface of the Moon or around the 0:47:16.239 --> 0:47:18.080 edge of the galaxy. It sounds like we need to 0:47:18.120 --> 0:47:20.719 shut those things down right away. It sounds like we 0:47:20.760 --> 0:47:25.920 need to build one and find out. That sounds like 0:47:26.000 --> 0:47:28.400 exactly the opposite thing. You want to find out if 0:47:28.400 --> 0:47:30.880 you can destroy the universe. I don't know. I'm pro curiosity. 0:47:30.880 --> 0:47:32.640 I don't know how you feel. I am pro not 0:47:32.760 --> 0:47:35.719 destroying the universe, because once you find out that you 0:47:35.719 --> 0:47:39.960 can destroy the universe, you've destroyed the universe, Daniel, but 0:47:40.080 --> 0:47:43.919 you've learned something along the way. No, because you won't 0:47:43.960 --> 0:47:46.520 be here. Look what I'm saying, is nobody ever regretted 0:47:46.560 --> 0:47:50.560 destroying the universe. Well, I think the answer here for 0:47:50.680 --> 0:47:53.879 Corney is that go ahead and buy that house you're 0:47:53.960 --> 0:47:55.880 thinking of buying. And maybe you should write to Daniel 0:47:55.880 --> 0:48:00.840 tell him not to destroy the universe. Send your questions, 0:48:00.840 --> 0:48:04.680 your ideas, your requests to not destroy the universe. Two 0:48:04.760 --> 0:48:07.680 questions at Daniel and Jorge dot com. All right, thank 0:48:07.719 --> 0:48:10.279 you everyone for sending us their question. A lot of 0:48:10.280 --> 0:48:12.560 interesting things we've learned about here. I think we can 0:48:12.600 --> 0:48:14.640 give ourselves a pat on the back, Daniel, maybe with 0:48:14.680 --> 0:48:17.000 a third army out at the top of your head. Yeah, exactly, 0:48:17.040 --> 0:48:18.960 it's busy scratching my head right now. You can give 0:48:19.000 --> 0:48:21.320 yourself three handshakes. Triple high five. It would be the 0:48:21.400 --> 0:48:24.840 highest of fives. M it would be a triple five. Yeah, 0:48:25.200 --> 0:48:28.320 it would be a fifteen. All right, Well, thanks for 0:48:28.400 --> 0:48:31.160 joining us. We hope you enjoyed that. See you next time. 0:48:39.000 --> 0:48:41.800 Thanks for listening, and remember that Daniel and Jorge Explain 0:48:41.880 --> 0:48:45.759 the Universe is a production of iHeartRadio. For more podcast 0:48:45.920 --> 0:48:49.799 from my heart Radio, visit the iHeartRadio app, Apple Podcasts, 0:48:49.920 --> 0:48:52.320 or wherever you listen to your favorite shows.