1 00:00:08,640 --> 00:00:12,360 Speaker 1: Why do we care so much about understanding the universe, 2 00:00:12,400 --> 00:00:16,639 Speaker 1: about revealing its deep truths? Why aren't we just happy 3 00:00:16,760 --> 00:00:19,840 Speaker 1: to live in it? I mean, does it change your 4 00:00:19,960 --> 00:00:23,639 Speaker 1: life to understand the Higgs Boson? Does it matter to 5 00:00:23,760 --> 00:00:27,440 Speaker 1: your day whether there's intelligent life on the other side 6 00:00:27,480 --> 00:00:32,120 Speaker 1: of the galaxy? Not practically, but it matters. It doesn't 7 00:00:32,120 --> 00:00:35,240 Speaker 1: matter to build spaceships or death stars, or to become 8 00:00:35,320 --> 00:00:38,600 Speaker 1: masters of the universe, but it matters to us to 9 00:00:38,760 --> 00:00:43,640 Speaker 1: know to understand it's just who we are as human beings. 10 00:00:59,680 --> 00:01:03,040 Speaker 1: I'm Daniel, I'm a particle physicist, and welcome to the 11 00:01:03,080 --> 00:01:07,520 Speaker 1: podcast Daniel and Jorge Explain the Universe, a production of 12 00:01:07,560 --> 00:01:11,000 Speaker 1: I Heart Radio in which we marinate in our desire 13 00:01:11,120 --> 00:01:14,600 Speaker 1: to understand everything in the universe. We cast our minds 14 00:01:14,640 --> 00:01:17,440 Speaker 1: out in the furthest reaches of space and hope to 15 00:01:17,520 --> 00:01:21,200 Speaker 1: understand what's going on out there. We turn our mental 16 00:01:21,280 --> 00:01:24,720 Speaker 1: eye down to the very smallest particles in our universe 17 00:01:24,959 --> 00:01:27,680 Speaker 1: and ask does this make sense to us? Can this 18 00:01:27,920 --> 00:01:31,160 Speaker 1: possibly make sense to us? Is there a mathematical way 19 00:01:31,160 --> 00:01:33,679 Speaker 1: that we could understand it? We talked about all of 20 00:01:33,720 --> 00:01:36,080 Speaker 1: these things on the podcast, and we try to make 21 00:01:36,080 --> 00:01:39,280 Speaker 1: sure they make sense to you, because we think that 22 00:01:39,360 --> 00:01:42,920 Speaker 1: everybody deserves to understand the universe. Because we know that 23 00:01:43,000 --> 00:01:46,720 Speaker 1: everybody wants to understand the universe. It's part of being 24 00:01:46,840 --> 00:01:50,080 Speaker 1: human to look around you and to try to understand. 25 00:01:50,280 --> 00:01:53,000 Speaker 1: And I don't know if there's an evolutionary reason to 26 00:01:53,120 --> 00:01:56,960 Speaker 1: want to understand our universe. May be fundamentally deriving the 27 00:01:57,040 --> 00:01:59,440 Speaker 1: laws of physics helps us plan the hunt for a 28 00:01:59,560 --> 00:02:02,840 Speaker 1: mammoth or chase down an antelope on the savannah. I'm 29 00:02:02,880 --> 00:02:06,360 Speaker 1: not sure, but here we are. We are curious creatures 30 00:02:06,600 --> 00:02:09,480 Speaker 1: and we have this desire inside us to make sure 31 00:02:09,520 --> 00:02:12,400 Speaker 1: that the world around us makes sense, to sort of 32 00:02:12,600 --> 00:02:15,919 Speaker 1: pull all of our observations together inside our mind into 33 00:02:16,000 --> 00:02:18,560 Speaker 1: a mental model that we can manipulate, that we can 34 00:02:18,600 --> 00:02:21,200 Speaker 1: probe and then we can use to predict what's going 35 00:02:21,240 --> 00:02:23,920 Speaker 1: to happen to us in the future and to make plans. 36 00:02:24,200 --> 00:02:27,880 Speaker 1: But also just to appreciate. There's a lot of talking 37 00:02:27,960 --> 00:02:31,519 Speaker 1: science these days about whether science and weather physics should 38 00:02:31,520 --> 00:02:33,960 Speaker 1: be searching for beauty. And I don't know if we 39 00:02:33,960 --> 00:02:36,280 Speaker 1: should be searching for it or whether we should prefer it, 40 00:02:36,560 --> 00:02:39,600 Speaker 1: but we can definitely appreciate it. There's a lot of 41 00:02:39,680 --> 00:02:43,600 Speaker 1: gorgeous beautiful results in physics that when we do reveal 42 00:02:43,720 --> 00:02:46,720 Speaker 1: something new and true about the universe, we are amazed. 43 00:02:46,919 --> 00:02:49,560 Speaker 1: We stand a gog and think, wow, there is some 44 00:02:49,639 --> 00:02:53,640 Speaker 1: real beauty and elegance to our universe. And so typically 45 00:02:53,680 --> 00:02:55,720 Speaker 1: on the podcast it's me and Jorge and we are 46 00:02:55,760 --> 00:02:58,760 Speaker 1: talking about some difficult to understand thing about physics and 47 00:02:58,840 --> 00:03:01,400 Speaker 1: explaining it to you or hey is not here today, 48 00:03:01,440 --> 00:03:03,760 Speaker 1: So I'm going to take the opportunity to catch up 49 00:03:04,000 --> 00:03:06,280 Speaker 1: not on the questions that science is asking, but on 50 00:03:06,360 --> 00:03:10,600 Speaker 1: the questions that listeners are asking you, specifically you. That's right, 51 00:03:10,639 --> 00:03:13,000 Speaker 1: I'm talking about you. You are sitting there or standing 52 00:03:13,000 --> 00:03:16,560 Speaker 1: there or driving around listening to our podcast because you 53 00:03:16,720 --> 00:03:19,760 Speaker 1: have questions about the universe, and I want to hear 54 00:03:19,800 --> 00:03:22,760 Speaker 1: those questions. I want to know what is it you'd 55 00:03:22,800 --> 00:03:26,680 Speaker 1: like explained, and so send us your questions to questions 56 00:03:26,760 --> 00:03:29,560 Speaker 1: at Daniel and Jorge dot com. If you're thinking that 57 00:03:29,680 --> 00:03:32,680 Speaker 1: physicists will never answer my email, you're wrong. I answer 58 00:03:32,800 --> 00:03:35,800 Speaker 1: all of our emails, and sometimes I put those questions 59 00:03:35,880 --> 00:03:38,800 Speaker 1: up on the podcast when I think somebody else might 60 00:03:38,840 --> 00:03:40,800 Speaker 1: want to hear the answer. When I think, oh, that's 61 00:03:40,800 --> 00:03:44,000 Speaker 1: a particularly interesting question that I bet a lot of 62 00:03:44,000 --> 00:03:46,160 Speaker 1: our listeners would like to hear about. So that's what 63 00:03:46,240 --> 00:03:49,320 Speaker 1: we're gonna do today. On today's program will be answering 64 00:03:54,440 --> 00:03:59,040 Speaker 1: real questions from listeners. And I love answering your questions 65 00:03:59,040 --> 00:04:01,280 Speaker 1: because they give me a sense for what people are 66 00:04:01,280 --> 00:04:04,160 Speaker 1: thinking about. What do people know about physics, what makes 67 00:04:04,360 --> 00:04:06,840 Speaker 1: sense to them? Because I've been doing physics for decades 68 00:04:06,880 --> 00:04:09,560 Speaker 1: and my brain is fully marinated in physics is a 69 00:04:09,680 --> 00:04:11,840 Speaker 1: language and is a way of thinking, So it's very 70 00:04:11,840 --> 00:04:14,400 Speaker 1: helpful to me to hear about the way people ask 71 00:04:14,440 --> 00:04:16,680 Speaker 1: about it when they're on the outside. So it's very 72 00:04:16,680 --> 00:04:19,640 Speaker 1: helpful to me to hear about what your questions are, 73 00:04:19,680 --> 00:04:22,080 Speaker 1: the way that you think about the universe and the 74 00:04:22,080 --> 00:04:24,880 Speaker 1: things that don't make sense to you. And also, because 75 00:04:24,920 --> 00:04:28,480 Speaker 1: while most podcasts are one directional is just a couple 76 00:04:28,520 --> 00:04:32,080 Speaker 1: of voices sending information and audio out there into your brain, 77 00:04:32,320 --> 00:04:35,960 Speaker 1: this podcast is interactive. That's right. We want to hear 78 00:04:35,960 --> 00:04:39,240 Speaker 1: from you. We want to know what you need to understand, 79 00:04:39,279 --> 00:04:42,120 Speaker 1: so please don't be shy. Send us your questions to 80 00:04:42,560 --> 00:04:46,479 Speaker 1: questions at Daniel and Jorge dot com. And if you 81 00:04:46,480 --> 00:04:49,279 Speaker 1: don't like writing emails or don't want to interact with 82 00:04:49,400 --> 00:04:52,479 Speaker 1: us on Twitter at Daniel and Jorge. Then hey, just 83 00:04:52,600 --> 00:04:56,200 Speaker 1: come to my free public office hours. I hang out 84 00:04:56,279 --> 00:04:58,719 Speaker 1: once a month for an hour on Zoom and answer 85 00:04:58,839 --> 00:05:01,880 Speaker 1: questions from all all commerce. It's an opportunity to have 86 00:05:01,960 --> 00:05:04,800 Speaker 1: a little bit more interactivity. You can ask a question, 87 00:05:05,120 --> 00:05:07,440 Speaker 1: you can ask a follow up question. I'll make sure 88 00:05:07,560 --> 00:05:11,159 Speaker 1: you go away with some understanding of the universe. So, 89 00:05:11,240 --> 00:05:14,520 Speaker 1: without further ado, let's dig into today's awesome pile of 90 00:05:14,640 --> 00:05:17,520 Speaker 1: listener questions. And thanks again to everybody who writes in, 91 00:05:17,960 --> 00:05:21,760 Speaker 1: and please don't be shy. So today's first question is 92 00:05:21,760 --> 00:05:25,080 Speaker 1: a rather stinky one from Bob Buyer. All right, Daniel, 93 00:05:25,200 --> 00:05:29,200 Speaker 1: this is Bob from Edmonds, Washington. Uh. Say, I have 94 00:05:29,400 --> 00:05:34,400 Speaker 1: always wondered, um if space might smell like something, or 95 00:05:34,440 --> 00:05:38,240 Speaker 1: even if it has a smell. I was thinking maybe 96 00:05:38,839 --> 00:05:43,200 Speaker 1: astronauts reported a smell after returning to the space station 97 00:05:44,600 --> 00:05:47,480 Speaker 1: when they're inside their decompression chamber and they take off 98 00:05:47,480 --> 00:05:51,960 Speaker 1: their helmets, or maybe Apollo mission astronauts after walking on 99 00:05:52,000 --> 00:05:54,960 Speaker 1: the Moon surface and returned back to their landing craft 100 00:05:55,880 --> 00:06:00,160 Speaker 1: and they take off their helmets inside there my be 101 00:06:00,279 --> 00:06:04,720 Speaker 1: residual smell from outdoors, and what would that smell like? 102 00:06:05,440 --> 00:06:09,000 Speaker 1: So anyway, I hope you can shed some light on 103 00:06:09,040 --> 00:06:11,320 Speaker 1: that question. Thanks a lot. All right, that's a super 104 00:06:11,360 --> 00:06:14,440 Speaker 1: fun question. Thank you so much Bob for sending that in. 105 00:06:14,600 --> 00:06:17,560 Speaker 1: I'm excited to talk about the smells of space or 106 00:06:17,600 --> 00:06:19,840 Speaker 1: the stinks of space, But first I want to think 107 00:06:19,880 --> 00:06:22,719 Speaker 1: for a minute about the motivation for this question. I 108 00:06:22,760 --> 00:06:25,080 Speaker 1: think it's super fun to look up at the night 109 00:06:25,160 --> 00:06:28,680 Speaker 1: sky and wonder about it and want to understand it. 110 00:06:29,080 --> 00:06:33,320 Speaker 1: And what does understanding mean. It means somehow transforming that 111 00:06:33,440 --> 00:06:37,320 Speaker 1: knowledge into something that makes sense to us, something that 112 00:06:37,400 --> 00:06:41,080 Speaker 1: relates to our everyday experience. And you know, how do 113 00:06:41,120 --> 00:06:43,680 Speaker 1: we interact with the world. We taste it, we touch it, 114 00:06:43,920 --> 00:06:46,480 Speaker 1: we smell it, and so there's a little bit there 115 00:06:46,480 --> 00:06:49,599 Speaker 1: about like trying to hook in the sky and bring 116 00:06:49,640 --> 00:06:51,800 Speaker 1: it down to Earth and wonder like what would it 117 00:06:51,800 --> 00:06:55,119 Speaker 1: be like to interact with the sky using our earth 118 00:06:55,279 --> 00:06:58,120 Speaker 1: based senses. So I totally applaud this idea. I think 119 00:06:58,120 --> 00:07:01,320 Speaker 1: it's wonderful, and frankly, it follows in the footsteps of 120 00:07:01,360 --> 00:07:04,920 Speaker 1: geniuses like Isaac Newton. He's the guy who thought, if 121 00:07:04,960 --> 00:07:07,560 Speaker 1: I have a theory of gravity that describes how an 122 00:07:07,600 --> 00:07:10,760 Speaker 1: apple falls from a tree, can I also use it 123 00:07:10,800 --> 00:07:13,640 Speaker 1: to describe the motion of the stars. There was this 124 00:07:13,800 --> 00:07:16,920 Speaker 1: idea that you could unify our understanding of what happens 125 00:07:16,920 --> 00:07:20,240 Speaker 1: here on Earth with what happens out there, the idea 126 00:07:20,320 --> 00:07:22,480 Speaker 1: that the Earth is not a special place, and the 127 00:07:22,560 --> 00:07:25,680 Speaker 1: laws of physics that we find should apply equally everywhere. 128 00:07:25,840 --> 00:07:27,880 Speaker 1: And so flip that around and think, well, if I 129 00:07:27,880 --> 00:07:30,760 Speaker 1: can smell stuff down here on Earth, could I smell 130 00:07:30,800 --> 00:07:33,600 Speaker 1: stuff out there in space? And what would it smell like? 131 00:07:33,960 --> 00:07:37,960 Speaker 1: So super fun, wonderful question. Now, of course, the easy 132 00:07:38,040 --> 00:07:41,920 Speaker 1: answer is that if you opened your helmet in space, 133 00:07:42,040 --> 00:07:46,040 Speaker 1: you wouldn't smell anything, because you're a news would freeze. Right. 134 00:07:46,440 --> 00:07:49,720 Speaker 1: Space is mostly a vacuum. It's very cold and very 135 00:07:49,720 --> 00:07:53,000 Speaker 1: low pressure, and so if you exposed yourself to the 136 00:07:53,080 --> 00:07:55,760 Speaker 1: vacuum of space, then of course you wouldn't smell anything. 137 00:07:55,840 --> 00:07:58,600 Speaker 1: But that's not the only way to smell space, right, 138 00:07:58,640 --> 00:08:02,360 Speaker 1: because space is not actually empty. We talked on this 139 00:08:02,400 --> 00:08:05,720 Speaker 1: podcast a lot about how space is actually filled with stuff. 140 00:08:05,920 --> 00:08:08,600 Speaker 1: And we're not talking here about like quantum fields and 141 00:08:08,680 --> 00:08:12,920 Speaker 1: other crazy low energy phenomena. I'm talking about actual particles. 142 00:08:13,040 --> 00:08:15,600 Speaker 1: There's a whole podcast episode we did about where is 143 00:08:15,640 --> 00:08:18,560 Speaker 1: the Emptiest Place? In space, and as you leave the Earth, 144 00:08:18,600 --> 00:08:21,160 Speaker 1: of course, the atmosphere gets thinner and thinner and thinner. 145 00:08:21,480 --> 00:08:24,840 Speaker 1: And then when you're out there in sort of interplanetary space, 146 00:08:25,160 --> 00:08:28,520 Speaker 1: it's not like there's nothing there. There are a lot 147 00:08:28,560 --> 00:08:32,000 Speaker 1: of particles out there, from big rocks which are pretty 148 00:08:32,080 --> 00:08:35,120 Speaker 1: rare and down to tiny grains of space dust which 149 00:08:35,160 --> 00:08:38,760 Speaker 1: are frankly everywhere. Space is not really empty at all. 150 00:08:39,200 --> 00:08:41,319 Speaker 1: Add to that, of course the solar wind, which is 151 00:08:41,360 --> 00:08:45,160 Speaker 1: pumping out huge numbers of particles all the time, protons 152 00:08:45,160 --> 00:08:48,400 Speaker 1: and electrons and other kinds of small particles mostly, But 153 00:08:48,480 --> 00:08:51,040 Speaker 1: there's a lot of stuff bumping around up there. So 154 00:08:51,080 --> 00:08:54,679 Speaker 1: it's a really fair question to ask, what would those 155 00:08:54,720 --> 00:08:57,400 Speaker 1: things smell like if you could somehow use your nose 156 00:08:57,600 --> 00:09:01,719 Speaker 1: to probe them, Because remember, the human nose is amazing. 157 00:09:02,160 --> 00:09:06,120 Speaker 1: It's a very sensitive, basically molecular detector. The way your 158 00:09:06,120 --> 00:09:08,360 Speaker 1: nose works is that you suck in air and has 159 00:09:08,400 --> 00:09:11,000 Speaker 1: a bunch of molecules in it, and those molecules hit 160 00:09:11,080 --> 00:09:14,320 Speaker 1: various sensors. These sensors are all sort of differently shaped 161 00:09:14,600 --> 00:09:17,600 Speaker 1: and they can lock into different molecules to detect it, 162 00:09:17,880 --> 00:09:21,040 Speaker 1: so they can detect lots of different molecules, and it's 163 00:09:21,200 --> 00:09:24,160 Speaker 1: very related to this sense of taste. You know, the 164 00:09:24,240 --> 00:09:27,160 Speaker 1: taste buds on your tongue, for example, are receptive to 165 00:09:27,320 --> 00:09:30,200 Speaker 1: sugar molecules or other kinds of molecules or salt, and 166 00:09:30,240 --> 00:09:32,920 Speaker 1: you have a handful of different sensors on your tongue 167 00:09:33,120 --> 00:09:36,080 Speaker 1: that can taste different kinds of molecules just the same way. 168 00:09:36,120 --> 00:09:40,080 Speaker 1: Your eyeballs, for example, have different cones and rods inside them, 169 00:09:40,240 --> 00:09:42,280 Speaker 1: and they use that to build up a picture of 170 00:09:42,320 --> 00:09:44,840 Speaker 1: what you're seeing. But there again, there's only a few 171 00:09:45,000 --> 00:09:48,280 Speaker 1: rods and cones. There's only really three different kinds of 172 00:09:48,280 --> 00:09:51,080 Speaker 1: colors that you can see, and the rest is interpretated 173 00:09:51,120 --> 00:09:53,520 Speaker 1: by your brain. But when it comes to your nose, 174 00:09:53,600 --> 00:09:57,480 Speaker 1: it's actually much much more powerful than those other senses. 175 00:09:57,679 --> 00:10:02,719 Speaker 1: Your nose can sense hundreds of individual different molecules. You 176 00:10:02,800 --> 00:10:05,960 Speaker 1: can identify them, It can pick them out even if 177 00:10:06,000 --> 00:10:09,320 Speaker 1: they're very, very faint. You ever smell something just a 178 00:10:09,440 --> 00:10:12,960 Speaker 1: tiny little bit that your nose picking out the tiniest 179 00:10:13,000 --> 00:10:16,360 Speaker 1: little serving of whatever it is that you're smelling. So 180 00:10:16,440 --> 00:10:19,520 Speaker 1: your nose is actually a pretty good way to explore 181 00:10:19,760 --> 00:10:23,000 Speaker 1: what's going on out there, and there really is plenty 182 00:10:23,040 --> 00:10:26,160 Speaker 1: of stuff out there to smell. Space is not just 183 00:10:26,320 --> 00:10:31,480 Speaker 1: filled with hydrogen gas. There are complex organic molecules out there. 184 00:10:31,760 --> 00:10:34,439 Speaker 1: We know because when we sample comments or get bits 185 00:10:34,480 --> 00:10:37,480 Speaker 1: of asteroids or meteors, we see these things. We see 186 00:10:37,520 --> 00:10:41,280 Speaker 1: the molecular composition, and there's fascinating stuff out there. You 187 00:10:41,360 --> 00:10:44,440 Speaker 1: know that, Like moons of Jupiter and Saturn have really 188 00:10:44,480 --> 00:10:48,000 Speaker 1: interesting organic molecules on them. Not signs of life we're 189 00:10:48,040 --> 00:10:51,520 Speaker 1: talking about here, like molecular precursors of life, like the 190 00:10:51,559 --> 00:10:55,439 Speaker 1: amino acids you might need to build life. And it's 191 00:10:55,600 --> 00:11:00,520 Speaker 1: very reasonable to expect that those molecules might smell like something. 192 00:11:00,880 --> 00:11:03,120 Speaker 1: So how would you actually go about smelling it. You 193 00:11:03,120 --> 00:11:06,120 Speaker 1: can't go out there into space and open your helmet 194 00:11:06,160 --> 00:11:08,360 Speaker 1: and take a deep whiff, right, Well, what you can 195 00:11:08,400 --> 00:11:11,319 Speaker 1: do is you can collect those molecules and then smell 196 00:11:11,360 --> 00:11:14,080 Speaker 1: them when you're back in an aerrated chamber. And one 197 00:11:14,080 --> 00:11:17,480 Speaker 1: way this has actually happened is by astronauts going out 198 00:11:17,520 --> 00:11:20,679 Speaker 1: into space and then coming back inside. Like if you 199 00:11:20,800 --> 00:11:24,000 Speaker 1: come back into the space station, then your suit and 200 00:11:24,040 --> 00:11:26,920 Speaker 1: your helmet have collected some of those particles that are 201 00:11:26,920 --> 00:11:29,280 Speaker 1: out there in space. They've stuck to you, and when 202 00:11:29,320 --> 00:11:31,880 Speaker 1: you go back inside into the airlock. Then the air 203 00:11:31,960 --> 00:11:34,440 Speaker 1: releases them and they swirled all around, and some of 204 00:11:34,440 --> 00:11:37,480 Speaker 1: them go up your nose and just smell them. The 205 00:11:37,559 --> 00:11:40,000 Speaker 1: most common thing that you're gonna be smelling if you 206 00:11:40,080 --> 00:11:43,000 Speaker 1: do take a whiff of space are these things called 207 00:11:43,080 --> 00:11:47,959 Speaker 1: aromatic hydrocarbons. These are molecules built out of carbon and hydrogen, 208 00:11:48,120 --> 00:11:51,280 Speaker 1: which is why they're called hydrocarbon, and they're aromatic, which 209 00:11:51,280 --> 00:11:53,920 Speaker 1: means you're gonna smell them. And most of these things 210 00:11:54,000 --> 00:11:57,560 Speaker 1: smells sort of like hot metal or like diesel gas, 211 00:11:57,679 --> 00:11:59,920 Speaker 1: or and some people have described them as like smell 212 00:12:00,040 --> 00:12:02,800 Speaker 1: thing like a barbecue, and that's because those are the 213 00:12:02,840 --> 00:12:07,440 Speaker 1: processes on Earth that generates similar kinds of molecules. So 214 00:12:07,480 --> 00:12:09,959 Speaker 1: it's not like somebody out there is have a barbecue 215 00:12:09,960 --> 00:12:12,880 Speaker 1: in space or or running a diesel engine. But those 216 00:12:12,920 --> 00:12:16,400 Speaker 1: things on Earth produce similar molecules which end up in 217 00:12:16,440 --> 00:12:18,960 Speaker 1: your nose on Earth, and you remember them, and so 218 00:12:19,080 --> 00:12:21,839 Speaker 1: when you smell them out there in space, or when 219 00:12:21,840 --> 00:12:25,160 Speaker 1: you just come back inside from space, then that's the 220 00:12:25,160 --> 00:12:27,760 Speaker 1: association you're going to get. But there are lots of 221 00:12:27,800 --> 00:12:31,280 Speaker 1: different possible smells of things in space. For example, there's 222 00:12:31,320 --> 00:12:34,559 Speaker 1: a vast dust cloud to the center of our galaxy 223 00:12:34,600 --> 00:12:37,360 Speaker 1: that's made of a chemical called ethyl formate, and evil 224 00:12:37,400 --> 00:12:40,199 Speaker 1: formate itself is something you can make here on Earth, 225 00:12:40,240 --> 00:12:43,720 Speaker 1: and it smells sort of like rum. That's right. It 226 00:12:43,800 --> 00:12:46,760 Speaker 1: smells like the pirate cloud of the galaxy. And if 227 00:12:46,800 --> 00:12:50,000 Speaker 1: you separated, then one part of it esther, among other things, 228 00:12:50,120 --> 00:12:54,800 Speaker 1: is the chemical responsible for the flavor of raspberries. So yeah, 229 00:12:54,840 --> 00:12:58,079 Speaker 1: we're talking about vast dust clouds that might smell like 230 00:12:58,400 --> 00:13:01,880 Speaker 1: raspberry rum. But you know, all the amino acids out 231 00:13:01,920 --> 00:13:04,600 Speaker 1: there have different smells. I was looking at a chart 232 00:13:04,720 --> 00:13:07,320 Speaker 1: yesterday and some of them have different smells. Some of 233 00:13:07,320 --> 00:13:09,959 Speaker 1: them would smell sour, some of them would smell sweet, 234 00:13:10,200 --> 00:13:12,800 Speaker 1: some of them would smell like, oh mommy. So it 235 00:13:12,840 --> 00:13:16,280 Speaker 1: really just sort of depends on the particular mixture of 236 00:13:16,400 --> 00:13:19,000 Speaker 1: stuff that you encounter, sort of like asking what does 237 00:13:19,080 --> 00:13:21,760 Speaker 1: Earth smell like? Well, it depends are you at the 238 00:13:21,760 --> 00:13:24,679 Speaker 1: center Manhattan or the top of a mountain or in 239 00:13:24,720 --> 00:13:28,040 Speaker 1: a wheat field in Kansas, Right, Different places have different 240 00:13:28,080 --> 00:13:31,280 Speaker 1: stuff floating around, and so lots of different smells. And 241 00:13:31,320 --> 00:13:33,880 Speaker 1: I think that's the most important answer is that space 242 00:13:34,000 --> 00:13:37,120 Speaker 1: does have a smell because it's filled with interesting stuff. 243 00:13:37,160 --> 00:13:40,160 Speaker 1: And those smells depend on where you are. So I 244 00:13:40,200 --> 00:13:43,319 Speaker 1: also looked up a bunch of reports from what astronauts 245 00:13:43,360 --> 00:13:46,120 Speaker 1: have said, what do they think it's smells like, because 246 00:13:46,120 --> 00:13:48,400 Speaker 1: there haven't been a lot of scientific studies because these 247 00:13:48,400 --> 00:13:51,800 Speaker 1: studies require people. You know, another really fascinating thing about 248 00:13:51,800 --> 00:13:56,120 Speaker 1: the nose is that it's something that's escaped digitization so far. 249 00:13:56,400 --> 00:13:59,800 Speaker 1: You know, we've been able to capture visual images and 250 00:14:00,040 --> 00:14:03,200 Speaker 1: store them digitally and recreate them with a screen. We've 251 00:14:03,200 --> 00:14:06,480 Speaker 1: been able to capture sounds right and store them digitally 252 00:14:06,520 --> 00:14:09,320 Speaker 1: as information and recreate them with a speaker. We haven't 253 00:14:09,400 --> 00:14:12,520 Speaker 1: yet been able to capture digital sense and store that 254 00:14:12,600 --> 00:14:15,840 Speaker 1: information electronically in a way so that some sort of 255 00:14:16,040 --> 00:14:19,760 Speaker 1: digital smell speaker would be able to recreate them so 256 00:14:19,840 --> 00:14:22,920 Speaker 1: you could experience them. That would be pretty awesome or 257 00:14:23,040 --> 00:14:25,480 Speaker 1: maybe pretty terrible. I'm not sure if you want your 258 00:14:25,520 --> 00:14:29,080 Speaker 1: like movie to necessarily have smells, do it. But one 259 00:14:29,160 --> 00:14:31,600 Speaker 1: reason that we haven't yet is that the nose is 260 00:14:31,800 --> 00:14:35,720 Speaker 1: much more complicated than the eye or the tongue in 261 00:14:35,880 --> 00:14:39,000 Speaker 1: terms of the complexity of sensors that it has, and 262 00:14:39,040 --> 00:14:41,160 Speaker 1: so the complexity of the information that needs to be 263 00:14:41,240 --> 00:14:45,720 Speaker 1: stored and then reproduced, so it's particularly difficult anyway. So 264 00:14:45,960 --> 00:14:49,560 Speaker 1: here are some reports from astronauts. Some report that it 265 00:14:49,640 --> 00:14:53,920 Speaker 1: smells like burned steak. Astronaut Tom Jones says that a 266 00:14:54,040 --> 00:14:58,360 Speaker 1: quote carries a distinct odor of ozone, a faint, accurate smell, 267 00:14:58,680 --> 00:15:03,240 Speaker 1: a little like gunpower, maybe sulfurous. Don Pettit said it 268 00:15:03,320 --> 00:15:08,680 Speaker 1: had a quote rather pleasant, sweet metallic sensation. Three times 269 00:15:08,920 --> 00:15:13,520 Speaker 1: Spacewalker Tom Jones says it quote carries a distinct odor 270 00:15:13,600 --> 00:15:16,920 Speaker 1: of ozone, a faint, acrid smell. There was even a 271 00:15:16,960 --> 00:15:21,440 Speaker 1: time when NASA was considering commissioning a perfume that smelled 272 00:15:21,520 --> 00:15:24,200 Speaker 1: like space to sort of get folks used to it 273 00:15:24,240 --> 00:15:27,040 Speaker 1: so they weren't sort of surprised and put off balance 274 00:15:27,160 --> 00:15:29,760 Speaker 1: by the smell of space when they came back inside 275 00:15:30,040 --> 00:15:32,960 Speaker 1: from their spacewalks. But I think they ditched that plan. 276 00:15:33,240 --> 00:15:36,080 Speaker 1: And there's also another side interesting question, which is what 277 00:15:36,240 --> 00:15:39,520 Speaker 1: does the space station smell like? Because the space station 278 00:15:39,640 --> 00:15:41,720 Speaker 1: is sort of like the inside of a tent, right, 279 00:15:42,040 --> 00:15:44,920 Speaker 1: These folks can't go outside. They're stuck inside there, living 280 00:15:44,920 --> 00:15:47,960 Speaker 1: together a lot, and so you might wonder, like, does 281 00:15:48,000 --> 00:15:50,760 Speaker 1: this smell good inside the space station? So here's one 282 00:15:50,800 --> 00:15:53,800 Speaker 1: report I found of what mirror smells like. They said, quote, 283 00:15:54,200 --> 00:15:58,040 Speaker 1: just imagine sweaty feet, stale body odor, and then mix 284 00:15:58,120 --> 00:16:02,080 Speaker 1: that odor with nail polish remover and gasoline. So that 285 00:16:02,200 --> 00:16:04,840 Speaker 1: doesn't sound particularly nice. I'd like to go after a 286 00:16:04,920 --> 00:16:08,120 Speaker 1: walk into space and smell the raspberry rum if I 287 00:16:08,160 --> 00:16:10,520 Speaker 1: was stuck inside with all those sweaty feet. All right, 288 00:16:10,560 --> 00:16:13,120 Speaker 1: so thanks very much Bob for that super fun question. 289 00:16:13,440 --> 00:16:15,880 Speaker 1: I'd like to dig into some more questions, but first 290 00:16:16,040 --> 00:16:31,680 Speaker 1: let's take a quick break. All right, we are back 291 00:16:31,720 --> 00:16:34,560 Speaker 1: and we were talking about the smells of space, but 292 00:16:34,600 --> 00:16:37,600 Speaker 1: now we're gonna turn our minds inwards and ask questions 293 00:16:37,640 --> 00:16:41,480 Speaker 1: about the tiniest little particles and how they work. So 294 00:16:41,680 --> 00:16:45,400 Speaker 1: here's a super fun question from Larry. Hello, it's my 295 00:16:45,440 --> 00:16:48,840 Speaker 1: favorite physicist and roboticist term cartoonist team. This is Larry 296 00:16:48,840 --> 00:16:52,760 Speaker 1: Garfield's Illinois We all, though there are four fundamental forces 297 00:16:52,760 --> 00:16:55,800 Speaker 1: in the universe, you've also said many times in previous 298 00:16:55,800 --> 00:16:58,800 Speaker 1: episodes that you've figured out that the week nuclear force 299 00:16:58,840 --> 00:17:02,960 Speaker 1: and electromagnetism are really the same thing, or different aspects 300 00:17:02,960 --> 00:17:05,800 Speaker 1: of the same thing, or linked or something. I don't 301 00:17:05,880 --> 00:17:08,479 Speaker 1: quite understand. It. Doesn't that mean there's only three forces. 302 00:17:09,400 --> 00:17:12,280 Speaker 1: More to the point, how can there be different representations 303 00:17:12,280 --> 00:17:15,360 Speaker 1: of the same thing if particles like neutrinos only interact 304 00:17:15,400 --> 00:17:18,359 Speaker 1: with the weak force. If the weak force and electromagnetism 305 00:17:18,440 --> 00:17:21,040 Speaker 1: are really the same thing, how can a particle only 306 00:17:21,040 --> 00:17:24,399 Speaker 1: interact with one of them? I'm very confused. All right, 307 00:17:24,680 --> 00:17:27,760 Speaker 1: super awesome, Western Larry, Thanks so much for asking this. 308 00:17:27,760 --> 00:17:30,080 Speaker 1: This is one of my favorite topics to think about, 309 00:17:30,119 --> 00:17:33,400 Speaker 1: not just to talk about and to explain the unification 310 00:17:33,480 --> 00:17:36,200 Speaker 1: of all the forces, trying to understand whether there are 311 00:17:36,240 --> 00:17:39,840 Speaker 1: connections and patterns between the forces and whether we can 312 00:17:39,880 --> 00:17:43,639 Speaker 1: pull them together into some sort of unified concept. And 313 00:17:43,680 --> 00:17:45,800 Speaker 1: you might wonder like, well, why would we want to 314 00:17:45,840 --> 00:17:48,640 Speaker 1: do that, Why do we think it's even possible. Well, 315 00:17:48,680 --> 00:17:51,800 Speaker 1: that's basically the goal of physics is to look around us, 316 00:17:51,840 --> 00:17:54,600 Speaker 1: observe what we see, and try to explain all of 317 00:17:54,640 --> 00:17:58,440 Speaker 1: it using a small set of ideas. It's not hard 318 00:17:58,480 --> 00:18:01,760 Speaker 1: to explain the universe if you need a different explanation 319 00:18:01,840 --> 00:18:04,560 Speaker 1: for every single event. Right If you say, well, that 320 00:18:04,600 --> 00:18:06,879 Speaker 1: apple falls down because that apple falls down, and this 321 00:18:06,960 --> 00:18:09,639 Speaker 1: apple falls down because this apple falls down, which you 322 00:18:09,680 --> 00:18:12,200 Speaker 1: want is a theory of apples that describes how every 323 00:18:12,240 --> 00:18:15,040 Speaker 1: apple works. So what we've done in physics is collect 324 00:18:15,080 --> 00:18:17,399 Speaker 1: all the weird effects that we've seen and try to 325 00:18:17,440 --> 00:18:20,199 Speaker 1: describe them in terms of a set of forces, and 326 00:18:20,200 --> 00:18:22,919 Speaker 1: then look at those and say, oh, look this is electricity. 327 00:18:22,960 --> 00:18:26,200 Speaker 1: That's electricity. Let's describe all of it using one theory. 328 00:18:26,359 --> 00:18:28,679 Speaker 1: Oh this is a magnet. That's a magnet. Let's have 329 00:18:28,720 --> 00:18:31,760 Speaker 1: a theory of magnetism. And then we slowly pull those 330 00:18:31,760 --> 00:18:35,199 Speaker 1: things together and look for relationships between the different forces 331 00:18:35,200 --> 00:18:37,760 Speaker 1: and see are these actually just two sides of the 332 00:18:37,800 --> 00:18:41,280 Speaker 1: same coin. So what we've accomplished so far is breaking 333 00:18:41,280 --> 00:18:44,960 Speaker 1: it down to a few fundamental forces. And how many 334 00:18:45,040 --> 00:18:48,280 Speaker 1: fundamental forces are there depends a little bit on how 335 00:18:48,359 --> 00:18:50,960 Speaker 1: you count. Some people are taught that there are five 336 00:18:51,119 --> 00:18:55,200 Speaker 1: fundamental forces. The strong nuclear force that's what holds the 337 00:18:55,280 --> 00:19:01,760 Speaker 1: nucleus together, gravity, electricity, magnetism, and then the weak nuclear force, 338 00:19:02,040 --> 00:19:04,560 Speaker 1: the one that's responsible for radioactive to k and all 339 00:19:04,600 --> 00:19:07,320 Speaker 1: sorts of cool neutrino effects. But about a hundred and 340 00:19:07,320 --> 00:19:12,120 Speaker 1: fifty years ago, physicists realized that electricity and magnetism are 341 00:19:12,200 --> 00:19:15,080 Speaker 1: not the same thing, but there are two parts of 342 00:19:15,119 --> 00:19:18,879 Speaker 1: a larger thing, and that's the essential concept. We're not 343 00:19:18,960 --> 00:19:21,359 Speaker 1: showing that two things are the same. We're showing that 344 00:19:21,400 --> 00:19:24,960 Speaker 1: there are two parts of something bigger, a more complete 345 00:19:25,000 --> 00:19:28,080 Speaker 1: idea that includes both of them, rather than just having 346 00:19:28,080 --> 00:19:30,600 Speaker 1: a list. Right, we don't want to explain the universe 347 00:19:30,600 --> 00:19:33,080 Speaker 1: in terms of just like, here's a big list of ideas. 348 00:19:33,359 --> 00:19:36,959 Speaker 1: We want a single concept that simplifies things, that pulls 349 00:19:37,000 --> 00:19:39,720 Speaker 1: back a layer of reality and shows us what's going 350 00:19:39,760 --> 00:19:43,720 Speaker 1: on underneath. So when we unified electricity and magnetism, we 351 00:19:43,760 --> 00:19:47,840 Speaker 1: didn't say, hey, magnets and lightning are the same thing. 352 00:19:48,119 --> 00:19:52,480 Speaker 1: We just showed that electricity and magnetism are so tightly connected. 353 00:19:52,960 --> 00:19:56,360 Speaker 1: That is that moving charges make magnetic field, and magnetic 354 00:19:56,440 --> 00:19:59,399 Speaker 1: fields can bend the path of charges. We showed that 355 00:19:59,440 --> 00:20:03,480 Speaker 1: it makes worse since mathematically and conceptually to think of 356 00:20:03,480 --> 00:20:05,920 Speaker 1: them as two parts of the same thing. And so 357 00:20:06,000 --> 00:20:08,600 Speaker 1: that's what's happened in the last fifty years with the 358 00:20:08,640 --> 00:20:11,960 Speaker 1: weak force. We've been able to integrate the weak force 359 00:20:12,359 --> 00:20:17,200 Speaker 1: into a theory of electromagnetism. We call this the electroweak theory, 360 00:20:17,320 --> 00:20:19,359 Speaker 1: which I always thought was weird because we basically just 361 00:20:19,560 --> 00:20:23,120 Speaker 1: ignore magnetism. Right. It's like when a law firm gets 362 00:20:23,119 --> 00:20:25,480 Speaker 1: a lot of partners, and they start dropping names from 363 00:20:25,520 --> 00:20:29,400 Speaker 1: the title of the law firm. Nobody was advocating for magnetism. 364 00:20:29,400 --> 00:20:32,520 Speaker 1: They should call it the electromagnetic weak force, but instead 365 00:20:32,760 --> 00:20:36,040 Speaker 1: they just call it electroweak. So let's dig in for 366 00:20:36,040 --> 00:20:38,400 Speaker 1: a moment about what that means. What does it mean 367 00:20:38,440 --> 00:20:41,679 Speaker 1: to have electroweak force. Well, first, let's remind ourselves what 368 00:20:41,800 --> 00:20:45,280 Speaker 1: electricity and magnetism and the weak force do. And the 369 00:20:45,359 --> 00:20:48,920 Speaker 1: question was specifically about why neutrinos only feel the weak 370 00:20:48,960 --> 00:20:52,760 Speaker 1: force if the weak force is connected to electricity and magnetism. 371 00:20:53,240 --> 00:20:56,359 Speaker 1: So let's talk about the interactions. What do we actually 372 00:20:56,359 --> 00:20:59,719 Speaker 1: mean by these forces. We mean that particles can interact, Right, 373 00:20:59,720 --> 00:21:01,640 Speaker 1: That's what a force is. It's a way for things 374 00:21:01,640 --> 00:21:04,960 Speaker 1: to push or pull on each other, including particles. So 375 00:21:05,040 --> 00:21:09,399 Speaker 1: electricity and magnetism that forces carried out by photons. Every 376 00:21:09,440 --> 00:21:14,399 Speaker 1: time there's an electromagnetic interaction, some lightning or magnetic field 377 00:21:14,560 --> 00:21:18,080 Speaker 1: or anything that's carried by photons. And you can think 378 00:21:18,119 --> 00:21:19,880 Speaker 1: about this in two different ways. You can think about 379 00:21:19,880 --> 00:21:23,040 Speaker 1: in terms of the fields they're like electromagnetic fields that 380 00:21:23,080 --> 00:21:25,400 Speaker 1: fill the universe, or you can think about in terms 381 00:21:25,440 --> 00:21:28,920 Speaker 1: of particles, little photons passing back and forth. It's really 382 00:21:28,960 --> 00:21:32,040 Speaker 1: the same thing. You can think alsose photons is little 383 00:21:32,119 --> 00:21:35,840 Speaker 1: ripples in those fields. They're two totally equivalent but different 384 00:21:35,840 --> 00:21:39,920 Speaker 1: conceptual ways of thinking about it. So what do photons 385 00:21:40,000 --> 00:21:43,200 Speaker 1: interact with? Well, photons fly around the universe and they 386 00:21:43,200 --> 00:21:47,600 Speaker 1: can interact with anything that has electric charge. So, for example, 387 00:21:47,640 --> 00:21:51,639 Speaker 1: electrons interact via photons. When you push two electrons together, 388 00:21:51,920 --> 00:21:54,879 Speaker 1: they exchange photons, or you can think about their electric 389 00:21:54,960 --> 00:21:59,040 Speaker 1: fields affecting each other. So photons only interact with things 390 00:21:59,119 --> 00:22:02,240 Speaker 1: that have electric charge. Right, If you put a neutral 391 00:22:02,320 --> 00:22:05,119 Speaker 1: particle in an electric field, it just ignores that. It 392 00:22:05,200 --> 00:22:08,200 Speaker 1: can't tell it's there, it's not affected at all. So 393 00:22:08,440 --> 00:22:12,480 Speaker 1: what does that mean, right, Why do photons only interact 394 00:22:12,560 --> 00:22:15,640 Speaker 1: with particles that have electric charge? We don't really know, 395 00:22:15,840 --> 00:22:19,080 Speaker 1: and you can kind of turn the question around. Electric 396 00:22:19,119 --> 00:22:21,399 Speaker 1: charge is sort of just like a description of the 397 00:22:21,440 --> 00:22:24,760 Speaker 1: fact that the particle does interact with an electric field. 398 00:22:24,920 --> 00:22:27,440 Speaker 1: We don't know what generates it, or where it comes from, 399 00:22:27,560 --> 00:22:30,000 Speaker 1: or why it's there. It's sort of like a label 400 00:22:30,119 --> 00:22:34,080 Speaker 1: that says whether or not the particle feels the electric field, 401 00:22:34,080 --> 00:22:37,199 Speaker 1: whether or not the particle can interact with photons. So 402 00:22:37,520 --> 00:22:40,639 Speaker 1: the picture we have of electromagnetism is that the photons 403 00:22:40,720 --> 00:22:42,960 Speaker 1: fly through the universe and they touch stuff that have 404 00:22:43,119 --> 00:22:46,960 Speaker 1: this special property we call electric charge either positive or negative. 405 00:22:47,160 --> 00:22:49,240 Speaker 1: All right, So let's take that sort of framework for 406 00:22:49,320 --> 00:22:52,399 Speaker 1: understanding and turn it around and look at the weak force. 407 00:22:52,760 --> 00:22:55,440 Speaker 1: The weak force has different particles it uses to interact 408 00:22:55,560 --> 00:22:59,400 Speaker 1: or equivalently, different fields and uses to interact with. These 409 00:22:59,400 --> 00:23:02,720 Speaker 1: particles are the W and Z boson. There's three of them. 410 00:23:02,960 --> 00:23:05,800 Speaker 1: There's Z boson and to W particles. There's a W 411 00:23:05,960 --> 00:23:08,639 Speaker 1: plus that has a positive electric charge and a W 412 00:23:08,840 --> 00:23:11,560 Speaker 1: minus that has a minus electric charge. So the weak 413 00:23:11,600 --> 00:23:15,240 Speaker 1: force has these three particles. These particles fly around and 414 00:23:15,280 --> 00:23:18,639 Speaker 1: they interact with any particle that has the weak version 415 00:23:18,720 --> 00:23:22,200 Speaker 1: of electric charge. So every particle out there has either 416 00:23:22,240 --> 00:23:25,200 Speaker 1: a positive, negative, or zero charge that tells you whether 417 00:23:25,240 --> 00:23:27,960 Speaker 1: a photon interacts with it. There's a version of that 418 00:23:28,040 --> 00:23:31,639 Speaker 1: electric charge which operates for the weak force, and it 419 00:23:31,680 --> 00:23:34,360 Speaker 1: works the same way. If a particle has we call 420 00:23:34,440 --> 00:23:38,199 Speaker 1: it weak hypercharge, that means that it feels the W 421 00:23:38,400 --> 00:23:40,800 Speaker 1: and Z boson so it can interact with them. And 422 00:23:40,840 --> 00:23:42,960 Speaker 1: so now you can think about every particle is having 423 00:23:43,240 --> 00:23:45,800 Speaker 1: two kinds of charges. One that we used to just 424 00:23:45,880 --> 00:23:48,640 Speaker 1: call charge. Now we think about as electric charge because 425 00:23:48,640 --> 00:23:52,800 Speaker 1: it refers to whether it interacts with electromagnetism, and another 426 00:23:52,920 --> 00:23:56,040 Speaker 1: kind of charge that tells us whether it interacts with 427 00:23:56,080 --> 00:23:59,520 Speaker 1: the weak force. So we have electric charge and weak hypercharge, 428 00:23:59,760 --> 00:24:03,320 Speaker 1: and only particles that have weak hypercharge will interact with 429 00:24:03,400 --> 00:24:06,719 Speaker 1: the weak force, and every particle that we discovered so 430 00:24:06,800 --> 00:24:10,359 Speaker 1: far has weak hypercharge. For those of you super into 431 00:24:10,359 --> 00:24:12,960 Speaker 1: particle physics, you know that that's a little bit of 432 00:24:12,960 --> 00:24:15,879 Speaker 1: a lie, because for example, electrons have a left and 433 00:24:15,920 --> 00:24:18,840 Speaker 1: a right handed version, and only the left handed version 434 00:24:18,880 --> 00:24:21,719 Speaker 1: interacts with the weak force. The right handed version doesn't 435 00:24:21,760 --> 00:24:25,359 Speaker 1: have weak hypercharge. But anyway, everything out there has it, 436 00:24:25,480 --> 00:24:28,320 Speaker 1: including the Higgs boson. So what does it mean then, 437 00:24:28,359 --> 00:24:31,639 Speaker 1: to say that electromagnetism and the weak force are linked? 438 00:24:31,880 --> 00:24:34,439 Speaker 1: Are there the same thing? If they were the same thing, 439 00:24:34,560 --> 00:24:36,639 Speaker 1: they should do the same thing, and for example, the 440 00:24:36,680 --> 00:24:40,000 Speaker 1: photon should interact with neutrinos. Right, Well, they are not 441 00:24:40,040 --> 00:24:42,879 Speaker 1: the same thing. There are two parts of something larger. 442 00:24:43,240 --> 00:24:47,159 Speaker 1: It's like saying, oh, our heads and tails the same thing. No, 443 00:24:47,600 --> 00:24:50,399 Speaker 1: they're connected. There are two parts of the same coin. 444 00:24:50,720 --> 00:24:53,240 Speaker 1: It doesn't mean that they are the same thing, right, 445 00:24:53,320 --> 00:24:55,359 Speaker 1: But what it means that when you fit them together 446 00:24:55,720 --> 00:24:58,480 Speaker 1: you get an object which makes sense, which sort of 447 00:24:58,640 --> 00:25:02,240 Speaker 1: reflects a larger concept. And so what we do here 448 00:25:02,320 --> 00:25:05,879 Speaker 1: is we take these three week bosons, the two ws 449 00:25:05,920 --> 00:25:09,720 Speaker 1: and the Z and the single electromagnetic boson, the photon, 450 00:25:10,040 --> 00:25:12,400 Speaker 1: and we put them together and we have four bosons. 451 00:25:12,560 --> 00:25:14,880 Speaker 1: But there's something very cool that happens when you put 452 00:25:14,960 --> 00:25:19,320 Speaker 1: these four particles together, because they snap together mathematically and 453 00:25:19,400 --> 00:25:22,400 Speaker 1: they work together. And when you consider them all together 454 00:25:22,440 --> 00:25:26,600 Speaker 1: instead of individually, you notice something really cool happens, something physical, 455 00:25:26,880 --> 00:25:30,600 Speaker 1: which is there's a new conserved quantity. You know, for example, 456 00:25:30,600 --> 00:25:33,919 Speaker 1: how energy is usually conserved, but parts of energy are 457 00:25:33,920 --> 00:25:36,680 Speaker 1: not always conserved. You can go, for example, from having 458 00:25:36,800 --> 00:25:40,520 Speaker 1: kinetic energy to potential energy and back. So kinetic energy 459 00:25:40,600 --> 00:25:44,119 Speaker 1: by itself is not conserved. Potential energy by itself is 460 00:25:44,119 --> 00:25:47,080 Speaker 1: not conserved. But when you put those together, boom, you 461 00:25:47,160 --> 00:25:50,440 Speaker 1: get a larger concept energy which is conserved. So when 462 00:25:50,440 --> 00:25:53,119 Speaker 1: you put these three bosons from the weak force to 463 00:25:53,200 --> 00:25:57,639 Speaker 1: gather with this boson from electromagnetism, they operate together to 464 00:25:57,800 --> 00:26:01,359 Speaker 1: create a new symmetry, as symmetry that protects this property 465 00:26:01,400 --> 00:26:03,960 Speaker 1: called weak isospin that we don't have to get into. 466 00:26:04,119 --> 00:26:06,240 Speaker 1: But that's what tells us that we think they really 467 00:26:06,280 --> 00:26:10,159 Speaker 1: are related. We think they really are part of something larger. 468 00:26:10,440 --> 00:26:13,600 Speaker 1: There's a lot of really beautiful mathematics that tells us 469 00:26:13,800 --> 00:26:16,520 Speaker 1: that these things really do fit together. And you know, 470 00:26:16,600 --> 00:26:20,360 Speaker 1: these four particles we think have more in common than 471 00:26:20,400 --> 00:26:23,280 Speaker 1: you might think. Three of them operate for the weak force, 472 00:26:23,520 --> 00:26:26,560 Speaker 1: one of them operates for electricity magnetism, And while they 473 00:26:26,600 --> 00:26:29,280 Speaker 1: look different, they do have a lot in common. One 474 00:26:29,320 --> 00:26:31,919 Speaker 1: way that they look different is that the photon doesn't 475 00:26:31,960 --> 00:26:35,240 Speaker 1: have any mass, but the W and the z bosons 476 00:26:35,440 --> 00:26:37,399 Speaker 1: do have a lot of mass. And that's why the 477 00:26:37,440 --> 00:26:40,560 Speaker 1: weak force is weak. It's weak because those particles are 478 00:26:40,600 --> 00:26:43,200 Speaker 1: so massive that they don't last very long. The weak 479 00:26:43,200 --> 00:26:46,040 Speaker 1: force becomes a very weak and very short range force, 480 00:26:46,320 --> 00:26:49,320 Speaker 1: whereas photons that have no mask can fly all through 481 00:26:49,359 --> 00:26:51,919 Speaker 1: the universe and last for billions of years before they 482 00:26:51,960 --> 00:26:55,200 Speaker 1: get to your eyeball or hit another star or whatever. Well, 483 00:26:55,200 --> 00:26:57,560 Speaker 1: the reason that the W and the Z bosons half 484 00:26:57,640 --> 00:27:00,960 Speaker 1: mass and the photons don't is the higg field. The 485 00:27:01,040 --> 00:27:04,360 Speaker 1: Higgs field is an idea that came out of this question. 486 00:27:04,600 --> 00:27:07,399 Speaker 1: We saw that all these particles had a lot in common. 487 00:27:07,440 --> 00:27:10,680 Speaker 1: It made perfect sense to fit the photon in with 488 00:27:10,760 --> 00:27:13,879 Speaker 1: the weak bosons, except for this one puzzle, which is 489 00:27:14,240 --> 00:27:16,680 Speaker 1: why is the photon have no mass while the other 490 00:27:16,680 --> 00:27:19,840 Speaker 1: ones do and the Higgs field is the answer to that. 491 00:27:20,119 --> 00:27:23,960 Speaker 1: It breaks what we call electro weak symmetry, the symmetry 492 00:27:24,000 --> 00:27:27,440 Speaker 1: that protects weak isospin this way that these four particles 493 00:27:27,480 --> 00:27:30,640 Speaker 1: fit together. They fit together beautifully and perfectly if all 494 00:27:30,680 --> 00:27:33,200 Speaker 1: the particles have no mass. But then the Higgs field 495 00:27:33,200 --> 00:27:36,480 Speaker 1: comes along and it gives mass to three of those particles, 496 00:27:36,480 --> 00:27:39,879 Speaker 1: which become the weak force, and so the Higgs boson 497 00:27:40,040 --> 00:27:44,440 Speaker 1: sort of breaks that otherwise beautiful symmetry. So it's awesome, 498 00:27:44,480 --> 00:27:46,760 Speaker 1: and we think it's real because it led us to 499 00:27:46,880 --> 00:27:50,800 Speaker 1: discover the Higgs boson. It's like a fun, interesting mathematical 500 00:27:50,840 --> 00:27:54,040 Speaker 1: puzzle that told us something was going on and led 501 00:27:54,119 --> 00:27:57,400 Speaker 1: us to discover the Higgs boson. So we don't think 502 00:27:57,400 --> 00:28:00,720 Speaker 1: that the weak force and electricity and magnetism are exactly 503 00:28:00,720 --> 00:28:02,919 Speaker 1: the same thing. That we think they fit together to 504 00:28:03,000 --> 00:28:06,160 Speaker 1: make a larger hole. That sort of makes more conceptual 505 00:28:06,200 --> 00:28:09,760 Speaker 1: sense and reflects something physical about our universe. That doesn't 506 00:28:09,800 --> 00:28:12,119 Speaker 1: mean they always have to do the same thing. And so, 507 00:28:12,160 --> 00:28:16,440 Speaker 1: for example, why don't neutrinos feel the photon. It's because 508 00:28:16,480 --> 00:28:20,040 Speaker 1: they have no electric charge, and the photon only interacts 509 00:28:20,080 --> 00:28:22,920 Speaker 1: with things that have electric charge, and so that might 510 00:28:22,960 --> 00:28:25,280 Speaker 1: seem like a non answer, Like you might also ask 511 00:28:25,640 --> 00:28:28,760 Speaker 1: why do neutrinos have no electric charge? And that's a 512 00:28:28,880 --> 00:28:31,600 Speaker 1: great question and not a question we have an answer to. 513 00:28:32,119 --> 00:28:34,600 Speaker 1: This is the kind of thing that we observe, we discover, 514 00:28:34,960 --> 00:28:38,640 Speaker 1: we catalog and we wait for the future generations of 515 00:28:38,720 --> 00:28:42,400 Speaker 1: physicists to understand these patterns. There are lots of obvious, 516 00:28:42,400 --> 00:28:45,520 Speaker 1: apparent patterns in the sort of periodic table of the 517 00:28:45,560 --> 00:28:48,760 Speaker 1: fundamental particles, the quirks and the leptons, that are not 518 00:28:48,920 --> 00:28:52,720 Speaker 1: explained at all, and one of them are these weird charges, 519 00:28:53,000 --> 00:28:55,760 Speaker 1: you know. Another one is like why do the charges 520 00:28:55,880 --> 00:28:59,640 Speaker 1: of the proton and the electron exactly balance? The proton 521 00:28:59,720 --> 00:29:02,520 Speaker 1: gets it's electric charges from the corks that make it up, 522 00:29:02,560 --> 00:29:05,400 Speaker 1: but we don't have any relationship in the standard model 523 00:29:05,480 --> 00:29:08,880 Speaker 1: between those charges. They could have any value basically, and 524 00:29:08,960 --> 00:29:11,880 Speaker 1: yet they magically add up to the proton and the 525 00:29:11,880 --> 00:29:15,600 Speaker 1: electronic exactly the opposite charge, not like opposite by one 526 00:29:15,640 --> 00:29:19,520 Speaker 1: percent or by point one percent exactly opposite. So that 527 00:29:19,680 --> 00:29:22,520 Speaker 1: seems like a clue. So there are lots of really 528 00:29:22,640 --> 00:29:25,760 Speaker 1: deep mysteries remaining about why particles have charged, why some 529 00:29:25,880 --> 00:29:28,520 Speaker 1: don't have charge, why other ones, for example, feel the 530 00:29:28,560 --> 00:29:31,680 Speaker 1: strong force, and electrons and neutrinos don't feel a strong force. 531 00:29:32,080 --> 00:29:35,720 Speaker 1: Not something we understand at all, just something we are observing. 532 00:29:35,920 --> 00:29:38,520 Speaker 1: But we're noticing these patterns, and we're fitting them together 533 00:29:38,560 --> 00:29:41,959 Speaker 1: into larger ideas that we think reflects sort of deeper 534 00:29:42,080 --> 00:29:45,720 Speaker 1: understandings of how these forces are connected and might one 535 00:29:45,840 --> 00:29:48,360 Speaker 1: day lead us on a path to unify even more 536 00:29:48,480 --> 00:29:51,680 Speaker 1: forces and take steps towards our goal of having the 537 00:29:51,760 --> 00:29:55,719 Speaker 1: one force that rules them all. All right, super fun question, 538 00:29:55,800 --> 00:29:58,240 Speaker 1: Thanks very much. I want to answer another question, but 539 00:29:58,320 --> 00:30:13,880 Speaker 1: first let's take a second break. All right, we're back. 540 00:30:13,920 --> 00:30:16,400 Speaker 1: We've been talking about the smells of space and the 541 00:30:16,600 --> 00:30:19,280 Speaker 1: nature of fundamental particles, and so now I want to 542 00:30:19,320 --> 00:30:22,200 Speaker 1: turn our minds again out into the depth of space 543 00:30:22,440 --> 00:30:27,240 Speaker 1: and answer a super fun question from Matha about aliens. Hi, Daniel, 544 00:30:27,320 --> 00:30:30,160 Speaker 1: and Hore. This is Massa from Boston. I love your 545 00:30:30,200 --> 00:30:33,360 Speaker 1: podcasts and have listened to every episode so far. I 546 00:30:33,400 --> 00:30:35,560 Speaker 1: have a question that was inspired by a recent episode 547 00:30:35,600 --> 00:30:39,680 Speaker 1: about how we can detect exo galactic exo planets. If 548 00:30:39,720 --> 00:30:42,160 Speaker 1: there were a solar system identical to ours, where Alpha 549 00:30:42,160 --> 00:30:45,720 Speaker 1: Centauri is four light years away, complete with a copy 550 00:30:45,760 --> 00:30:47,840 Speaker 1: of our Sun as well as a copy of Earth 551 00:30:48,120 --> 00:30:50,680 Speaker 1: with over seven billion people, and there are f and 552 00:30:50,800 --> 00:30:54,480 Speaker 1: atmospheric output, would we be able to detect that planet's presence. 553 00:30:55,240 --> 00:30:58,000 Speaker 1: Would we be able to detect life? Would we be 554 00:30:58,040 --> 00:31:00,360 Speaker 1: able to detect intelligent life if it had to our 555 00:31:00,480 --> 00:31:03,840 Speaker 1: level of technology, and if not, at the rate of 556 00:31:03,880 --> 00:31:07,560 Speaker 1: which our detection and capabilities presently advantacy roughly one, might 557 00:31:07,640 --> 00:31:09,760 Speaker 1: we be able to detect human activity from a range 558 00:31:09,760 --> 00:31:13,240 Speaker 1: of four light years? Would it be ten years, fifty years? 559 00:31:14,240 --> 00:31:17,000 Speaker 1: For the sake of this hypothetical exercise, let's assume that 560 00:31:17,040 --> 00:31:19,840 Speaker 1: whatever alignment necessary to use the various detection methods is 561 00:31:19,880 --> 00:31:22,720 Speaker 1: in place. Keep up the good work, guys. All right, 562 00:31:22,840 --> 00:31:25,440 Speaker 1: thank you very much Maza for that really fun and 563 00:31:25,520 --> 00:31:29,200 Speaker 1: detailed question. I'm really looking forward of digging into how 564 00:31:29,240 --> 00:31:32,920 Speaker 1: we might detect life around our nearest star. Though. It's 565 00:31:32,920 --> 00:31:35,960 Speaker 1: a reasonable question, because you know now we are developing 566 00:31:36,000 --> 00:31:39,000 Speaker 1: this capability to see planets around other stars and to 567 00:31:39,200 --> 00:31:42,600 Speaker 1: study their atmospheres. And our technology is increasing, and so 568 00:31:42,760 --> 00:31:45,360 Speaker 1: you might ask, you know, is it likely that we 569 00:31:45,400 --> 00:31:48,880 Speaker 1: could find aliens around nearby stars? And you know, should 570 00:31:48,960 --> 00:31:52,880 Speaker 1: we be expecting this news any day? Or equivalently, the 571 00:31:52,920 --> 00:31:55,360 Speaker 1: fact that we haven't yet announced to discovery of aliens, 572 00:31:55,400 --> 00:31:57,640 Speaker 1: does that mean that we haven't found them or that 573 00:31:57,680 --> 00:32:01,680 Speaker 1: we're just not yet capable. So super fun question. Let's 574 00:32:01,720 --> 00:32:04,360 Speaker 1: break it up into three parts. First, he was just wondering, 575 00:32:04,680 --> 00:32:08,120 Speaker 1: could we tell if there was a planet around Alpha Centauri. 576 00:32:08,280 --> 00:32:11,680 Speaker 1: Alpha Centauri is a nearby star system. It's one of 577 00:32:11,720 --> 00:32:14,479 Speaker 1: the closest ones in our neighborhood in the Milky Way. 578 00:32:14,520 --> 00:32:18,240 Speaker 1: There just aren't that many stars. Is on average several 579 00:32:18,400 --> 00:32:21,600 Speaker 1: light years between stars, which means you want to get 580 00:32:21,600 --> 00:32:23,080 Speaker 1: from here to there, it's going to take you a 581 00:32:23,120 --> 00:32:25,520 Speaker 1: long long time. And so that's why I think massa 582 00:32:25,560 --> 00:32:28,720 Speaker 1: pick like the nearest solar system, one that we might 583 00:32:28,920 --> 00:32:32,040 Speaker 1: possibly be able to visit or at least talk to 584 00:32:32,640 --> 00:32:36,239 Speaker 1: or observe aliens. So let's remind ourselves how do we 585 00:32:36,320 --> 00:32:40,880 Speaker 1: find planets around other stars? Because mostly looking at them 586 00:32:41,080 --> 00:32:44,479 Speaker 1: is impossible. These planets are very close to their stars 587 00:32:44,520 --> 00:32:47,720 Speaker 1: compared to their distance from Earth, so basically right on 588 00:32:47,840 --> 00:32:50,239 Speaker 1: top of the star, which makes it very hard to 589 00:32:50,280 --> 00:32:53,840 Speaker 1: distinguish them from their star. You can't seem the reflected 590 00:32:53,920 --> 00:32:56,800 Speaker 1: light from a planet that's so far away and so 591 00:32:56,880 --> 00:32:59,480 Speaker 1: close to something else really really bright. So we have 592 00:32:59,520 --> 00:33:02,800 Speaker 1: a few methods of observing planets around other stars. The 593 00:33:02,840 --> 00:33:05,960 Speaker 1: first one is called the wobble method, is just using 594 00:33:05,960 --> 00:33:10,120 Speaker 1: the gravitational tug of the planet on the star. The planet, 595 00:33:10,160 --> 00:33:12,640 Speaker 1: of course, is also a big massive object. It has 596 00:33:12,680 --> 00:33:15,240 Speaker 1: its own gravity, and so it pulls on the star 597 00:33:15,360 --> 00:33:17,680 Speaker 1: and makes it wobble a little bit, and we can 598 00:33:17,800 --> 00:33:21,360 Speaker 1: use that to detect the existence of a planet. Another method, 599 00:33:21,400 --> 00:33:24,520 Speaker 1: which is even more powerful. It's called the transit method. 600 00:33:24,720 --> 00:33:27,400 Speaker 1: This allows us to find a planet when it passes 601 00:33:27,520 --> 00:33:31,280 Speaker 1: in front of the star, effectively blocking some of the 602 00:33:31,360 --> 00:33:34,920 Speaker 1: life from the starts like a many planetary eclipse. Of course, 603 00:33:34,960 --> 00:33:37,680 Speaker 1: it doesn't completely block the star because the star is 604 00:33:37,840 --> 00:33:40,600 Speaker 1: much much bigger than the planet, but by the fraction 605 00:33:40,680 --> 00:33:43,520 Speaker 1: of the star's light that dips, we can tell how 606 00:33:43,600 --> 00:33:46,560 Speaker 1: big that planet is. So that's pretty awesome because it 607 00:33:46,640 --> 00:33:50,160 Speaker 1: lets us measure the radius of that planet, and by 608 00:33:50,160 --> 00:33:53,520 Speaker 1: the orbital period we can tell the mass of the planet, 609 00:33:53,720 --> 00:33:56,320 Speaker 1: so then we can get a pretty good sense of 610 00:33:56,440 --> 00:33:59,760 Speaker 1: how big and how large, and therefore how dense that 611 00:34:00,000 --> 00:34:03,160 Speaker 1: and it is, and therefore what it's made out of. 612 00:34:03,400 --> 00:34:05,520 Speaker 1: Is it big and fluffy like cotton candy or does 613 00:34:05,560 --> 00:34:08,160 Speaker 1: it have the density of Jubiter or like the density 614 00:34:08,160 --> 00:34:10,400 Speaker 1: of Earth. So we can get a pretty good sense 615 00:34:10,560 --> 00:34:13,200 Speaker 1: for what's going on with these planets, and these methods 616 00:34:13,200 --> 00:34:16,640 Speaker 1: work for really distant planets. We have studied planets across 617 00:34:16,640 --> 00:34:19,720 Speaker 1: a big swath the Milky Way. The Milky Way remembers 618 00:34:19,719 --> 00:34:23,080 Speaker 1: about a hundred thousand light years across, and we've detected 619 00:34:23,080 --> 00:34:26,480 Speaker 1: planets as far away as about twenty five thousand light 620 00:34:26,560 --> 00:34:29,480 Speaker 1: years away. That's because some of these methods are pretty 621 00:34:29,560 --> 00:34:33,160 Speaker 1: insensitive to the distance of the star. If you're looking 622 00:34:33,200 --> 00:34:35,719 Speaker 1: at the wobble method, for example, we get that information 623 00:34:35,880 --> 00:34:38,319 Speaker 1: by how the light from the star is shifting as 624 00:34:38,360 --> 00:34:41,640 Speaker 1: the star is wobbling, and that information doesn't fade as 625 00:34:41,680 --> 00:34:44,120 Speaker 1: the star gets further and further away, so we can 626 00:34:44,160 --> 00:34:47,279 Speaker 1: detect planets around stars that are much further away than 627 00:34:47,320 --> 00:34:50,960 Speaker 1: Alpha Centauri. Typically, though, it's easier to detect really big 628 00:34:51,000 --> 00:34:54,960 Speaker 1: planets like Jupiter size planets, because they're bigger, they block 629 00:34:55,040 --> 00:34:57,480 Speaker 1: more light, and they have more mass, they tug on 630 00:34:57,520 --> 00:35:00,319 Speaker 1: their star and they block their star more dramatically. But 631 00:35:00,480 --> 00:35:03,920 Speaker 1: for a nearby star like Alpha Centauri, it's really no problem. 632 00:35:04,200 --> 00:35:06,960 Speaker 1: And in fact, there's even a star that's a tiny 633 00:35:07,000 --> 00:35:10,960 Speaker 1: bit closer. It's called Proxima Centauri, and we have found 634 00:35:11,040 --> 00:35:14,719 Speaker 1: an earth like planet around Proxima Centauri. It's about the 635 00:35:14,760 --> 00:35:18,040 Speaker 1: same size of Earth's about bigger, and it has about 636 00:35:18,080 --> 00:35:20,799 Speaker 1: the right density to be a rocky planet. So we 637 00:35:20,880 --> 00:35:24,239 Speaker 1: think that there is an Earth like rocky planet in 638 00:35:24,320 --> 00:35:28,120 Speaker 1: ahabitable zone around a nearby star. So that one we 639 00:35:28,160 --> 00:35:31,400 Speaker 1: can definitely check off the answer to be yes, we 640 00:35:31,440 --> 00:35:35,560 Speaker 1: can detect nearby planets in nearby solar systems, So that 641 00:35:35,600 --> 00:35:38,960 Speaker 1: we have done. The next question is much harder. Could 642 00:35:39,040 --> 00:35:42,160 Speaker 1: we detect life on that planet? How could we do it? 643 00:35:42,320 --> 00:35:44,720 Speaker 1: This is really chicky because before you even get started 644 00:35:44,800 --> 00:35:47,520 Speaker 1: you have to ask a definitional question. Right if Jorgey 645 00:35:47,600 --> 00:35:49,640 Speaker 1: would hear, he would say, hold on a second, what 646 00:35:49,680 --> 00:35:52,719 Speaker 1: do you even mean by life? Do we mean animals, 647 00:35:52,840 --> 00:35:55,359 Speaker 1: do we mean plants? Do we just mean microbes? Are 648 00:35:55,400 --> 00:35:58,760 Speaker 1: we open to something which is completely different from life 649 00:35:58,800 --> 00:36:02,280 Speaker 1: on Earth? And it sort of gets to what question 650 00:36:02,360 --> 00:36:05,239 Speaker 1: are you asking? What do you want to discover, And 651 00:36:05,320 --> 00:36:08,000 Speaker 1: for me, I'd like to discover life on other planets 652 00:36:08,040 --> 00:36:10,120 Speaker 1: just because it gives me a sense that there might 653 00:36:10,160 --> 00:36:12,640 Speaker 1: be life all over the universe, which tells me there 654 00:36:12,680 --> 00:36:15,200 Speaker 1: might be intelligent life, there might be an incredible diversity 655 00:36:15,200 --> 00:36:17,719 Speaker 1: of things to learn from. And so I don't want 656 00:36:17,760 --> 00:36:20,080 Speaker 1: to discover life as we know it. I don't want 657 00:36:20,120 --> 00:36:23,480 Speaker 1: to find an alien planet with trees and slugs and 658 00:36:23,520 --> 00:36:25,960 Speaker 1: all sorts of other familiar things on it, because that 659 00:36:26,000 --> 00:36:28,680 Speaker 1: would be kind of boring. I want to see other 660 00:36:28,920 --> 00:36:34,320 Speaker 1: examples of life, things I couldn't have imagined myself. That's 661 00:36:34,360 --> 00:36:38,040 Speaker 1: the joy of doing science in this universe is being surprised, 662 00:36:38,160 --> 00:36:41,200 Speaker 1: is finding things you couldn't have imagined that even science 663 00:36:41,280 --> 00:36:45,560 Speaker 1: fiction writers hadn't considered. Those are the best moments in science. 664 00:36:45,960 --> 00:36:48,839 Speaker 1: Those are also the hardest discoveries to make, because you 665 00:36:48,920 --> 00:36:51,440 Speaker 1: somehow have to be open to them. The only ways 666 00:36:51,480 --> 00:36:53,719 Speaker 1: we know to look for life are the ways we 667 00:36:53,800 --> 00:36:56,200 Speaker 1: have thought to look for life, which are limited to 668 00:36:56,480 --> 00:36:59,520 Speaker 1: the kinds of life we have thought of. So let's 669 00:36:59,520 --> 00:37:02,399 Speaker 1: focus on that. Even though I prefer to discover something 670 00:37:02,440 --> 00:37:05,640 Speaker 1: super weird and something super surprising, But could we detect 671 00:37:05,960 --> 00:37:08,440 Speaker 1: life as we know a massa was imagining, You know, 672 00:37:08,480 --> 00:37:10,600 Speaker 1: a bunch of people around a planet a few light 673 00:37:10,680 --> 00:37:13,480 Speaker 1: years away, could we tell they were there? So, the 674 00:37:13,520 --> 00:37:16,479 Speaker 1: only way we can really study distant planets and ask 675 00:37:16,520 --> 00:37:19,000 Speaker 1: the question about whether there's life on them is looking 676 00:37:19,040 --> 00:37:21,160 Speaker 1: at their atmosphere. And you might think a whole lot 677 00:37:21,200 --> 00:37:23,960 Speaker 1: of second, we only recently figured out how to detect 678 00:37:23,960 --> 00:37:25,960 Speaker 1: the existence of those planets. How are we going to 679 00:37:26,080 --> 00:37:29,880 Speaker 1: possibly sample their atmosphere. We can sample their atmosphere using 680 00:37:30,040 --> 00:37:34,000 Speaker 1: light from their star when that planet eclipses the star. 681 00:37:34,440 --> 00:37:37,920 Speaker 1: The light passes through the atmosphere of the planet before 682 00:37:38,000 --> 00:37:40,680 Speaker 1: coming to Earth, and we can tell We can tell 683 00:37:40,680 --> 00:37:42,719 Speaker 1: when the planet starts to eclipse the star, and we 684 00:37:42,719 --> 00:37:45,120 Speaker 1: can try to study just that light that sort of 685 00:37:45,239 --> 00:37:49,000 Speaker 1: skimmed the surface of the planet went through that atmosphere 686 00:37:49,000 --> 00:37:51,680 Speaker 1: and came to us. And that light will be changed 687 00:37:51,960 --> 00:37:55,239 Speaker 1: by what's in the atmosphere because the atmosphere, based on 688 00:37:55,320 --> 00:37:58,640 Speaker 1: its chemistry, will absorb different things. If there's water in 689 00:37:58,680 --> 00:38:02,120 Speaker 1: that atmosphere, it will absorb light at the right energy 690 00:38:02,239 --> 00:38:04,480 Speaker 1: levels for water to absorb it, and then we will 691 00:38:04,520 --> 00:38:08,080 Speaker 1: notice some frequencies missing in the light that comes from 692 00:38:08,120 --> 00:38:11,400 Speaker 1: the atmosphere. Or if there's methane in the atmosphere, or 693 00:38:11,440 --> 00:38:14,319 Speaker 1: if there's phosphing, for example, in that atmosphere, and so 694 00:38:14,400 --> 00:38:16,879 Speaker 1: we can use that technique to sort of probe the 695 00:38:16,960 --> 00:38:20,400 Speaker 1: atmosphere of that alien planet. It's not great, it's not 696 00:38:20,520 --> 00:38:23,279 Speaker 1: super high precision, but we're getting much much better at it, 697 00:38:23,320 --> 00:38:26,680 Speaker 1: and it's very promising. On the other hand, it's not 698 00:38:26,760 --> 00:38:30,799 Speaker 1: always conclusive. Right, So we see methane around Mars, does 699 00:38:30,840 --> 00:38:33,399 Speaker 1: that mean that there's life on Mars. We don't really know. 700 00:38:33,800 --> 00:38:36,520 Speaker 1: Nobody really believes that there's life on Mars until we 701 00:38:36,560 --> 00:38:39,800 Speaker 1: see those criters wriggling around. We know that there's methane 702 00:38:39,800 --> 00:38:42,920 Speaker 1: production on Mars. We even know that it's seasonal. It 703 00:38:43,040 --> 00:38:45,640 Speaker 1: seems like maybe something is waking up on Mars and 704 00:38:45,680 --> 00:38:48,040 Speaker 1: farting and during the summer and then in the winter 705 00:38:48,280 --> 00:38:51,239 Speaker 1: less cell. But there are other explanations you could come 706 00:38:51,280 --> 00:38:54,680 Speaker 1: up with, like geological explanations for the production of methane 707 00:38:54,719 --> 00:38:58,239 Speaker 1: on Mars. And we recently saw the signal on Venus 708 00:38:58,280 --> 00:39:01,680 Speaker 1: of phosphing production. Phosphing is something people imagine could only 709 00:39:01,719 --> 00:39:06,040 Speaker 1: be produced by processes we understand to be life, but 710 00:39:06,360 --> 00:39:08,440 Speaker 1: it's a difficult thing to see in there's a lot 711 00:39:08,440 --> 00:39:12,640 Speaker 1: of background, and recently those discoveries have been kind of debunked. 712 00:39:12,800 --> 00:39:15,560 Speaker 1: It looks like the signal isn't really there. That sort 713 00:39:15,560 --> 00:39:19,360 Speaker 1: of a data analysis problem, but the takeaway messages it's hard. 714 00:39:19,600 --> 00:39:22,359 Speaker 1: You might be able to detect specific gases in the 715 00:39:22,400 --> 00:39:26,279 Speaker 1: atmospheres on planets around other stars, but having like a 716 00:39:26,520 --> 00:39:31,400 Speaker 1: really smoking guns signal for life just from atmosphere composition 717 00:39:31,680 --> 00:39:34,200 Speaker 1: is pretty difficult. So what we really need is a 718 00:39:34,320 --> 00:39:38,160 Speaker 1: much clear signal that there's intelligent life. Massa is asking 719 00:39:38,239 --> 00:39:40,760 Speaker 1: if there are folks on that planet broadcasting the golden 720 00:39:40,800 --> 00:39:44,040 Speaker 1: age of television, would we be able to see it? 721 00:39:44,520 --> 00:39:47,040 Speaker 1: And so this again is more like life as we 722 00:39:47,160 --> 00:39:50,280 Speaker 1: know it, except it's intelligent life as we know it. Questions, 723 00:39:50,640 --> 00:39:53,040 Speaker 1: you know, could there be intelligent life that's out there 724 00:39:53,080 --> 00:39:56,600 Speaker 1: that's broadcasting messages that we are missing because we don't 725 00:39:56,680 --> 00:39:59,400 Speaker 1: know to look for them, or we haven't imagined the 726 00:39:59,440 --> 00:40:02,839 Speaker 1: format it could exist in. Absolutely, there could be life 727 00:40:02,880 --> 00:40:05,840 Speaker 1: that exists on very long time scales and their message 728 00:40:06,040 --> 00:40:09,279 Speaker 1: takes a hundred years even just to listen to, or 729 00:40:09,400 --> 00:40:11,839 Speaker 1: life that lives on short time skills, or life that's 730 00:40:11,840 --> 00:40:15,080 Speaker 1: communicating in some medium we haven't even imagined maybe they've 731 00:40:15,080 --> 00:40:17,960 Speaker 1: discovered axions and they are the best way to communicate 732 00:40:17,960 --> 00:40:20,240 Speaker 1: in the universe, and we don't even know the exist 733 00:40:20,320 --> 00:40:23,160 Speaker 1: and so we're missing all the information. Think about how 734 00:40:23,160 --> 00:40:27,080 Speaker 1: many thousands of years humans lived on Earth and didn't 735 00:40:27,200 --> 00:40:30,120 Speaker 1: understand all the information around us before we even knew 736 00:40:30,239 --> 00:40:33,360 Speaker 1: new trinos existed, and the wealth of information they encode 737 00:40:33,600 --> 00:40:35,680 Speaker 1: about the nature of the universe and what's going on 738 00:40:35,760 --> 00:40:39,239 Speaker 1: in supernova So it's certainly very possible that there's a 739 00:40:39,320 --> 00:40:42,919 Speaker 1: huge amount of information, maybe even about alien life that's 740 00:40:42,920 --> 00:40:45,480 Speaker 1: just washing over us now because we do not know 741 00:40:45,600 --> 00:40:48,160 Speaker 1: how to recognize it. But that's again, that's sort of 742 00:40:48,200 --> 00:40:52,680 Speaker 1: an unprobable question. It's potentially infinite. It's the unknown unknowns. 743 00:40:52,920 --> 00:40:55,279 Speaker 1: So let's focus on the known knowns. If there was 744 00:40:55,280 --> 00:40:59,440 Speaker 1: a civilization on this planet around Proxima Centauri, would we 745 00:40:59,520 --> 00:41:02,080 Speaker 1: be able to pick up their signals. Well, if they're 746 00:41:02,120 --> 00:41:06,680 Speaker 1: not broadcasting to us, then probably not. The reason is 747 00:41:06,719 --> 00:41:10,360 Speaker 1: that they are still pretty far away. Remember that signals 748 00:41:10,480 --> 00:41:13,440 Speaker 1: fade with distance and not a little bit. They fade 749 00:41:13,440 --> 00:41:17,240 Speaker 1: with distance squared. If you shine a flashlight, for example, 750 00:41:17,480 --> 00:41:20,479 Speaker 1: then the photons you're sending out from your flashlights spread out, 751 00:41:20,800 --> 00:41:23,440 Speaker 1: and as the area that they cover gets bigger and bigger, 752 00:41:23,680 --> 00:41:27,840 Speaker 1: the density of photons per area falls. And so, for example, 753 00:41:27,840 --> 00:41:31,040 Speaker 1: if you broadcast a signal in every direction, then it 754 00:41:31,040 --> 00:41:33,640 Speaker 1: gets spread across the inside of a sphere, and as 755 00:41:33,680 --> 00:41:36,560 Speaker 1: the radius of that sphere grows, the area of that 756 00:41:36,600 --> 00:41:40,200 Speaker 1: sphere grows with the radius squared. So that's why signals 757 00:41:40,239 --> 00:41:43,400 Speaker 1: fall by one over the distance squared. The same thing 758 00:41:43,480 --> 00:41:47,040 Speaker 1: for the law of gravity and electromagnetism. It's all very geometrical. 759 00:41:47,760 --> 00:41:50,600 Speaker 1: But the problem is if you're not beaming us a signal, 760 00:41:50,840 --> 00:41:53,279 Speaker 1: then your signal has to be really powerful at the 761 00:41:53,320 --> 00:41:56,280 Speaker 1: source for it to still be detectable by the time 762 00:41:56,320 --> 00:41:59,399 Speaker 1: it lasts four light years. The reason we can see 763 00:41:59,440 --> 00:42:03,480 Speaker 1: those stars is because they are incredibly bright. If you 764 00:42:03,520 --> 00:42:06,480 Speaker 1: were close to the Centauri, of course, it would blind you. 765 00:42:06,840 --> 00:42:08,600 Speaker 1: The reason that we can see the light from the 766 00:42:08,680 --> 00:42:11,920 Speaker 1: star is because that sun is so luminous. So a 767 00:42:11,960 --> 00:42:15,480 Speaker 1: message from a planet around Proximus Centauri would have to 768 00:42:15,520 --> 00:42:18,680 Speaker 1: be extraordinarily strong. We are not yet capable as the 769 00:42:18,719 --> 00:42:22,680 Speaker 1: species of generating a signal that strong if it's beamed 770 00:42:22,680 --> 00:42:26,640 Speaker 1: in all directions. For example, our most powerful radio telescope 771 00:42:26,760 --> 00:42:32,200 Speaker 1: until recently was Arecibo. Aricibo could detect a message from 772 00:42:32,200 --> 00:42:36,400 Speaker 1: a similar telescope to Aricibo if it was within one 773 00:42:36,719 --> 00:42:39,280 Speaker 1: light year, but of course there are no other stars 774 00:42:39,280 --> 00:42:41,719 Speaker 1: within one light year, and even the closest star is 775 00:42:41,760 --> 00:42:46,160 Speaker 1: four light years away, so we couldn't detect omnidirectional messages 776 00:42:46,200 --> 00:42:49,720 Speaker 1: sent in every direction from a technology similar to ours. 777 00:42:49,960 --> 00:42:52,120 Speaker 1: They would have to be beaming it to us, which 778 00:42:52,120 --> 00:42:54,840 Speaker 1: is totally possible. If you knew we were here, you 779 00:42:54,880 --> 00:42:58,080 Speaker 1: could send a message directly to us from that planet, 780 00:42:58,120 --> 00:43:00,319 Speaker 1: But they would somehow have to know we were here 781 00:43:00,400 --> 00:43:03,000 Speaker 1: and then send us a message, and that we could 782 00:43:03,040 --> 00:43:07,240 Speaker 1: definitely hear. If we detected somehow aliens existing on that planet, 783 00:43:07,280 --> 00:43:09,879 Speaker 1: we could definitely beam them a message that they would 784 00:43:09,920 --> 00:43:13,399 Speaker 1: be able to pick up. Now, remember that conversation would last, 785 00:43:13,400 --> 00:43:16,480 Speaker 1: you know, decades, because it takes five years almost just 786 00:43:16,560 --> 00:43:19,080 Speaker 1: for our message to arrive. Then they have to argue 787 00:43:19,080 --> 00:43:21,080 Speaker 1: about how to respond and then send us a reply, 788 00:43:21,200 --> 00:43:24,759 Speaker 1: so it's like ten years between responses, and you know 789 00:43:24,840 --> 00:43:26,800 Speaker 1: how we're going to figure out how to even talk 790 00:43:26,800 --> 00:43:29,560 Speaker 1: to them. It takes ten minutes even just to start 791 00:43:29,560 --> 00:43:32,040 Speaker 1: a Skype conversation these days, and make sure everybody can 792 00:43:32,080 --> 00:43:34,759 Speaker 1: hear you. Imagine how many back and force it takes 793 00:43:34,800 --> 00:43:38,239 Speaker 1: to establish like the basis for communication and learn each 794 00:43:38,280 --> 00:43:41,000 Speaker 1: other's languages and understand what a language even is and 795 00:43:41,040 --> 00:43:43,239 Speaker 1: do they use mathematics, and like, we would have a 796 00:43:43,239 --> 00:43:46,400 Speaker 1: lot to learn and taking ten years between questions and answers. 797 00:43:46,719 --> 00:43:49,319 Speaker 1: It would take a long time, but I hope that 798 00:43:49,360 --> 00:43:51,720 Speaker 1: it happens, and I look forward to one day listening 799 00:43:51,719 --> 00:43:55,239 Speaker 1: to that message from Proximus Centauri. Alright, so thank you 800 00:43:55,360 --> 00:43:58,240 Speaker 1: everybody for sending in your questions and for coming along 801 00:43:58,239 --> 00:44:01,680 Speaker 1: with us on this ride and curiosity and wondering about 802 00:44:01,760 --> 00:44:04,920 Speaker 1: the universe. I want to make sure your questions are answered. 803 00:44:04,920 --> 00:44:08,040 Speaker 1: That's right, I'm talking to you specifically. You've got a 804 00:44:08,120 --> 00:44:10,840 Speaker 1: question in there you haven't asked. Please send it to 805 00:44:10,920 --> 00:44:13,480 Speaker 1: us to questions at Daniel and Jorge dot com. I 806 00:44:13,560 --> 00:44:23,960 Speaker 1: promise you you'll get an answer. Thanks for listening, and 807 00:44:24,000 --> 00:44:26,719 Speaker 1: remember that Daniel and Jorge explained. The Universe is a 808 00:44:26,760 --> 00:44:30,200 Speaker 1: production of I Heart Radio or more podcast from my 809 00:44:30,320 --> 00:44:33,880 Speaker 1: Heart Radio visit the I Heart Radio app, Apple Podcasts, 810 00:44:34,040 --> 00:44:42,000 Speaker 1: or wherever you listen to your favorite shows. Ye