WEBVTT - Can you slow down light? 0:00:08.360 --> 0:00:12.160 Hey, jorgey, do you think there's anything good about getting older? 0:00:12.400 --> 0:00:14.920 Why are you asking me? I'm only twenty three. How 0:00:14.920 --> 0:00:21.440 long you've been twenty three for a while? Yeah? All right, 0:00:21.480 --> 0:00:23.760 But do you think like there's any advantage to getting 0:00:23.760 --> 0:00:29.080 old and slowing down? I guess fewer speeding tickets. Maybe 0:00:29.080 --> 0:00:33.520 like new kinds of joint pain to feel so new experiences. Yeah, 0:00:33.920 --> 0:00:37.479 the early bird specials at restaurants. Sometimes I wonder if 0:00:37.520 --> 0:00:40.440 it's good to forget some of those painful memories of youth. 0:00:40.600 --> 0:00:44.600 So there are advantages. Maybe physics should try slowing down. 0:00:45.360 --> 0:00:48.280 You want me to tell these photons to take it easy, 0:00:48.479 --> 0:00:51.000 you know. I know they're billion years old and they've 0:00:51.000 --> 0:00:53.760 been going at the speed of light for a long time, 0:00:53.800 --> 0:00:56.440 but maybe it's time for them to slow down. They 0:00:56.440 --> 0:01:16.680 can get the early Photon special. Hi'm Jorge Mae, cartoonist 0:01:16.760 --> 0:01:20.000 and the creator of PhD comments. Hi. I'm Daniel. I'm 0:01:20.040 --> 0:01:23.399 a particle physicist and I hope to be aging gracefully 0:01:23.560 --> 0:01:26.640 and welcome to our podcast. Daniel and Jorge age and 0:01:26.720 --> 0:01:29.480 explain the universe. At the same time, Daniel and Jorge 0:01:29.520 --> 0:01:32.560 explained the aging of the universe, which is mostly my 0:01:32.680 --> 0:01:37.040 knees at this point, which is technically happening right now, 0:01:37.240 --> 0:01:40.560 right now, as you're listening to us. We are getting older, yes, 0:01:40.640 --> 0:01:43.280 and the universe is getting older. You will finish this 0:01:43.360 --> 0:01:46.360 podcast in a different, older universe than the when you 0:01:46.480 --> 0:01:50.000 started it in, right, A little bit bigger, a little 0:01:50.000 --> 0:01:53.240 bit older and wiser, a little bit cooler, a little 0:01:53.240 --> 0:01:56.600 bit darker. The universe is getting older and colder and slower. 0:01:56.880 --> 0:02:00.440 Um though dark energy, of course is accelerating. But those things, 0:02:00.440 --> 0:02:03.280 when they get older, so to slow down, just like us, 0:02:03.480 --> 0:02:07.720 it gets a little bit more boring. No, we are 0:02:07.760 --> 0:02:11.639 getting funnier as we get older. Jorge, Oh right, right, No, 0:02:11.720 --> 0:02:14.919 I mean like entropy, Like entropy is increasing in the universe, 0:02:15.040 --> 0:02:18.760 and so is the entropy of our knees and jokes. Well, 0:02:18.760 --> 0:02:20.800 maybe as we get older we don't get funnier, but 0:02:20.880 --> 0:02:23.320 we think we're funnier, So I laugh more at your jokes, 0:02:23.440 --> 0:02:26.519 even as they decay in quality. It's all about perspective. 0:02:27.040 --> 0:02:30.120 It's all about perspective. Just like in relativity, there is 0:02:30.160 --> 0:02:33.600 no universal time or distance in comedy, right, there is 0:02:33.639 --> 0:02:37.520 no universal humor. There's no universal law for jokes. Is 0:02:37.560 --> 0:02:41.040 there no theory of special comedy. Um, well, there are 0:02:41.040 --> 0:02:46.520 a lot of jokes about relatives, but everybody jokes about 0:02:46.520 --> 0:02:51.720 their family, right, Yeah. Yeah, this idea that everything is 0:02:51.720 --> 0:02:55.760 slowing down is kind of inevitable. But there are some 0:02:55.800 --> 0:02:57.959 things in the universe and maybe we'll never slow down. 0:02:58.000 --> 0:03:01.040 That's right. Even though photons travel through billions of light 0:03:01.120 --> 0:03:03.800 years of space, when they get here, they're still moving 0:03:03.960 --> 0:03:06.920 at the speed of light. You you fired that photon 0:03:06.960 --> 0:03:10.040 from your flashlight at Alpha Centauri, It's gonna get there, 0:03:10.320 --> 0:03:12.560 and it's going to be going the same speed when 0:03:12.600 --> 0:03:14.359 it does. Yeah, I kind of thought about it. I 0:03:14.360 --> 0:03:17.800 guess photons are going at the same speed wherever they go, 0:03:18.080 --> 0:03:20.760 no matter how long they've been going. Yeah, photons don't 0:03:20.760 --> 0:03:23.520 get tired, right. You push a photon and it goes, 0:03:23.560 --> 0:03:25.600 and it just goes and goes and goes and goes 0:03:25.639 --> 0:03:27.920 and goes, and it doesn't like run out of energy, 0:03:28.320 --> 0:03:30.800 you know, unless it gets absorbed by something or bounces 0:03:30.840 --> 0:03:33.399 off something. It will just keep going forever. It's sort 0:03:33.400 --> 0:03:36.280 of amazing at the maximum speed of the universe, not 0:03:36.400 --> 0:03:39.880 just at any speed. At the maximum speed of the universe. Yeah, 0:03:39.960 --> 0:03:42.600 and photons. People have been asking me on Twitter whether 0:03:42.680 --> 0:03:46.400 photons experienced time, Like do photons even get old? You know, 0:03:46.440 --> 0:03:49.160 because photon has taken a billion years to get here 0:03:49.560 --> 0:03:53.240 from somewhere else, And they wonder do photons experienced time? 0:03:53.280 --> 0:03:55.800 And it's a tricky question because you have to imagine, 0:03:55.800 --> 0:03:58.200 like a photon having a clock. What is that clock 0:03:58.320 --> 0:04:01.400 made out of? If it has mass than the photons can, 0:04:01.480 --> 0:04:04.280 how does it look at the clock? Photons to look 0:04:04.320 --> 0:04:06.600 at the clock. What is it like to be a photon? Man? 0:04:06.720 --> 0:04:09.640 It seems like maybe more of a philosophical question than 0:04:09.680 --> 0:04:11.760 a physics question. Yeah, I don't think photons even have 0:04:11.840 --> 0:04:16.480 knees to feel their joint. Paine, I'm not asking whether 0:04:16.520 --> 0:04:19.200 we have anything in common with photons. There are weird 0:04:19.240 --> 0:04:22.279 quantum mechanical little particles. But where we ended up with 0:04:22.320 --> 0:04:24.920 that question was that photons are moving at the speed 0:04:24.960 --> 0:04:28.080 of light, and so they see most of the universe contracted. 0:04:28.640 --> 0:04:31.400 So a photon leaves here and it feels like it 0:04:31.440 --> 0:04:33.360 hasn't gone very far because the universe has been sort 0:04:33.400 --> 0:04:37.279 of shortened. To them, the universe is just it's it's 0:04:37.279 --> 0:04:41.360 it's basically tiny, right, It's the size of a point. Maybe, Yeah, 0:04:41.400 --> 0:04:43.320 that's right, And it's bizarre to imagine what it might 0:04:43.320 --> 0:04:45.560 be like to travel as a photon. But again, I 0:04:45.600 --> 0:04:47.240 don't think we want to get into the question of 0:04:47.400 --> 0:04:49.039 what is it like to be a photon? But it 0:04:49.120 --> 0:04:51.520 is sort of a good life example to not slow down, 0:04:51.600 --> 0:04:55.640 you know, take some inspiration. Photons are my new heroes. 0:04:55.800 --> 0:04:57.920 But other folks have been writing in and asking about 0:04:58.040 --> 0:05:01.279 whether photons always do at the speed of light? Can 0:05:01.320 --> 0:05:04.120 they not go at the speed of light? Can they 0:05:04.160 --> 0:05:07.160 throttle down? Yeah? When photons get old, is there any 0:05:07.160 --> 0:05:09.320 way they can sort of chill out a little bit 0:05:09.400 --> 0:05:11.440 and relax? So to the on the podcast, we'll be 0:05:11.440 --> 0:05:14.839 askering this question dead several, he says. Several readers wrote 0:05:14.839 --> 0:05:16.720 in about there are a bunch of people who've been 0:05:16.800 --> 0:05:20.920 reading articles online about physicists managing to slow down light, 0:05:21.040 --> 0:05:24.000 and they thought, what we better get Daniel and Jorge 0:05:24.000 --> 0:05:26.200 to explain that to us, So to be on the program, 0:05:26.279 --> 0:05:35.240 we'll be asking the question can light be slowed down? 0:05:35.560 --> 0:05:39.360 It's fascinating because people think that, of course, photons travel 0:05:39.480 --> 0:05:41.800 at the speed of light, right, that's why we call 0:05:41.839 --> 0:05:43.560 it the speed of light, And we make a big 0:05:43.560 --> 0:05:46.040 deal about how that's constant. How if you shoot a 0:05:46.080 --> 0:05:48.400 photon out you measure traveling at the speed of light, 0:05:48.520 --> 0:05:50.800 somebody else measures it traveling at the speed of light. 0:05:50.960 --> 0:05:55.000 This sort of this like fundamental constancy, This like stubbornness 0:05:55.040 --> 0:05:57.599 of photons to always go with the same speed. Other 0:05:57.640 --> 0:06:01.200 things can vary their speed, right, Electrons orcs sure, pretty 0:06:01.240 --> 0:06:04.840 much all the other trinos. Right, they can go slow, 0:06:05.080 --> 0:06:07.240 they can sit in the palm of your hand, or 0:06:07.279 --> 0:06:09.600 they can go at nearly the speed of light. Yeah, 0:06:09.640 --> 0:06:13.039 anything that's massive that has any mass to it, electrons, 0:06:13.080 --> 0:06:16.560 even newtrinos, anything like that has a rest mass, Like 0:06:16.640 --> 0:06:19.880 you can catch up to it and have no relative velocity. 0:06:19.920 --> 0:06:23.440 You can exist next to it, hold it, throw it around, etcetera. 0:06:23.680 --> 0:06:26.760 But things that have no mass, what would happen if 0:06:26.800 --> 0:06:28.520 you caught up to them? Right, If there's a photon 0:06:28.560 --> 0:06:32.080 and you caught up to it, a photon is just motion, right, 0:06:32.120 --> 0:06:35.240 There's nothing to it other than it's motion. So if 0:06:35.279 --> 0:06:37.320 you catch up to it and there's no motion, there's 0:06:37.320 --> 0:06:40.680 no velocity relative to the photon, it's not there anymore. 0:06:41.240 --> 0:06:43.560 So that's why you can never catch up to a photon. 0:06:43.560 --> 0:06:45.880 It just doesn't make sense. It's like what happens if 0:06:45.880 --> 0:06:49.760 you catch a wave. It's no longer a wave. Yeah, 0:06:49.839 --> 0:06:51.800 that's right. If you're surfing right and you look down, 0:06:51.800 --> 0:06:53.800 then it's not really a wave anymore. It's just sort 0:06:53.839 --> 0:06:57.279 of like a stationary shape of the water, and so 0:06:57.360 --> 0:07:00.560 there's no relative motion there. Yeah, So don't surf on 0:07:00.600 --> 0:07:04.839 photons people. Not a good idea, especially as you get older. Yeah, 0:07:05.000 --> 0:07:07.120 and so this is an interesting question and so that 0:07:07.240 --> 0:07:09.320 we're going to tackle it today. We're gonna talk about 0:07:09.320 --> 0:07:12.640 whether or not you can slow light down and whether 0:07:13.040 --> 0:07:15.680 it seems that people some people have. Yeah, there's been 0:07:15.720 --> 0:07:20.080 some pretty exciting experiments with click baby headlines about slowing 0:07:20.120 --> 0:07:22.680 down light and stopping light, and so we're gonna dig 0:07:22.680 --> 0:07:24.680 into that today. And see doesn't make any sense. What 0:07:24.760 --> 0:07:27.600 are they actually doing and is it cool or what? 0:07:27.880 --> 0:07:30.160 Oh stopping You're gonna slow it down to the point 0:07:30.160 --> 0:07:34.280 of maybe stopping light. Yeah, yeah, wow, these faces are 0:07:34.280 --> 0:07:37.120 trying to break the rules of the universe. Well, as usual, 0:07:37.240 --> 0:07:40.000 I was curious, do people think it's possible to slow 0:07:40.040 --> 0:07:42.920 down light or is that just sound like crazy talk? 0:07:43.200 --> 0:07:45.560 So I walked around campus at you see Irvine. Yeah, 0:07:45.720 --> 0:07:47.760 so before you listen to these answers, think about it 0:07:47.760 --> 0:07:50.240 for a second, do you think that light can be 0:07:50.360 --> 0:07:54.320 slowed down? Here's what people have to say. I don't 0:07:54.400 --> 0:07:59.120 think so. I don't know. I would say no, theoretically right, yes, yes, 0:07:59.160 --> 0:08:01.200 how would you do it? I'm no clue. I don't 0:08:01.200 --> 0:08:04.400 know that that photons within the sun, they it takes 0:08:04.560 --> 0:08:07.480 very long time until they actually reach the surface of 0:08:07.520 --> 0:08:10.240 the sun and are released into space. I don't know. 0:08:10.560 --> 0:08:13.480 I mean it's not actually it's it's learned on the photons. 0:08:14.040 --> 0:08:17.800 I mean, there's there's relativity obviously, so I closed down time. 0:08:17.880 --> 0:08:20.320 But that's that's time. But that's light is supposed to 0:08:20.320 --> 0:08:22.760 be the constant nation. Because it is a constant. I 0:08:22.760 --> 0:08:26.040 think if you put light through different media, that should 0:08:26.120 --> 0:08:28.640 be slow. But I don't think that it is like 0:08:28.680 --> 0:08:30.720 I would expect that if you put light through water, 0:08:31.360 --> 0:08:33.400 I would expect there would be some sort of effect. 0:08:33.480 --> 0:08:36.160 But but we have a constant for light, So how 0:08:36.200 --> 0:08:38.480 can it be how can it change through different media? 0:08:38.520 --> 0:08:40.560 And if we have a constant for it, that's like, 0:08:41.120 --> 0:08:44.320 but we that's constants for an error? Yes, isn't it okay? 0:08:44.360 --> 0:08:48.240 So maybe it is okay? So I think there might 0:08:48.280 --> 0:08:52.040 be slight changes possibly, but I think it's inherently supposed 0:08:52.040 --> 0:08:55.520 to be constant. No, because it isn't like a constant number. 0:08:55.760 --> 0:08:58.120 I think somehow through velocity or something of that, changing 0:08:58.200 --> 0:09:01.080 velocity at a very high rate might be able to 0:09:01.720 --> 0:09:04.719 I'm not too sure. Maybe like a black hole type 0:09:04.760 --> 0:09:08.199 gravity type of situation. Yeah, No, cool, some pretty cool 0:09:08.240 --> 0:09:11.439 answers here. A lot of a lot of yeses and 0:09:11.480 --> 0:09:14.400 a lot of maybes. I don't know how how did 0:09:14.400 --> 0:09:16.920 people react to the question itself, because it's not a 0:09:17.000 --> 0:09:20.240 question that I had heard much about before you send 0:09:20.280 --> 0:09:23.720 me the email this morning. Uh, you know it's you 0:09:23.760 --> 0:09:27.120 don't think about the slowing down light down much. Well. 0:09:27.160 --> 0:09:29.600 I think that feeling is backed up by these people's experience, 0:09:29.679 --> 0:09:31.680 because when I asked them, do you think it's possible 0:09:31.720 --> 0:09:33.600 to slow down light? I got a lot of quizzical 0:09:33.640 --> 0:09:36.560 looks and a lot of long pauses as people thought 0:09:36.600 --> 0:09:40.360 about it, And you can hear people reaching for answers. 0:09:40.400 --> 0:09:42.920 They're like, I don't know, is a black hole involved? Maybe? 0:09:43.160 --> 0:09:45.320 Or you kind of have to stop and parse the 0:09:45.360 --> 0:09:49.200 words a little bit, like slow down light, slow down 0:09:49.400 --> 0:09:52.960 something that is not quite there, yep, And parsing the 0:09:53.000 --> 0:09:55.600 words is going to be a solution to today's question 0:09:55.679 --> 0:09:59.240 because the answer is sort of technical and legalistic. It's 0:09:59.240 --> 0:10:01.840 sort of one of these pole loopholes in the laws 0:10:01.880 --> 0:10:04.040 of physics, like have you really slowed it down? Some 0:10:04.080 --> 0:10:06.560 people would say they have. Some people would, you know, 0:10:06.679 --> 0:10:08.600 quibble with that. All right, So we have to put 0:10:08.640 --> 0:10:12.559 on our physics lawyer heads today. Whenever you're reading the 0:10:12.600 --> 0:10:14.840 laws of physics, you've got to be very careful, you know, 0:10:14.880 --> 0:10:17.400 to understand exactly what they mean and what they don't mean. 0:10:17.559 --> 0:10:19.880 Are we sort of the shark type of physics lawyer? 0:10:19.960 --> 0:10:24.040 Are we been nice type of physics lawyers today? Are 0:10:24.040 --> 0:10:26.560 we out to get the universe? Are we up to? 0:10:26.960 --> 0:10:29.000 Are we out for justice? Danny? We are not the 0:10:29.000 --> 0:10:31.440 physics police, right, we are on this. We're on the 0:10:31.480 --> 0:10:33.840 defense side here. We are trying to make sure physicists 0:10:33.840 --> 0:10:36.319 can do whatever they like. We're trying to allow physics 0:10:36.320 --> 0:10:39.160 to do weird stuff with the universe because in the end, 0:10:39.600 --> 0:10:41.600 that's how we learn what the rules really are. We 0:10:41.679 --> 0:10:44.559 find the cracks and we exploit them, try to figure 0:10:44.600 --> 0:10:47.040 out what's actually possible given the rules that we know. 0:10:47.200 --> 0:10:49.640 It seems like people had a sense that, you know, 0:10:49.679 --> 0:10:53.520 the universe is interesting enough that maybe there are situations 0:10:53.559 --> 0:10:55.839 in which you can slow light down. Like that didn't 0:10:55.840 --> 0:10:58.040 seem impossible to a lot of people. Yeah, that's an 0:10:58.040 --> 0:11:00.520 optimistic way to look at it. Like, no matter how 0:11:00.559 --> 0:11:03.400 constant you think that law is, there must be some way, 0:11:03.559 --> 0:11:06.160 someplace in the universe where we could break and we 0:11:06.160 --> 0:11:09.240 could find something crazy happening. I like thinking that people 0:11:09.280 --> 0:11:11.520 are open to the fact that the universe is filled 0:11:11.520 --> 0:11:14.120 with crazy bunker stuff. Okay, so let's break it down 0:11:14.160 --> 0:11:17.520 for folks here, Daniel, and let's talk about light and 0:11:17.640 --> 0:11:22.560 how facet travels and what we know about light. And 0:11:22.640 --> 0:11:25.240 it's the first thing to understand, which I think most 0:11:25.240 --> 0:11:28.080 people already do, is that light does always travel at 0:11:28.120 --> 0:11:31.400 the same speed in a vacuum. And remember what light 0:11:31.600 --> 0:11:34.040 is like. You can think about light as a photon 0:11:34.160 --> 0:11:37.280 is a little particle, and it is quantized. But if 0:11:37.320 --> 0:11:39.720 fundamentally think about light is a sort of a ripple. 0:11:40.240 --> 0:11:44.240 Space is filled with quantum fields. Even empty space has 0:11:44.240 --> 0:11:47.160 the possibility to have these particles in it because it 0:11:47.400 --> 0:11:51.120 contains within it these quantum fields, like the electromagnetic field 0:11:51.280 --> 0:11:53.480 that can ripple. So I think of space is sort 0:11:53.480 --> 0:11:57.120 of like having these different possible sort of sheets rubber 0:11:57.160 --> 0:12:00.000 sheets in it, and mostly they're just sort of spread. 0:12:00.040 --> 0:12:02.440 It's smooth, but occasionally you can get a ripple in one, 0:12:02.800 --> 0:12:05.200 and that ripple is like a particle. I see. So 0:12:05.280 --> 0:12:07.200 I think the main idea is that light is a 0:12:07.200 --> 0:12:09.720 photon is not a thing. It's not like a little 0:12:09.960 --> 0:12:13.520 spherical thing. It's more like like a little divid in 0:12:13.720 --> 0:12:16.360 the kind of the fabric of the universe. Yeah, it's 0:12:16.400 --> 0:12:18.160 got no stuff to it, if that's what you mean 0:12:18.200 --> 0:12:21.720 by it's not a thing. It's a it's a transient property, right, 0:12:21.720 --> 0:12:24.560 It's that's why it's always moving. It's a it's a ripple. 0:12:24.559 --> 0:12:26.719 It's like a change in information. It's saying, oh, the 0:12:26.760 --> 0:12:28.839 electromag than the field was this, so now it's that, 0:12:29.200 --> 0:12:31.760 And it's that change that is the photon. That's why 0:12:31.760 --> 0:12:34.959 we say that photons carry information because they're like they're 0:12:35.000 --> 0:12:37.800 carrying information about how these fields are changing, the fields 0:12:37.800 --> 0:12:39.280 going up, and then it's going down, the fields going 0:12:39.320 --> 0:12:41.400 up and then it's going down. That is, the photon 0:12:41.760 --> 0:12:44.440 doesn't actually move like a like a thing. We can 0:12:44.440 --> 0:12:46.880 think of a coffee mug moving from one side of 0:12:46.920 --> 0:12:49.720 my desk the other side of the desk, but a particle. 0:12:49.760 --> 0:12:52.560 A quantum particle is more like um like an effect. 0:12:53.040 --> 0:12:56.240 This part tells the other part, and then that part 0:12:56.240 --> 0:12:58.920 there's the next part, and then it just propagates. Yeah, 0:12:58.960 --> 0:13:00.840 Like if you and I hold it ump rope between 0:13:00.960 --> 0:13:03.360 us and we spind the jump rope, no part of 0:13:03.360 --> 0:13:05.840 the jump rope is moving sideways, like closer to me 0:13:05.960 --> 0:13:08.400 or to you. That's just moving up and down. But 0:13:08.480 --> 0:13:11.080 we can send pulses down that jump rope. Right, if 0:13:11.120 --> 0:13:13.040 I wiggled it really fast, I can send what looks 0:13:13.080 --> 0:13:15.320 like a pulse, But no part of the rope is 0:13:15.400 --> 0:13:18.400 moving sideways. But the pulse is moving sideways that the 0:13:18.480 --> 0:13:21.520 wiggle is moving, but the rope isn't moving. Yeah, and 0:13:21.600 --> 0:13:23.920 even the coffee cup, and the coffee cup is made 0:13:23.920 --> 0:13:27.040 of particles, and those particles are ripples in their fields, 0:13:27.280 --> 0:13:31.079 electron fields, cork fields, whatever, So when the coffee cup moves, 0:13:31.200 --> 0:13:34.000 it's actually the same thing. It's just like a bunch 0:13:34.040 --> 0:13:37.000 of little tiny ripples are moving sideways through the universe. 0:13:37.120 --> 0:13:39.600 That's such a hard warming image, you know, the two 0:13:39.600 --> 0:13:43.520 of us jumping rope together. I feel like I feel 0:13:43.520 --> 0:13:46.520 like I imagine we're in some you know, like city 0:13:46.520 --> 0:13:50.000 block and we're jumping rope and there's children singing, and 0:13:50.040 --> 0:13:52.200 we're having the time of our lives and there's leaves 0:13:52.200 --> 0:13:55.199 blowing everywhere. And afterwards we're sipping hot cocoa and sort 0:13:55.240 --> 0:13:59.079 of a warm, fuzzy camera glow, and we're being interviewed 0:13:59.080 --> 0:14:02.360 by Oprah Like, that's what you're imagining. Yeah, you're sure 0:14:02.400 --> 0:14:05.559 that's going to happen for us. I feel so much 0:14:05.600 --> 0:14:08.600 lighter there. Well, that's good because we're talking about light. 0:14:09.040 --> 0:14:11.600 And so that's what photons are, right, their ripples in 0:14:11.640 --> 0:14:14.360 this electromagnetic field. And the reason that they move at 0:14:14.360 --> 0:14:16.679 the speed of light in a vacuum is that then 0:14:16.679 --> 0:14:19.880 it's just pure electromagnetic field, and they move at the 0:14:19.920 --> 0:14:22.840 maximum speed of information, which is the speed of light 0:14:22.880 --> 0:14:25.800 in a vacuum. So things that are not photons, like 0:14:25.840 --> 0:14:30.040 electrons and corks, they're also you're saying, they're also a 0:14:30.160 --> 0:14:34.640 little perturbations in fields as well. They're just like photons 0:14:35.520 --> 0:14:38.560 in that they're They also don't move in the universe. 0:14:38.600 --> 0:14:42.280 They just propagate. Yes, they propagate through the electron field 0:14:42.360 --> 0:14:44.600 or the cork field, for example. And so an electron 0:14:44.640 --> 0:14:47.480 moves through the universe and it moves at whatever speed 0:14:47.520 --> 0:14:50.600 it's moving, and it's a wiggle in that field. And 0:14:50.600 --> 0:14:53.400 you might ask, well, how come the electron field wiggles 0:14:53.480 --> 0:14:56.840 and it doesn't wiggle the same speed as the photon field? Right, Yeah, 0:14:56.960 --> 0:15:00.360 how come an electron wiggle can variate its speed? Boom? 0:15:00.360 --> 0:15:02.360 We have a gray answer for that. It's the Higgs 0:15:02.360 --> 0:15:06.320 boson because the electron field is not free, it's tied 0:15:06.400 --> 0:15:09.280 to this other field, the Higgs field, that changes how 0:15:09.280 --> 0:15:11.640 it wiggles. And that's what it means for a particle 0:15:11.680 --> 0:15:14.320 to have mass, is that it interacts with this Higgs 0:15:14.360 --> 0:15:17.880 Boson field that changes how ripples move through it, and 0:15:17.880 --> 0:15:20.640 it changes it exactly the way you would expect if 0:15:20.680 --> 0:15:24.040 something had mass. It gives those fields inertia. So mass 0:15:24.120 --> 0:15:26.720 is more like whether or not it interacts with the 0:15:26.800 --> 0:15:29.560 Higgs field, which would slow it down as it moves 0:15:29.560 --> 0:15:31.960 through the universe. Yeah, it doesn't actually slow it down. 0:15:31.960 --> 0:15:33.960 It gives it inertia. It makes it harder to speed 0:15:34.040 --> 0:15:37.200 up and harder to slow down. Right, It's a tiny 0:15:37.240 --> 0:15:39.480 bit more complicated than just slowing down. The Higgs field 0:15:39.520 --> 0:15:41.600 is not like molasses that tries to get everything to 0:15:41.640 --> 0:15:44.200 go to zero speed. It just keeps things at the 0:15:44.240 --> 0:15:47.400 same speed. It makes it hard to change velocity. Oh, 0:15:47.440 --> 0:15:50.720 I see, but light light doesn't interact with the Higgs field, 0:15:50.920 --> 0:15:55.000 so it just always kind of ignores the Higgs field 0:15:55.000 --> 0:15:57.000 and just goes as fast as it can. Yeah, and 0:15:57.040 --> 0:15:59.680 it's actually fascinating. We should do an entire podcast on 0:15:59.720 --> 0:16:03.440 this electroweak symmetry. Like the photon doesn't interact with the 0:16:03.520 --> 0:16:06.240 Higgs field at all, but the W and the Z particles, 0:16:06.240 --> 0:16:09.120 which are very similar to the photon, do interact with 0:16:09.160 --> 0:16:11.320 the Higgs field and become really heavy, and that's why 0:16:11.360 --> 0:16:13.560 the weak field is weak. All right. So there's a 0:16:13.600 --> 0:16:16.240 lot of details in there, but the main idea is 0:16:16.320 --> 0:16:19.920 that a light is a wiggle and it always travels 0:16:19.920 --> 0:16:23.120 at this speed of light in a vacuum, in a 0:16:23.200 --> 0:16:25.640 vacuum precisely. All right, Let's get into this idea of 0:16:25.760 --> 0:16:29.520 maybe whether or not you can slow this wiggle of 0:16:29.640 --> 0:16:31.920 light and how you would do that and why you 0:16:31.960 --> 0:16:34.200 would want to do that. First, let's take a quick 0:16:34.200 --> 0:16:49.680 break up. Okay, Daniel, So you're telling me that light 0:16:49.760 --> 0:16:53.280 always moves at the speed of light. Yeah, deep inside 0:16:53.280 --> 0:16:57.200 here from did you know horge also always travels at 0:16:57.200 --> 0:17:00.920 the speed of Horge that's gonna to a hundred dollars 0:17:00.960 --> 0:17:04.159 physics consulting feed speed of X moves at the speed 0:17:04.240 --> 0:17:08.280 of X. Yeah, but I guess on like light, my 0:17:08.520 --> 0:17:11.640 the horhead, the speed of horhead slows down, is going 0:17:11.720 --> 0:17:14.679 to be slowing down, is slowing down, is going to 0:17:14.720 --> 0:17:17.040 slow down as I get older. But the speed of 0:17:17.160 --> 0:17:19.960 light doesn't seem to change at all. Yeah, And so 0:17:20.000 --> 0:17:23.240 we should separate because again, physics has been terrible about naming, 0:17:23.280 --> 0:17:25.920 because when we talk about the speed of light, often 0:17:25.960 --> 0:17:29.600 what we mean is maximum speed of information in the universe. 0:17:30.040 --> 0:17:32.600 Light in a vacuum happens to travel at that speed, 0:17:32.640 --> 0:17:35.399 and because of historical reasons, we called that speed the 0:17:35.440 --> 0:17:41.359 speed of light. Oh man, you mean physicists name things wrong, Yes, badly, 0:17:42.480 --> 0:17:46.320 and they could have really named it that really the 0:17:46.400 --> 0:17:49.200 speed of light, We should just call it the maximum 0:17:49.240 --> 0:17:51.600 speed of the universe. Yes, the maximum speed the universe 0:17:51.640 --> 0:17:54.000 is separate from the speed of light, because it turns 0:17:54.040 --> 0:17:56.520 out there are lots of different ways to make light 0:17:56.600 --> 0:17:59.800 move slower than the maximum speed of the universe. So 0:18:00.040 --> 0:18:02.840 it's really like a definitions thing, like we just have 0:18:02.920 --> 0:18:06.119 to wrap our shift that little lever in our heads 0:18:06.400 --> 0:18:08.560 and not call it the speed of light anymore. That's right, 0:18:08.600 --> 0:18:13.080 Welcome to physics legalities. Right, But officer, I was not 0:18:13.240 --> 0:18:16.280 traveling faster than the maximum speed of the universe. It 0:18:16.400 --> 0:18:20.040 technically didn't break the speed limit of this highway. It's 0:18:20.080 --> 0:18:23.679 just that the speed limit of this highway is not 0:18:23.800 --> 0:18:27.399 the maximum speed of the universe. I'm sure that that's 0:18:27.400 --> 0:18:30.760 going to get you off that ticket yet. Well, well, well, 0:18:30.840 --> 0:18:33.480 and in the ideal scenario, the officer is a fan 0:18:33.560 --> 0:18:36.959 of our show and just pulled you over to get 0:18:37.000 --> 0:18:42.600 your autograph. That's right on this speeding ticket. And we 0:18:42.720 --> 0:18:46.000 talked in the podcast UM recently actually about drink off 0:18:46.119 --> 0:18:49.560 radiation and what happens when life gets slowed down as 0:18:49.600 --> 0:18:53.520 it passes through a material and other particles zip passed it. 0:18:53.880 --> 0:18:56.560 That's a whole fun, complicated topic. Okay, so we can't 0:18:56.600 --> 0:18:59.600 decrease the maximum speed of the universe, but you can 0:18:59.760 --> 0:19:04.000 make the light go slower than it would in a vacuum, 0:19:04.280 --> 0:19:07.920 or slower than the maximum pet Yeah, you can make 0:19:07.960 --> 0:19:10.920 photons move slower than the maximum speed. And the way 0:19:10.960 --> 0:19:13.000 you do it is you get them to go through 0:19:13.040 --> 0:19:16.320 some material. Because we said that photons move at the 0:19:16.359 --> 0:19:19.399 maximum speed when it's just a pure electromagnetic field and 0:19:19.400 --> 0:19:21.600 a ripple. But if you put other stuff in there, 0:19:21.640 --> 0:19:25.639 like an electron field. Electrons interact with electromagnetic fields, right, 0:19:25.680 --> 0:19:28.720 They have charge and so they will interact with it. 0:19:28.760 --> 0:19:31.280 And like a photon can get absorbed by an electron, 0:19:31.560 --> 0:19:33.960 you have an electron that's zipping around a nucleus, it 0:19:34.000 --> 0:19:36.760 can absorb that photon, hang onto it for a minute, 0:19:36.760 --> 0:19:40.320 and then re emit it. So that effectively slows down 0:19:40.320 --> 0:19:42.000 the photon because it gets from A to B in 0:19:42.119 --> 0:19:45.080 more time than it would if it hadn't been absorbed. Right, 0:19:45.119 --> 0:19:47.040 Like if you want to slow down Hussain Bolt, you 0:19:47.040 --> 0:19:49.240 would have him run through a crowd of people, not 0:19:49.359 --> 0:19:52.240 on an empty track, That's right. Or Jorge driving to 0:19:52.359 --> 0:19:55.119 work takes less time than Jorge driving to work past 0:19:55.119 --> 0:19:58.359 the banana shop because he stops, he takes some bananas. 0:19:58.640 --> 0:20:01.400 It takes some ten minutes. Everybody wonders why he's late. 0:20:01.960 --> 0:20:05.719 You know, I'm not sure anyone wonders anymore why I'm late. 0:20:05.880 --> 0:20:09.119 Daniel put, I'm just glad that you didn't say that 0:20:09.160 --> 0:20:13.840 I drove through a crowd of people. That's where where 0:20:13.840 --> 0:20:15.520 you were going. I'm like, oh, it just just got 0:20:15.560 --> 0:20:19.960 really dark though this is a family friendly podcast, that's right, right, Yeah, 0:20:19.960 --> 0:20:21.760 I guess what you mean is if you want to 0:20:21.800 --> 0:20:25.040 slow light down, you sort of keep it busy. Yeah, 0:20:25.119 --> 0:20:27.760 you interact with it. You you know, Jorge passing through 0:20:27.760 --> 0:20:29.720 a crowd of his admirers is going to have to 0:20:29.760 --> 0:20:32.359 stop and sign autographs more often, and so he's not 0:20:32.400 --> 0:20:34.080 going to get to the other side of the room 0:20:34.119 --> 0:20:36.480 as quickly. Yeah, although these days people don't ask for 0:20:36.480 --> 0:20:40.919 autograph date just asked for selfies mostly. Well, that saves 0:20:40.920 --> 0:20:43.440 your risk, I hope. And to listeners that might feel 0:20:43.480 --> 0:20:46.560 like a technicality, like is the light really traveling less 0:20:46.560 --> 0:20:48.880 than the speed of light? Because it's not really. It's 0:20:49.000 --> 0:20:52.520 between interactions. It's still moving at the maximum speed limit. 0:20:52.560 --> 0:20:55.719 It's just that those interactions take some time. And and 0:20:55.760 --> 0:20:58.280 that's that's totally fair. And again it just depends on 0:20:58.320 --> 0:21:00.320