WEBVTT - How does a plasma thruster work? 0:00:08.680 --> 0:00:11.119 Hey, Daniel, have you guys made any progress on the 0:00:11.240 --> 0:00:15.200 new spaceship engine that can cross the vast distances between stars? 0:00:15.880 --> 0:00:19.400 Nothing to report yet? Sorry? Oh man, I feel kind 0:00:19.400 --> 0:00:21.639 of cheated that I made that a rush order. Well, 0:00:21.720 --> 0:00:24.599 no problem. You know, once we finished building it, delivery 0:00:24.760 --> 0:00:26.720 is going to be a snap. Yeah. Are you going 0:00:26.760 --> 0:00:30.120 to deliver my spaceship on a spaceship now? It's sort 0:00:30.160 --> 0:00:31.840 of like when you buy a new car, it comes 0:00:31.880 --> 0:00:35.080 on a huge truck. Oh nice, So I can expect 0:00:35.120 --> 0:00:37.960 a huge giant space truck pulling up next to my 0:00:38.000 --> 0:00:41.120 house soon. Absolutely. The kids are gonna love it. It's 0:00:41.240 --> 0:00:43.320 gonna come with a nice big bowl tied around it. 0:00:43.360 --> 0:00:45.320 For an extra twenty million dollars, I'll put a bowl 0:00:45.360 --> 0:01:02.640 on it. Hi am more handmade cartoonists and the creator 0:01:02.680 --> 0:01:06.720 of PhD comics. Hi. I'm Daniel. I'm a particle physicist, 0:01:06.760 --> 0:01:09.120 and I've never actually bought a new car. You've never 0:01:09.160 --> 0:01:11.840 bought a new car, Never bought a new car, always 0:01:11.840 --> 0:01:14.120 a used car. Wow. I guess they are cheaper, right, 0:01:14.120 --> 0:01:15.920 because as soon as you buy a car and they 0:01:15.959 --> 0:01:18.760 start depreciating. That's right. But I've never had that amazing 0:01:18.800 --> 0:01:22.040 experience of seeing your brand new, shiny zero miles car, 0:01:22.120 --> 0:01:24.680 pull up on the fancy truck. What's new to you? 0:01:25.040 --> 0:01:28.039 So it is technically a new car, that's right. And 0:01:28.080 --> 0:01:30.360 we like to drive our cards into the ground until 0:01:30.400 --> 0:01:33.120 they're falling apart around us, like the podcast is that 0:01:33.200 --> 0:01:36.720 what we're doing here now? Is this a used podcast? Technically? 0:01:36.800 --> 0:01:39.000 It is right because we record this a few weeks 0:01:39.000 --> 0:01:41.000 in the van, so by the time people listen to it, 0:01:41.000 --> 0:01:43.520 it's got some mileach on it, but it's new to them. 0:01:43.560 --> 0:01:46.200 That's right. Let's maybe spray some of that new car 0:01:46.240 --> 0:01:50.200 smell around. That's right, new podcast smell yeah. Whip an 0:01:50.280 --> 0:01:53.120 end people, But anyways, welcome to our podcast. Daniel and 0:01:53.160 --> 0:01:56.360 Jorge explain the university production of I Heart Radio, in 0:01:56.400 --> 0:01:59.800 which we take you around this very very old universe 0:01:59.840 --> 0:02:02.640 that been around longer than we have and trying to 0:02:02.680 --> 0:02:05.520 answer some questions about it and what questions do we ask? 0:02:05.600 --> 0:02:08.400 We ask all the questions we asked, the biggest questions, 0:02:08.440 --> 0:02:12.120 the hardest questions, the silliest questions, and the deepest questions, 0:02:12.200 --> 0:02:14.399 and we try to find answers, and when we don't 0:02:14.400 --> 0:02:17.440 find them, we are happy to admit what science doesn't know. 0:02:17.680 --> 0:02:19.440 We take all that, we mix it around, we throw 0:02:19.480 --> 0:02:21.320 in some bananas, and we serve it to you as 0:02:21.360 --> 0:02:24.320 a podcast smoothie. That's right, because the universe might be 0:02:24.360 --> 0:02:27.440 old and it might be used. In fact, it's actually 0:02:27.480 --> 0:02:30.280 a several billions of years old, but it's still full 0:02:30.280 --> 0:02:33.640 of amazing and new things to discover for us puny humans. 0:02:33.840 --> 0:02:35.280 That's right. Do you think we have to pay full 0:02:35.320 --> 0:02:37.600 price for this universe? I mean it's like really pretty 0:02:37.600 --> 0:02:39.200 old by time we got it, we should have gotten 0:02:39.240 --> 0:02:41.240 some kind of discount. Really, did you think we have 0:02:41.280 --> 0:02:44.280 an option? Do we have like other newer universe we 0:02:44.320 --> 0:02:46.120 could have bought. I guess you've got to have another 0:02:46.120 --> 0:02:48.280 option if your negotiation is gonna be credible, Right, you're 0:02:48.280 --> 0:02:50.600 gonna be able to walk out of the universe dealership 0:02:50.639 --> 0:02:52.320 and say, I'm just gonna go down the street and 0:02:52.360 --> 0:02:56.600 get a universe somewhere else. We have no leverage. We 0:02:56.680 --> 0:02:59.880 have no leverage. We're stuck with this universe, and we 0:03:00.120 --> 0:03:02.880 love it. It's the only car and a lot, that's right, 0:03:03.120 --> 0:03:05.880 And let's not protect we don't love it. It's a wonderful, amazing, 0:03:06.000 --> 0:03:09.080 crazy place filled with all sorts of mysteries. I just 0:03:09.160 --> 0:03:11.720 sometimes wish we could see more of it. Well, we 0:03:11.720 --> 0:03:13.440 can see a lot of it, right, We can see 0:03:13.560 --> 0:03:16.639 up to billions and billions and billions of light years away. 0:03:16.760 --> 0:03:18.959 But the hard part is getting to those places and 0:03:19.000 --> 0:03:21.320 seeing them up close. Yes, exactly. That's why I mean 0:03:21.360 --> 0:03:23.519 that we could visit more than that, we could go there, 0:03:23.520 --> 0:03:26.160 that we could walk on the surface of Pluto, or 0:03:26.160 --> 0:03:28.200 we could see what the atmosphere of Venus is like. 0:03:28.400 --> 0:03:30.520 It feels like there are so many amazing mysteries of 0:03:30.600 --> 0:03:33.360 science and physics that are right in our neighborhood, and 0:03:33.440 --> 0:03:36.560 yet it's still so strangely hard to get there. Yeah, 0:03:36.640 --> 0:03:39.119 or not just even our Solar system. It'd be cool 0:03:39.160 --> 0:03:41.400 to travel to other galaxies and see if things are 0:03:41.600 --> 0:03:43.480 quite the same as they are here in the Milky Way. 0:03:43.520 --> 0:03:45.320 That's right. I'd like to be home before dinner, though, 0:03:45.320 --> 0:03:46.680 so I'm not sure I'm gonna join you on that 0:03:46.800 --> 0:03:50.880 intergalactic voyage. But somebody should go, and somebody should report back. 0:03:51.000 --> 0:03:52.920 What if you make the spaceship your home, Daniel, and 0:03:52.960 --> 0:03:55.520 then you'll always be home like a space RV. That 0:03:55.560 --> 0:03:58.600 sounds great. It's just a couch and a rocket and 0:03:58.720 --> 0:04:01.920 rocket field. That's all. Well, if my family is going along, 0:04:02.000 --> 0:04:04.200 then my kids definitely need their own rooms, because there's 0:04:04.200 --> 0:04:06.240 no way they're getting along if they're sharing a room 0:04:06.240 --> 0:04:09.400 in the space RV. Al right, we can at an addition, 0:04:11.240 --> 0:04:14.680 but yeah, getting around space is difficult because space is 0:04:14.760 --> 0:04:18.560 so big. It's gigantic, it's ginormous, it's a pretty spacious. 0:04:18.680 --> 0:04:21.000 It's hard to really wrap your mind around how big 0:04:21.040 --> 0:04:23.760 space is. We have this image of the Solar System 0:04:23.839 --> 0:04:25.839 is sort of this cozy place where all the planets 0:04:25.839 --> 0:04:28.000 are zooming around the Sun and kind of near each other, 0:04:28.080 --> 0:04:30.800 but there are vast distances. You know, even just from 0:04:30.839 --> 0:04:33.560 the Earth to the Moon is a much bigger distance 0:04:33.560 --> 0:04:35.440 than most people imagine. Did you know that if you 0:04:35.480 --> 0:04:37.920 took all the planets in the Solar System you could 0:04:38.000 --> 0:04:41.240 fit them in the distance between the Earth and the Moon. Wow? 0:04:41.800 --> 0:04:43.440 I take it that's a bad idea that you're not 0:04:43.480 --> 0:04:45.360 actually planning on doing that. You know what, I'd love 0:04:45.400 --> 0:04:46.880 to see it. So if you have somehow the power 0:04:46.920 --> 0:04:49.600 to do that, go ahead from your underground layer. Well, 0:04:49.640 --> 0:04:51.000 if you just want to see it, then you know, 0:04:51.080 --> 0:04:54.560 I can do that in photoshop easily. But the idea 0:04:54.600 --> 0:04:56.400 I think is that space is big right, like between 0:04:56.400 --> 0:04:59.240 here and the Moon, it's several hundred thousand miles even 0:04:59.320 --> 0:05:01.839 right absolute, it's really really far. And you know, the 0:05:01.880 --> 0:05:05.000 outer planets are really really far away, Like we are 0:05:05.120 --> 0:05:08.039 much much closer to the Sun than we are to Jupiter, 0:05:08.120 --> 0:05:10.640 for example. Yeah, I think we're used to maybe thinking 0:05:10.640 --> 0:05:13.320 of our Solar System is this cozy, little like collection 0:05:13.360 --> 0:05:16.000 of planets, but really it's quite sparse. It's quite empty, 0:05:16.040 --> 0:05:17.640 like if you took a picture of it, you would 0:05:17.640 --> 0:05:20.680 always see little tiny thoughts as the planets. Yeah, that's 0:05:20.680 --> 0:05:23.640 why Jupiter seems like almost a star because it's so big, 0:05:23.680 --> 0:05:26.880 but it's so so far away, and so the Solar 0:05:26.920 --> 0:05:29.560 System is hard to get around because everything is so 0:05:29.600 --> 0:05:32.039 far away. And when we launch even robotic probes to 0:05:32.040 --> 0:05:35.360 the outer Solar System, it can take ten, fifteen, twenty 0:05:35.480 --> 0:05:38.160 years to reach those places. Yeah. I think the trip 0:05:38.200 --> 0:05:40.960 to Mars, just to Mars, it takes several months, right, Yeah, 0:05:40.960 --> 0:05:43.400 and that's if you're lucky, right Earth end Mars are 0:05:43.480 --> 0:05:46.520 near each other sometimes and far apart other times, and 0:05:46.560 --> 0:05:49.719 so the shortest trip to Mars is like more than 0:05:49.760 --> 0:05:52.120 half a year, and so it'd be awesome to be 0:05:52.160 --> 0:05:54.520 able to get to Mars much faster and make it 0:05:54.560 --> 0:05:56.960 easier to explore the Solar System, to send people there 0:05:56.960 --> 0:05:59.000 if they didn't have to spend like seven months in 0:05:59.000 --> 0:06:01.960 a tin can together. Yeah, I think the big question 0:06:02.040 --> 0:06:04.040 is like, how can we get to these planets faster? 0:06:04.200 --> 0:06:06.440 Like how can we you know, make a new kind 0:06:06.440 --> 0:06:09.000 of spaceship or a new kind of propulsion technology to 0:06:09.320 --> 0:06:13.800 basically pushes there faster, because traveling through space is really hard. 0:06:14.000 --> 0:06:16.360 It's all about the speed. You know. A hundred years ago, 0:06:16.520 --> 0:06:19.040 the Earth seemed much bigger because it was a bigger 0:06:19.040 --> 0:06:21.240 deal to get to the other side of it. To 0:06:21.279 --> 0:06:23.760 go to China two or three hundred years ago was 0:06:23.800 --> 0:06:26.919 a days, weeks, months long endeavor. Now you can do 0:06:26.960 --> 0:06:28.760 it in just you know, eighteen hours or so on 0:06:28.800 --> 0:06:30.599 an airplane. It's not that big a deal. And that 0:06:30.640 --> 0:06:34.040 transformation came because we had new technology, new engines that 0:06:34.080 --> 0:06:36.360 could take us there faster. And so we hope we 0:06:36.520 --> 0:06:39.280 fantasize about the technology that could take us around the 0:06:39.279 --> 0:06:42.800 Solar system faster, that could effectively compress the Solar system 0:06:42.839 --> 0:06:46.200 so it doesn't seem so big to shrink the Solar system. 0:06:46.240 --> 0:06:49.200 In a sort of metaphorical way of speaking, right, maybe 0:06:49.200 --> 0:06:51.280 when day you could buy a ticket to Jupiter and 0:06:51.320 --> 0:06:52.880 all you have to worry about is like, how many 0:06:52.920 --> 0:06:55.040 movies am I going to watch? Have they made enough 0:06:55.040 --> 0:06:57.480 Avengers movies so I could just watch them all between 0:06:57.480 --> 0:07:01.480 here and Jupiter. Well, by then they will make five 0:07:01.560 --> 0:07:04.280 months worth of Avenger movies. Yeah, and maybe by then 0:07:04.320 --> 0:07:07.840 the Avengers movies will each be forty hours long. So right, yeah, 0:07:07.960 --> 0:07:10.080 they seem to be getting longer and longer. That's right. 0:07:10.080 --> 0:07:12.560 It's the opposite of time dilation. It's movie dilation, which 0:07:12.600 --> 0:07:16.600 works in the opposite direction. It's marvel dilation. Marvel, it's 0:07:16.600 --> 0:07:19.320 like the quantum realm. Yeah, well, what if I watched 0:07:19.360 --> 0:07:22.200 the Avengers movies while moving at high speed? Maybe they'll 0:07:22.240 --> 0:07:25.200 shrink it back down to two hours long. Maybe you 0:07:25.280 --> 0:07:30.160 actually like them? I like those movies. Come on. But anyways, 0:07:30.200 --> 0:07:33.240 there are people out there working on new technologies that 0:07:33.320 --> 0:07:35.760 might get us to other planets and other stars faster 0:07:35.840 --> 0:07:38.160 and faster. And in particular, there's kind of a new 0:07:38.280 --> 0:07:41.280 exciting technology with a pretty cool name. That's right. People 0:07:41.280 --> 0:07:43.920 are working on this, People trying to develop ideas. People 0:07:43.920 --> 0:07:46.680 have all sorts of different plans for how to develop 0:07:46.760 --> 0:07:49.680 new engines for spaceships. So today on the program, we'll 0:07:49.680 --> 0:07:59.400 be asking the question how do plasma thrusters work? Now, Daniel, 0:07:59.400 --> 0:08:01.600 I'd just like to say the word plasma thrusters. I 0:08:01.600 --> 0:08:05.040 feel like that's so you know, science fiction. I feel like, 0:08:05.120 --> 0:08:07.720 you know, some some something out of a movie. I know, 0:08:07.800 --> 0:08:10.240 it sounds a lot like plasma blaster, right, it sounds 0:08:10.280 --> 0:08:12.920 like a weapon you could use against something with like 0:08:13.200 --> 0:08:16.080 lots of limbs and gooey insides. Yeah, some sort of 0:08:16.080 --> 0:08:19.360 glowing technology that you know, kind of like what you 0:08:19.400 --> 0:08:22.800 see behind the starship Enterprise. Yes, but that's the exciting 0:08:22.800 --> 0:08:25.560 thing about science fiction is that it gives people ideas 0:08:25.560 --> 0:08:28.360 and then we try to make it real. Scientists watch 0:08:28.360 --> 0:08:31.200 science fiction and go, man, why can't we actually do that. 0:08:31.640 --> 0:08:34.360 We've got an idea, maybe we could actually do that, 0:08:34.400 --> 0:08:36.040 And then they go off into their laboratories and they 0:08:36.080 --> 0:08:39.160 tinker until boom, it's a reality. And the funny thing 0:08:39.200 --> 0:08:41.880 is that those science fiction writers probably got these names 0:08:41.880 --> 0:08:45.079 and these ideas from science itself, like plasma is a 0:08:45.160 --> 0:08:47.640 real thing and thrusters are a real thing. They just 0:08:47.640 --> 0:08:49.880 but hey, why don't we put the two together and 0:08:49.960 --> 0:08:52.480 sell more books? Is that the process of science fiction. 0:08:52.480 --> 0:08:54.839 You're like, take two things sticking together. Can we get 0:08:54.840 --> 0:08:58.280 a banana thruster or a plasma banana? Yeah, it's like 0:08:58.280 --> 0:09:01.120 taking two words like science and fiction and then sticking 0:09:01.120 --> 0:09:06.880 them together and see what happens. Boom, new genre invented. Yeah, 0:09:06.920 --> 0:09:10.160 I think that's the whole process. So plasma thrusters sounds cool, 0:09:10.400 --> 0:09:13.480 but what is it? So we were wondering what people 0:09:13.520 --> 0:09:15.800 out there knew about these two words stuck together and 0:09:15.840 --> 0:09:18.760 whether or not they can actually be real. As usual, 0:09:18.840 --> 0:09:21.240 Daniel went out there into the internet to ask people 0:09:21.360 --> 0:09:24.760 if they knew how a plasma thruster works. And so 0:09:24.880 --> 0:09:27.360 my eternal gratitude to those of you who volunteered to 0:09:27.440 --> 0:09:30.800 answer random physics questions for the podcast and enjoy hearing 0:09:30.840 --> 0:09:33.880 your voice speculating on the podcast. If you'd like to 0:09:33.920 --> 0:09:36.480 contribute your voice as well, please write to me two 0:09:36.559 --> 0:09:39.840 questions at Daniel and Jorge dot com. So think about 0:09:39.840 --> 0:09:41.960 it for a second. Do you know how a plasma 0:09:42.000 --> 0:09:45.360 thruster works? Here's what people had to say. I have 0:09:45.760 --> 0:09:49.440 absolutely no idea what a plasma thruster is or how 0:09:49.480 --> 0:09:54.640 it works, but it sounds pretty naughty. Well, I don't 0:09:54.640 --> 0:09:59.560 know exactly, but it's way better than a chemical like 0:09:59.640 --> 0:10:02.559 we have now would luck to us. I'm guessing the 0:10:02.640 --> 0:10:08.320 plasma thrusters would work by igniting this ionized gas in 0:10:08.760 --> 0:10:13.640 one direction that causes a force that pushes whatever rocket 0:10:13.720 --> 0:10:16.200 or object it's in in the other direction. I'm a 0:10:16.320 --> 0:10:22.000 hundred cent sure that the plasma thrust is a dance 0:10:22.080 --> 0:10:27.160 move that particle physicists do at parties. Well, this is 0:10:27.200 --> 0:10:30.880 a guess on my part based on the words, but 0:10:31.920 --> 0:10:35.880 I assume that it excites an atom to the point 0:10:35.920 --> 0:10:39.400 where the electron is stripped off, and it throws the 0:10:39.520 --> 0:10:46.920 nucleus through some sort of magnetic or field at rather 0:10:47.040 --> 0:10:50.640 high velocity out the back, which gives you thrust the 0:10:50.760 --> 0:10:53.920 same way any normal rocket motor would work, except instead 0:10:53.960 --> 0:10:58.400 of using chemical energy, you're using magnetic or electric energy 0:10:58.840 --> 0:11:05.520 to throw out plasma. Uh nuclear, All right, pretty cool answers. 0:11:05.800 --> 0:11:07.560 I like the one that says it's a dance move 0:11:07.640 --> 0:11:10.480 that particle physicists do at parties. You like that? Do 0:11:10.520 --> 0:11:13.160 you really want to imagine a bunch of particle physicists dancing? 0:11:13.160 --> 0:11:14.640 I mean, does that a mental image you want in 0:11:14.679 --> 0:11:17.000 your mind? I've seen it, and trust me, you don't 0:11:17.440 --> 0:11:21.760 the particle physicists have party coal parties. There are particularly 0:11:21.800 --> 0:11:25.680 good parties, yes, particularly awkward, as I think, when we 0:11:25.720 --> 0:11:28.000 discover a nice particle, then yes, we have a party. 0:11:28.040 --> 0:11:30.200 We celebrate, we drink champagne, we shake our booties just 0:11:30.240 --> 0:11:34.480 like everybody else. Wow. Sounds exciting, all right, And so 0:11:34.559 --> 0:11:36.079 a lot of people don't seem to have a pretty 0:11:36.080 --> 0:11:39.320 good idea, although they definitely you know, I have some 0:11:39.440 --> 0:11:41.680 ideas of what plasma is, but maybe not what a 0:11:41.679 --> 0:11:44.800 plasma thruster is. Yeah, but they're excited about it. They 0:11:45.000 --> 0:11:47.440 want this thing to be a reality. That sounds like 0:11:47.480 --> 0:11:50.080 a promising step in the direction of getting us around 0:11:50.080 --> 0:11:52.240 the Solar System. And so I think everybody is in favor. 0:11:52.480 --> 0:11:55.120 All right, Well, Daniel, let's talk about first why we 0:11:55.200 --> 0:11:58.960 might need a plasma thruster. You know why this idea 0:11:59.040 --> 0:12:02.640 of creating something that can push you in the vacuum space, 0:12:02.800 --> 0:12:04.600 why is that so hard? Right? So, one of the 0:12:04.640 --> 0:12:08.320 reasons that this is a hard problem is that when 0:12:08.320 --> 0:12:11.600 you are in space, you need to push against something. Right, 0:12:11.640 --> 0:12:13.640 If you're in space and you want to get speed, 0:12:13.920 --> 0:12:16.640 what you have to do is throw something out the 0:12:16.679 --> 0:12:19.840 back of your rocket ship. Because of conservation momentum. If 0:12:19.880 --> 0:12:22.880 you're going to go in one direction, something else has 0:12:22.920 --> 0:12:25.720 to go in the other direction. So this is like 0:12:25.760 --> 0:12:28.560 the reaction. You know, you could like fire a bullet, 0:12:28.600 --> 0:12:31.839 for example, out the back of your spaceship and the 0:12:31.880 --> 0:12:34.080 gun will push you in one direction and the bullet 0:12:34.120 --> 0:12:36.800 in the other direction. So the basic elements you need 0:12:36.840 --> 0:12:40.360 of any thruster are some energy and then something to 0:12:40.440 --> 0:12:42.960 throw out the back, some reaction mass to push the 0:12:43.000 --> 0:12:45.720 other direction, right, Because I guess when you're in space, 0:12:45.760 --> 0:12:47.800 you're if you're out there floating, it's not like you 0:12:47.800 --> 0:12:50.840 can swim your way to Mars or to the moon. 0:12:51.280 --> 0:12:53.760 You can't just there's something to like push against, right, 0:12:53.800 --> 0:12:56.080 So you need to throw something out the back, and 0:12:56.120 --> 0:12:58.040 for that you need energy. So that's what you're saying. 0:12:58.040 --> 0:13:00.400 You need energy and then something to throw out the bag. 0:13:00.559 --> 0:13:03.400 Using that energy exactly, you have to carry with you 0:13:03.520 --> 0:13:06.240 stuff that you can throw away so that you can 0:13:06.280 --> 0:13:08.880 move along. As you say, you can't like grab space 0:13:08.960 --> 0:13:11.920 and swim through space itself, right, it's not like air 0:13:12.120 --> 0:13:14.680 or water that you can pull against, right. You can't 0:13:14.720 --> 0:13:17.080 just like blow out the back like or maybe you 0:13:17.120 --> 0:13:19.520 can can you Yeah, actually that would work. I mean, 0:13:19.559 --> 0:13:22.280 that is a form of a rocket engine, right, you 0:13:22.320 --> 0:13:24.480 blow air out the back, and you can even use 0:13:24.480 --> 0:13:26.640 a flashlight. Right, if you turn on a flashlight on 0:13:26.679 --> 0:13:29.319 a spaceship out the back of your spaceship, then that's 0:13:29.360 --> 0:13:32.800 a form of a thruster because you're shooting energy in 0:13:32.880 --> 0:13:36.040 one direction and so the spaceship will go the other direction. Right, 0:13:36.040 --> 0:13:38.800 that would be a photon thruster. That's a different episode. 0:13:38.840 --> 0:13:41.160 That's a different episode. Yeah, exactly. But you know, it 0:13:41.200 --> 0:13:44.440 reminds me some listener rode in and asked about their headlights. 0:13:44.640 --> 0:13:46.920 Every time you turn on headlights in your car, are 0:13:46.920 --> 0:13:50.320 those effectively like photon brakes? And they kind of are, 0:13:50.640 --> 0:13:53.839 because you're like throwing energy forwards, sort of like having 0:13:53.960 --> 0:13:57.680 tiny little thrusters pointing forward. So every time you turn 0:13:57.679 --> 0:14:00.160 on your headlights, your car slowed down the tiny a 0:14:00.160 --> 0:14:02.040 little bit. And it just made me think when you 0:14:02.200 --> 0:14:04.200 hit the brakes and you turn on the brake lights 0:14:04.200 --> 0:14:07.880 in the back, and you're also sort of working against 0:14:07.920 --> 0:14:10.040 yourself there because you're breaking, but you're also kind of 0:14:10.200 --> 0:14:12.800 propelling yourself using photons. Yeah, brake lights should be in 0:14:12.800 --> 0:14:15.840 the front. Oh my god, it's so much better. I 0:14:15.840 --> 0:14:18.800 think that would defeat the purpose of brake lights. So 0:14:18.880 --> 0:14:21.480 one of the problems with using a rocket is that 0:14:21.480 --> 0:14:23.440 you've got to have all this stuff on board. You're 0:14:23.440 --> 0:14:25.480 gotta have the fuel, you've got to have the stuff 0:14:25.520 --> 0:14:27.360 to throw out the back, and then the further you 0:14:27.360 --> 0:14:29.640 want to go, the more fuel you need, and the 0:14:29.640 --> 0:14:32.000 more fuel you need, the more fuel you need to 0:14:32.040 --> 0:14:34.840 push that fuel, and so pretty quickly this is sort 0:14:34.840 --> 0:14:37.360 of like a runaway mass problem. You need to have 0:14:37.400 --> 0:14:40.560 a really really big ship to get anywhere at all 0:14:40.760 --> 0:14:43.080 because you need fuel to push all the fuel that 0:14:43.120 --> 0:14:45.800 you're pushing with all the fuel, right, And that's kind 0:14:45.800 --> 0:14:48.600 of how rockets work right now, right like the ones 0:14:48.680 --> 0:14:51.920 on current spaceships and spacecraft and rockets, that's how they work. 0:14:51.960 --> 0:14:55.000 They use a chemical reaction to explode something and then 0:14:55.000 --> 0:14:57.760 that explosion pushes the stuff out the back. That's right. 0:14:57.800 --> 0:15:01.520 The fuel itself is the propellant and the source of energy, 0:15:01.960 --> 0:15:05.120 right Like, you have something along like diesel fuel or 0:15:05.240 --> 0:15:08.680 liquid oxygen or something that has energy stored inside of it, 0:15:08.760 --> 0:15:11.040 and then you release that energy and at the same 0:15:11.080 --> 0:15:14.320 time creates something at high velocity which can get thrown 0:15:14.360 --> 0:15:17.520 out the back. So most chemical rockets work in that way. 0:15:17.560 --> 0:15:20.560 They're both the propellant and the source of energy. And 0:15:20.600 --> 0:15:23.080 that's how, for example, rockets lift off the Earth, and 0:15:23.080 --> 0:15:26.000 that's how the Space Shuttle maneuvers in space. All these 0:15:26.000 --> 0:15:29.200 are chemical rockets, right, And what makes it work, I 0:15:29.240 --> 0:15:31.840 think is the idea is this kind of this difference 0:15:31.920 --> 0:15:34.400 or this ratio between the energy and the mass of 0:15:34.440 --> 0:15:36.960 what you're throwing behind you. If your planets to like 0:15:37.080 --> 0:15:40.240 throw out you know, your trash or throughout your couch 0:15:40.360 --> 0:15:42.720 to propel yourself in space, that wouldn't last very long, right, 0:15:42.760 --> 0:15:48.080 because you would run out of couches. Yeah, and you 0:15:48.120 --> 0:15:50.440 know maybe r vs and children you want to get 0:15:50.520 --> 0:15:53.000 very far. But the idea with the chemical fuel is 0:15:53.040 --> 0:15:55.080 that it has a lot of energy stored in it, right, 0:15:55.360 --> 0:15:57.840 So like it you release that energy, it throws a 0:15:57.920 --> 0:15:59.480 little bit of mass out there back, but with so 0:15:59.560 --> 0:16:02.040 much energy it actually pushes you forward, that's right. The 0:16:02.120 --> 0:16:05.800 key thing is having high exhaust velocity, so that those 0:16:05.840 --> 0:16:08.320 particles you're throwing out, whatever they are, particles of couch 0:16:08.440 --> 0:16:12.120 or particles of smoke, or particles of burnt rocket fuel, whatever, 0:16:12.360 --> 0:16:15.400 are carrying a lot of momentum. Because any momentum that's 0:16:15.400 --> 0:16:17.960 going at the back is equivalent to the momentum gained 0:16:18.000 --> 0:16:21.000 by your rocket ship. Right, This is all about conservation 0:16:21.080 --> 0:16:23.840 of momentum. And so the higher speed, the higher exhaust 0:16:23.960 --> 0:16:26.560 velocity that goes out the back, the more momentum you're 0:16:26.560 --> 0:16:29.200 throwing away in your exhaust, and so the more momentum 0:16:29.360 --> 0:16:31.720 your rocket ship is going to get. Right, because momentum 0:16:31.800 --> 0:16:34.240 is like mass times velocity. So if you want to 0:16:34.240 --> 0:16:36.160 conserve on how much stuff you throw out the back 0:16:36.480 --> 0:16:40.240 the mass, then you just need a lot of velocity. Yeah, exactly, 0:16:40.480 --> 0:16:42.520 that's the way to do it. So those are chemical 0:16:42.720 --> 0:16:44.560 kind of rockets, and that's what we used to get 0:16:44.600 --> 0:16:46.680 off the Earth, but those are kind of tough for 0:16:46.880 --> 0:16:50.320 going across to other planets or stars. Right. Yeah, if 0:16:50.360 --> 0:16:53.520 you wanted to travel, for example, to the nearest star 0:16:53.600 --> 0:16:57.320 system like Alpha Centauri, and get up to a reasonable speed, 0:16:57.400 --> 0:16:59.520 like you know, a few percent of the speed of light, 0:16:59.640 --> 0:17:01.320 so that a trip which is just a few light 0:17:01.400 --> 0:17:04.080 years would only take you know, fifty or a hundred years, 0:17:04.359 --> 0:17:06.960 you would need an enormous amount of chemical fuel to 0:17:07.040 --> 0:17:10.280 accelerate you up to that speed. And because you need 0:17:10.320 --> 0:17:12.359 so much fuel, you need a lot more fuel to 0:17:12.400 --> 0:17:14.639 push that fuel, and so you'd end up with like 0:17:14.680 --> 0:17:18.480 a toothpick sized chip pushing a Jupiter sized gas tank. 0:17:19.280 --> 0:17:22.320 That sounds crazy. I think A good analogy I think 0:17:22.320 --> 0:17:24.600 we've read once was that it's sort of like if 0:17:24.640 --> 0:17:29.159 you're trying to drive a truck across the country without 0:17:29.240 --> 0:17:31.399 stopping for fuel, you sort of need to bring all 0:17:31.440 --> 0:17:35.320 your fuel with you. But then the more fuel you bring, 0:17:35.560 --> 0:17:38.160 the more fuel you have to use because you're heavier, exactly. 0:17:38.160 --> 0:17:41.919 And then pretty quickly you're driving basically like a stadium 0:17:42.040 --> 0:17:45.119 size gas tank behind you, and that's pretty inefficient and 0:17:45.240 --> 0:17:48.120 takes a lot of fuel, so it really limits how 0:17:48.200 --> 0:17:50.320 far you can go, right, And that's kind of why 0:17:50.400 --> 0:17:52.439 rockets are so big. Like if you look at a 0:17:52.520 --> 0:17:54.359 rocket that goes to space, most of it is just 0:17:54.400 --> 0:17:56.920 a giant fuel tank. Right. Yeah, I'm not sure people 0:17:56.960 --> 0:18:00.320 really understand how massive these things are. Like the Earned 0:18:00.320 --> 0:18:03.679 five rockets, one of the workhorses of the American space program, 0:18:03.800 --> 0:18:06.840 is taller than the Statue of Liberty. Like, this thing 0:18:06.960 --> 0:18:09.840 is enormous, but most of the actual active part of 0:18:09.880 --> 0:18:13.520 it is this tiny little nose cone on the very top. Basically, 0:18:13.560 --> 0:18:16.800 it's a huge gas tank with a tiny little cab 0:18:16.880 --> 0:18:18.720 on top, because you need to bring a lot of 0:18:18.760 --> 0:18:21.200 that fuel with you. And so that's really the hard 0:18:21.240 --> 0:18:23.840 part about space travel, is like bring all the fuel 0:18:23.920 --> 0:18:25.720 that you will need later because there are no gas 0:18:25.720 --> 0:18:29.360 stations in other planets. Right, there are no gas stations 0:18:29.359 --> 0:18:31.320 out there in space. It sounds like you're identifying a 0:18:31.320 --> 0:18:34.639 business opportunity here, you know, rocket fuel for sale on 0:18:34.760 --> 0:18:37.680 Pluto or halfway between here and Alpha Centauri. You could 0:18:37.680 --> 0:18:40.320 sell a lot of slim gyms also, you know, yeah, 0:18:40.359 --> 0:18:43.720 there you go and and turkey turkey. But then what 0:18:43.760 --> 0:18:46.400 do you do with the restroom waste? That's the hard part. 0:18:46.640 --> 0:18:48.640 That's just more rocket fuel. Man, you can just mix 0:18:48.640 --> 0:18:53.640 it all in there you go, biomass, biomass fuel, biofuels 0:18:53.640 --> 0:18:56.760 and solutions solved all at once. All right, Well, so 0:18:56.840 --> 0:18:59.879 that's the main problem with thrusters and getting around the 0:19:00.320 --> 0:19:02.879 Solar system in space. And so there's this new idea 0:19:02.960 --> 0:19:06.239 of using plasma based thrusters. So let's get into that 0:19:06.400 --> 0:19:08.760 and whether or not they're real and where they they 0:19:08.840 --> 0:19:24.359 can work. But first let's take a quick break. Alright, 0:19:24.400 --> 0:19:28.360 we're talking about plasma based thrusters. Now, this sounds really 0:19:28.359 --> 0:19:31.080 sci Fi Daniel, Plasma. Anything I think with the word 0:19:31.080 --> 0:19:35.199 plasma sounds cool, but it's the opposite. It's not cool, No, 0:19:35.359 --> 0:19:38.000 it's not cool. It's very very hot, and it's actually 0:19:38.000 --> 0:19:41.040 one of the most common forms of matter in the universe. Right. 0:19:41.080 --> 0:19:43.680 People think of plasma is weird and rare and unusual, 0:19:43.960 --> 0:19:46.200 but it's really just weird and rare and unusual here 0:19:46.240 --> 0:19:49.199 on Earth, where it's sort of weirdly cold, Like the 0:19:49.280 --> 0:19:52.680 Sun is basically a huge ball of plasma. And since 0:19:52.720 --> 0:19:54.760 the Sun is most of the stuff in the Solar System, 0:19:54.840 --> 0:19:57.359 the Solar system is basically all plasma with a few 0:19:57.440 --> 0:20:00.520