WEBVTT - Put on Your Jetpacks and Let's Fly! 0:00:04.480 --> 0:00:12.639 Technology with tech Stuff from hastaff works dot com. Hey there, 0:00:12.640 --> 0:00:16.400 and welcome to tech Stuff. I am your host, Jonathan Strickland, 0:00:16.680 --> 0:00:19.440 lover of all things tech, and today I thought i'd 0:00:19.440 --> 0:00:22.720 talked about the technology that has often been associated with 0:00:22.760 --> 0:00:26.720 our general concept of the future. When you hear the 0:00:26.800 --> 0:00:30.920 terms the future, there's certain things that tend to pop 0:00:31.000 --> 0:00:33.319 up over and over again in people's minds. Now, when 0:00:33.320 --> 0:00:35.440 I think of the future, I think of stuff like 0:00:35.920 --> 0:00:40.720 artificially intelligent computers or robots. I think about meals and 0:00:40.800 --> 0:00:42.960 pill form because you know, I was a kid of 0:00:42.960 --> 0:00:45.240 the seventies and eighties, and that was, for some reason, 0:00:45.640 --> 0:00:47.960 the concept of how we were all going to survive 0:00:48.000 --> 0:00:50.680 in the future was have these these meals that would 0:00:50.720 --> 0:00:53.280 just be in a pill and uh, if you're really lucky, 0:00:53.320 --> 0:00:56.440 you turn into a giant blueberry. But I also would 0:00:56.440 --> 0:00:58.320 think of something else that's going to be the subject 0:00:58.320 --> 0:01:01.560 for today's episode, jet pack x Uh. I've talked about 0:01:01.560 --> 0:01:04.280 flying cars in the past, so that's off the table. 0:01:04.280 --> 0:01:07.200 But jet packs are totally something I can tackle. They 0:01:07.240 --> 0:01:10.480 are prominent in pop culture, and there are a few 0:01:10.560 --> 0:01:15.440 real world examples of jet packs or variations on the theme. 0:01:15.560 --> 0:01:18.720 In some cases it's not a jet pack. It might 0:01:18.760 --> 0:01:22.520 be more like a jet hoverboard, and in some cases 0:01:22.560 --> 0:01:24.800 it might be more of a rocket pack than a 0:01:24.880 --> 0:01:28.600 jet pack. But we're going to cover all of that today, uh, 0:01:28.640 --> 0:01:30.480 and I want to talk about some of the gadgets, 0:01:30.560 --> 0:01:33.720 how they work, and what their limitations are, and also 0:01:33.760 --> 0:01:36.280 explain why I think jet packs will never become a 0:01:36.319 --> 0:01:41.800 real consumer technology. Now, first, let's define a few things. 0:01:41.880 --> 0:01:44.839 I'm going to talk about several different types of technology 0:01:44.880 --> 0:01:47.960 today that tend to get lumped under the general category 0:01:47.960 --> 0:01:50.080 of jet pack. But as I said, not all of 0:01:50.080 --> 0:01:54.120 them use jet engine technology. Some of them are more 0:01:54.160 --> 0:01:57.320 like rocket packs rocket belts because they use a type 0:01:57.320 --> 0:02:00.960 of combustible fuel to generate thrust. And at least one 0:02:01.000 --> 0:02:02.520 of the ones I want to talk about isn't a 0:02:02.560 --> 0:02:05.320 pack at all. It's a platform you would stand on, 0:02:05.480 --> 0:02:08.320 kind of like a quad copter or a drone, but 0:02:08.800 --> 0:02:11.240 souped up to the point where it's powerful enough to 0:02:11.360 --> 0:02:15.480 carry a human being standing on top of it, and 0:02:15.639 --> 0:02:17.560 all of it I think can kind of sort of 0:02:17.600 --> 0:02:22.280 be generously lumped under the term jet pack, even in 0:02:22.360 --> 0:02:25.720 though in some cases you're not wearing a pack at all. Now, 0:02:25.760 --> 0:02:29.560 the concept of strapping jets or rockets to your back 0:02:29.639 --> 0:02:33.280 so that you can achieve flight is pretty old. In 0:02:33.400 --> 0:02:37.679 the October second issue of Scientific American, all the way 0:02:37.720 --> 0:02:41.200 back in nineteen o nine, there was a piece that 0:02:41.240 --> 0:02:45.320 was written by a guy named John Elfrith Watkins, and 0:02:45.400 --> 0:02:49.600 it relayed the story of a supposed ancient Chinese astronaut. 0:02:50.280 --> 0:02:56.000 In his story, this astronaut's name was Wong two. Watkins 0:02:56.160 --> 0:02:59.160 said that according to legend, Wong to set upon a 0:02:59.240 --> 0:03:02.000 chair moult to do on a platform and attached to 0:03:02.040 --> 0:03:07.480 that platform where forty seven rockets. Forty seven attendants lit 0:03:07.520 --> 0:03:11.359 these rockets which were meant to all ignite simultaneously and 0:03:11.480 --> 0:03:16.600 lift Wong two to the heavens in a glorious demonstration 0:03:16.800 --> 0:03:21.400 for the Emperor of China. But Watkins explained, one of 0:03:21.440 --> 0:03:28.079 those rockets exploded and the explosion badly burned Wong too. 0:03:28.360 --> 0:03:31.000 On top of that, the Chinese emperor was quite unhappy 0:03:31.080 --> 0:03:35.280 about the whole thing, And supposedly this event happened all 0:03:35.320 --> 0:03:39.480 the way back in two thousand b c. E. Now, 0:03:39.480 --> 0:03:42.080 there's a very good chance that this whole piece was 0:03:42.160 --> 0:03:45.960 just a tongue in cheek take on the idea and 0:03:46.080 --> 0:03:48.960 a figment of watkins imagination that it was not meant 0:03:48.960 --> 0:03:53.120 to actually relay a real Chinese legend, but it's still meant. 0:03:53.120 --> 0:03:55.560 You've got a precursor to jet packs described in a 0:03:55.680 --> 0:04:00.160 nineteen o nine periodical, which is still fairly early. In 0:04:00.240 --> 0:04:03.760 nineteen forty five, Herbert s. Zem would tell a very 0:04:03.800 --> 0:04:08.040 similar story to Watkins, except in his story the protagonist 0:04:08.320 --> 0:04:11.200 was named Wan Who, and it took place in the 0:04:11.280 --> 0:04:16.120 sixteenth century Common era, so well nearly three thousand, what 0:04:16.240 --> 0:04:18.960 three thousand, six hundred years later it was crazy. In 0:04:19.000 --> 0:04:21.360 any case, we still think the story is probably bunk 0:04:21.520 --> 0:04:24.560 and was invented in the twentieth century, not an ancient 0:04:24.680 --> 0:04:28.000 or medieval China. Also, this was one of the stories 0:04:28.040 --> 0:04:31.760 that would later be tested on the series MythBusters, where 0:04:31.800 --> 0:04:35.240 they would attempt to create a rocket powered chair and 0:04:35.560 --> 0:04:38.280 things went about as well as you would expect. So 0:04:39.000 --> 0:04:41.600 if you haven't seen that episode, you should probably dig 0:04:41.640 --> 0:04:43.599 it up see if you can watch and see what 0:04:43.600 --> 0:04:45.599 happens when someone tries to light a whole bunch of 0:04:45.680 --> 0:04:50.039 rockets mounted underneath the chair. Now, between the accounts of 0:04:50.120 --> 0:04:53.719 Wong two in nineteen o nine and Wan Who in 0:04:53.839 --> 0:04:58.080 nineteen forty five falls. Another early depiction of jet packs, 0:04:58.400 --> 0:05:01.159 and this was an illustration on the cover of the 0:05:01.320 --> 0:05:07.040 short story periodical Amazing Stories. And man, did I love 0:05:07.160 --> 0:05:09.520 Amazing Stories. Not that I was around when it was 0:05:09.560 --> 0:05:11.520 first being published, but I've read several of the stories 0:05:11.560 --> 0:05:14.600 that were that were originally published in Amazing Stories. And 0:05:14.680 --> 0:05:18.240 I even enjoyed to some extent the television series that 0:05:18.279 --> 0:05:21.200 was inspired by it, the TV series that was produced 0:05:21.200 --> 0:05:24.240 by Steven Spielberg in the nineteen eighties. Uh, if you've 0:05:24.279 --> 0:05:26.440 ever had a chance to watch it, it's pretty terrible, 0:05:26.520 --> 0:05:30.880 but I still enjoyed it anyway. Frank R. Paul created 0:05:30.920 --> 0:05:35.200 the illustration for the cover of that issue of Amazing Stories, 0:05:35.560 --> 0:05:38.360 and there is a man wearing a jet pack flying around. 0:05:38.400 --> 0:05:43.000 He's got a hand hold control, uh, the handheld control rather, 0:05:43.120 --> 0:05:46.919 and it's tethered to his harness, So it's clearly the 0:05:46.960 --> 0:05:51.160 control for the jet pack. There's no visible signs of 0:05:51.200 --> 0:05:54.880 what is creating the levitation effect, like there's no exhaust 0:05:55.000 --> 0:05:58.080 or any other designs of what might be creating the thrust. 0:05:58.200 --> 0:06:00.640 So it's not clear what Paul had in my mind 0:06:00.960 --> 0:06:04.640 that would keep this guy up there, but it is 0:06:04.680 --> 0:06:09.599 an evocative image, and it's it's certainly illustrating a certain 0:06:09.600 --> 0:06:11.720 sense of wonder that a lot of people have had 0:06:11.760 --> 0:06:14.880 at the thought of soaring through the skies without you know, 0:06:15.400 --> 0:06:20.000 a plane around you. Now. In that issue of Amazing Stories, 0:06:20.320 --> 0:06:25.320 there was also a tale titled Armageddon twenty four nineteen 0:06:25.440 --> 0:06:29.960 a d and it featured a protagonist called Anthony Rogers, 0:06:30.279 --> 0:06:33.920 or Buck to his friends. The world of Buck Rogers 0:06:34.000 --> 0:06:37.920 featured many science fiction technologies, including those that ran on 0:06:38.040 --> 0:06:42.520 the fictional substance inner Ton or inner Ton if you 0:06:42.600 --> 0:06:45.960 prefer I N E R T O N. This was 0:06:46.000 --> 0:06:49.360 supposedly the densest substance in the universe. It was completely 0:06:49.440 --> 0:06:52.240 fictional for the purposes of the story, and the author 0:06:52.320 --> 0:06:56.560 Philip Nolan, described how that particular substance would allow scientists 0:06:56.560 --> 0:07:00.599 to create magnificent technologies, including a belt. I would allow 0:07:00.600 --> 0:07:04.440 you to adjust the effect that gravity would have on yourself, 0:07:04.960 --> 0:07:07.800 so you could reduce the effects of gravity to the 0:07:07.839 --> 0:07:09.840 point where you could, you know, kind of kind of 0:07:09.880 --> 0:07:12.160 float around a little bit, and if you paired it 0:07:12.200 --> 0:07:15.840 with some rockets, you could even fly, or at least 0:07:16.400 --> 0:07:19.320 float with some sort of sense of direction. As for 0:07:19.400 --> 0:07:22.360 working devices in the real world. One of the earliest 0:07:22.600 --> 0:07:28.000 supposed jet pack precursors was the himmel Stummer. Now, this 0:07:28.040 --> 0:07:31.520 was a mythical flight pack that supposedly was created by 0:07:31.640 --> 0:07:35.560 Nazi scientists during World War Two, and it has been 0:07:35.600 --> 0:07:38.800 widely reported as being an actual thing, but I'm here 0:07:38.800 --> 0:07:44.520 to tell you that's likely not to be the case anyway. 0:07:44.600 --> 0:07:49.600 Himil Schemer literally means sky stormer or heaven stormer, and 0:07:49.720 --> 0:07:52.840 legend would have you believe that the himmel Schemer jet 0:07:52.840 --> 0:07:56.280 pack used what's called a pulse engine, which is a 0:07:56.320 --> 0:07:59.320 real thing, and actually it was supposedly using multiple jet 0:07:59.360 --> 0:08:03.200 pulse and and that these would create enough thrust for 0:08:03.280 --> 0:08:06.000 a soldier to make a really powerful leap, so they 0:08:06.000 --> 0:08:08.480 wouldn't really fly so much as they would jump really 0:08:08.560 --> 0:08:11.800 high and really far, kind of like how Superman originally 0:08:11.840 --> 0:08:14.840 couldn't fly, but he could leap tall buildings in a 0:08:14.920 --> 0:08:18.960 single bound. It's true, like the original Superman didn't fly around, 0:08:19.040 --> 0:08:22.120 he just jumped around a lot. Well we're talking jumps 0:08:22.120 --> 0:08:25.239 that would be around a hundred eighty feet in length 0:08:25.280 --> 0:08:30.160 and fifty feet high, so it's pretty spectacular. And supposedly 0:08:30.600 --> 0:08:33.960 it would allow soldiers to clear entire mine fields or 0:08:34.000 --> 0:08:38.199 other obstacles. But as the story goes, the war ended 0:08:38.240 --> 0:08:41.560 before any of these left the prototype phase and got 0:08:41.600 --> 0:08:45.160 deployed in the field, and that the units that were 0:08:45.200 --> 0:08:49.840 created were either destroyed or, as French theory advocates argue, 0:08:50.160 --> 0:08:52.960 they were confiscated by the United States as part of 0:08:53.040 --> 0:08:57.720 Operation paper Clip. Operation paper Clip was this super secret, 0:08:57.920 --> 0:09:01.680 real operation that the US had. This part is absolutely true, 0:09:02.200 --> 0:09:07.320 where they brought over science and scientists from the Nazi 0:09:07.840 --> 0:09:11.760 Germany area and put them to work for the United States. 0:09:11.840 --> 0:09:14.800 So a lot of the early rocketry program in the 0:09:14.920 --> 0:09:19.720 US was courtesy of scientists who had previously been working 0:09:19.760 --> 0:09:23.720 for the Nazis, So that part has some truth to it, 0:09:24.000 --> 0:09:27.000 although there's no evidence that the himmel Schemmer was ever 0:09:27.200 --> 0:09:31.800 part of this real operation. Now, supposedly these engines would 0:09:31.800 --> 0:09:35.040 burn at temperatures low enough that soldiers would not need 0:09:35.160 --> 0:09:39.920 special protective clothing. Only here's the thing, like I said, 0:09:39.960 --> 0:09:42.880 there is no evidence that any of this ever existed, 0:09:43.120 --> 0:09:46.160 that any jet packs were ever made. There are no photographs, 0:09:46.440 --> 0:09:50.280 there's no documentation, and you know, it's impossible to prove 0:09:50.320 --> 0:09:53.280 a negative. It's impossible to say there's absolutely no way 0:09:53.280 --> 0:09:55.840 these existed, because you know, what you have to do 0:09:55.880 --> 0:09:59.520 is find evidence to actually support the existence, but there's 0:09:59.520 --> 0:10:02.559 no such evidence around. There are photos of a soldier 0:10:02.600 --> 0:10:05.600 supposedly using the heimmel Strmer jet pack, but those are 0:10:05.640 --> 0:10:09.480 just of a toy model that was photoshop to look 0:10:09.520 --> 0:10:12.880 like it was a vintage photograph circa ninety four. If 0:10:12.880 --> 0:10:15.160 you look at the original picture, it's a full color 0:10:15.200 --> 0:10:17.520 picture of a toy with some rockets strap to it. 0:10:17.960 --> 0:10:21.000 The earliest account of any sort of jet pack attributed 0:10:21.080 --> 0:10:24.320 to the Nazis appears to be from a book titled 0:10:24.679 --> 0:10:28.800 German Secret Weapons and Wonder Weapons of World War Two, 0:10:29.080 --> 0:10:32.280 which was written in nineteen seventy six, and it was 0:10:32.320 --> 0:10:35.280 written by a guy who was essentially a Nazi sympathizer 0:10:35.320 --> 0:10:40.600 living in Toronto, Canada, so not exactly an unbiased source, 0:10:41.679 --> 0:10:43.280 and as far as we can tell, it was the 0:10:43.360 --> 0:10:46.920 first and only appearance of well first appearance of this 0:10:47.000 --> 0:10:50.319 jet pack idea that nothing predated that, and the same 0:10:50.360 --> 0:10:54.480 author wrote lots of other stuff, including some Holocaust denial 0:10:55.080 --> 0:11:00.880 uh literature, which is pretty awful, so devinly not a 0:11:00.960 --> 0:11:05.040 reliable source. However, you'll find information on the Internet that 0:11:05.040 --> 0:11:08.720 treats it like the Himmel Schemer was definitely a gadget 0:11:08.760 --> 0:11:12.000 that existed in history, despite the fact that there is 0:11:12.040 --> 0:11:14.920 no evidence that such a thing happened, and the person 0:11:15.000 --> 0:11:20.120 who who first started sharing the story has no credibility whatsoever. 0:11:20.800 --> 0:11:23.480 The first personal flying device, a real note that actually 0:11:23.559 --> 0:11:26.120 did exist that I can really talk about it is 0:11:26.160 --> 0:11:29.600 probably the Hiller VZ one, which was built in the 0:11:29.600 --> 0:11:32.520 early nineteen fifties, And this was not a jet pack, 0:11:32.920 --> 0:11:36.400 but rather a platform upon which the pilot would stand, 0:11:36.800 --> 0:11:42.040 so kind of similar to that that apocryphal Chinese legend 0:11:42.040 --> 0:11:45.560 in a way, except it wasn't powered by rockets. It 0:11:45.640 --> 0:11:49.000 was powered by an enormous ducted fan that had a 0:11:49.040 --> 0:11:53.920 pair of counter rotating coaxial propellers to generate the thrust 0:11:53.960 --> 0:11:57.120 needed to lift the whole thing, pilot and all off 0:11:57.160 --> 0:11:59.679 the ground, and to steer it you actually had to 0:11:59.720 --> 0:12:02.559 shift your weight, which, as it turns out, is not 0:12:02.679 --> 0:12:06.080 the most precise way to conduct maneuvers. And some folks 0:12:06.080 --> 0:12:08.640 in the Navy had a real fun little nickname for 0:12:08.679 --> 0:12:11.560 this setup, and they called it the flying pie pan. 0:12:12.880 --> 0:12:17.520 A December nine issue of Popular Science described some other 0:12:17.640 --> 0:12:20.720 real world attempts at jet pack technology, or at least 0:12:20.760 --> 0:12:24.280 ancestors to jet packs. These were rocket belts also known 0:12:24.360 --> 0:12:28.200 as jump belts, so like the fictional Himmel Schemer, the 0:12:28.280 --> 0:12:31.400 concept was these belts would use rocket power to give 0:12:31.480 --> 0:12:34.120 a boost to a soldier needing to clear an obstacle 0:12:34.559 --> 0:12:38.439 or jump over hazardous terrain. There were some that were 0:12:38.440 --> 0:12:43.520 created by the thecal Chemical Corporation Theicle and I'm probably 0:12:44.240 --> 0:12:47.719 mispronouncing their name, it's th h I O K O L. 0:12:48.559 --> 0:12:52.160 They created the coal jump belts. Uh. These were solid 0:12:52.320 --> 0:12:57.000 fuel rockets strapped to a belt. Uh. There is include 0:12:57.080 --> 0:12:59.560 rockets that would be part of the early Space program 0:12:59.559 --> 0:13:03.120 projects like Gemini and Mercury or Jiminy. If you prefer 0:13:03.679 --> 0:13:06.840 I do not. I prefer Gemini. But the jump belt 0:13:07.480 --> 0:13:11.240 ended up earning a nickname called Grasshopper. The whole idea 0:13:11.280 --> 0:13:14.200 being that again gives a boost to someone who's trying 0:13:14.240 --> 0:13:17.960 to jump over, say, an obstacle. But the project never 0:13:17.960 --> 0:13:22.520 received any funding beyond some early prototypes, so it ultimately 0:13:23.080 --> 0:13:25.280 ended up fading away. It did not go beyond the 0:13:25.280 --> 0:13:28.760 prototype phase. And then there was the flying belt from 0:13:28.840 --> 0:13:32.120 Reaction Motors, which was detailed in that same issue of 0:13:32.160 --> 0:13:35.839 popular Science that talked about the vehicle jump belts. Uh. 0:13:35.880 --> 0:13:38.480 This prototype look like an actual jet pack. It included 0:13:38.520 --> 0:13:42.000 thrusters that you would then extend to either side, so 0:13:42.160 --> 0:13:46.600 they kind of would go behind and uh and beyond 0:13:46.679 --> 0:13:49.280 your shoulders and stick out to the sides a little 0:13:49.280 --> 0:13:53.880 bit pointing downward, obviously, And it also had a couple 0:13:53.920 --> 0:13:55.920 of large canisters on the back and or to hold 0:13:55.960 --> 0:13:59.280 the fuel, because you need fuel to use. These rocket 0:13:59.280 --> 0:14:02.880 thrusters had a hand control that was mounted by an 0:14:03.040 --> 0:14:05.440 arm to the jet pack harness, so it kind of 0:14:05.480 --> 0:14:09.200 came up over one shoulder and then the arm came 0:14:09.280 --> 0:14:12.120 down so that the handle would be right at arm 0:14:12.240 --> 0:14:14.800 level and you would be able to use that to control, say, 0:14:14.840 --> 0:14:17.800 the throttle. But this was a model of the concept 0:14:17.920 --> 0:14:19.840 in Popular Science. It was just a kind of a 0:14:19.920 --> 0:14:22.280 mock up, and it wasn't indicative of an actual working 0:14:22.360 --> 0:14:24.880 jet pack. In fact, the piece said that we were 0:14:24.920 --> 0:14:27.240 at least a couple of years away from a working 0:14:27.320 --> 0:14:29.520 one that would allow you to fly several miles. As 0:14:29.560 --> 0:14:32.760 it turns out, it would take three years before we 0:14:32.800 --> 0:14:35.200 had a working jet pack, and the first one, i'll 0:14:35.280 --> 0:14:37.760 let you go a couple of feet, uh, turns out, 0:14:37.800 --> 0:14:40.240 if you're gonna strap rocket steer back, you tend to 0:14:40.280 --> 0:14:42.360 be a little cautious the first time you take it 0:14:42.360 --> 0:14:45.960 out for a spin. Now, before I jump into the 0:14:46.080 --> 0:14:50.160 jet packs, that really worked figuratively speaking, um, not really 0:14:50.200 --> 0:14:52.120 going to jump into any jet packs at all in 0:14:52.120 --> 0:14:55.640 this episode, sad to say, Let's talk about the problems 0:14:55.640 --> 0:14:58.080 the jet pack has to overcome in order to allow 0:14:58.080 --> 0:14:59.920 a human being to take flight in the first place. 0:15:00.200 --> 0:15:03.320 And these are not trivial problems. The first is that 0:15:03.400 --> 0:15:06.840 we've got this pesky concept called gravity, and we've got 0:15:06.840 --> 0:15:09.440 to deal with that. Gravity is one of the four 0:15:09.720 --> 0:15:13.360 fundamental forces of the universe. It's the weakest of the four. 0:15:13.760 --> 0:15:16.160 A's the one that we aren't really able to incorporate 0:15:16.200 --> 0:15:19.040 into our standard model in a way that makes nice 0:15:19.240 --> 0:15:22.840 clear sense. The other three fundamental forces are the strong 0:15:22.920 --> 0:15:27.480 nuclear force, the weak nuclear force, and electromagnetism. Gravity is 0:15:27.520 --> 0:15:31.280 the force that describes the attraction between any two objects 0:15:31.280 --> 0:15:33.960 that have mass, and I'm talking about any two objects 0:15:34.000 --> 0:15:37.240 in the universe. That's the interesting thing about gravity, because 0:15:37.240 --> 0:15:41.280 technically speaking, you have a gravitational pull on everything else 0:15:41.280 --> 0:15:45.240 in the universe around you that has mass, But gravity 0:15:45.280 --> 0:15:48.840 is a force dependent upon two things, the mass of 0:15:48.880 --> 0:15:52.800 the two respective objects, and then the distance between them. 0:15:52.840 --> 0:15:55.920 The formula to determine the gravitational attraction between any two 0:15:55.920 --> 0:15:59.320 objects goes like this. First, you take the mass of 0:15:59.360 --> 0:16:03.920 the two object x, and you multiply those figures together. So, 0:16:04.280 --> 0:16:06.280 if you're talking about two people, you've been taking the 0:16:06.280 --> 0:16:08.480 mass of two people and multiplying that together and you 0:16:08.520 --> 0:16:11.720 get a figure. Next, you would divide that number by 0:16:11.760 --> 0:16:15.680 the distance between the two masses squared. So if the 0:16:15.720 --> 0:16:18.400 two people are a thousand kilometers apart, you would take 0:16:18.400 --> 0:16:21.240 a thousand kilometers and you would square that. You would 0:16:21.240 --> 0:16:24.920 then divide the product of the two masses by that, 0:16:25.520 --> 0:16:27.920 and that that a result you've got, which I think 0:16:27.960 --> 0:16:30.800 would be what one million kilometers. That's so you end 0:16:30.880 --> 0:16:34.720 up with a very small number. Uh So, the this 0:16:35.440 --> 0:16:38.640 part of the formula already tells us that the greater 0:16:38.720 --> 0:16:42.800 the distance between the two masses, the smaller the gravitational 0:16:42.800 --> 0:16:46.680 effect is going to be between them. Finally, there's a 0:16:46.720 --> 0:16:50.360 gravitational constant that you have to multiply against this number. 0:16:50.840 --> 0:16:54.120 This was determined by Newton's law of universal gravitation, and 0:16:54.120 --> 0:16:57.400 the constant in case you're curious, is six point six 0:16:57.560 --> 0:17:00.760 seven four times ten to the minus a leventh power 0:17:01.240 --> 0:17:05.679 meters cubed per kilogram per second squared. Now, the important 0:17:05.680 --> 0:17:08.400 thing to remember is you need this constant to make 0:17:08.400 --> 0:17:10.439 the math work out properly. We're not going to go 0:17:10.480 --> 0:17:14.320 into greater detail of where this constant came from because 0:17:14.760 --> 0:17:17.720 it gets super complicated, but we multiply this times the 0:17:17.760 --> 0:17:20.200 result we got before, and what you end up with 0:17:20.480 --> 0:17:23.280 is a figure that describes the force of gravitational attraction 0:17:23.320 --> 0:17:27.520 between those two masses. So for relatively small masses, this 0:17:27.640 --> 0:17:30.359 attraction is so weak that we can ignore it. So 0:17:30.400 --> 0:17:32.840 while it is true that I have a gravitational pull 0:17:32.920 --> 0:17:36.240 on all of you listening right now, it's so weak 0:17:36.520 --> 0:17:40.399 that you can just ignore that. It's it's the gravitational 0:17:40.440 --> 0:17:42.680 pull to a pencil that is close to you is 0:17:42.720 --> 0:17:45.560 greater than the gravitational pull I have on you, unless 0:17:45.560 --> 0:17:47.480 you're sitting really really close to me right now, in 0:17:47.480 --> 0:17:52.239 which case back off, man. I'm a scientist. But if 0:17:52.280 --> 0:17:55.560 one of those masses is considerably large and the distance 0:17:55.760 --> 0:17:59.920 is relatively small between the two masses, that gravitational attraction 0:18:00.000 --> 0:18:04.000 can be significant, such as the attraction between Earth, and 0:18:04.480 --> 0:18:09.600 you know people on Earth. Now we're gonna talk more 0:18:09.640 --> 0:18:12.320 about gravity and how we can overcome it in just 0:18:12.440 --> 0:18:15.159 a second. But before I do that, let's take a 0:18:15.280 --> 0:18:25.760 quick break to thank our sponsor. So, here on Earth, 0:18:26.080 --> 0:18:29.440 the acceleration of gravity is nine point eight meters per 0:18:29.440 --> 0:18:32.240 second per second. At least that's the value of the 0:18:32.280 --> 0:18:35.520 acceleration of gravity at sea level here on Earth. Because 0:18:35.560 --> 0:18:37.800 remember I talked about how the force of gravity is 0:18:37.840 --> 0:18:42.840 dependent upon partly upon the distance between two centers of mass. Uh, 0:18:43.040 --> 0:18:46.960 Since that magnitude depends upon that distance, the acceleration of 0:18:46.960 --> 0:18:52.720 gravity decreases as you climb in elevation. It's actually lower. 0:18:53.480 --> 0:18:56.160 But for most practical applications, it's fine to say nine 0:18:56.160 --> 0:18:58.800 point eight meters per second per second, because the difference 0:18:58.880 --> 0:19:02.120 is for again, for most practical applications are so small 0:19:02.160 --> 0:19:05.199 as to not really be that that important. They're not 0:19:05.200 --> 0:19:07.680 going to make a world of difference for what we're 0:19:07.680 --> 0:19:10.800 talking about. So if you want to slip the surly 0:19:10.920 --> 0:19:14.680 bonds of Earth and dance the skies on laughter, silvered 0:19:14.720 --> 0:19:17.800 wings points to whomever can tell me what that's a 0:19:17.840 --> 0:19:21.280 reference to. You need to create enough force to counteract 0:19:21.280 --> 0:19:25.560 the gravitational pull you experience here on the ground. So 0:19:25.640 --> 0:19:29.600 you need something has a good thrust to weight ratio, 0:19:29.800 --> 0:19:32.720 meaning you need a mechanism that can provide enough thrust 0:19:32.960 --> 0:19:36.600 downwards to nullify the effects of gravity and allow you 0:19:36.640 --> 0:19:39.000 to climb into the air. This ratio has to be 0:19:39.080 --> 0:19:41.720 greater than one, and it means that the thrust must 0:19:41.760 --> 0:19:44.080 be more than the mass of the object you want 0:19:44.119 --> 0:19:47.120 to send into the air, namely, you plus your jet 0:19:47.119 --> 0:19:52.520 pack multiplied by nine point eight one. Now, let's complicate 0:19:52.600 --> 0:19:55.919 things a little bit. In popular culture, you'll see characters 0:19:56.000 --> 0:20:00.480 use jetbacks to do amazing aerobatics and maneuvers. Characters like 0:20:00.480 --> 0:20:03.200 the Rocketeer can fly like a bullet to another location, 0:20:03.280 --> 0:20:07.000 kind of like Superman. This, unfortunately, is not realistic, and 0:20:07.000 --> 0:20:10.720 that's because we humans don't have bodies that can really 0:20:10.800 --> 0:20:15.000 generate lift. Now, for aircraft, lift is the force that 0:20:15.040 --> 0:20:18.720 opposes the weight of an airplane or a helicopter. Clearly, 0:20:18.760 --> 0:20:22.320 they're not shooting any kind of thrust straight down in 0:20:22.440 --> 0:20:24.840 order to maintain height, unless it's a vt O L. 0:20:25.520 --> 0:20:28.919 Helicopter kind of is, but an airplane's not. So. For 0:20:28.960 --> 0:20:31.720 a plane, the wings generate the bulk of lift. Although 0:20:31.760 --> 0:20:34.560 the entire body is responsible for lift, it's the wings 0:20:34.560 --> 0:20:37.200 that have the majority of this. And this is an 0:20:37.200 --> 0:20:41.359 aerodynamic force is dependent upon the atmosphere. If we didn't 0:20:41.359 --> 0:20:43.800 have an atmosphere, lift would not be a factor. You 0:20:43.840 --> 0:20:47.159 wouldn't be able to fly. So this is one of 0:20:47.200 --> 0:20:50.080 the reasons why places like Mars, which has a very 0:20:50.080 --> 0:20:53.080 thin atmosphere, it would be very difficult to fly through 0:20:53.400 --> 0:20:56.280 mars atmosphere just because there's not a whole lot of 0:20:56.320 --> 0:20:59.879 density there. Now Earth has a nice dense atmosphere. Flight 0:21:00.040 --> 0:21:04.320 means you're flying through a fluid because the gas typically 0:21:04.400 --> 0:21:08.440 is described as fluid. We would say fluid dynamics play 0:21:08.480 --> 0:21:13.040 apart here. Lift is directed perpendicular to the flow direction. 0:21:13.520 --> 0:21:16.280 So think of an airplane wing. UH an airplane wing 0:21:16.320 --> 0:21:18.640 as it's flying through the air, the flow of atmosphere 0:21:19.119 --> 0:21:22.520 is across the wing, both above and below it. The 0:21:22.560 --> 0:21:25.160 direction of lift is up. It's a ninety degree angle 0:21:25.280 --> 0:21:28.800 from the flow direction. Lift is generated when a fluid 0:21:28.920 --> 0:21:31.639 is turned by a solid object, and lift is a 0:21:31.680 --> 0:21:35.439 force that's in opposite direction to that turn. Now, this 0:21:35.520 --> 0:21:38.399 is in line with Newton's third law of action and reaction. 0:21:38.480 --> 0:21:41.080 There has to be a motion between the object and 0:21:41.119 --> 0:21:43.199 the fluid. So in other words, the wing has to 0:21:43.240 --> 0:21:46.760 travel at a different speed than the air it's moving through. 0:21:47.119 --> 0:21:49.800 If you had incredibly strong winds, I mean, like super 0:21:49.840 --> 0:21:52.640 strong blowing in the same direction as a plane that's 0:21:52.680 --> 0:21:55.320 trying to take off, the plane would not be able 0:21:55.359 --> 0:21:57.280 to get off the ground because the air and the 0:21:57.320 --> 0:21:59.560 wings would be moving at the same speed. You have 0:21:59.640 --> 0:22:03.280 to have a difference in velocity in order to generate lift. Now, 0:22:03.320 --> 0:22:06.479 to go deeply into the concept of lift would require 0:22:06.480 --> 0:22:10.320 a discussion of the work of Danielle Bernowley and Isaac Newton, 0:22:10.560 --> 0:22:12.399 and it would take a long time because there are 0:22:12.400 --> 0:22:15.400 a lot of misconceptions about lift. There are a lot 0:22:15.440 --> 0:22:18.800 of of uh hypotheses that have been talked about that 0:22:18.920 --> 0:22:22.040 are kind of correct but not really correct, and it 0:22:22.200 --> 0:22:24.600 just that's a whole episode on itself. So let's just 0:22:24.640 --> 0:22:27.240 cut to the chase. The human body does not have 0:22:27.320 --> 0:22:31.000 a shape conducive to generating lift, So to stay up 0:22:31.040 --> 0:22:35.440 in the air, you have to consistently apply thrust downwards 0:22:35.480 --> 0:22:39.440 to counteract gravity. You can't just turn the thrusters directly 0:22:39.520 --> 0:22:43.400 behind you and then shoot off into the distance. Otherwise 0:22:43.520 --> 0:22:46.919 you would just come crashing down. The only way you 0:22:46.960 --> 0:22:50.399 could avoid this is if you were moving forward fast 0:22:50.480 --> 0:22:53.199 enough so that as you fall, you're falling at the 0:22:53.240 --> 0:22:57.360 same rate as the Earth's surface is curving away from you. 0:22:57.720 --> 0:23:01.040 Because you're moving forward that fast. Uh, the Earth is 0:23:01.040 --> 0:23:05.520 a sphere. Just news flashed any out there who were 0:23:05.560 --> 0:23:07.960 not aware of this, So you'd have to be going 0:23:08.000 --> 0:23:10.200 wicked fast. You'd have to be going just as fast 0:23:10.400 --> 0:23:12.439 as the Earth is falling away from you. There's actually 0:23:12.440 --> 0:23:17.040 a name for this particular type of falling. It's called orbit. 0:23:17.880 --> 0:23:20.119 But there's no way you would ever achieve a speed 0:23:20.280 --> 0:23:23.439 that incredible using a jet pack. And still, you know, 0:23:24.440 --> 0:23:27.320 keep all your skin on you. So even if you 0:23:27.359 --> 0:23:29.760