WEBVTT Kind: captions Language: en 00:00:00.429 --> 00:00:05.729 Hey, Vsauce. Michael here. I've been watching Bravest Warriors on Cartoon Hangover lately. 00:00:05.729 --> 00:00:11.580 It's great, it was created by Pendleton Ward, and in the show teenagers zip around the universe 00:00:11.580 --> 00:00:20.480 visiting star systems and planets and here is my question: When will we do the same? 00:00:20.480 --> 00:00:22.640 Us humans, in real life. 00:00:22.640 --> 00:00:28.460 I mean, we've managed to put people on the Moon, and land robots on asteroids, and Mars, 00:00:28.460 --> 00:00:32.000 and even Titan, a moon of Saturn. 00:00:32.240 --> 00:00:41.160 Interplanetary travel is scary cool. But will we ever travel interstellarly? Certainly 00:00:41.170 --> 00:00:47.899 it will happen, right? I mean, Voyager 1 is expected to reach interstellar space sometime 00:00:47.899 --> 00:00:55.579 this year, or maybe in the next year or two. And it was launched way back in 1977. So, 00:00:55.579 --> 00:01:01.329 shows like Bravest Warriors are pretty much just a glimpse of our future, maybe even one 00:01:01.329 --> 00:01:05.169 within our lifetimes. Right? 00:01:07.080 --> 00:01:11.960 Well, we're going to need a DONG for this one. Something you 00:01:11.970 --> 00:01:14.200 can Do Online Now Guys. 00:01:14.200 --> 00:01:19.920 The Hayden Planetarium's digital universe allows you to explore a 3-dimensional map 00:01:19.920 --> 00:01:27.420 of our Milky Way. Now, there are about 81 visible stars within just 20 lightyears of 00:01:27.420 --> 00:01:33.980 our own Sun. The nearest is Proximus Centauri, which is only 4.3 lightyears away. 00:01:33.980 --> 00:01:42.300 Getting there? Piece of cake. Piece of difficult cake, because a lightyear is an incredibly 00:01:42.310 --> 00:01:48.500 long distance. It's the distance that light in a vacuum will travel in an entire year. 00:01:48.500 --> 00:01:54.420 And in just one second light can travel so far as to circle the entire Equator of 00:01:54.420 --> 00:01:58.560 Earth...7 times. 00:01:59.780 --> 00:02:08.819 Now, a fast bullet can travel at about 1,500 m/s. And Voyager 1 is traveling at about 17,000 00:02:08.819 --> 00:02:15.169 m/s, relative to the Sun. Also relative to the Sun, our Earth is orbiting at a speed 00:02:15.169 --> 00:02:23.989 of 29,800 m/s - that's pretty fast. But the fastest man-made object ever was the Helios 00:02:23.989 --> 00:02:32.140 2 Solar Probe, which traveled at a maximum speed of 70,220 m/s. 00:02:32.660 --> 00:02:40.640 Impressive, right? Well, even at that speed, the fastest speed ever reached by any man 00:02:40.640 --> 00:02:47.980 made object, crossing this little ol' gap and reaching Proximus Centauri would take 00:02:47.980 --> 00:02:51.640 19,000 years. 00:02:51.640 --> 00:02:57.400 But technology in the future is bound to be improved, along with the maximum speeds we 00:02:57.400 --> 00:03:03.180 are able to obtain. Even using what we know now, a solar sail could easily provide the 00:03:03.180 --> 00:03:10.180 acceleration needed to reach near-lightspeed speeds. And our current understanding of physics theoretically 00:03:10.249 --> 00:03:15.930 allows for things like wormholes which, in theory, could move a spacecraft from one point 00:03:15.930 --> 00:03:20.029 in space to another faster than light normally could. 00:03:20.640 --> 00:03:25.440 And who could forget the famous Alcubierre drive? An idea that fits within most models 00:03:25.449 --> 00:03:31.999 of our universe, and proposes a way to deliver a space craft to a distant object faster than 00:03:31.999 --> 00:03:38.999 light can get there - not by moving the spacecraft, but, instead, by collapsing and expanding 00:03:39.180 --> 00:03:41.300 space itself. 00:03:41.420 --> 00:03:47.100 Things like wormholes and Alcubierre drives are theoretical, but if they could one day 00:03:47.109 --> 00:03:54.949 become a reality, how far away might that day be? It matters. And figuring out exactly 00:03:54.949 --> 00:04:02.199 when in time we should begin an interstellar journey is called a Wait Calculation. Leave 00:04:02.199 --> 00:04:09.379 too soon and before a ship launched today, full of frozen embryos, ever got to its destination 00:04:09.379 --> 00:04:15.309 it would be passed by astronauts who left hundreds, or thousands, of years later, at 00:04:15.309 --> 00:04:21.449 a point in time when technology was advanced enough to lap what we have today. 00:04:21.449 --> 00:04:26.770 Andrew Kennedy calculated that given the pace of our progress, as far as travel velocity 00:04:26.770 --> 00:04:31.009 is concerned, and Earth's mean annual economic growth, 00:04:31.009 --> 00:04:37.289 the soonest human civilization might ever reach Bernard Star, 6 lightyears away, is 00:04:37.289 --> 00:04:48.039 1,104 years from today, which isn't within any of our lifetimes. It might also be a bit 00:04:48.039 --> 00:04:53.349 optimistic because it assumes that we not only solve the problem of speed, but that 00:04:53.349 --> 00:04:58.689 we also solve problems like "how to survive interstellar radiation for years?" or "how 00:04:58.689 --> 00:05:03.360 to avoid collisions with interstellar material at high speeds?" 00:05:03.360 --> 00:05:09.199 It also assumes that before we achieve the technology needed to successfully interstellarly 00:05:09.199 --> 00:05:17.479 travel, all of human kind isn't wiped out by some cataclysmic natural disaster. It may 00:05:17.490 --> 00:05:22.699 sound unlikely, but we're not talking about the near-future, we're talking about thousands 00:05:22.699 --> 00:05:29.859 of years from now. Let's put it this way. Even given our current, slow means of space 00:05:29.860 --> 00:05:37.000 travel, it's estimated that within 5 to 50 million years, we could theoretically explore and 00:05:37.009 --> 00:05:39.049 colonize our whole galaxy. 00:05:39.220 --> 00:05:46.460 That's a lot of time, though. In fact, statistically speaking, within the next 500,000 years, it's 00:05:46.460 --> 00:05:54.280 very likely that Earth will encounter a meteorite nearly a kilometer across. Hopefully when 00:05:54.280 --> 00:05:59.349 that happens we have the prevention abilities needed to keep ourselves safe. But given 00:05:59.349 --> 00:06:06.669 all of this information it's easy to see why the 2008 Joint Propulsion Conference concluded 00:06:06.669 --> 00:06:13.669 that it was improbable that humans would ever explore beyond the solar system. 00:06:14.120 --> 00:06:20.319 It's quite depressing to think that scenes like this one from Shutterstock may be destined 00:06:20.319 --> 00:06:24.739 to only ever remain that - science fiction. 00:06:25.580 --> 00:06:30.040 Wait, how quickly is the camera moving in 00:06:30.050 --> 00:06:36.509 that clip? We're used to seeing science fiction scenes like this, but a Nebula tends to be 00:06:36.509 --> 00:06:41.330 lightyears across, which means that in this clip we're traveling at least the speed of 00:06:41.330 --> 00:06:46.080 light, if not faster. Would it really look like that? 00:06:46.080 --> 00:06:52.469 I covered this briefly in my black hole video, but not completely. If you were to travel 00:06:52.469 --> 00:06:58.330 at the speed of light, or near the speed of light, the universe ahead of you wouldn't 00:06:58.330 --> 00:07:03.990 look like it usually did. First of all, your field of view would increase. It would appear 00:07:03.990 --> 00:07:10.319 as if the universe was receding away from you as you accelerated. At the same time, 00:07:10.319 --> 00:07:16.560 all of the light reaching you would be blueshifted until you were left with this. You may have 00:07:16.560 --> 00:07:22.849 seen this on Vsauce 2. It's the cosmic background radiation blueshifted all-the-way up into 00:07:22.849 --> 00:07:25.069 the visible range. 00:07:25.700 --> 00:07:31.539 MIT Game Lab offers a free, downloadable game that puts you in an environment where the 00:07:31.539 --> 00:07:38.029 speed of light can be lowered all-the-way down to typical walking speed. You can experience 00:07:38.029 --> 00:07:43.039 all of the visual effects I just discussed, but I wanted to know what it would look like 00:07:43.039 --> 00:07:48.189 if the speed of light was where it is, and I took a journey from Earth to the Moon. 00:07:48.189 --> 00:07:53.849 So, I enlisted my friend Liam from World of the Orange and New Music to put together a 00:07:53.849 --> 00:07:59.909 simulation of what it might actually look like to accelerate to nearly the speed of 00:07:59.909 --> 00:08:06.069 light and then slow down, during a trip from Earth to the Moon. Enjoy. 00:08:11.980 --> 00:08:16.419 Whether or not you should believe that all the right factors will come together and humans 00:08:16.419 --> 00:08:22.830 will one day travel that quickly or reach interstellar destinations largely comes down 00:08:22.830 --> 00:08:28.059 to whether you want to be an optimist or a pessimist. But what we've accomplished so 00:08:28.059 --> 00:08:35.599 far is quite amazing considering how weak, flimsy and vulnerable the human body is in 00:08:35.599 --> 00:08:37.819 the vacuum of space. 00:08:37.820 --> 00:08:43.380 Bad Astronomer and SciShow have great videos discussing this topic. And now, thanks to 00:08:43.380 --> 00:08:51.140 the brilliant team at Bravest Warriors, I'm going to go to space. But not while wearing 00:08:51.149 --> 00:08:58.289 a Vsauce suit, no, no, no, I'll do it naked. Whoa. Ok, not that naked. And also maybe some 00:08:58.290 --> 00:09:01.199 muscles? Yep, so that's pretty much what I'd look like. 00:09:01.199 --> 00:09:06.740 The moment I'm exposed to the vacuum of space my body would not inflate and explode. Now, 00:09:06.740 --> 00:09:13.610 the body is a very nicely contained system. But those parts of me that aren't well contained...they'll 00:09:13.610 --> 00:09:20.570 be the first to go. The air in my lungs and digestive tract would quickly rush out. Moist, 00:09:20.570 --> 00:09:26.120 soft tissues would rapidly lose water. My mouth and lips and eyes would dry out and 00:09:26.120 --> 00:09:30.540 swell. As water was pulled to the surface of these things it would vaporize, and the 00:09:30.540 --> 00:09:36.089 decrease in its pressure would cool my mouth and eyes to near-freezing. My body would inflate 00:09:36.089 --> 00:09:42.870 to about twice its normal size as gasses in my blood came out of solution, slowly evaporating 00:09:42.870 --> 00:09:48.269 away, cooling the surface of my skin. Oh, and the blood vessels in my eyes would likely 00:09:48.269 --> 00:09:52.639 burst, spilling blood into my eyes which, along with all the other fluid in my eyes, 00:09:52.639 --> 00:09:57.529 would be rapidly vaporizing on the surface, freezing and drying them out. 00:09:57.529 --> 00:10:03.509 Within about 15 seconds I would go unconscious because oxygen wasn't reaching my brain. And, 00:10:03.509 --> 00:10:09.130 as far as I'm concerned, that would be the end of the entire ordeal. For another 90 seconds 00:10:09.130 --> 00:10:15.420 or so I would still, technically, be alive, but I wouldn't be aware of it or remember 00:10:15.420 --> 00:10:22.680 any of it. My dead body would remain, internally, quite warm for a while because in the near 00:10:22.690 --> 00:10:28.790 vacuum of space there isn't much matter to conduct of convect heat away from me. Instead, 00:10:28.790 --> 00:10:35.160 I would really only lose heat through radiation, a much less efficient method. It would take 00:10:35.160 --> 00:10:39.620 hours for me to cool down to the temperature of space, and by then, I would be nothing 00:10:39.620 --> 00:10:46.620 but a dried-up piece of slightly bloated and stretched, dessicated human jerky. 00:10:47.140 --> 00:10:52.800 If I was exposed to the Sun's full-on radiation, not filtered by the usual atmosphere of Earth, 00:10:52.810 --> 00:10:57.139 I would be a grossly sunburnt piece of jerky. 00:10:57.139 --> 00:11:02.550 In case that makes you hungry, let me give you some nutritional facts: 200 pounds of 00:11:02.550 --> 00:11:09.550 human meat, in outer space, would eventually become about 120 pounds of freeze-dried jerky. 00:11:09.740 --> 00:11:16.480 And given what would be left of me that would be edible as a snack, I'd be worth about 115,000 00:11:16.480 --> 00:11:18.470 calories. 00:11:18.470 --> 00:11:24.750 Maybe humans are the only intelligent life in the universe. But if you believe that intelligent 00:11:24.750 --> 00:11:32.310 life could have arisen on other planets, an interesting idea occurs: The Fermi Paradox. 00:11:32.560 --> 00:11:38.620 Enrico Fermi calculated that given the number of planets believed to exist in our galaxy, 00:11:38.620 --> 00:11:44.300 at least some of them must have been habitable to life as we know it. And, in many cases, 00:11:44.300 --> 00:11:48.750 millions and millions of years before life on Earth even existed. 00:11:48.750 --> 00:11:54.079 So, if interstellar travel, traveling between stars and different solar systems, really 00:11:54.079 --> 00:12:04.999 is possible for intelligent life to do, why have we not been visited by aliens yet? Well, 00:12:05.000 --> 00:12:09.069 maybe we have been visited. Maybe they're here right now and we just can't perceive 00:12:09.069 --> 00:12:18.220 them. Or maybe we haven't been discovered. Or maybe we are alone. Or maybe we're just 00:12:18.220 --> 00:12:20.060 not worth visiting... 00:12:20.060 --> 00:12:26.529 So, what are you waiting for? Live your life in a way that makes traveling lightyears just 00:12:26.529 --> 00:12:29.389 to hang out with you worth it. 00:12:29.389 --> 00:12:30.329 And as always, 00:12:30.329 --> 00:12:31.529 thanks for watching.