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  • Hey, Vsauce, Michael here. I've been watching Bravest Warriors on Cartoon Hangover lately.

  • It's great, it was created by Pendleton Ward, and in the show teenagers zip around the universe

  • visiting star systems and planets, and here is my question: When will we do the same?

  • Us humans, in real life.

  • I mean, we've managed to put people on the Moon, and land robots on asteroids, and Mars,

  • and even Titan, a moon of Saturn.

  • Interplanetary travel is scary cool. But, will we ever travel interstellarly? Certainly

  • it will happen, right? I mean, Voyager 1 is expected to reach interstellar space sometime

  • this year, or maybe in the next year or two. And it was launched way back in 1977. So,

  • shows like Bravest Warriors are pretty much just a glimpse of our future, maybe even one

  • within our lifetimes. Right? Well, we're going to need a DONG for this one. Something you

  • can Do Online Now Guys.

  • The Hayden Planetarium's digital universe allows you to explore a 3-dimensional map

  • of our Milky Way. Now, there are about 81 visible stars within just 20 lightyears of

  • our own Sun. The nearest is Proximus Centauri, which is only 4.3 lightyears away.

  • Getting there? Piece of cake. Piece of difficult cake, because a lightyear is an incredibly

  • long distance. It's the distance that light in a vacuum will travel in an entire year.

  • And, in just one second, light can travel so far as to circle the entire Equator of

  • Earth...7 times.

  • Now, a fast bullet can travel at about 1,500 m/s. And Voyager 1 is traveling at about 17,000

  • m/s, relative to the Sun. Also relative to the Sun, our Earth is orbiting at a speed

  • of 29,800 m/s- that's pretty fast. But, the fastest man-made object ever was the Helios

  • 2 Solar Probe which traveled at a maximum speed of 70,220 m/s.

  • Impressive, right? Well, even at that speed, the fastest speed ever reached by any man

  • made object, crossing this little ol' gap and reaching Proximus Centauri would take

  • 19,000 years.

  • But technology in the future is bound to be improved, along with the maximum speeds we

  • are able to obtain. Even using what we know now, a solar sail could easily provide the

  • acceleration needed to near-lightspeed speeds. And our current understanding of physics theoretically

  • allows for things like wormholes which, in theory, could move a spacecraft from one point

  • in space to another faster than light normally could.

  • And who could forget the famous Alcubierre drive? An idea that fits within most models

  • of our universe, and proposes a way to deliver a space craft to a distant object faster than

  • light can get there- not by moving the spacecraft, but, instead, by collapsing and expanding

  • space itself.

  • Things like wormholes and Alcubierre drives are theoretical, but, if they could, one day,

  • become a reality, how far away might that day be? It matters. And figuring out exactly

  • when in time we should begin an interstellar journey is called a Wait Calculation. Leave

  • too soon, and before a ship launched today, full of frozen embryos, ever got to its destination,

  • it would be passed by astronauts who left hundreds, or thousands, of years later, at

  • a point in time when technology was advanced enough to lap what we have today.

  • Andrew Kennedy calculated that, given the pace of our progress, as far as travel velocity

  • is concerned, and Earth's mean annual economic growth.

  • The soonest human civilization might ever reach Bernard Star, 6 lightyears away, is

  • 1,104 years from today, which isn't within any of our lifetimes. It might also be a bit

  • optimistic because it assumes that we not only solve the problem of speed, but that

  • we also solve problems like "how to survive interstellar radiation for years?" or, "how

  • to avoid collisions with interstellar material at high speeds?"

  • It also assumes that before we achieve the technology needed to successfully interstellarly

  • travel, all of human kind isn't wiped out by some cataclysmic natural disaster. It may

  • sound unlikely, but we're not talking about the near-future, we're talking about thousands

  • of years from now. Let's put it this way- even given our current, slow means of space

  • travel, it's estimated that within 5-50 million years, we could theoretically explore and

  • colonize our whole galaxy.

  • That's a lot of time, though. In fact, statistically speaking, within the next 500,000 years, it's

  • very likely that Earth will encounter a meteorite nearly a kilometer across. Hopefully when

  • that happens we have the prevention abilities needed to keep ourselves safe. But, given

  • all this information, it's easy to see why the 2008 Joint Propulsion Conference concluded

  • that it was improbable that humans would ever explore beyond the solar system.

  • It's quite depressing to think that scenes like this one from Shutterstock may be destined

  • to only ever remain that- science fiction. Wait, how quickly is the camera moving in

  • that clip. We're used to seeing science fiction scenes like this, but a Nebula tends to be

  • lightyears across, which means that in this clip we're traveling at least the speed of

  • light, if not faster. Would it really look like that?

  • I covered this briefly in my black hole video, but not completely. If you were to travel

  • at the speed of light, or near the speed of light, the universe ahead of you wouldn't

  • look like it usually did. First of all, your field of view would increase- it would appear

  • as if the universe was receding away from you as you accelerated. At the same time,

  • all of the light reaching you would be blueshifted until you were left with this. You may have

  • seen this on Vsauce 2. It's the cosmic background radiation blueshifted all-the-way up into

  • the visible range.

  • MIT game lab offers a free, downloadable game that puts you in an environment where the

  • speed of light can be lowered all-the-way down to typical walking speed. You can experience

  • all of the visual effects I just discussed, but I wanted to know what it would look like

  • if the speed of light was where it is, and I took a journey from Earth to the Moon.

  • So, I enlisted my friend Liam from World of the Orange and New Music to put together a

  • simulation of what it might actually look like to accelerate to nearly the speed of

  • light and then slow down, during a trip from Earth to the Moon. Enjoy.

  • Whether or not you should believe that all the right factors will come together and humans

  • will one day travel that quickly or reach interstellar destinations largely comes down

  • to whether you want to be an optimist or a pessimist. But, what we've accomplished so

  • far is quite amazing considering how weak, flimsy, and vulnerable the human body is in

  • the vacuum of space.

  • Bad Astronomer and SciShow have great videos discussing this topic. And now, thanks to

  • the brilliant team at Bravest Warriors, I'm going to go to space. But not while wearing

  • a Vsauce suit, no, no, no, I'll do it naked. Whoa. Ok, not that naked. And also maybe some

  • muscles? Yep, so that's pretty much what I'll look like.

  • The moment I'm exposed to the vacuum of space my body would not inflate and explode. No,

  • the body is a very nicely contained system. But those parts of me that aren't well contained...they'll

  • be the first to go. The air in my lungs and digestive tract would quickly rush out. Moist,

  • soft tissues would rapidly lose water. My mouth, and lips, and eyes would dry out and

  • swell. As water was pulled to the surface of these things it would vaporize, and the

  • decrease in its pressure would cool my mouth and eyes to near-freezing. My body would inflate

  • to about twice its normal size as gasses in my blood came out of solution, slowly evaporating

  • away, cooling the surface of my skin. Oh, and the blood vessels in my eyes would likely

  • burst, spilling blood into my eyes which, along with all the other fluid in my eyes,

  • would be rapidly vaporizing on the surface, freezing and drying them out.

  • Within about 15 seconds I would go unconscious because oxygen wasn't reaching my brain. And,

  • as far as I'm concerned, that would be the end of the entire ordeal. For another 90 seconds

  • or so I would still, technically, be alive, but I wouldn't be aware of it or remember

  • any of it. My dead body would remain, internally, quite warm for a while because in the near

  • vacuum of space there isn't much matter to conduct of convect heat away from me. Instead,

  • I would really only lose heat through radiation, a much less efficient method. It would take

  • hours for me to cool down to the temperature of space, and by then, I would be nothing

  • but a dried-up piece of slightly bloated and stretched, dessicated human jerky.

  • If I was exposed to the Sun's full-on radiation, not filtered by the usual atmosphere of Earth,

  • I would be a grossly sunburnt piece of jerky.

  • In case that makes you hungry, let me give you some nutritional facts: 200 pounds of

  • human meat, in outer space, would eventually become about 120 pounds of freeze-dried jerky.

  • And given what would be left of me that would be edible as snack, I'd be worth about 115,000

  • calories.

  • Maybe humans are the only intelligent life in the universe, but if you believe that intelligent

  • life could have arisen on other planets, an interesting idea occurs: The Fermi Paradox.

  • Enrico Fermi calculated that given the number of planets believed to exist in our galaxy,

  • at least some of them must have been habitable to life as we know it. And, in many cases,

  • millions, and millions of years before life on Earth even existed.

  • So, if interstellar travel, traveling between stars and different solar systems, really

  • is possible for intelligent life to do, why have we not been visited by aliens yet? Well,

  • maybe we have been visited. Maybe they're here right now and we just can't perceive

  • them. Or, maybe we haven't been discovered. Or, maybe we are alone. Or, maybe we're just

  • not worth visiting...

  • So, what are you waiting for? Live your life in a way that makes traveling lightyears just

  • to hang out with you worth it. And, as always, thanks for watching.

Hey, Vsauce, Michael here. I've been watching Bravest Warriors on Cartoon Hangover lately.

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我們會不會去拜訪其他明星? (Will We Ever Visit Other Stars?)

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    Bing-Je 發佈於 2021 年 01 月 14 日
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