Full transcript
0:00The latest limited Edition Pin is here.
0:02Now available on the kurzgesagt Shop.
0:06You will never leave the solar system.
0:09Nobody alive today will.
0:11And maybe no human ever.
0:13Locked in by an invisible barrier, impossible to overcome for carbon based animals like us.
0:20And not just us – there may be millions of alien civilizations in the universe,
0:25none of them ever able to venture into deep space in a meaningful way.
0:30Ok but how can this be? We've made countless videos imagining how the
0:35exploration of the galaxy and beyond should just be a question of time.
0:39Sort of mandatory for civilizations at a certain point.
0:43But there is a catch: We are pushing up against fundamental physics.
0:47What is this barrier, made of dust and nothingness? And why is it so hard to overcome?
0:54You Don’t Understand How Large Space Is.
0:57We Don’t Either.
0:58Conceptualizing the size of space is impossible for our ape brains
1:03that evolved to understand distances like “right here” and “over the next hill”.
1:08Space is so absurdly huge that we just check out and just hear “very far”.
1:14“Very far” and “A million times very far” feels the same but it is not.
1:21To help our brains, let us start with what makes us cross distances: speed.
1:27The fastest a human ever traveled in space were Astronauts at 40,000 km/h,
1:32returning from the Moon in 1969.
1:35Not bad, but way too slow.
1:38The fastest thing humans have ever built by far is the Parker Solar Probe,
1:42which at this moment uses a physics cheatcode,
1:45hurling around the gravity well of Venus, accelerating to get closer to the sun.
1:49After seven years of doing this,
1:50the probe is shooting through space at a breathtaking 635,000 km/h.
1:56Fast enough to go around the world in 4 minutes
1:58or to cover the distance from Earth to the moon in 36.
2:02So let’s pretend we had a spaceship that fast, with a human crew ready to explore the universe!
2:08Current rockets would need 7-10 months to reach Mars,
2:11but our new spaceship covers the distance in just two weeks! Pretty good!
2:16The next stop is Pluto which we will reach after about a year – ok much longer,
2:21but still ok! It only takes two more years to pass the heliopause
2:25and one more to pass Voyager II, which traveled over 50 years to get this far.
2:30Great!
2:31The next stop is the end of the Oort cloud,
2:34the true edge of the solar system where open space begins! We reach it in… 2,500 years.
2:42Oh.
2:43Oh no.
2:45Not only did we travel for the amount of time it took to get from the founding of
2:48the Roman Republic to the present day, there is NOTHING out here.
2:52This is the invisible barrier.
2:54The barrier of nothingness that might trap us in the solar system forever.
3:00Space tends to be like that.
3:02There is a place that is very far away but with human ingenuity and billions of dollars
3:06we can get there! Then you zoom out one more time and all hope leaves your body.
3:11And the problem is that we have barely started zooming out...
3:14Why don’t we just go faster?
3:17Well we don’t know of a non-magic way to travel faster than light, teleport or freeze people.
3:22So no warp drive for now.
3:24But things like a propulsion system that uses nuclear fusion or antimatter,
3:28powerful enough to reach a substantial fraction of the speed of light,
3:31are in the realm of the physically possible.
3:34Ignoring the technical details and various problems that these energy sources have,
3:38we’ll be very optimistic and make the reasonable assumption that we
3:41can get a spaceship to fly at around 20% the speed of light!
3:44Which is extremely fast – 60,000 kilometers per second, 216 million kilometers per hour.
3:52Fast enough to reach the edge of the solar system in just 3.5 days
3:56and the outer edge of the Oort cloud in eight years.
3:59Alpha Centauri, the closest star system to our own in 20 years!
4:04We can work with that!
4:05There is only one small problem:
4:07We don’t have internet! Wait, what?
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5:12All you have to do is pick your next destination – we'll
5:15go back to solving our trickier travel problems.
5:18Everything should be sorted out now, right? Well..there is only one small issue:
5:24Space Hates You: The Barrier of Dust
5:28Unfortunately we will run into a few obstacles on the way.
5:32Literally.
5:33Because while space is very empty, it is not actually empty.
5:38There are energetic particles, gas, dust and things bigger than dust.
5:43As a lot of unhappy people experience every day,
5:46if you are going really fast and smash into something, you have a huge problem.
5:50And at 20% the speed of light,
5:53this is true even if the thing you are smashing into is just an atom.
5:57An individual iron atom that hits your spaceship at this speed
6:01has enough energy to carve a damage track tenths of a millimeter deep.
6:04Over time its hull would be riddled with microscopic bullet holes, which is not great.
6:09Of course our engineers knew this and created a shield for our ship.
6:13A sort of protective sail that absorbs or at least slows down most molecules we smash into.
6:19And while this makes the journey much safer,
6:21there are things floating around in space that are larger than atoms.
6:24Running into a single grain of dust at 20% the speed of light is like running into a grenade,
6:29causing a tiny detonation as the dust explosively evaporates, grinding away our protective shield.
6:35But you can also hit something bigger than a grain of dust.
6:38Like a small rock, the size of a golf ball.
6:41Hitting that at 20% the speed of light releases more than double
6:44the energy of the nuclear bomb that was dropped over Hiroshima.
6:48We’ll not even talk about anything larger.
6:50Atoms, dust and pebbles are dangerous enough.
6:54We might have reached our natural speed limit here – besides the fact
6:58that we don’t have a good idea how we could possibly fly any faster,
7:01all of the damaging effects of hitting stuff floating around in the void get much worse fast.
7:07Having said all that, it’s probably fair to assume that with enough shielding,
7:10our spaceship should be able to survive traveling through space at roughly 20% the speed of light
7:16long enough to get to at least nearby stars in a reasonable amount of time!
7:21Only one more issue to overcome!
7:24Almost Everything in Space that's Close is Super Lame
7:29The first proper target outside the solar system is the Alpha Centauri System.
7:33Which is roughly 10,000 years with our original slow,
7:36more realistic ship but only 20 years with our super fast fictional ship!
7:41So let’s cram a few unlucky humans into a tiny box for 20 years and send them
7:46on their way and assume they somehow make it without murdering each other!
7:50Four years after their arrival, their message reaches earth.
7:53People around the globe gather together and hold their breath, eager to listen to it:
7:59“We arrived! Alpha Centauri and its planets are very pretty up close!
8:04Unfortunately they are all super deadly and uninhabitable.
8:08But we are doing extremely cool astrophysics and are learning a LOT, which is pretty exciting!
8:13We are getting kind of tired of freeze dried food and desperately need new shows to watch though.
8:18Not sure what we were thinking coming here…”
8:21The thing with space is that almost all “close destinations”,
8:25if close means something different from what it usually means, are pretty lame.
8:30Not from a scientific perspective of course! It would be an absolute dream to have the
8:34privilege to set foot on foreign planets and marvel at the wonders of our universe!
8:39But if 20% of the speed of light might be our speed limit, and we give humans a realistic
8:43travel time of say, 40 years, we could reach things that are up to 8 light years away.
8:48None of the targets remotely within this range, within a human lifetime, may be worth traveling
8:53dozens of years in a tiny box, through one of the deadliest environments imaginable.
8:58Our solar system is a bit unlucky in that regard, we are in a relatively empty pocket of the galaxy.
9:03This might change in a few million years as we move through the galaxy, and there might be small,
9:08localized star spanning civilizations – we discussed this in another video.
9:13Let’s say that we could go much further, to any of the stars within our stellar neighborhood,
9:17a sphere about 25 lightyears in diameter.
9:200.02% of the milky way by the way.
9:23This tiny bubble is currently inhabited by 34 stars, and 6 brown dwarfs.
9:29Only three stars in our neighbourhood are similar to the sun.
9:32But one of them is actually the sun and another one is Alpha Centauri A.
9:37The other stars close to us are mostly red dwarfs with
9:40planets that vary from deadly to super deadly.
9:43There are a few planets in the habitable zones of their stars, where water can be liquid.
9:48But, Mars is also in the habitable zone of the Sun and it is really bad.
9:53Even the planets that we think look most like Earth, like GJ1061 d, come with no guarantees.
10:00Imagine traveling your entire life and then arriving at a Mars.
10:04What a brutal letdown that would be.
10:07There are a few stars that would be interesting targets
10:10and may have actual habitable planets – planets with oceans and atmospheres that are breathable,
10:15which probably would mean that they have some form of microbial life, if not more.
10:20It would be extremely interesting and definitely worth it to check them out!
10:24But they could be dozens, if not thousands of light years away.
10:28Which means journeys of hundreds or thousands of years,
10:30even at a large fraction of the speed of light.
10:34Of course it is maybe feasible that a future humanity that is
10:37technologically way more advanced than us and very motivated could find solutions.
10:42Maybe they have solved biological aging and a travel time of a few hundred years
10:46doesn't seem that bad to them.
10:48Maybe they could send AI spaceships with embryos or some version of that into space.
10:53They would probably have way more advanced telescopes
10:55to make sure they don’t choose star systems that are deadly and empty.
10:59But it is still hard to imagine without real science fiction technology,
11:03how they could build and sustain a connected civilization.
11:07Conclusion
11:09The longer you think about deep space, the less it makes sense.
11:12The distances are too vast, there is a deadly speed limit and even if we could
11:17solve these issues almost all destinations even remotely reachable may not be worth the trip.
11:23Space is the greatest challenge humanity will ever face.
11:27Right now we are just not equipped or able to solve it.
11:30Rockets, computers and even nuclear fusion reactors are hopelessly underpowered.
11:35We need technology that is overwhelmingly transformative.
11:39Something as wild to us as flying to the moon would have been to a hunter gatherer.
11:44Will we ever get there?
11:45We genuinely don’t know.
11:48But it is good to remind yourself of something:
11:50there are few things that make you look dumber than predicting the future of technology.
11:55In 1903 the New York Times published an editorial, "Flying Machines Which Do Not Fly” that
12:01confidently predicted it would take humans one to ten million years to achieve powered flight.
12:0669 days later the first successful flight happened.
12:1166 years later humans landed on the moon.
12:14So we really hope this video will seem as dumb as this article in a hundred years.
12:20And there is another option entirely – maybe our thinking about all this is just completely wrong.
12:25Maybe the future is not out there, but deep down – but we’ll explore that in another video…
12:34The latest LTD. Edition Pin is here, continuing the Cosmic Time Collection.
12:39Predicting the future is really hard.
12:41But this device offers you a rare glimpse into the end of the Universe.
12:45Spoiler: one by one, all the stars will die, until everything is swallowed by darkness.
12:51Wear this animated, lenticular pin as a reminder that you exist right now,
12:56in a brief and extraordinary moment in time when the Universe is still filled
12:59with stars and light and there is so much left to discover.
13:03You are exactly where you belong in cosmic time and the Universe.
13:07Only 10,000 Vanishing Stars Pins exist, and each one is individually numbered.
13:12Add it to your collection, or start a new one while supplies last.
13:16And while humanity may still be confined to a tiny corner of the cosmos,
13:20we've already achieved some remarkable things.
13:23To celebrate these milestones, we created our Cosmic Milestones Poster Collection,
13:27featuring the first Moon landing, the Mars rover Curiosity, and the Wilson Observatory,
13:32all enhanced with shimmering foil details.
13:35Get your favorite, or better, all of them and create a gallery wall that
13:39will inspire you every day and remind you of what humanity is capable of.
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