Interstellar travel is not impossible, no matter what anyone tells you. We know how, it's just wildly impractical. We've barely even left our own planet, and we've managed to throw a few chunks of metal out of our solar system so far. We lack the industrial capacity to build an interstellar ship, we do not lack the physics.
IIRC, it is possible to get anywhere in the observable universe in one human lifetime assuming 1g of constant acceleration.
This does not permit you to slow down and halt at your target, which greatly increases travel times.
It is also effectively a one-way ticket for anything other than objects in our immediate stellar neighborhood. If you turned around and returned to Earth after getting to an object 1,000ly away—still well within our own arm of the galaxy—at least 2,000 years will have passed on Earth. It’s probable that no civilization you know of would still exist, nor would anyone be able to understand your language.
This isn’t even beginning to address the problem of running into stray atoms at 99.99…% of the speed of light. Or god forbid a handful of stray molecules. We also haven’t discussed the real elephant in the room which is the sheer amount of energy required to accelerate a human and human life support systems at 1g for several decades.
"The design and calculations discussed above are using 20%-enriched uranium salts. However, it would be plausible to use another design which could achieve much higher exhaust velocities (4,725 km/s) and use a 30,000-tonne ice comet along with 7,500 tonnes of highly enriched uranium salts to propel a 300-tonne spacecraft up to 7.62% of the speed of light and potentially arrive at Alpha Centauri after a 60-year journey."
Sure, not 99% the speed of light or continuous 1 g acceleration but IMHO good enough for an oversized nuclear squirt gun.
Sure, a thousand generations will live and die along the way, but once we get over there, you've got stars every 0.1 ly or so, and with very plausible future tech, you could navigate between them in a few years. You could set up a proper starfaring, interplanetary civilization, with tradeships either going back and forth between two neighboring systems, or winding on long, never-repeating routes, visiting a dozen or so star systems in a human life.
(Most globular clusters appear to be old and metal-poor, and we haven't found a lot of planets there, and this only works if you find a globular cluster where ~every star can support a colony.)
Unless you're planning on forcing those thousand generations to live in inhumane conditions (e.g. force a static culture), that should probably be "if we get over there". I'd be very surprised if, after 1000 generations, the chance for arrival is > 50%.
It takes only one generation to decide not to go along, be that by changing course, or by not reproducing enough, or internal warfare, ...
Yeah, right we are 300 hundred years from the target but & 500 years on the way but so what ? You go for somo zero-g polo, do some cooking and pottery classes with firends, maybe learn machining so you can help with ship maintenance and so on.
It is the same on Earth - you go on with your life knowing you will propabably not live long enough to see some far future projects to be complete, like the final form of the Hagia Sophia Catthedral or Half Life 3 release. And thats mostly fine ?
And that's just conflict. What if an early generation decides to target a planet that's less useful re/ metals etc., but that's much better suited for human life? How can you guarantee they won't decide to change course as a gift to their descendants, without draconian measures against such ideas?
> Also as for changing course - that is in many cases impossible, at least unless you want to make it 100% certain that you will die alone in the coldness of space. Just too much energy needed to signficantly change the trajectory & starts, at least in our part of the Galaxy, being too far apart.
Sure, the later generations wouldn't have that choice, but the first few definitely would. You need to bring a ton of fuel anyway to slow down, and 1000 generations is plenty of time to increase fuel efficiency a little. So a minor change e.g. at generation 5 seems very much doable, unless you have concrete examples that prove otherwise.
> It is the same on Earth - you go on with your life knowing you will propabably not live long enough to see some far future projects to be complete, like the final form of the Hagia Sophia Catthedral or Half Life 3 release. And thats mostly fine ?
I'm not forced to live my entire life working towards the Hagia Sophia or HL3, with the choice to do otherwise being taken away from myself AND from 1000 generations of my descendants.
If I was on that ship, I'd vote to blow it up, just so those responsible won't get away with it.
Sure there will always be some people who want to explore for exploration’s sake. But a generation ship leaving a garden of Eden we’re quite literally built for in order for our children’s grand^(1000)children to terraform a rock half a galaxy away in order to have a different mix of resources?
That’s a hard sell for the first generation, to say nothing of those who come after.
I suspect education on that ship would look a lot different than it does on Earth.
At best that's slavery, at worst it's reducing those 1000 generations to cattle.
This gives you energy, but I'm not sure how to turn that into velocity. Presumably you'd want some kind of ion beam emitter on board to propel your craft forward. Halfway through the journey, you'd turn the ion beam around to decelerate as you approach your destination.
In the Arthur C Clarke novel Songs of Distant Earth, spacecraft pushed huge blocks of ice ahead of them to absorb stray interstellar dust.
GP has it backwards too. For 1g of acceleration, none of the beam that is produced after a year will ever reach the accelerating spacecraft. You only need to run it for a year.
Some recent findings do give it lower feasibility though.
Second, the faster you’re going, the less useful a gravitational slingshot is because you spend less time in the object’s gravity well.
It’s a fun and useful trick within our solar system, but I don’t think the physics plays out well for interstellar travel.
But assume for example that you don't care about how long it is going to take (you are an immortal cyborg, an upload living in the computer or a popsicle in hibernation & the AI is driving. Then you can just "island hop" between Kuiper Belt/Oort Cloud objects, never gaining any high % of the speed of light but always having the next body in your sights, not farther than a few decades or a couple hundred years of flight at most.
You reach the body, refuel, repair, maybe upgrade and then off you go, to the next one. And eventually, you might be at you destination, with a fully fueled and repaired ship. It might just take like 20000 years for start to finish, but hey, you can use it for something productive like learning to play Go or something. :)
In this setting this was first done when a bunch of immortal vyborgs was on a colony ship, about hundred years from arrival but there was a probe with a matter printer already in the destination. So their got the idea to send the probe both blueprints for a humanoid body printer as well as their mind backups. That got their colony going quite a bit faster but might have resulted in some funny/awkward moments once they met in person later. :)
Presumably you could also run this withou a mind upload and let he individual develop normally.
Or better yet, send some cancer cells so they can replicate during the journey, then switch from cancer mode to gamete mode for the final generation. That way they're fresh when you need them. You're gonna want DNA repair happening continuously, rather than all at once upon a thaw.
Mothers provide more than a growth vat to their children, not to mention the immunities passed on in breast milk.
To birth a child in a sterile vat, they would likely need to be kept in a bubble the rest of their lives too.
Huh? We already have machines that can understand any language from a sample.
Huh? You can’t go faster than light speed, and the observable universe is way larger than ~100 light years.
Greek and Latin are still understood. I don't know if the Chinese spoken today resembles Chinese from 2000 years ago, but maybe some of the written language would be understandable. Both Hebrew and Tamil are comprehensible that far back, and farther. Arabic goes nearly that far back.
Of course, that's six languages out of... how many do we speak?
Nerds specifically kept the archaic forms alive, but they'd also tell you that Latin and ancient Greek were not static for their whole existence (Attic != Homeric != Koine), and modern Greek is somewhat different from what is taught as "ancient" Greek.
Treat Latin and (ancient) Greek like you would Quenya or Esperanto.
If this were to happen with English, I'd expect us to keep Chaucer, Shakespeare, and enough to understand Victorian literature, but it's anyone's guess if modern English would survive at all.
Arabic… kinda? It has an international standard form, but from what I've been told the language also comes with local dialects which can be difficult to mutually comprehend (though this is also the same with English just by going from central London to Sheffield).
Apart from that - solved problem.
Sealed terrariums? Unless you mean something more complex than plants, soil, sunlight, and water?
https://laidbackgardener.blog/2019/10/14/the-worlds-second-o...
"That means it has been growing inside its bottle with no additional air, water or fertilizer for 47 years."
The 'biosphere 2' attempt at building a self-sustaining environment with humans, did not succeed.
12 years with bugs, but no mammals of course.
It's bad enough to do on Mars (or an asteroid or other solar system environment) where you can get spare parts sent over in a few years and ask ground control for answers to problems, have them simulate things on Earth or in cislunar space and put a lot of engineers on it. The more I think about it the worse it seems in our solar system -- but interstellar travelers are truly on their own.
This was provocative and intriguing so I looked into it and this is my understanding of some of the options (theoretically).
First, "interstellar" means between stars and the closes star is 4.2465 light years away (Proxima Centauri in Alpha Centauri star system) so I used that. c=speed of light
- Chemical (Voyager), ~0.006% c: ~75,000 years
- Nuclear pulse (Orion), ~3-10% c: ~40-130 years
- Fusion (Daedalus), ~12% c, flyby: ~35 years
- Laser sail (Starshot), ~20% c, flyby: ~21 years (gram-scale probes only)
- Antimatter, ~20-30% c stopping: ~14-21 years; ~50% c flyby: ~8-9 years
Also past LEO you don't really have issues with fallout.
So the only real hurdle is securing the supply of couple thousand nuclear bombs for the trip.
But if you told people in 1903 that you can build a plane that will get 850 people 14000 km but you need 250 tons of kerosene to fuel it, they would also think you are insane (e.g. an Airbus A380).
But over time, even with Orion, people will just get used to it. :)
If we consider the low end your time estimates, we could theoretically have received data from Alpha Centauri by now.
And IMHO that's the main explanation for the Fermi paradox: we don't see aliens everywhere because they don't have a good reason to colonize other planets than their own either.
Nobody would chose to sacrifice themselves and their descendants (because that's what such an expedition is about), for mere curiosity. And nobody would fund an expedition that will not reach destination before multiple hundreds of years, even if the said expedition doesn't consume the entire industrial output of a major nation.
Space is BIG.
I bet if you had a one-way mission to Mars leaving in 12 months, you’d have a flood of applicants. Many hundreds minimum and probably several thousand.
Out of 8 billion people, assuming you had selection criteria that were even as strict as 1 in 1000 qualify, out of that 8 million, I think you’d easily be able to raise a crew.
Travelling to another star would require a fully self-contained spaceship with energy, life support, food, medical facilities, even production facilities able to function for centuries or millenia. We simply don't know how to do that.
With a sustained nationwide effort comparable to WW2 we could most likely send a spaceship out if the solar system in ten years or so. But why would anyone do that?
Typical these things fall into one, two, many. Can you build one, two, many? These are very different propositions.
One means you know understand how to do it, mostly.
Two means you can repeat it, so you do understand it, it wasn't a fluke.
Many is scaling the process.
Its not 'if' question, just 'when'. You cant be space faring civilization and not know this.
Maybe they even live inside asteroids or ships orbiting a dwarf star, because they are mostly in a Matrix-like existence and don't have much of a physical life?
If someone provided a matrix world where you could live your dream life, I think a lot of us would choose to live in it. It would be so much better than real life. Our physical bodies could be maintained by robots, providing us with the perfect mix of sustenance and physical exercise to increase our life spans. Your body would eat healthy, but your mind would experience whatever food you would like.
That assumes reaching 5 light years in say 50 years
However once it's done a few times, then it can't be stopped. If you're going at say 1/1000th of the speed of light (50 years to travel, 450 years to settle and build the next wave is 1% the speed of light) then your successor species will have colonised the galaxy in 100 million years, and we know that hasn't happened.
It could help us learn how our habitable environment works and operates, it might be applicable for terraforming or habitat construction.
There is also a non-zero chance of some sort of life, possibly intelligent developing in such an environment (as proven by our sample size of 1). That life can be active at the moment (from our PoV - light speed and all) or was active in the past, so we should look for bio signatures or even signs of mega scale engineering.
Interstellar travel is not a propulsion problem. It's a space travel problem. The medium itself, is the vast majority of the problem.
That's not actually a problem, because dangerous GRBs are simply not that common. Earth gets hit by one every day, but, that includes GRBs from very distant galaxies that are so weak when they hit us that they would not be any danger even to a completely unshielded person in orbit. GRBs of sufficient power to be an actual threat to people in a tin can is one/millions of years, at which point it's a propulsion problem again.
Yes, there are lots of things that could kill the ship on route. No, none of those are actually a significant problem compared to the basic "how to get there before everything breaks down from internal issues".
It's highly unlikely that a ship gets hit by a GRB.
On the other hand, general radiation gets worse the faster you go, so you need shielding either way. All you have to do is line the walls of your ship with a shit ton of water, which can be mined in space.
We don't have fuel sources that can run long enough for the trip, and deep space won't have enough solar radiation. We would need reliable mining spots along the way to replace metals made brittle by exposure or punctured by micro asteroids.
Even travelling at 1% the speed of light, stray hydrogen atoms become a problem. Not counting acceleration or deceleration time, that would be over 400 years just to get to the nearest star, let alone one with a habitable planet.
But that water needs to be encased in something, and your problem now becomes protecting the encasement.
Collecting it while usefully en route to another star system seems like it would be tricky from a delta-v perspective, but maybe the solution is to:
1) build a small worldship from an appropriate asteroid 2) fill your internal ocean in the outer solar system over the course of a generation or three 3) dive back down the gravity well for a gravitational assist from the Sun as you head to your interstellar destination 4) en route, slowly use part of your ocean as propellant, while living inside the rest of it as shielding
It would not really be about primarily traveling anywhere, just people settling this are with its immense resources over many generations, until possibly the ones on the furthest reaches would be able to make the jump to the next systems Oort cloud & slowly settling it down the gravity well, maybe even reaching the inner system eventually, provided something so tiny and sweltering would be of interest for them by that point. ;-)
IMHO this is actually much closer to how humans spread along the Earths surface. It was no like someone just get up and walked from Afrika to Australia. The various human group just expanded their habitat over time until they spread all over the place over many thousands of years and this would be similar.
https://en.wikipedia.org/wiki/Gamma-ray_burst :
> (GRBs) are extremely energetic events occurring in distant galaxies that represent the brightest and most powerful class of explosion in the Universe.
> The sources of most GRB are billions of light years away from Earth, implying that the explosions are both extremely energetic (a typical burst releases as much energy in a few seconds as the Sun will in its entire 10-billion-year lifetime)[11] and extremely rare (a few per galaxy per million years).
> All in all, a GRB within a few kiloparsecs, with its energy directed towards Earth, will mostly damage life by raising the UV levels during the burst itself and for a few years thereafter.
I'm guessing without an atmosphere protecting a ship it'd be a bit worse? But it's like winning a very bad lottery to get hit by one. I guess if you're traveling thousands of years in deep sleep odds get higher?
There are plenty of designs that get you to 0.1c or above if you are Kardashev 2, things like light sails powered from the Dyson sphere.
Nothing plausible for anyone living today AFAIK.
https://en.wikipedia.org/wiki/Launch_loop
https://en.wikipedia.org/wiki/Space_fountain
Dense atmosphere might enable getting your air breathing first stage higher & could still enable chemical or nuclear assisted reactive launch.
And Orion would likely still launch just fine, just with less payload.
The Cologne Cathedral in Germany was started in 1248 and finished in 1880. That's 632 years.
No.
My hypothesis has always been, hey, have enough kids out there, and sooner or later, they'll learn enough about the physical sciences to at least explore far away worlds. (If not go there in person.)
But yeah, expecting we can get there with what we currently know is a bit naive. We need to, <gasp>, horror of horrors, fund more research.
There are laws of radio propagation that mean I doubt we ever will.
In turn this means a probe needs to get there, and then come back. That is a lot of energy...
I can't say it is impossible, but it is highly unlikely the laws of physics will ever give us a loop hole big enough to pull this off.