There would only be another 34 stars / fruit-and-veg within this 10000km wide sphere. It's pretty empty out there!

That is still beyond humans with present day life spans, but extend life span to ~1000 years or go full AI and you can totally ride the "devil's pogo stick" to stars <=20ly or so awat.

Fusion rockets would probably be better. I mention Orion because we sort of know how to build it today... at ludicrous cost. No new physics and not that much fundamentally new engineering is needed. Orion is a fabulous and quite valid counter to the folks that seem to like to repeat the canard that interstellar flight is impossible. Hard as hell, sure, but not impossible by any means.

To a fully Kardashev type I civilization it might be around Apollo moon shot difficulty.

I’d never say it’s impossible, if we maintain a civilisation for long enough it might even be inevitable at least at a minimal level.

However, Daedalus/Orion is far from as straightforward as has been suggested by you and others. It’s based on projections of technology made in the 70s, not 70s technology. There are also formidable obstacles, such as obtaining enough Helium3. The authors suggested extracting it from the atmosphere of Jupiter or Uranus. That by itself would be as hard as building the vehicle itself, if not harder. I’d like to see a design for a Jupiter atmospheric scoop and return vehicle.

Also Daedalus couldn’t take people. Staggeringly huge as it was, it was a flyby mission with a 450 ton payload. If it was going to decelerate instead it’s payload was about the size of a washing machine.

Orion is kind of shockingly practical. It was forgotten for some time as it was a military research project not NASA or academic.

Once you have propulsion and a ship you're pretty well there.

https://www.wolframalpha.com/input/?i=1%2F2+*+10%5E-4kg+*+(0...

it's 35% of the fission energy released by totally fissioning 1g of U-235!

i.e. I don't know whether this it's feasible to just have a heavy water & lead shield, as 0.1g is fairly optimistic to be the heaviest particle hitting you. Already at this size we're in range of tactical nuclear weapons.

Or more general: Space travel isn't just about speed.

https://www.wolframalpha.com/input/?i=time+dialation+at+0.08...

The unspeakable horrors and mind defying deities in his oeuvre are effectively just reiteration of the "the human race is an irrelevant blip on the universe's radar" concept.

"We live on a placid island of ignorance in the midst of black seas of infinity, and it was not meant that we should voyage far. The sciences, each straining in its own direction, have hitherto harmed us little; but some day the piecing together of dissociated knowledge will open up such terrifying vistas of reality, and of our frightful position therein, that we shall either go mad from the revelation or flee from the deadly light into the peace and safety of a new dark age." - H.P. Lovecraft "The Call of Cthulhu"

I grew up reading and watching a lot of sci-fi. Today I recognize that most of it was garbage in terms of physics, but I'm still saddened that the universe isn't that easy - we can't just hop on a space cruise ship and do a tour of a nearby nebula...

The bigger issue is actually living on mars - as romantic as that idea is, human habitation on the surface is really dumb, the radiation level is not insignificant, so anything long term would either have to be shielded or be under ground. And if we are going to build an underground colony....then why not start with one here on Earth?

If regular travel becomes a reality, you wouldn't shield the launch vehicle, but the cycler[1].

[1] https://en.wikipedia.org/wiki/Mars_cycler

You would accelerate a small vessel (like a crew dragon or orion), intercept and dock with the much larger cycler, then enter the ship for your x-month trip.

When you near mars, you get back into your dragon, and burn away from the cycler, entering into martian approach.

7 people in a Crew Dragon for 18-24 months would not be pleasant. 7 people in a flying space hotel would be far nicer.

You could presumably look at using a small asteroid to provide the bulk of the "cycler", offering plenty of shielding for the trip, you'd only have to get it into position once - far less fuel requirement.

My understanding though is Musk is planning on using BFR to go surface-to-surface, with maybe a refuel in earth orbit. I believe this is because of the amount of material that needs transporting to Mars for the first 20 years or so, and that mass can be used as useful shielding. Even if Mars becomes self sustaining and doesn't require a large amount of cargo:people ratio, I believe Musk is aiming for a much shorter transit time than 2 years.

Or maybe even something like, as some have suggested (not me!), Phobos:

http://enterprisemission.com/Phobos.html

Warning: it's kind of out there. At the very least, it's perhaps interesting as speculative sci-fi.

Not as crazy as claiming Phobos is an alien spaceship though, with highly places ESA sources due to announce it soon (article date 2010)

Because if an asteroid hits Earth or if the world superpowers decide to go full nuclear, the underground colony in Mars will survive (unless superpowers decide to nuke that from here as well...)

So the tradeoff would be risking a finite amount of human lives in the short term to reduce the risk of a total loss in the long term. I.e. over time it becomes fixed vs. fractional cost.

[1] https://en.wikipedia.org/wiki/Martian_lava_tube

Personally I doubt that meat will go to the stars. Planets, sure, and maybe bases or settlements. The stars take too long.

We already organize space missions over the 20 year mark. Communicating effectively with another civilization could be taken just as seriously and done in an organized and effective manner.

It would take a while to get going but once the sharing starts it would be immensely productive.

If we had the political will, the Orion design could get people there in, what, 200 years, and that's with '70s technology.

It takes more than that. We need political maturity and stability. There is no way we can send people today on a 200 years journey and be sure they will both make it and be able to create a somewhat stable society on the other side.

Also, that would be a earth level effort, another thing that is seriously irrealistic right now. The very best we can achieve right now is the ISS and that's pathetic even compared to current tech.

The biggest push in recent years has been around privatisation of space exploration. It is going to take decades, probably centuries before a commercial model of space settles down and non-profit utopist project like that would be conceivable.

Political will in this case brings us more understanding of the feasibility of this propulsion method, but it's way too big of a stretch that political will alone would get us to the nearest starts in 200 years.

A pusher plate can in fact transfer net positive momentum from a series of explosive shockwaves detonated aft of the pusher plate in the desired direction of travel. There’s plenty of video footage from the Hot Rod tests showing it working. https://youtu.be/Q8Sv5y6iHUM

The hot rod test article was actually donated to the national air and space museum unfortunately it is not currently on display. https://airandspace.si.edu/collection-objects/propulsion-tes...

And for the realities of scaling up from conventional explosives to nuclear detonations you can read a little more here http://www.spacedaily.com/news/nuclearspace-03h.html and http://www.projectrho.com/public_html/rocket/realdesigns2.ph... (scroll down till you get tot project Orion and they have a pretty good summary) And the Project Rho information has links to lots of the technical details and material as well if you want to learn a lot more.

What about interstellar debris?

What about deceleration?

And that's just the feasibility of the colony ship, then there's colonization/terraforming, etc.

I'd be thrilled to see such an effort take shape, but to say "it would work" has marginal relevance to "the project is feasible".

https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propuls...

No,the version of Orion that is mostly an integration challenge over 1970s tech would take almost 7 times that long to get to Alpha Centauri as a missile (i.e., without turnover to decelerate to relative rest.)

The even more speculative version was estimated to cut that by a factor for ten to only 133 years, but that's still to a target 1/3 the distance of this one, and still without deceleration.

133, but that's getting there as a missile (one-way acceleration, no turnover and decel to relative rest.)

a) that the planet is not habitable and there were some wrong assumptions about it

b) that the planet is already occupied by a different form of life and there's no warm welcome to us

A) Human engineering can create something that can last 200+ years of space travel. We don't even build houses anymore that can feasibly last 100 years.

2) People don't go mad and kill each other or do a mutiny

III) Any number of stray objects from asteroids to rogue planets that just slams into the ship and causes major malfunctions

d) Food and life support sustainability

I mean... there are SOOOOOOOO many more problems than actual politics. This is where, and it hurts me to say this, the politicians are right to say "are you insane?".

Could we just send frozen embryos of humans and then have the ship auto thaw and gestate them 16 years to arrival?

With another 2-300 years of technological progress this doesn’t seem outlandish mission at all.

If the no-sayers really won and nobody tried, we would have neither.

Which is doable but exceptionally expensive.

Not a strong argument against the ship unless you're calling it a waste of money.

Not trying to be edgy, but I think a lot of society problems stem from more and more globalization. When you're less than a drop in a gigantic pool of people, it's hard to feel like anything matters. Not saying the closed off, nationalism system is any better in the long term. It's just hard to determine a balance to the system. And with that lack of balance, we run away into the escapes you mentioned.

Sigh... well, I just ruined my day thinking about this crap again.

It's weird to be honest. A lot of books/movies think utopia arises in the land of plenty. But I guess a real utopia is where we all suffer against a common threat/enemy. That's when we're most human?

But when it comes to communism, it does have it's upsides. Like now in Venezuela, almost everyone is equally poor as shit. Thus, criminals don't rob people. Bullets cost too much money compared to how much they can rob from people, if they even have anything. That's a win... I guess. Great way to stomp out crime. Make everyone too poor to even bother robbing.

Here's one for you. What if WE are the children currently on a 'ship' (Earth) being sent somewhere..? ;-)

"They sent us a space ship full of corpses?" "Must be an intergalactic message of war."

That's almost as bad as receiving an unlabeled box with a copy of Misery in it.

> Torchship (or torch ship) is a term used by Robert A. Heinlein in several of his science fiction novels and short stories to describe fictional rocket ships that can maintain high accelerations indefinitely, thus approaching the speed of light. The term has subsequently been used by other authors to describe similar kinds of fictional spaceships.

I wonder how long it'd take, seen from the perspective of the ship, if we had an engine capable of delivering a constant 1g acceleration.

That's the way we'll want to travel, after all.

The faster you go, the higher your relativistic mass, so if you accelerate by constant force, the lower your acceleration. Conversely, to keep acceleration constant, you would need larger and larger forces, in the limit ‘infinite force’.

For more and better info, see https://en.wikipedia.org/wiki/Space_travel_using_constant_ac....

The Wikipedia article you linked to calls this (rightly) a "half-myth". It depends on your reference frame.

The spaceship's own reference frame will be a whole different story. If I understand correctly, it will perceive its own mass to be constant, the rest of the universe's relative speed to asymptotically approach the speed of light, but also the rest of the universe to get progressively squashed in the direction of travel (length contraction dual to time dilation), with the two effects multiplying up in such a fashion that the Newtonian relation between the integral of your acceleration and the time it takes to the destination seems to hold throughout.

In other words, for the spacefarer's schedule, it's as if the speed of light does not actually play a role: they can always accelerate more/go arbitrarily faster to get to their destination faster. However, from their point of view, it is as if the universe around them will deform in the process to accommodate this, and from the stationary observer's point of view, it is as if they are actually still moving slowly but tricking themselves into thinking otherwise by accelerating their passage of time.

Seen from Earth, it'll be around 13 years (takes a year to got close to c and another to decelerate - that is two years to travel roughly a lightyear, then 11 to travel 11).

With current tech spread thinly an alpha emitter like Po (2% mass ejected at 5% c) on the backplate and you’ll get 100km/s with 10% payload. Adding an electromagnetic “nozzle” to axially redirect sideway alphas would make it past 200km/s, ie. less then 20k years. Spread thinly enough for the decay leftover - Pb - to be ejected too and you can get to something like 600 km/s, just 6000 years.

Honestly it's far far far better to focus on reaching superhuman intelligence and AGI and then just creating a Dyson sphere around our sun.

At that point we can try to figure out FTL travel...

Can someone explain this situation, what if the travelers reach almost speed light, they will reach on 12 years from earth perspective but for them how long will it take?

EDIT: I wonder how feasible it would be to gather a large enough store of fuel from asteroids or comets before even beginning acceleration. You'd likely have to do it both ways which may make it a one-way trip if the destination doesn't have the necessary resources.

The only way I'm aware of that we could power a long-running acceleration is via a nuclear-powered ion drive. But I don't believe the acceleration is great enough to make a dent in approaching the fraction of the speed of light we need for such a journey in a human lifetime.

Please someone correct me if I'm wrong. I'd love to be wrong.

Physical travel is out of scope, but we could share knowledge in the (extremely) unlikely case that we found intelligent life with radio technology.

It seems technically possible, it is just a matter of paying for something like this and pinning hopes on the next generations to follow through with it and appreciate it. It seems like if we had that sort of will, climate change and some other issues would almost be non-issues.

just pointing that out to say that i think we have technology that would take less time than 450k years :)

so it looks like they'd want to launch by 2036. In the 'technical challenges' section, it does mention that some technologies would have to be miniaturized sufficiently, but it doesnt really mention much about whether that technology has reached viable stages or not, or whether it's a realm they'd have to specifically research further.

So I guess maybe the technology doesn't exist today? Sounds like probably not, but maybe the near future -- or at least they expect it to exist by 2036.

It's worth noting this project has backing by some pretty influential folks, including Stephen Hawking when he was still alive.

So that the signal can be relayed by a bunch of short range transmitters all the way back to earth