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Comment by petercooper | Hacker News Reader

"just 12 light-years away"

I love the "just". I know it's nearby on galactic scales but it's practically about 450,000 Earth years away with current technology :-)

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To give a sense of the scales involved - if the sun were an orange and the earth a grain of sand 6 meters away, this star would be a pea about 5000km away.

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

I’m amazed that the specks on the grain of sand can even be aware of the pea that’s 5000km away in the first place.

Look into Project Orion. With thermonuclear bombs you could hit 8% c, which would get you there in "only" 150-200 years including acceleration and deceleration time.

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.

Is that subjective time for the crew or objective time? Is there much of a difference at 8% c?

Little time dilation at 8%, so not a big difference.

Assuming 200 years for people on earth, the traveler would experience 199.4 years

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

>Orion is a fabulous and quite valid counter to the folks that seem to like to repeat the canard that interstellar flight is impossible.

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.

Not Daedalus, Orion. It was a 1960s research project involving Freeman Dyson and others. Google it. There is a fantastic documentary that I think is on YouTube.

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

Do you acknowledge the fact that interstellar travel entails more than just speeding up and slowing down? Because that's what Dyson would be telling you if he were here.

You need a nuclear-powered airtight bunker that can sustain dozens of people, but that's also buildable with 70s technology.

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

One of the main unsolved problems is the electromagnetic shielding, both front and back (as you need to turn to decelerate). Even at 0.08c every speck of interstellar dust has enormous impact energy, far worse than the radiation of your own bombs. AFAIK this is unsolved.

follow-up: here is what wolfram alpha spits out for a 0.1 grams dust particle hitting you at 0.08c:

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.

You will essentially kill dozens of people once they hit an interstellar cloud with anything bigger than a sugar molecule at 2/5c.

Nuclear salt water rocket would likely be even faster, but unlike Orion is still just a paper concept at this time.

Do we actually have navigation technology to travel at 8% c without crashing into deadly space debris?

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

Space is called space for a reason. Even in real life asteroid rich orbits the odds of hitting something are very low. Pulp sci-fi asteroid fields like the ones depicted in Star Wars are just not a thing. Outside the inner solar system the odds of hitting anything are so low the risk doesn't really rank in comparison with things like major equipment failure in transit.

And "just" 24 years over radio if there's anyone there to talk with ;).

I doubt I'm alone in this, but I do find it simultaneously amusing and depressing how mind bogglingly big the universe (or even the galaxy) is. It's clear that discovering entirely new levels of physics will be necessary to stand a chance of going anywhere.

Or extreme life extension, or fully digital AI. Life span is a big part of the problem.

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

You're not alone.

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...

Going to Mars may be routine some day, though!

Just going to Mars will significantly increase your risk of cancer, unless we find smart ways to repair our genetic material as we go.

Well, for the journey itself the problem has a simple solution - more shielding. Then of course we have to answer the question of how can we get ships into orbit when they are full of shielding, but that's not insurmountable.

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?

Then of course we have to answer the question of how can we get ships into orbit when they are full of shielding, but that's not insurmountable.

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

The benefit of using a cycler rather than a ship that travels orbit-to-orbit is that there is no need to accelerate/decelerate the mass of the ship, just the perishables (people and provisions for the voyage)

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.

> 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.

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.

Grand theft moon? That's as crazy as Space 1999.

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

> And if we are going to build an underground colony....then why not start with one here on Earth?

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...)

I'd argue that a colony at the bottom of our own ocean would survive literally any event of any magnitude, maybe except for a direct asteroid strike. In terms of survivability of the human race, that's a better project to start with - and of course then move on to other planets, but underwater/underground colonies would give us lots of insights into living in such environments permanently.

Fair point, but then we forgo learning how to build a rocket to leave this rock should there ever be a need.

Just....do both? Have a proper, city-size, self-sustaining colony on the bottom of the ocean, and at the same time keep developing rockets and vehicles to bring as much material and and many robots over to Mars as physically possible. Like, I don't think getting to Mars is an issue - we probably could send and even land someone on Mars within a couple years if we absolutely had to. But then the question is - what then? That's the hard problem.

The pressure range range between vacuum, mars atmosphere and earth atmosphere is 10⁵Pa. The pressure at the bottom of the ocean is 10⁸Pa. Humans can survive the former with little more than strong tensile garment and a breathing apparatus, the latter requires massive, crumple-resistant pressure vessels around everything.

Finally someone with the sense to realize what difference an order of magnitude can make to a decision. Now lets compute how likely we are to die by an asteroid vs how likely we are to die being stranded on a barren, frozen rock 60M Km away from the nearest source of critical supplies.

That depends on your time horizon. Probabilities of catastrophic events tend towards 1.0 individually. But within the same time horizon you can keep it close to 0 with sufficient redundancy and recovery.

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.

The good thing is that Mars is chock full of dormant lava tubes[1]. That provides a solution to the problem you propose assuming we figure out how to seal them and make them habitable for human life. It is an exceptionally difficult, but tractable problem. FTL travel however, is not tractable at all with our current tech and (lack of) understanding of physics.

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

you are not alone

Count your blessings. The vast separation between stars means that star systems can have stable planetary orbits for billions of years, which is important for life to develop.

I've read that most of Lovecraft's is derived from the horror at realizing how insanely large in both space and time the universe is.

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.

Well that just cries out for a quote :)

"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"

beautiful, thank you!

Or entirely new levels of lifespan. Just upload yourself to the grid and boot up in a few million years.

Why 24 years? Radio travels at the speed of light, not half the speed of light, right?

Roundtrip time.

HAHA! Thanks, sometimes I need a kick in the rear. I was thinking one way.

Any response would take 12 years as well.

To me this sounds feasible.

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.

> I know it's nearby on galactic scales but it's practically about 450,000 Earth years away with current technology :-)

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

Are you talking about the propulsion system where a series of nuclear explosions push the vessel along?

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

yes, we should explore (and eventually exploit) all forms of propulsion and decide between them based on physics, not politics

That Orion project was a failure though. No tangible results to exploit.

my point is that because of fear of nuclear no further research was done. It is now super hard to even get enough material for a rector/battery such as the one on Curiosity

I think it more just ended than failed.

Imagine being the child born on the ship on a crash course to this new planet.

And imagine you're the first ship to arrive only to find out

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

Sounds like the premise of Aurora! Which definitely turned me off the idea of multi generational starship travel. It's not ethical.

This is also assuming

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?".

Of course we’re far from it, if ever possible. I was just being playful on the whole premise of “colonizing” another earthlike planet

Oh, I'm not bashing you at all. You're absolutely correct. You bring up extremely important things to realize when discussing space travel. Especially long term missions. Political will being the reason why these missions haven't happened, as someone else mentioned, is total crap. It's just an easy excuse to not think of ACTUAL consequences and live in a scifi fantasy.

Yes I agree, we seem to be working on the wrong problems or get the priorities wrong. We keep on inventing newer technologies which come with newer problems while the ship is slowly but surely sinking. Sometimes I wonder what would it take for all of us to join a concerted effort to concentrate on the real problems we have. Technologies seem to veer into an escapist route, some way for us to run away from the problems we do have: virtual reality, leisure space travel, AGI, synthetic life, immortality.. I hope we'll eventually wake up in the last hour, at least to acknowledge where we've gone wrong.

I think this is exactly why there's an apocalypse fantasy/fetish. It's in our psyche that we're all focused on... well... dumb shit. A post-apocalypse lifestyle makes you focus on what I think we can all truly appreciate as important. There's a lot of interesting studies done on localized disasters where the idea of community actually erupts out of it. People working together and sharing, regardless of their "social status". It's all short lived until the outside world aid arrives and you still get a few bad actors in the mix (though it seems statistically, no where near as many as we think). Generally though, it takes hell on Earth for us to regain our "humanity".

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.

I have a similar experience from my childhood. I grew up under communism in eastern europe and I remember the crisis we were going through at the time, food was rationed and there were long queues everywhere. People were even joining queues without knowing what was being sold and some would start lining up overnight. I was a kid back then and didn't experience the adversity first hand but I could see and sense what was going on. Aside from these things, however, I remember how helpful and inclusive the community was. People were sharing whatever they had, whatever they cooked, recipes, anti-establishment jokes, books, video tapes, etc. There was this sense of belonging that now has dissipated completely. I was struck with a deja vu when I visited Cuba a couple of years ago. People are poor but are sane and happy in their own ways and they have time for one another. There are still disparities but not like in a western society when one counts their pennies and the other their billions. Romania, the country I grew up in, has been engulfed in corruption and asides from a cities with large concentration of wealth, everything is in disrepair, the community disappeared almost completely and everything seems to have gone downhill for the past 30 years. In no way am I decrying the communism, it was brutal to many, but what has ensued after the fact was a veneer of shiny nothing.

So, I was born in the USA, but my parents are from Poland and left a few years before the collapse. They shared many similar stories with me over the years. Generally, when the environment is bad, the local people are good. But the reverse is true too. When the environment is good, people tend to suck.

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.

Meh. 200 years aro they would have called you insane for wanting to fly between continents, let alone to the moon.

They also would have called you crazy for saying you wanted to turn lead into gold with alchemy. Fact is, most of the time the people who say something can't be done are right.

Yeah but they don't matter. All the trying was worth it, because I can fly halfway around the Earth for a few hundred bucks now. If in a different world I got gold out of lead but no airplanes, it would be fun too, but in a different way.

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

> They also would have called you crazy for saying you wanted to turn lead into gold with alchemy.

Which is doable but exceptionally expensive.

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

Nitpick: we can actually transmute, either by fusion or fission. Sure it's not economically effective, but then neither was Apollo.

The crazy ones are the ones that change the world/universe. For the right price, it would make sense to invest in such a venture.

> d) Food and life support sustainability

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.

that sounds highly unethical. none of those people agreed to go on the trip

did any of us agree to go on our current trip? I do see your point but I think eventually humans might do it.

Man, B is a good problem to have.

Imagine being the child born on a small island, or in a country to which few other countries are willing to grant visas, or simply to parents who don't have much money.

Imagine being the child born on the ship on a crash course to this new planet.

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

> If we had the political will

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.

Would a vessel from 50 years from now beat the original crew there? If we assume we are advancing speed-wise by X% each year, the poor folks sent and likely put into cryo-stasis would get lapped by people who left 10 years or 25 years after them.

There are a number of SF stories where this is the plot.

Imagine waking up out of your cryo-stasis and seeing humans already living on the planet you were sent to colonize? That would be weird, to say the least.

I bet there's a science fiction novel about that

If there isn't someone should write it.

I have read one. Many years ago, don't remember much about it. But I'm pretty sure it also discussed how all of the "future folk" were disgusted with the smell of the ones that had been traveling in cryo for 200 years. Too much perfume/deodorant...they didn't like the flower smells anymore as I believe they had engineered themselves to not perspire any more.

You could get their corpses there, sure.

Just got to make sure we put on the side of the ship, "Greetings from Earth!"

"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.

The Orion program had this potential on paper. Nuclear bomb propulsion is a complicated thing, but we don't understand if it's a feasible propulsion method in practice, like, at all.

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.

Actually we do know it would work. The fundamental physics are sound.

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.

The propulsion could work. What about sustaining life for 200 year biospehere without any external resources?

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".

If I remember it correctly, the fast project would make 4 light years in ~150 years. So that would be 450 years (probably less, because it's on constant acceleration).

> If I remember it correctly, the fast project would make 4 light years in ~150 years.

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

If you enjoy the idea of propelling space ships using nuclear explosions, look up nuclear salt-water rockets (NSWRs, or Zubrin Drives). The idea is to dump pipes full of sub-critical amounts of radioactive salts out engine, combining outside the ship in a continuous nuclear explosion.

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

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.

I smiled as well but with a slowly but steadily accelerating ship we can reach half the light speed and get there in 50 years. It put things in the realm of "possible" which is amazing.

now do some napkin math on the reaction mass and energy you need to slowly accelerate that much for that long

And the energy transferred by an impact with a piece of dust at luminal speeds

Now do some napkin math on the amount of gears and levers you need to reach such calculating power, mr. Babbage.

don't forget, you're going to have to slow down at some point, too

https://en.wikipedia.org/wiki/Torchship

> 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 think current technology makes no sense when talking about interstellar travel.

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.

constant 1g acceleration gets you to speed of light pretty quickly (around 1 year), so still around 12 years.

If our current ideas about physics are correct, acceleration _never_ gets you to speed of light.

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 faster you go, the higher your relativistic mass, so if you accelerate by constant force, the lower your acceleration.

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

As far as I understand, viewed from Earth's reference frame, a spaceship accelerating by constant force will get heavier and heavier as it gets faster, and thus get less and less speed out of it, asymptotically approaching the speed of light but never exceeding it. Moreover, crucially, any pingbacks from clocks on the spaceship we observe will appear to be progressively going slower than they should. (Time dilation)

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.

Unfortunately, radiation from hitting hydrogen atoms in interstellar space starts to become deadly around 0.25c or so, IIRC.

No, it will be much less as seen from the ship.

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).

Course, assuming you want to orbit your destination when you arrive ... at some point you'd need to turn that 1g in the opposite direction to decelerate. (And I'm mighty impressed by the energy source that provides two years of continuous thrust.)

Lot of details relevant to this question here: http://math.ucr.edu/home/baez/physics/Relativity/SR/Rocket/r...

>450,000 Earth years away with current technology

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.

By way of comparison the entire 'human'species is about that age. += 250-500k years depending on how you measure.

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...

This! If you look at all the life on Earth, humans are the only ones to have maximized brain functionality and evolved to change their surroundings on a global scale. We should continue focusing on superhuman intelligence and AGI which will solve problems that we cannot simply right now due to our evolutionary limit at this point in time.

Time for the travelers will go slower, for earth time will be 450k years but for travelers will be less.

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?

I believe the problem is that with current technology it isn't realistic to expect to accelerate continuously to a fraction of light speed where time dilation will be noticeable. We lack the ability to get a large enough amount of fuel off the planet and we obviously can't decelerate to harvest more fuel on the way there because then we lose the benefits of the continuous acceleration.

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.

let's see if someone will try to upsell the Musk

No, it's 12 years away by radio wave, which means 24 years for a round trip communication.

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

If we were to realize Breakthrough Starshot, then it'd be right around the cusp of how long I'd think we could maintain institutional interest in it. 60 years to get there, 12 years to get the signals back, so 76 years. If you worked on it right out of college and longevity stays around where it is, you might live to see some pictures. You definitely could tell your grand kids about it though.

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.

there is an effort to put super mini spaceships on missions to other solar systems, and they would travel at something like 20% the speed of light. I think it works by having the probes be like the size of a cellphone or something, and being attached to a solar sail, then using an incredibly high powered laser to pump the solar sail full of energy to get it going so fast. I think if that architecture works they could reach ... proxima centauri? ... in something like 20 years.

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

However, a transmitter with enough power to signal earth would be too massive to get fast with a solar sail, given today's technology. Maybe a chipsat gets to 20% c, but no way a dish does.

Found the wiki page for the project: https://en.wikipedia.org/wiki/Breakthrough_Starshot

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.

What if the chipsat sends the signal to the chipsat behind it which sends the signal to the chipsat behind it which....

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

Probably requires a surprising amount of short range transmitters to be launched then. I wonder if a formula could be developed that relates the energy needed to place one large transceiver at a given distance versus the energy needed to place small transceivers all along that given distance.

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