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Humans will not 'migrate' to other planets, Nobel winner says (phys.org)
43 points by lelf 12 days ago | hide | past | web | favorite | 83 comments

Thank goodness someone is saying it

"We are talking about hundreds of millions of days using the means we have available today. We must take care of our planet, it is very beautiful and still absolutely liveable."

The 77-year-old said he felt the need to "kill all the statements that say 'OK, we will go to a liveable planet if one day life is not possible on earth'."

"It's completely crazy," he added.

You do the math on the energy, resource, and time requirements and it's pretty stark. Only 12 humans have set foot on a body other than the Earth. We have no permanent human settlements elsewhere in the solar system outside of low Earth orbit. We're more likely to set ourselves back hundreds of years in progress with warm or climate change.

Agree with all your points except that "never migrate to another planet"

Humor me for a minute: (from strictly scientific view point)

Universe began with just photons disintegrating to matter and anti-matter. Starting from that somehow proteins evolved and eventually animated matter (life). On a very boring planet after 5 complete extinctions of "animated matter", humans show up who have the audacity to attempt to understand beginning of universe and controlling the forces which created them.

And now, you sir, suggest that this rudimentary life form will never be able to travel to an exo-planet and thrive. Well, to put it mildly, you are lacking perspective.

Ever notice how all the "Ya just gotta believe, man!" are largely non-technical SF fans whereas the people who say it's impossible are mostly scientists who are intimately familiar with the relevant science and engineering?

Ever heard human flight was impossible?

Ever heard that faster than sound was impossible?

Ever heard splitting of atom was impossible?

I understand that I might sound dreamy but here is the thing it's far better to believe, try and fail than to never believe.

I recommend you read the Accidental Scientist book. Its insane how many of human inventions were discovered out of luck. A super fast propulsion tech may be just around the corner and we don't know about it.

My point here is that you can never say never, its not a matter of belief its a matter of the future being unpredictable.

You can never say never. But you can often say "not at all likely".

0.000001% odds are "unlikely", but across a sufficiently large number of attempts by a sufficiently large number of scientists over a sufficiently large number of years, something great is bound to be discovered.

Sure. The odds of any particular "wouldn't it be cool" great thing are fairly low, though.

While we cannot say never, we know enough about the laws of physics to say that FTL won't happen. While there are still unknowns in physics, since those unknowns have to decay to our known physics in all areas we currently know about. That makes finding a loophole hard - assuming one exists.

Note that some physics predicts loopholes, but it isn't clear if they are real loopholes or places where out model isn't right in some detail.

I see your point but the same way as having loopholes which may be a mistake in our model our model can also be flawed in the sense that there are actually more loopholes than we can currently see.

I understand its inconceivable that something can exist that we haven't predicted with our current understanding of physics but we also need to realise that scientists 150 years ago thought the stuff we understand and use daily today were also inconceivable. I am talking about breakthroughs that may arise and after a few decades we'll be looking back and thinking how blind we are not to see them earlier. It happened before it may happen again.

There have always been scientists or natural philosophers or shamans (or whoever else was the most learned of their respective times) who have said "X is impossible" for some X. So far, they've always been proven wrong by a new discovery, often from an unrelated field, that somehow makes X possible. Are we so certain that it's different this time? Interstellar migration won't come soon enough to save us from the climate crisis, but to say it'll never happen is a strong statement.

> You do the math on the energy, resource, and time requirements and it's pretty stark.

The SF author Charles Stross summarized the math on his blog a while ago (and got pilloried for it) and, yes, it's indeed bleak: http://www.antipope.org/charlie/blog-static/2007/06/the_high...

I don't even think it will come to this. The Earth has already starting fighting back. I think it is much more likely that we have massive loss of human life long before the planet becomes unlivable. Empty aquifers, food monoculture, and antibiotics overuse are going to come home to roost and we'll quickly learn what a sustainable population is.

Humans live in stories not in reality. In modern times we have figured out how to sublimate reality with stories, but this process is as old as civilization and propaganda.

So no matter how much stupid shit we do that makes no sense from any rational perspective we can tell a story about how it's good and make it all better. Then when someone like that 16 year old Thunberg girl tells a story that's against all the stories we have been telling we get angry about it going against progress, development, and technology... which are all stories of their own that obfuscate the fact that all of these things are not capable of co-existing with any sort of stable natural system here on earth... as they are meant to continuously destroy and recreate reality. They are in effect to turn reality into fantasy (we call it science fiction) by any means necessary.

it's true that each of us usually lives in a story and we all live in a collective delusion.

But. We all know the feeling in our own lives of suddenly waking up getting real.

You can't wake up as that's all also a story. It's turtles all the way down. All you can do is tell a different story, to change the script so to say. So far we have gone through a few scripts... Polytheism (many gods) -> Monotheism (one god) -> Economism (money is god and the way to reach god (get more money) is through science perhaps). We need to figure out the next story. I think Economism is terminal.

There is no science and epistemology without their drivers. They are in fact the political economy. You can not divorce how they are used from politics.

I don't even think travel time is the biggest problem; that could imaginably be solved with (far) future engineering.

The bigger problem is that our bodies, even our psychologies, are so finely-tuned for this exact environment. Even if we found another planet that could technically sustain us, our bodily rythms, our diets, everything, would be miserably unsuited to it for thousands of years. Not even getting into the possibility of foreign micro-organisms.

People have a hard enough time dealing with the light cycles being off at extreme latitudes, or with not seeing enough greenspace in daily life. You know what doesn't have greenspace? The entire rest of the universe, probably.

So you're willing to allow for far future engineering to solve the time problem, but not the problem of bioengineering the human body?

I think the issue here is that you rapidly get into some sort of absurd state in which you have no idea what to optimize for, or even if you do, you end up "evolving" another species entirely.

Imagine that we could do all of that on Earth. Imagine an individual that has no need for natural light, no need to green space. Go further - perhaps they don't need to socialize, they don't need a diet any more varied than a few pills, they don't need entertainment of any kind.

Combine those mental changes with physical ones (for example, who needs limbs that can support weight if you're in zero-g).

You easily get to the state in which what you're making is no longer a human being but some sort of 'creation'.

It's possible in the sense of "this is not against the laws of physics", it's just hard to really fathom what it means, it becomes a Theseus' ship of "is that thing really still human", I think.

> You easily get to the state in which what you're making is no longer a human being but some sort of 'creation'.

So what? They're still our progeny. Natural evolution will change us just as it always has even if we do nothing. That some future descendant of a human is classed as a different species entirely is inevitable. All the engineering does is accelerate and direct the process.

Right, as I said, there's nothing theoretically stopping this.

I just don't think that creating versions of humans that don't share any of the desires of humans is particularly interesting.

You might consider that the other approach would be to have a general AI that runs in software.

In some sense they are two paths towards the same goal.

It also sterilizes the process. Diversity and complexity and mess are not only beautiful, but robust. Artificial evolution would reduce us to mere mechanisms.

Artificial evolution, whatever that is, can still have randomness. Tom Ray’s program Tierra is a simple and real example. There is no rule saying randomness cannot be introduced. And it can be situated in chaotic environments that further vary what happens.

I'm personally against transhumanism; I think our human nature is the only thing that gives life any meaning. But I understand there may be people here who don't agree with that perspective.

But even just on a practical level, I think it's still a taller order than figuring out high-speed space travel and some sort of cryogenic system.

The only thing! That is a remarkable assertion. I think our surroundings, which determine where our actions land and what impact they have, is another thing that gives life meaning. If we were just living in a void our human nature would not mean much.

And with those two elements: 1) an environment and 2) a conscious being (whether it’s human, dolphin, dog, machine, or otherwise) it would seem that meaningful things can happen. Can’t see why the conscious being needs to be human.

> I think our surroundings, which determine where our actions land and what impact they have, is another thing that gives life meaning. If we were just living in a void our human nature would not mean much.

Sure, but I consider that relationship with our environment to be an aspect of our humanness. Were we perfectly rational systems divorced from nature (and our own natural history), our surroundings would become mere resources.

> And with those two elements: 1) an environment and 2) a conscious being (whether it’s human, dolphin, dog, machine, or otherwise) it would seem that meaningful things can happen. Can’t see why the conscious being needs to be human.

What I meant was that our humanness is what gives our lives meaning, not that humanness is what gives any life meaning.

Given our track record, if we designed our own new form it wouldn't be some higher natural form but a dispassionately "optimal" one. That fact would kill us, in any meaningful sense.

>Sure, but I consider that relationship with our environment to be an aspect of our humanness.

It all gets very circular.

The important "meaning" stuff could survive in the next successor apex life form, let's call it "whatever." Which btw will have an environment, which you may consider an aspect of its whateverness, if not its humanness. And its whateverness will give its life meaning, etc. etc. So there is nothing all that special about humans, in other words, other than we have achieved a lot (not only technologically, but also intellectually) to date relative to other organisms we know about.

>Given our track record, if we designed our own new form it wouldn't be some higher natural form but a dispassionately "optimal" one.

This reminds me of the artist Pablo Picasso who said of computers "...they are useless. They can only give you answers." implying that they can't ask questions or come up with new things.

Why did he think that? I'm at a loss to come up with any reason other than ignorance. Computers are perfectly capable of surprising everyone with new capabilities each year.

We don't have a track record to speak of with artificial life creation, but the danger of creating a boring monolithic life form is not unknown. Usually when we identify problems like this, we find solutions for them. Imagining that we can't is like imagining that computers can only give answers. It's closing yourself off to possibilities emerging from something that is very much open ended and continuing to evolve. It's a kind of religious thinking in that it comes down to faith that humans are, for some slippery reason, uniquely special in ways that nothing else ever can be.

“If an elderly but distinguished scientist says that something is possible, he is almost certainly right; but if he says that it is impossible, he is very probably wrong.”

Arthur C. Clarke

A lot of not so elderly and not so distinguished scientists would also agree with his statement though. All it takes is familiarity with the physical constraints imposed by the speed of light and the distances to the planets in question.

Our current belief is that the speed of light cannot be exceeded. Will we still believe that in a hundred years? A thousand? I have no idea.

He didn't say it was impossible. He said it was impractical. "will not" vs "can not"

I’m not sure that changes anything.

Before anyone has their own opinions and conclusions over what may or may not happen over the next who-knows-how-many years, consider this:

We already have a planet with water, life, food, resources, ecosystems, and everything we need. Isn't it a hell of a lot easier to maintain and respect what we currently have than jump to "re-creating the Earth" somewhere else from scratch?

It is a false choice that we have to protect this planet OR work on the technology to move elsewhere. It doesn't have to be either or. In fact, right now even it isn't. We're putting effort toward both, but the amount spent on moving to another planet is so little it is practically rounding error, so really we are putting effort toward preserving this planet and not moving when looked at through that lens.

There are, however, problems outside of human-made pollution that threaten the planet. Asteroids aren't fiction. The one that was famously recorded in Russia a few years ago shattered windows, but if, by chance, had impacted at a different angle we would have been looking at a crater in the ground and we'd probably be discussing increases to the asteroid defense budget on Hacker News today still. Historically we can see the effects of the asteroid that caused the K-T mass extinction in a variety of places. Reducing, reusing, and recycling won't help us in the cases of stellar-based threats like large asteroids, a field of millions of smaller asteroids that gets captured by earth, or some, as of yet, barely understood phenomenon like a hypothetical traveling black hole or radiation burst of some kind.

Europe already had a continent with water, life, food, resources, ecosystems, and everything they needed. Wouldn't it have been a hell of a lot easier to stay there rather than sailing off over the horizon?

European explorers and early colonist would write back letters or come back with stories about how lush, rich and plentiful the new world was. Walk up to any stream, and just scoop up a fish with your bare hands. Mountains of silver and gold, just under your feet. Of course you would want to sail off into the horizon for a place like that. And they weren't lying either, the new world was an untapped treasure trove. What's the likelihood that another planet is more than just a dull rock. Sure, we can go to other planets, but space looks incredibly dull and inhospitable to me. Compare that to the excitement and prospect of riches early European explorers must have felt, there's just no comparison.

I like that the argument is traveling to a new continent is more exciting than traveling to a new planet. Some of the first people to Australia and the colonies were criminals. The first settlers also dealt with disease and untimely death on a regular basis. You've glamorised it quite a bit when in fact it was miserable.

You are absolutely correct about one thing though. There were many people traveling for a new life. Just like the travels from East to West in the US during the gold rush people went there for wealth, opportunity, and land but not for easy living. I suspect the push for exo planets will be the same.

If we are able to unlock FTL and the time and finacial investment to get there is low or comparable enough to a human lifetime then I see people, assuming we aren't just digital intelligence by then, moving there to start a new life and get away from whatever society is going through. There is always a disenfranchised portion of the population willing to give up their life for a new one somewhere else. Even if the journey and new life is relatively harder to what the rest of society is living in.

There was certainly some very creative and fraudulent promotion going on, leading to families emigrating for the fabulous opportunity and finding themselves in indentured servitude or on some marginal land even worse than at home. Or, like early many colonists rapidly succumbing to new and interesting fatal diseases.

Course having got there they were mostly stuck without coin for passage home.

I too suspect the push to space might go similarly.

In order for there to be letters, someone had to go first before there were any letters in order to write them.

Europeans sailed "off over the horizon" because they could get spices, gold, silk, furs, and slaves. Meanwhile, tech bros want us to collectively invest trillions of dollars to satisfy their infantile power fantasies by bringing back some red rocks.

That's colonization, not migration. Migration implies moving the majority population, while colonization is just sending seed colonists out and letting the colony mostly grow via internal births.

If the future is stable than chances are very good we will be flinging colonists everywhere, but the majority of earth's population will still stay planetbound

Yes I agree. In fact I'd argue migration is much less of a concern than colonisation. If colonies are established and work is put in to make it at least a decent liveable environment, people will move. Hands down, people will move.

But they didn’t have ‘spices’ and they knew who did.

There's certainly an argument to be made that even the absolute worst places on Earth to try to establish a settlement (Sahara desert, Antarctica, Mariana Trench, top of Everest) are all orders of magnitude less challenging than going to Mars, which is in turn orders of magnitude easier than leaving the solar system.

But it still isn't a reason not to try, especially now. Elon isn't wrong about the possibility of the window closing, especially in various future scenarios where climate change and war disrupt global supply chains.

I don't believe the message is "don't even try", it's more "this isn't anywhere near as realistic as you think it is and if you're relying on it for our continued survival you're a fool".

There's the potential of a lot more money to be made exploiting new frontiers. Europeans already had all that stuff in Europe and it didn't slow anybody down to the colonies.

He who controls the spice controls the universe!

Is there anyone (in discussions about this topic) advocating not maintaining and not respecting what we currently have? I've seen comments similar to yours made in every single discussion about colonizing off Earth, and I've never seen a useful discussion as a result.

Not when the sun grows to envelop Earth. Sure that’s a long time from now but eventually it will happen.

And a life-ending asteroid strike very likely will happen many orders of magnitude sooner than that. Could even be in the next hundred years. We don’t have a way of knowing when.

Given the progress on climate agreements in the last years: yes

I've always felt this kind of view seems rather bleak. Humans will only go down one of two paths. Either humans and human history will be entirely wiped out from the universe when Earth inevitably becomes uninhabitable, or human ingenuity will triumph and humans will be spread out all over the universe and not be just a blip in time confined to the lifespan of our solar system.

Why not hope for the latter? The argument being made here, "Earth is good enough and we need to take care of it, it's crazy to think that we'll ever live anywhere outside of this solar system", is essentially, in the long term, "the human species is doomed to die out when our sun dies, and probably much sooner than that". That feels so pessimistic to me.

Of course, protecting Earth is important, and probably a higher priority. But if you don't believe humans will make it off-world, then it's just delaying the inevitable. And if that's what you believe, I guess there's no point trying to convince you otherwise; it's not like any of us will be around to see that happen anyways. But if you do believe humans will survive longer than Earth, why is it "crazy" to start working on ideas to make that a reality? Even if it's not feasible, as Mayor says, "using the means we have available today", surely the path to inventing the means that do make it feasible starts from improving the tech we have today? We can work harder on taking good care of our planet while also starting to think in earnest about the plan for the survival of humankind - there are plenty of people and resources in the world, working on this doesn't necessarily substantially detract from efforts to protect Earth.

The article is about exoplanets, so Mars etc isn't what he is talking about.

That said, if we are talking about Mars, I would guess that by the time it becomes an economically viable solution to overpopulation, early 21st century technology will be insignificant. (sorry, Elon) We have an immense amount of space on Earth that is cheaper to populate, and will remain so for a long time. While it's sad to think of all the regions of Earth becoming densely populated with humans, its unrealistic to think we'll populate Mars prior to having all our oceans and deserts covered with people.

Its too late for your pessimism - I was heavily conditioned by Star Wars and video games as a child, and you're saying "will not" which means "never" (only a Sith deals in absolutes). Therefore I will not stop wondering how we could better reorganize elements and people to the end of extra-terrestrial Earth-sourced-life-propagation.

To be fair - I interpret his statement as one that calls for us to not keep our heads exclusively in the clouds (pun). Fixing our current planet certainly requires priority, focus, career choices, and lifetimes. This is required of us to develop the Type 1 Civilization that can be handed down to the predecessors that will, in fact, "migrate to other planets".

"We used to look up at the sky and wonder at our place in the stars. Now we just look down, and worry about our place in the dirt." -Joseph Cooper, Interstellar (media propaganda meant to inspire current generations. Ad Astra is the most recent push)

Another good one, same character:

“We’ve always defined ourselves by the ability to overcome the impossible. And we count these moments. These moments when we dare to aim higher, to break barriers, to reach for the stars, to make the unknown known. We count these moments as our proudest achievements. But we lost all that. Or perhaps we’ve just forgotten that we are still pioneers. And we’ve barely begun. And that our greatest accomplishments cannot be behind us, because our destiny lies above us.”

Wasn’t Ad Astra the antithesis of Interstellar though? Ad Astra seemed to argue against horrors committed for the sake of achieving greatness, eventually destroying us when we lose sight for what it is all for—people. Interstellar seemed to argue for the necessity of losing this humanity on the chance that it will work out anyway (an optimistic take on Murphy’s Law)—Cooper abandoning his daughter; Brand pushing the artifice of Plan A; Mann sanctifying his survival instinct; all to “rage against the dying of the light”.

For example, look at Clifford McBride of Ad Astra. He’s the “best of us” succumbing to the same tests of character as Dr. Mann of Interstellar—even repeating his same poignant line “yes…yes…yes” to affirm absolute commitment to the mission: the fall of the brightest angels to evil committed for an ostensible good. The difference of messaging is in the outcome of their missions: the failure in Ad Astra to find intelligent life, versus the success in Interstellar to save the species.

Also fun mentioning that Ad Astra ends like Blade Runner 2049, where the cold protagonist, employed as the system’s greatest weapon, regains a sense of humanity after subverting the system’s mission. Though Roy actually completes it for them, still pedaling the propaganda that you should ultimately still serve the oppressive system.

I saw Ad Astra as a story told with a backdrop of a near-future humanity that has established permanent settlements on multiple terrestrial bodies. At the time of your comment, I had not yet seen the movie - I'd only seen the cover poster displaying a well-known space-suit-clad citizen chosen by society throughout the past couple of decades to demonstrate ideas and experiences (Brad Pitt, same with Matt McConaughey). Movie, television, music, and now algorithmic news feed themes are my preferred methods of gauging public sentiment (programmed or natural). The final detail of the end credits says that there were "15,000 jobs created by this film". This verifies the interest and subsequent investment channeled into a theory and demonstration of the interstellar human experience.

Now I am fresh out of the movie theater, and have consumed the media in it's entirety. The first person narration of Roy began the film with this line:

"I always wanted to be an astronaut... at least that's what I told myself."

This seemingly confirmed my theory of "propaganda meant to inspire current generations". But then the protagonist's ailments became apparent post-primate-attack when he is conducting his psychological evaluation. He describes how he is familiar with the rage of the primate. He understands their pain, but unlike them he is able to discard it and carry on, "remain calm" as he says at the beginning (debrief psych eval describing the fall from the antennae). This is the first instance of violence committed by a life-form confined to a metal tube in a vacuum for an undisclosed amount of time (the Norwegian craft was meant for biomedical research, and perhaps the primate aggression was exacerbated by human experimentation).

Then there are the comfort rooms - a solution meant to simulate conditions on Earth so as to soothe the distressed extra-terrestrial-human.

To paraphrase one of the final quotes of the movie, Roy describes the need to "rely on others and share their burdens as they share his". The pain of solitude was not worth the prospect of discovering "other life". He has no children to orphan in the name of relentless exploration ("yes, yes, yes"), as his father did - yet he realizes he is living out a similar life while underwater on Mars sneaking his way onto the Neptune-bound ship...

It should be exoplanets rather than planets in the title.

+1 to this. Article has no bearing on Mars development efforts, refers only to exoplanets. Also seems to attempt to dispel misunderstandings about exoplanet distances and feasibility - perhaps some people think that a solution to climate change is for us to move to an exoplanet?

This may be a common misconception outside of nerd circles, I'm not sure. And in that way, this take is correct. But it was my understanding that with mostly-present-day technology we could construct generation starthips and eventually one day create civilizations on exoplanets themselves. I see nothing stopping that - contrary to the statements in the article.

As a solution for problems on Earth? Sure, not possible. As something humans could do one day? Sure, very possible.

If we can send people for generations in space, we believe we can live sustainably.

If we believe we can live sustainably, we should be able to do it here.

We aren't doing it here, suggesting we're dreaming if we think we can do it elsewhere. Even if we aren't, the best we to show we can do it is to live sustainably. We're not.

We could at least show we could live sustainably underwater or in Antarctica, but we can't, even with a world of resources and help, and they're easier than space.

It seems the best way to make other planets possible is to live here sustainably. I suggest we devote the resources we're using on those problems (space travel) on this problem (sustainability on Earth), since it will also help those problems, if they're possible.

It would be easy to find thousands of people to volunteer to set forth on an ark that wouldn't arrive at another planet for generations. It'd be an enormous technical challenge, and cost a fortune, so it's unlikely to be funded any time soon, but there's no technical limitation if the will is there. Some day the will may very well be there.

I'm not endorsing the idea, nor do I think it's likely in my lifetime. It won't be necessary for the survival of the human race any time in the next billion years. That doesn't mean people won't want to do it eventually, if for no other reason than to explore. There was never any reason to climb Everest either, yet individuals devote their entire lives and fortunes to doing so.

Just because we don't have to do it doesn't mean it's not something people will want to do.

We'll probably become a hive-mind synthetic species long before anyone considers it, but if you call that human, eventually it'll get there.

We don't have experience dealing with the psychological consequences of certain death among thousands of people confined in a tin can without any chance of external help.

To prove your theory, we would have to gather these thousands of people in a dome in the middle of nowhere, not help, not let them leave at all costs, and maybe enforce a % of deaths to simulate what could reasonably happen in space. Find volunteers for that.

N.B.: He’s talking about extrasolar planets, not Mars.

"Never" is a word used by those with a poverty of the imagination.

We still need some way to live on a planet other than Earth for the sake of insurance in case something happens to Earth that we cannot control.

Humans may not migrate to other planets but our nonbiological descendents might.

The problem is that we don't have the foresight necessary to know this. If we crack FTL or inertial propulsion, a whole ton of options open up.

FTL travel is straight up science fiction, ok? Look, I would absolutely love to be proven wrong on this, but literally everything we know about physics is telling us that FTL is impossible. Ditto inertia-less propulsion to a slightly lesser extent.

> If we crack FTL

.. we can time travel.

But we don't see anyone from the future here, so it seems to be impossible.

Not if the Alcubierre drive works, which there's no reason to believe it doesn't. Cracking FTL doesn't mean just stepping on the gas really hard.

There is a good reason to believe that Alcubierre drive does not exist. It's allowed by Eninsteins equations if you have negative energy but quantum gravity would invalidate it.

Einstein's equations allow all kinds of weird solutions that physicists don't believe can really exist. Discovering them is just a way to study the equations theoretically. Alcubierre Warp Drive Metric or Gödel metric (rotating universe) are just two of them.

no need for FTL travel if we can just bend the universe hard enough.

If you bend the universe, you're bending time, as well.

> Clarke's First Law: When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong.

Transporting people with current human lifetimes might not be practical. But brain scans on a computer? Or people in some form of cryogenic state or with life extension tech?

I'd say that's a fair bit easier. Still not trivial, but manageable with a lightsail.

> Transporting people with current human lifetimes might not be practical. But brain scans on a computer? Or people in some form of cryogenic state or with life extension tech?

Or a generation ship. The most common approach proposed is a self-contained ecosystem that can grow the food and recycle the waste necessary to keep the ecosystem going and to support a breeding population of people, plants, and animals for the hundreds of years the trip takes.

That approach seems pretty far in the future. I don't think anyone has ever built a self-contained ecosystem that comes anywhere near close to being able to be self-sustaining for any great length of time.

Another approach might be possible that doesn't require a self-sustaining ecosystem, and seems much more in reach. The idea is to send most of the people as frozen eggs and sperm. Same for the animals that will be needed to establish a colony at the destination. Send the colony plants as frozen seeds.

The only already born people you would send is a small crew to operate the ship. They operate the ship for one generation, then make the next generation crew from some of the frozen eggs and sperm, train them, and hand off the ship to them. Repeat until the ship reaches the destination, and the final crew then uses the remaining frozen eggs and sperm to make and raise the colonists. Same for the animals and plants.

Because this approach only has a small crew on the ship at any time, it should be feasible to include their food upfront when the ship leaves. If you use food that has a large calorie/volume ratio, a lifetime supply of food for a person fits in a space that is probably smaller than you would guess.

For example, a typical protein bar is about 200 calories. If you need 3000 calories a day (space crewing is hard work!) for 100 years that works out to about 547500 bars. If each bar has a volume of 10 cm^3, you could store all that in a cube 176 cm on a side. Enough for a crew averaging 10 people at a time for 400 years would fit in the volume of a small single family house.

Why would volume matter at all when it comes to storing food? Space in space is the next best thing to free, after all.

The real thing to be concerned about is mass.

None of the things you listed are possible or realistic in the next 50 years.

Even if I accept that life extension tech and destructive brain scanning is more than 50 years out, why would that mean humanity will never reach the stars?

50 years or 5000, as a species it just needs to happen eventually.

too late for major climate disruption.

Occurrences of the word "Impossible" in the article: 0.

It's not a great idea to just reject what could be the "great filter" for the species.

“Humans” is a huge and unfounded assumption. It doesn’t need to be humans as we know them today.

If we destroy ourselves first, agree.

If we persist and advance technologically, disagree.

Only a tech limitation.

Reminds me of those who didn't believe atom bombs were possible of those who believed humans wouldn't have flying machines.

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