Alien life, probabilities, and interstellar propagation of human life

[BWV]

Re the generation ship, SF author Kim Stanley Robinson wrote a good piece in Scientific American a few years back

In addition to the ship by necessity becoming a totalitarian hellhole, this part about out internal ecosystem is one of the unknown unknowns

https://www.scientificamerican.com/article/what-will-it-take-for-humans-to-colonize-the-milky-way1/

We are not autonomous units; about eighty percent of the DNA in our bodies is not human DNA, but the DNA of a vast array of smaller creatures. That array of living beings has to function in a dynamic balance for us to be healthy, and the entire complex system co-evolved on this planet’s surface in a particular set of physical influences, including Earth’s gravity, magnetic field, chemical make-up, atmosphere, insolation, and bacterial load. Traveling to the stars means leaving all these influences, and trying to replace them artificially. What the viable parameters are on the replacements would be impossible to be sure of in advance, as the situation is too complex to model. Any starfaring ark would therefore be an experiment, its inhabitants lab animals.

 

[Hornbein]

an experiment, its inhabitants lab animals.

Wouldn't be the first time. And some people volunteer for such situations.,

 

[BWV]

Wouldn't be the first time. And some people volunteer for such situations.,

but is it ethical / permissible to volunteer generations of your unborn descendants?

 

[PeroK]

Re the generation ship, SF author Kim Stanley Robinson wrote a good piece in Scientific American a few years back

In addition to the ship by necessity becoming a totalitarian hellhole, this part about out internal ecosystem is one of the unknown unknowns

https://www.scientificamerican.com/article/what-will-it-take-for-humans-to-colonize-the-milky-way1/

The last section sums it up, in my opinion:

Unless all these steps are taken, humans cannot successfully travel to and inhabit other star systems. The preparation itself is a multi-century project, and one that relies crucially on its first step succeeding, which is the creation of a sustainable long-term civilization on Earth. This achievement is the necessary, although not sufficient, precondition for any success in interstellar voyaging. If we don’t create sustainability on our own world, there is no Planet B.

 

[.Scott]

I think the Fermi paradox is different than what has been stated here. I think it goes like this:
(1) We can already envision our species spreading through the galaxy. With technology that we know, we could reach nearby stars in a generation ship in a few hundred years. ...

One key phrase is "technology that we already know" - which is not the same as "technology that has already been developed".

There's been some discussion in this thread about how humane it would be to arrange a life for some of our progeny that amounts to a long cruise ship voyage. I don't think this is an issue. People can live fruitful lives under a wide range of conditions - and life onboard a cruise ship venturing to a new star system would be no worse than growing up under threat of nuclear annihilation, rampant neighborhood carnivores, or failed potato harvests. The crew may end up cursing their parents and ancestors, but since when is that new?

But if we are going to develop technologies to make this transit work, we would probably be better off building a genetic human ark. The ark would operate automatically and autonomously. It would simply carry its cargo of biology equipment, training material, and human genome until it was within about 20 years of its destination. It would then begin "extracorporeal pregnancies", followed by automated up-bringing, and then finally graduation to planetary exploration. Before being deployed, the entire 2-decade sequence would be tried and retried on Earth until it was developed to the point of reliably producing the intended results. While we are at it, as we near our destination, we could automatically hunt down and listen in on any alien communications, identify language, political, and cultural norms and include that in the exploration training. Or, we could use that information to avoid the planned destination and seek out an alternative.

One advantage to projecting humans in this manner would be to reduce "cultural drift". A ship carrying fourth (or more) generation Earthlings would deliver a society that would have only the faintest attachment to its remote cousins on Earth.

 

[Hornbein]

but is it ethical / permissible to volunteer generations of your unborn descendants?

You'd have to ask them.

 

[PeroK]

One advantage to projecting humans in this manner would be to reduce "cultural drift". A ship carrying fourth (or more) generation Earthlings would deliver a society that would have only the faintest attachment to its remote cousins on Earth.

It seems to me a no-brainer in terms of resources that any ship would carry the blueprint for life and not generations of live human beings. That said, a major problem would be to identify a planet where we know that we could survive (and thrive). The reality would be a far cry from the Star Trek fantasy, where Captain Kirk and his crew can step out onto any planet and live and breath and get served local food. This is all nonsense.

The planet would have to be uninhabited by advanced life. There could be no question of colonizing someone else's planet. That would be asking for trouble.

The ship would still have to transport the capability to bootstrap human civilization to a large degree. Here on Earth, we have a global supply chain involving billions of people. Everything on the planet B would have to be built from scratch. That means transporting a lot of stuff - even if it's the capability to build the factories that build the required stuff.

Unlike the Polynesians, we can't just take a few tools. Although, you could argue that the colonists would return to a simpler way of life. No roads, cars, airports, hospitals etc. Who knows?

The ship would be enormous. In fact, we'd probably need a whole fleet for a single planet. Getting them off the Earth would be an enormous practical barrier. As would accelerating them to a significant fraction of the speed of light. And, decelerating them at the other end. And, landing all that equipment on the new planet.

These are all problems we have no solution for. Possibly we could have a permanent scientic base on Mars in the next 100 years. I don't see that humans could colonize Mars. It's the old argument: if we could do that, then we wouldn't have the problems of climate change and pollution on Earth.

Even finding a suitable planet B would take centuries. We would have to send an unmanned probe first to confirm that it really is habitable and meets the requirements for long-term human civilization.

 

[Jaime Rudas]

If the universe is truly flat and homogeneous than it's infinite with infinite energy [...] In that case the question is answerable as a definite it's not very rare, because it's happened an infinite number of times, [...]

No, the fact that the universe is infinite doesn't imply that a certain configuration will repeat infinitely.

 

[javisot]

Even finding a suitable planet B would take centuries. We would have to send an unmanned probe first to confirm that it really is habitable and meets the requirements for long-term human civilization.

And then you have to plan the trip and travel there. Perhaps after a certain time the planet will become uninhabitable. That's a lot of complications...definitely.

 

[DaveC426913]

It is a common fallacy that any event one observes must have a probability greater than zero. That is true with finite sets but not infinite sets.

I think it best to think of it like this. If the Universe is infinite then all events have measure zero. All finite sets of events have measure zero. Infinite sets of events may or may not have a measure greater than zero. This is however a slippery topic as it is not easy to rigorously define criteria for set membership here in the real world. "World with intelligent life" is a good example. If you can't define precisely the rule for membership in a set then you can't figure out what the measure of that set might be, even if you somehow were somehow able get enough data.

The upshot is that observing one event tells you nothing about the measure of any set in which it is a member.

Yeah. Which is why such a probability score in an infinite universe is kind of useless.

What we want is a density.

i.e. per given volume what is the likelihood of event x happening?

 

[DaveC426913]

Yes! But it may be childish to point this quoate by agent smith on the matrix that we as in "Humans" are not ujnlike another lifeform on this planet "A Virus" "You infest consume and destroy" as morphus fights to hang on .

That's using it as a metaphor. Like the 'fire' example. Fire is only alive metaphorically.

There's nothng about the definition of life that says it must - or cannot - spread to consume its resources.

 

[Filip Larsen]

The ship would still have to transport the capability to bootstrap human civilization to a large degree. Here on Earth, we have a global supply chain involving billions of people. Everything on the planet B would have to be built from scratch. That means transporting a lot of stuff - even if it's the capability to build the factories that build the required stuff.

Assuming the drive for extrasolar colonization has been preceded by development of autonomous robotic vessels for mining, refining and construction in the solar system, an obvious solution to keep a seed ship "light weight" is to include a set of such robots with it to bootstrap any needed infrastructure from local resources while the biologic (genetic, embryonic or frozen) cargo can be kept dormant for the decades or centuries that will take. Or never, in case the boostrapping fails, which for genetic or embryonic cargo seems to pose lesser of an ethical issue than if "frozen humans" are the cargo.

Of course, the autonomy required for such bootstrapping has to be significant, probably requiring adaptive planning and problem solving skills on the level of a large group of dedicated humans, complete with self preservation and yet also a strong unwavering selfless drive toward seeding the biologic cargo.

 

[QuarkyMeson]

No, the fact that the universe is infinite doesn't imply that a certain configuration will repeat infinitely.

If the universe is infinite and matter is distributed randomly and uniformly, patterns have to repeat. This is because there’s a limit to how many ways you can arrange particles inside a single observable universe. Once you run out of unique arrangements, nature is forced to start repeating them.

 

[.Scott]

If the universe is infinite and matter is distributed randomly and uniformly, patterns have to repeat. This is because there’s a limit to how many ways you can arrange particles inside a single observable universe. Once you run out of unique arrangements, nature is forced to start repeating them.

A couple of comments:
First, you presume an infinite universe but you call out "observable universe" - which may not be infinite.
Second, this is not-with-standing "A-Periodic Tilings" that can take a single simple shape and arrange groups of it in as many ways as needed to fit any size region with unique variations.

I think the conclusion is that "patterns have to repeat", but by the time you have a large enough pattern to meet the definition of intelligent life, even with "enough time" and "optimal remote sensing", you may have exceeded an interesting limit: The Heisenberg Uncertainty Principle (HUP).

There will be some radius "r" from our solar system (think in terms of billions of light years) where only a small percentage of the information between spheres of radii r and 2r could ever be encoded within an object the size of Earth. As "r" increases, that percentage drops. At some large enough (but very finite) "r", we would need to extend our sensors well beyond the solar system to be able to capture and contain enough information to recognize any "intelligent life" patterns in the r to 2r zone.

Edit: After posting this, I went to lunch and realized that I should have made the connection between HUP and information capacity. It turns out that the event horizon of a Schwarzschild black hole reflects the maximum information density allowed by QM. Reducing either the mass of what is bound by that sphere or the radius of that sphere will reduce its information capacity. See "Bekenstein Bound" for additional details.

 

[Rive]

if life started on earth exactly once in 4.5 billion years

Once there is life, every precursor material is just food. No more rolls with that dice.
Regarding probability, a better perspective is that only in ~ half billion years after forming a crust and having liquid water, there was already life.

 

[DaveC426913]

but is it ethical / permissible to volunteer generations of your unborn descendants?

Every culture that has set out to find a new life in a new land has made this choice.

The Polynesians that headed out in canoes for distant islands, the Europeans that headed to the Americas. You can say 'that's not the same thing' but I'd argue it is merely a quantitative difference, not a qualitative difference. Sure, the perils may come in differnt flavours but the results of failure are no less permanent.

They didn't know that their children would survive the storms or the harsh winters or a hundred other dooms. They didn't know what was on the other side of the world. It was as alien to them as zero-g is to us. Perhaps moreso.

 

[DaveC426913]

I think the conclusion is that "patterns have to repeat", but by the time you have a large enough pattern to meet the definition of intelligent life, even with "enough time" and "optimal remote sensing", you may have exceeded an interesting limit: The Heisenberg Uncertainty Principle (HUP).

A scientific American article (that has been referenced here more than once) calculates how far one must go in an infinite (and eternal) universe before one finds a duplicate Earth (or somesuch).

It is far, but not infinitely far. It is somewhere on the order of 10^10^120 metres.

 

[QuarkyMeson]

A couple of comments:
First, you presume an infinite universe but you call out "observable universe" - which may not be infinite.
Second, this is not-with-standing "A-Periodic Tilings" that can take a single simple shape and arrange groups of it in as many ways as needed to fit any size region with unique variations.

Yes, a big caveat to all this is that the universe is truly infinite and that energy is also randomly and uniformly distributed. It appears to be so, but we will never know for sure. I called out the observable universe wrt the notion that there is only a finite number of configurations for our observable universe, so if the universe meets the above qualities then our observable universe repeats infinitely.

Unless I'm misunderstanding the Quasicrystal wiki it appears while there is no translation symmetry, every finite patch repeats infinitely many times. The observable universe is that finite patch.

I think the conclusion is that "patterns have to repeat", but by the time you have a large enough pattern to meet the definition of intelligent life, even with "enough time" and "optimal remote sensing", you may have exceeded an interesting limit: The Heisenberg Uncertainty Principle (HUP).

There will be some radius "r" from our solar system (think in terms of billions of light years) where only a small percentage of the information between spheres of radii r and 2r could ever be encoded within an object the size of Earth. As "r" increases, that percentage drops. At some large enough (but very finite) "r", we would need to extend our sensors well beyond the solar system to be able to capture and contain enough information to recognize any "intelligent life" patterns in the r to 2r zone.

That's true in the mathematical model of an infinite universe. The question is how relevant that is. We may never be certain that the universe is infinite and not just big enough for an infinite model to be appropriate.

Yea I agree 100%. While it would answer the question is there Alien life out there in the affirmative, it does so in a very uninteresting and trivial way.

 

[PeroK]

If the universe is infinite and matter is distributed randomly and uniformly, patterns have to repeat. This is because there’s a limit to how many ways you can arrange particles inside a single observable universe. Once you run out of unique arrangements, nature is forced to start repeating them.

That's true in the mathematical model of an infinite universe. The question is how relevant that is. We may never be certain that the universe is infinite and not just big enough for an infinite model to be appropriate.

 

[BWV]

Every culture that has set out to find a new life in a new land has made this choice.

The Polynesians that headed out in canoes for distant islands, the Europeans that headed to the Americas. You can say 'that's not the same thing' but I'd argue it is merely a quantitative difference, not a qualitative difference. Sure, the perils may come in differnt flavours but the results of failure are no less permanent.

They didn't know that their children would survive the storms or the harsh winters or a hundred other dooms. They didn't know what was on the other side of the world. It was as alien to them as zero-g is to us. Perhaps moreso.

you really think the choices made by premodern tribal groups or European settlers compares to a modern technological society? They also thought nothing of forcibly settling slaves and undesirables and pushing aside natives. I think I would bloody hate my parents if I discovered they had doomed me to a life on a totalitarian hellship, never to see the light of day

 

[DaveC426913]

you really think the choices made by premodern tribal groups or European settlers compares to a modern technological society?

Inasmuch as it is germane to this topic, yes.

The people who decided go to a new land were risking their children's lives on an unknown future. That's inarguable.

They also thought nothing of forcibly settling slaves and undesirables and pushing aside natives.

One of the very real perils those migrants faced was getting slaughtered or enslaved by the natives in the very land they set out for.

And yet, they still went.

By contrast, our modern expeditions into deep space will probably not have to worry too much about slaughter or enslavement where they're going. So, arguably, a safer bet than historically.

I think I would bloody hate my parents if I discovered they had doomed me to a life on a totalitarian hellship, never to see the light of day

I guess you still live in the Olduvai Gorge then?

'cuz unless you're still there, your ancestors at some point, risked their offsprings' survival to bring them - and, ultimately, you - a better life. Inarguable.

 

[BWV]

Inasmuch as it is germane to this topic, yes.

The people who decided go to a new land were risking their children's lives on an unknown future. That's inarguable.



One of the very real perils those migrants faced was getting slaughtered or enslaved by the natives in the very land they set out for.

And yet, they still went.

By contrast, our modern expeditions into deep space will probably not have to worry too much about slaughter or enslavement where they're going. So, arguably, a safer bet than historically.


I guess you still live in the Olduvai Gorge then?

'cuz unless you're still there, your ancestors at some point, risked their offsprings' survival to bring them - and, ultimately, you - a better life. Inarguable.

A few months on the Mayflower, as bad as that was, hardly compares to generations in a dark void

if society is rich enough to build all the necessary infrastructure and technology for a generation ship then it can provide a decent life on Earth that would not require anyone to migrate to another solar system to survive. I don’t buy the analogy of space colonization with the historical migration of humans on Earth.

 

[Algr]

Carl Sagan's Cosmos shows this guy as basically making life, back in the late 1970s.

"These nucleic acids can even make identical copies of themselves. "

That seems like a definition of life to me. In addition to the hypothesis of more advanced life eating any new startups, he also mentions that these specific reactions don't work now that our atmosphere has free oxygen.

But if we are going to develop technologies to make this transit work, we would probably be better off building a genetic human ark. The ark would operate automatically and autonomously. It would simply carry its cargo of biology equipment, training material, and human genome until it was within about 20 years of its destination. It would then begin "extracorporeal pregnancies", followed by automated up-bringing, and then finally graduation to planetary exploration.

I agree that the genetic ark seems far more viable than a generation ship. If a society somehow became so docile as to be able to survive hundreds of generations in that ship, it seems unlikely that they would want to leave it once they arrived at the new planet.

I disagree about automated upbringing though. If AI was advanced enough to do that, it would render the presence of humanity irrelevant. And think of the ethics of testing an AI with a bunch of human babies to see if it can raise them.
More plausible would be to write data to their brains like in a hard drive. The bodies would then wake up with the memories and skills of those who had trained for the mission. You could potentially store millions of people like this, assuring a wide variety of genetic and experiential diversity.

The AI would at least be able to manage terraforming the planet. So no need to regenerate humanity until a breathable atmosphere and some small towns and infrastructure had been built.

 

[Algr]

if society is rich enough to build all the necessary infrastructure and technology for a generation ship then it can provide a decent life on Earth that would not require anyone to migrate to another solar system to survive. I don’t buy the analogy of space colonization with the historical migration of humans on Earth.

True. Living in a cave in Antarctica would be far safer and more comfortable than living on a generation ship.

 

[phyzguy]

There have been discussions here of genetic and cultural drift. If we (or some other race) were to colonize the galaxy, it would take millions of years. Evolutionary changes and cultural drift would be inevitable. This isn't necessarily a bad thing.

 

[DaveC426913]

I agree that the genetic ark seems far more viable than a generation ship. If a society somehow became so docile as to be able to survive hundreds of generations in that ship, it seems unlikely that they would want to leave it once they arrived at the new planet.

I disagree about automated upbringing though. If AI was advanced enough to do that, it would render the presence of humanity irrelevant. And think of the ethics of testing an AI with a bunch of human babies to see if it can raise them.
More plausible would be to write data to their brains like in a hard drive. The bodies would then wake up with the memories and skills of those who had trained for the mission. You could potentially store millions of people like this, assuring a wide variety of genetic and experiential diversity.

The problem is this is just magic/sci-fi/fantasy.

A ship carrying live humans is certainly a challenge but at least it is a tractible challenge.

 

[256bits]

if society is rich enough to build all the necessary infrastructure and technology for a generation ship then it can provide a decent life on Earth that would not require anyone to migrate to another solar system to survive. I don’t buy the analogy of space colonization with the historical migration of humans on Earth.

I think the point is that some people will take the risk, not necessarily for survival or any other comfy reason, to set out to explore strange new worlds, without knowing the actual odds of success due to limited knowledge.

A generation ship would be appealing for many due to different reasons - new frontier, economic gain for the builders, tape cutting ceremony for the politicians, ... Take AI - for all the doom and gloom forecasts. the industry plows ahead into the unknown - the money spent could have been spent on more immediate 'beneficial' endeavors - same argument for war machines, but more destructive capability is always desired - why build a society if the chances that it will get blown up at some point is quite certain.

ElonXVIII in the future proclaiming building ship to the stars, investors and clingers will surely be attracted to something new and shiny.

 

[DaveC426913]

A few months on the Mayflower, as bad as that was, hardly compares to generations in a dark void

Tell that to any of the babies who died en route. Does the ethics matter if, in the end, they dIed anyway becuae of their parents' decisions?

But I'm talking about survival once they got here. Many communities came looking for a better life and disappeared in the harsh of winter without a trace. The Roanoke Colony is a well-known example.

Our history books are fraught with survivor bias; we don't hear much from the dead.

if society is rich enough to build all the necessary infrastructure and technology for a generation ship then it can provide a decent life on Earth that would not require anyone to migrate to another solar system to survive.

This is a very simplisitic view.

After all, one could say the same thing about European colonization. And yet, they still came.

People leave their homeland for a wide array of reasons that have little to do with infrastructure and technology. Some seek isolation, some seek new economy, some seek adventure, some seek freedom from religious persecution. Some are just natural explorers. It has always been the human way.

I don’t buy the analogy of space colonization with the historical migration of humans on Earth.

Then show how can't be analogous. So far, your attempted disqualifiers haven't born fruit.

 

[Jaime Rudas]

If the universe is infinite and matter is distributed randomly and uniformly, patterns have to repeat. This is because there’s a limit to how many ways you can arrange particles inside a single observable universe. Once you run out of unique arrangements, nature is forced to start repeating them.

Is there really a limit to the number of ways particles can be arranged within a limited space? For example, is there a finite number of values for the distance or velocity between two particles?

 

[javisot]

There have been discussions here of genetic and cultural drift. If we (or some other race) were to colonize the galaxy, it would take millions of years. Evolutionary changes and cultural drift would be inevitable. This isn't necessarily a bad thing.

Perhaps it is a problem. Consider that the civilization that spotted a habitable planet in the distance has likely been traveling and evolving for millions of years inside a spaceship. I doubt they're specifically prepared for the new ecosystem. The planet that was "habitable" millions of years ago may not be so upon their arrival.

The best idea is a genetic ark (panspermia in some sense), but it has a problem: we don't know how to create life and civilizations in a laboratory. We put all that genetic material into the ark, and then what?