Alien life, probabilities, and interstellar propagation of human life

[Algr]

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 tractable challenge.

That sounds like a personal theory to me.

https://www.technologyreview.com/20...brain-cells-chip-organoid-speech-recognition/
https://www.science.org/content/art...n-cells-electronic-circuits-and-make-it-think

Meanwhile, the closest thing we've tried to a generation ship was Biosphere II. Not a promising start.

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

North America was more "habitable" than Europe for a variety of reasons, especially once they figured out most of the tricks of living here. It was also possible for people to return to the new world and tell everyone how wonderful it was. Colonization efforts were expected to return a profit to investors back in Europe. (This rarely succeeded, but was plausible enough that people kept trying.)

And living in the new world meant freedom from the restrictions of Europe - a freedom that you'd likely actually live to see. Living on a generation ship will be anything but free - Not an m³ of unclaimed space anywhere on the ship. Strict limits on reproduction, including with whom. And even when your descendants got to the new planet, they would still be stuck living in caves - perhaps forever if terraforming can't be made to work.

The planet that was "habitable" millions of years ago may not be so upon their arrival.

Humans would have to wipe out almost all existing life on any new planet we'd find. There are millions of different organisms floating around in our atmosphere, the new planet would likely be the same. But our immune systems would never have encountered any of them before. If 1/1000 of those organisms decided that humans were yummy, that would be a thousand black plagues at once.

Tribes encountering Europeans for the first time sometimes saw 95% of their populations wiped out by disease. This would be worse. Our only consolation would be that it might go both ways. So what we would really want is a planet like very early Earth, around the time of the oxygen catastrophe? Because maybe such primitive life would be easier to defend against?

 

[phyzguy]

That sounds like a personal theory to me.

https://www.technologyreview.com/20...brain-cells-chip-organoid-speech-recognition/
https://www.science.org/content/art...n-cells-electronic-circuits-and-make-it-think

Meanwhile, the closest thing we've tried to a generation ship was Biosphere II. Not a promising start.

North America was more "habitable" than Europe for a variety of reasons, especially once they figured out most of the tricks of living here. It was also possible for people to return to the new world and tell everyone how wonderful it was. Colonization efforts were expected to return a profit to investors back in Europe. (This rarely succeeded, but was plausible enough that people kept trying.)

And living in the new world meant freedom from the restrictions of Europe - a freedom that you'd likely actually live to see. Living on a generation ship will be anything but free - Not an m³ of unclaimed space anywhere on the ship. Strict limits on reproduction, including with whom. And even when your descendants got to the new planet, they would still be stuck living in caves - perhaps forever if terraforming can't be made to work.


Humans would have to wipe out almost all existing life on any new planet we'd find. There are millions of different organisms floating around in our atmosphere, the new planet would likely be the same. But our immune systems would never have encountered any of them before. If 1/1000 of those organisms decided that humans were yummy, that would be a thousand black plagues at once.

Tribes encountering Europeans for the first time sometimes saw 95% of their populations wiped out by disease. This would be worse. Our only consolation would be that it might go both ways. So what we would really want is a planet like very early Earth, around the time of the oxygen catastrophe? Because maybe such primitive life would be easier to defend against?

You're being too planet-centric. The future of space exploration is living in space habitats that we construct. Try reading, "The High Frontier" by Gerard O'Neill. We can build structures in space that will be very pleasant places to live.

 

[QuarkyMeson]

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?

Yeah, see Scotts post here for more information:

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.

Given a finite volume and finite amount of energy there are only a finite number of possible states.

 

[BWV]

The High Frontier" by Gerard O'Neill.

from 1976? For a more contemporary look at the difficulties would recommend

https://www.amazon.com/City-Mars-settle-thought-through/dp/1984881728?tag=pfamazon01-20

https://astrobites.org/2023/10/31/book-review-a-city-on-mars-by-kelly-and-zach-weinersmith/

 

[phyzguy]

What does settling Mars have to do with space habitats?

 

[BWV]

What does settling Mars have to do with space habitats?

The book also talks about moon bases, but in any case the biological and habitat problems are the same.

 

[DaveC426913]

That sounds like a personal theory to me.

It doesn't even come close being a theory. It's simply a supposition.

But it's a darn site less wild than "we can send embryos out in a ship and a magical AI will thaw them, feed them, raise them, train and them and they will not only survive but somehow still qualify as functional humans."

 

[DaveC426913]

North America was more "habitable" than Europe for a variety of reasons, especially once they figured out most of the tricks of living here.

Hindsight is always 20/20. Those that set out didn't have that benefit. They still went.

Ask the Roanoke settlers if they were confident they would not encounter any perils that put their children in danger. They didn't say "let's don't go".

 

[PeroK]

Hindsight is always 20/20. Those that set out didn't have that benefit. They still went.

Ask the Roanoke settlers if they were confident they would not encounter any perils that put their children in danger. They didn't say "let's don't go".

I think you underestimate the difference in scale and technical feasibility between living on a single planet and finding and moving to a new planet. Whales swim across the oceans and birds migrate significant distances every year. From that point of view, there is nothing technically difficult about roaming the Earth. The first voyage of Columbus lasted 7 months.

The early European explorers had a wealth of sea-faring experience. There were dangers, of course, and they were courageous and adventurous men. But, ultimately, they knew what they were doing. And, these voyages could be financed with a realistic expectation of financial return for the investors.

By the time the Mayflower sailed, 130 years after Columbus, a lot was known about the New World. Raleigh had brought potatoes and tobacco back and the Spanish has colonized (and oppressed) much of South and Central America.

And, the US was not populated by the Pilgrim's and their descendents. The population came from later mass migration.

By contrast, sending a hundred or a thousand people to planet B would be a one-way trip lasting hundreds of years. If we were routinely travelling around the Solar system - taking holidays to Jupiter etc - then, we might have some grip on the scale of the technical problems. Even that first step of manned travel across the Solar system may be centuries away. That's why a scientific base on Mars is relevant. Because that's a first, necessary step in the technical and engineering progression. In fact, perhaps a Moon base before that.

We are nowhere near a Moon base. We are nowhere near a base on Mars. We are nowhere near a manned spaceflight (even with a few astronauts) to the planets of the Solar system. It's impossible to talk about doing stuff beyond that until we are able to the basics.

There seems to be a common way of thinking where things that are closer to reality are accepted as impossible (e.g. massive carbon capture to control climate change or artificial human incubation or genuine AI). Yet, things that are many times more complex, expensive and far-fetched are assumed to have to technical barriers.

The key example, which has been argued on here previously, is the idea that if we can't control climate change on Earth, we'll have to move to Mars and other planets. That way of thinking makes no sense to me.

Until we know how to do the basics of manned space travel, we cannot seriously talk about expanding to other planets. That is so far beyond our current capability as to be impossible to seriously consider.

 

[256bits]

Yet, things that are many times more complex, expensive and far-fetched are assumed to have to NO technical barriers.

That is your meaning I do dare declare.

By contrast, sending a hundred or a thousand people to planet B would be a one-way trip lasting hundreds of years.

No one would give a hoot with so few.
The thing would get cancelled before laying the foundation.

I would think a 100,000 to a million for the endeavor on a living generation ship.
Extravagance would pay off. Human nature the more expensive the more desirable and more justifiable. Human nature shows its irrationality, Every village, town, community, gets to send a couple so that they all are in it for the game to support their favourite son and daughter on a one way trip of a lifetime. And once your in, you reap the awards in real time with jobs, job, jobs. No need for future return on investment. The present paycheck is the reward to keep the project going, even through generations of employment.
Pretty much how the present day economic system works, and has worked throughout history. Egypt's Valley of Kings, Sistine Chapel, Stonehenge, Cern were all projects known to take wealth and spend it on the elite, the ego, the community belief, the highly educated for no immediate apparent benefit and payoff to the society at large, except that it was desirable and necessary.
Of course all these projects succeeded and are still standing today.

The 'still standing' concept for the generational ship does have the detractors in that it, the trip, would not be a sure thing as to its arrival at destination, or the sustainability of a colony, even if all technological hurdles could be overcome.

I can envision one ship, and if it and the colony make it then good; of not then, s__t, we ain't gonna build another one. And get on with out lives some other way on the next other mega project round the corner of which I can not think of one. ( maybe a hollow earth ).

 

[PeroK]

I would think a 100,000 to a million for the endeavor on a living generation ship.
Extravagance would pay off.

It's impossible to debate with anyone who has lost all touch with reality!

 

[256bits]

It's impossible to debate with anyone who has lost all touch with reality!

1 million for a generational ship is reasonable.
20 million for military world wide personnel is not reasonable. --> but it does keep the jobs, jobs, jobs continuing and the immediate, rather than future, return on investment is apparent.

China, USA, and Russia, all considered some of the worlds largest, in total employ some five to six million individuals. World wide, the military personnel is close to 20 million, with expenditures just short of 3 trillion $. All that metal and know how, put out together with the idea that the machine and personnel will survive, but might not, in action. Any action is expected and recognized, with returns from deployment is cherished, and with the unliving solemnly honored or martyred.

There is little to no difference in sending soldiers into action, from sending a group to a far distant planet. They survive or they don't, on pre-planned decision making. Larger the contingent, the greater chance of success.

 

[PeroK]

There is little to no difference in sending soldiers into action, from sending a group to a far distant planet.

I guess you are right. Just a few days ago, almost 100,000 cricket fans packed into the Melbourne Cricket Ground (MCG). If you can transport 100,000 people to the MCG and get them back home safely, why not transport 100,000 people to Alpha Centauri? Or, all the way to the Andromeda Galaxy, come to think of it?

Melbourne, Australia or Alpha Centauri. What difference can it possibly make?

 

[javisot]

We don't have the technology to make our planet permanently habitable. We don't have the technology to make another planet permanently habitable. We don't have the technology to make interstellar space permanently habitable. We don't have the technology necessary to produce civilizations in a laboratory.

It seems our future (lacking the necessary technology) is to be nomads who alternate between interstellar space and some hypothetical habitable planet, like Earth. Of course, we could also become extinct before all that.

 

[Filip Larsen]

20 million for military world wide personnel is not reasonable.

With that line of reasoning, then why not just go for the entire human population if its that easy? Just build bigger. Or fit some rockets to the Earth. Then everyone is literally in the same boat so the added benefit is there is no ethical issues as no one needs to volunteer.

 

[BWV]

ISTm that so many of these arguments are so far ahead of themselves - the technological prerequisites for seriously contemplating this -new technology, advances in biology, off-earth infrastructure, not to mention a sufficient history of interstellar probes to identify a possible target planet (and presumably these would have to be 2-way trips to analyze the environmental chemistry of potential targets)- are centuries away

This will become all the more obvious when it becomes obvious to everyone that permanent human settlement off Earth in our solar system is not going to happen for many of the same biological and engineering reasons argued in this thread

 

[PeroK]

YouTube was inspired by this thread and served up Interstellar Overdrive by Pink Floyd:

 

[256bits]

I guess you are right. Just a few days ago, almost 100,000 cricket fans packed into the Melbourne Cricket Ground (MCG). If you can transport 100,000 people to the MCG and get them back home safely, why not transport 100,000 people to Alpha Centauri? Or, all the way to the Andromeda Galaxy, come to think of it?

Melbourne, Australia or Alpha Centauri. What difference can it possibly make?

Technologically you are correct. Doing stuff on earth surface is way easier than outside the biosphere.

You are missing the point, though.
The hurdle of human ingenuity can surpass logic, even before the details of the actual engineering is finalized.

1. NAWAPA - the plan to divert most water from as far north as Alaska to the parched N. American western-central area. Afterall, the water was being wasted, just running into the ocean. NAWAPA plan is presently dormantm but still could be resurrected, under the right conditions.
NAWAPA, Kelly once observed, was “10 percent engineering and 90 percent politics.”
NAWAPA would require the construction of 369 individual dams, canals, pipelines, tunnels, and pumping stations. Its builders would have to move 32 billion cubic yards of earth and 30 million tons of steel. Its largest proposed dam would be 1,700 feet tall, more than twice the height of Hoover Dam (and far taller than any dam in the world today). Parsons and his staff estimated that the project would cost between $100 and $200 billion over 30 years — or, in today’s dollars, somewhere around $760 billion and $1.5 trillion.
https://www.buzzfeednews.com/articl...-forgotten-project-that-could-have-saved-amer
Not surprisingly, there was political support.

2. The Red Sea Dam project 2007 estimated to produce 50 GW of hydroelectric power, explored the damning of the southern part ( and northern ) of the Red Sea, a crossing 20 miles wide, 200 to 500m depth, costing somewhere 200 billion $. The damn itself would be 1000 miles across when (if) completed, with an optimal head of 611 meters ( if reached ) as the Red Sea level drops by evaporation.
Not really going anywhere.

 

[256bits]

With that line of reasoning, then why not just go for the entire human population if its that easy? Just build bigger. Or fit some rockets to the Earth. Then everyone is literally in the same boat so the added benefit is there is no ethical issues as no one needs to volunteer.

Why?
Just add engines to the earth then and tow it then.
You too are missing the insane proposals that some human will make, and get support for if conditions are in their favour.

 

[256bits]

This will become all the more obvious when it becomes obvious to everyone that permanent human settlement off Earth in our solar system is not going to happen for many of the same biological and engineering reasons argued in this thread

I so feel the same way.

But the Mars colony is being proposed and discussed as if it ( the engineering ) is a done deal by the proponents that have the money, and supposed knowledge
Complications? What complications? We have to get off earth and expand into space to survive.
To me that is just hustle to win people over, curry favour, win investment and keep the game going.

My argument is that in the future, the generational ship will be hustled as necessary.
And bigger the lie, the more it is to be believed.
So, not some rinky dinky generational ship, but a humongous one to inspire awe and the feeling that the guru must know their stuff.

 

[Filip Larsen]

You too are missing the insane proposals that some human will make

In this case that someone was you. Which is my reply was thick with (unmarked) sarcasm. Are you now saying your hand-waving arguments on generation ships also have been meant as sarcasms all along?

 

[PeroK]

I so feel the same way.

But the Mars colony is being proposed and discussed as if it ( the engineering ) is a done deal by the proponents that have the money, and supposed knowledge
Complications? What complications? We have to get off earth and expand into space to survive.
To me that is just hustle to win people over, curry favour, win investment and keep the game going.

No one with any sense takes Musk seriously in this regard. Not only will no one finance his plans (because there is explicitly no ROI) but no one with any sense believes we can build a city on Mars.

My argument is that in the future, the generational ship will be hustled as necessary.

You can hustle all you like, but the engineering realities will have the final say.

 

[256bits]

In this case that someone was you. Which is my reply was thick with (unmarked) sarcasm. Are you now saying your hand-waving arguments on generation ships also have been meant as sarcasms all along?

No. And not hand wavy on human nature.
Look at all the casinos that people go to to win big time, knowing its a scam.

Once some colonies on moon, Mars, or wherever pan out, if they do, the generational ship thing tagged as being the 'next step' for the future, people that buy in, whether to reap the benefits of $ building the thing, or signing up to go on the ride for adventure.

 

[256bits]

You can hustle all you like, but the engineering realities will have the final say.

Cost overruns may get it cancelled in the end.

 

[256bits]

No one with any sense takes Musk seriously in this regard. Not only will no one finance his plans (because there is explicitly no ROI) but no one with any sense believes we can build a city on Mars.

I gave no idea what the minimum size of humans would be necessary to have a viable self sufficient community on Mars, so yeah, I don't take him seriously either with the tin can proposal of limited living space.

 

[PeterDonis]

the engineering realities

On time scales of thousands or millions of years, the engineering realities can change drastically. The engineering realities of Stone Age humans ten thousand years ago would not even have comprehended something like computers or the Internet or sending humans into space, let alone been able to assign any kind of probability estimate to them.

The only realities that will not change are those of the laws of physics, and those do not forbid humans from colonizing other planets. So I think it's quite plausible that if we humans survive long enough, something like that is likely to happen. The key barrier I see is that qualifier I just put in, which is not an issue that can be addressed by engineering.

 

[DaveC426913]

I think you underestimate the difference in scale and technical feasibility between living on a single planet and finding and moving to a new planet.

I do not. It was my point was that it is a difference in scale. The vast majority of the difference is a quantitive difference, less so a qualitative difference.

Recall the genesis of this argument. This is where it all started:

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

Yes, I assert by historical example. People have always gone into the unknown risking their born and unborn children to do so since pre-history.

That is as true for a space journey as it is for an atlantic voyage.

The numbers and percentages may be different (quantitative) but the sentiment does not change (qualitative).

That's it. That was my whole point.

 

[DaveC426913]

No one with any sense takes Musk seriously in this regard. Not only will no one finance his plans (because there is explicitly no ROI) but no one with any sense believes we can build a city on Mars.

I didn't think I'd see self-driving cars in my lifetime. But it seems if you throw enough money at something, miracles can occur.

Musk is well on his way to being the world's first trillionaire.

I am skeptical about a Mars colony, but I am a little less skeptical now.

 

[PeroK]

On time scales of thousands or millions of years, the engineering realities can change drastically. The engineering realities of Stone Age humans ten thousand years ago would not even have comprehended something like computers or the Internet or sending humans into space, let alone been able to assign any kind of probability estimate to them.

The only realities that will not change are those of the laws of physics, and those do not forbid humans from colonizing other planets. So I think it's quite plausible that if we humans survive long enough, something like that is likely to happen. The key barrier I see is that qualifier I just put in, which is not an issue that can be addressed by engineering.

Absolutely. The problem is that we have made so little progress since the Moon landings. In an alternate human history, we might have had a Moon base by 1990-2000 and a Mars base by about now, and have mastered Solar-system exploration by about 2100. We could achieve that with spaceships doing 100,000km/hr, perhaps?

The next step would be to develop probes going at perhaps 0.2c to explore a series of exoplanets. Perhaps by 2200-2300 we might have had a shortlist of possible exoplanets. Assuming, of course, that living on a different planet is feasible.

At that point, we would have some idea of the feasibility of sending humans to one or more of those planets. At the moment, we have little idea of the feasibility of any of this.

 

[PeroK]

I do not. It was my point was that it is a difference in scale. The vast majority of the difference is a quantitive difference, less so a qualitative difference.

It's a fundamentally different project to a) build a city on Earth; b) build a city on Mars; c) build a city on an exoplanet.

They are qualitatively fundamentally different projects.

It's a bit like the difference between walking up a hill in your local park against climbing the face on El Capitan. The latter requires the development of rock-climbing techniques and equipment that are not inherent in the former. It's not just a question of scale. It's a question of technical difficulty.

It's not just that Alpha Centauri is further than Melbourne. The project to get there has almost no similarities.

PS the Saturn V rocket wasn't just a big commercial aircraft. And, getting back from the Moon was all unique and inovative technology.