I would assume generational ships could be staffed with farms that grow high calorie, high micronutrient crops that can be grown under artificial lights powered by nuclear power. So it wouldn’t be an issue I would assume.
Also, in theory, a more advanced civilization could probably transfer their consciousness to robotic bodies that required far less upkeep and were far more robust than our biological bodies. It would be easier to transfer your brain (or if possible, just your consciousness) to a robotic body than to terraform an entire planet’s atmosphere to make it friendly to our biological bodies. Right now this is science fiction, but it won’t be in 200 years.
The number is probably bigger than 1 in a trillion. If there are 10 filters to having intelligent life capable of technology, and each one is 1 in 100 of being passed, that means you have a 1 in 100,000,000,000,000,000,000 chance of intelligent life in the universe.
Dolphins and Elephants are intelligent, but they don’t have the biology of primates which allows for civilization (opposable thumbs, writing, etc). Instead of their being one giant filter, there may be dozens of smaller filters and each one has to be passed for intelligent life capable of technology to evolve.
I think the biggest problem with generation ships is that they are a closed system - if something breaks down, and you can’t fix it, you’re screwed, so you have to take not only your equipment, but pretty much your whole industrial civilisation, and a lot of spares of things. It’s an engineering issue, but not a small one.
Or have robotic custodians who look after the equipment that vat-grows new humans once the ship arrives safely - the outcome is the same as a generation ship, but without people needing to expend their whole lives on the journey.
But that’s part of the thing that, for me, makes it kind of futile (and so very different from any kind of travel, emigration or colonisation humans have ever done before). If I can fly to another Earthlike planet in a tolerably short space of time, I’m up for it. If I have to spend my life travelling there so that my grandchildren, who aren’t even concieved yet, can grow up there, why bother? Why not just not-bother?
I agree about the closed system issue. I do not know what the solution is. In theory in the reasonably far future technologies like 3D printing and nanotechnology will make manufacturing broken parts much easier, but if you run out of raw materials it isn’t like you can just stop at a random planet and mine a bunch of new elements to convert into ship parts. I guess part of the issue is that just as long as you have enough raw elements (and the ship itself isn’t going anywhere, its parts will just break) you can repair and replace them with broken parts if your technology is advanced enough.
Shutting down consciousness would probably be a better idea than living in our biological bodies for 60 years while we travel to a star 12 light years away. I assume it would be more like that.
I’m really not sure what the appeal of colonizing the entire galaxy is. I’m assuming by the time we have the ability to do that, that we will require far fewer natural resources since many of us will live in virtual reality. So it isn’t like we will need the raw materials of a trillion planets and suns for our civilization.
There is no serious scientific doubt about the presence of life elsewhere in the Universe. It’s out there, somewhere. The relevant question is not whether it exists, but how far away it is. It’s possible, for instance, that it’s so rare that most galaxies don’t even have a single planet with life, meaning that our nearest neighbors are many galaxies away. In that case, we probably won’t ever communicate or interact with them in any way. But that’s not the same thing as them not existing.
Or, of course, it’s possible that the Universe really is teeming with life, with some form of it being found around nearly every star, and possibly independent instances around different worlds around the same star. We just don’t know.
That’s a bit too strong. There is a little evidence for multiple origins of life on this planet, but it’s very circumstantial. All extant life that we’ve found uses the same genetic code, true, and thus must have a common origin. But I’ve seen studies which suggest that, out of all possible genetic codes, some would be better than others, and that the one we have is in fact better than 99.9% of the others. That still leaves a combinatorically-huge number of possible codes which are at least as good as ours, but it suggests that in our planet’s history, there has been life based on many different genetic codes competing against each other, a competition which our lineage won long ago (long enough ago that no trace remains of the other lineages). Of course, that still leaves open the possibility that the different code-lineages still had a common ancestry, but you’d have to have an awfully simple organism indeed for a significant change in the code to be possible: At that point, you start getting into questions of how complex you have to get before you call it “life”
yes, there are simply too many other galaxies out there containing too many stars for there not to be at least one other body (be it a planet or a moon of one) containing complex life forms.
but we will never know for sure. I don’t believe FTL travel will ever be anything other than a device to move along the plots of sci-fi media.
Not seeing your point. Maybe it would help if you defined what you mean by “Earthlike”. If you are actually including “comfortable for humans” in your definition, then you’re not really discussing what the OP is asking about.
I certainly think the OP is making an unsubstantiated assumption when he says:
but the gist of the OP is not about worlds that can support human life.
which sounds like massively overwhelming odds but…even with a conservative estimate of stars in the observable universe it still suggest a thousand incidences of intelligent life.
But “human life” (by which I mean life based on proteins and nucleic acids, likely evolved in energetic hydrothermal vent environments) is the only kind of life that we know for sure is possible. Alternate chemical structures/energy sources/temperature ranges/solvent enviroments are pure speculation.
Well, that’s the broadest definition of “human life” I’ve ever heard, but even if we go with that, we don’t know that life on earth likely evolved in hydrothermal vent environments (it’s one hypothesis), and even if it did, we don’t know that the planet I linked to does not have such environments.
Someone on this board mentioned a gradual spreading out. Start with Mars perhaps, then asteroid mining, then Titan, Oort Cloud…Alpha Centari and so on, reaching farther out as technology advances .
This would take a long time but, assuming we last long enough, does not seem out of reach. Barring a breakthrough in physics and given the will, this approach might work.
I think that life is probably very common given the number of star systems.
However, intelligence does not necessarily inevitably lead to the development of technology. It does not seem unreasonable to speculate that an intelligent lifeform might exist that has a rich, highly advance culture but evolved in an environment that does not require technology.
A familiar example might be whales. Having the ability to feed simply by swimming along with your mouth open, travel long distances by propelling yourself through the sea, being able to communicate over long distances could lead to never needing to develop technology. This does not stand in the way of developing a culture that may be unrecognizable to a human, and which remain undetectable because there is never a signal to detect.
It is possible that intelligent technological culture is very rare and may never be found. This is not a reason to stop trying but as much as I would like to see contact, I am not confident.
The universe is definitely not teeming with life; it’s not even teeming with mass. Matter is spaced pretty thin: star systems are trillions of kilometers apart.
Mars, which is in the habitable zone, may have had life in the past and might have life on it now. But it’s not “Teeming” with life, and our probes haven’t spotted any dinosaur-like fossils. Crack open a meteor and while there might be traces of inter-stellar micro-organisms inside that we’ve yet to discover, it isn’t exactly a flower garden. Volcanic vents notwithstanding, life isn’t especially tenacious. If it was, some of the micro-organisms blown off the earth would have adapted to the vacuum of space, and managed to feed off lunar rocks and the sun’s rays. Titan would be covered with slow-crawling megafauna. Asteroids would be encrusted with space barnacles.
Space? Teeming with life? That isn’t teeming, this is teeming.
I have a hazy recollection of a sci-fi story where the first extraterrestrial message received on Earth is something like, “Be Quiet! They’ll hear you.”
Perhaps I shouldn’t point out that life forms living around hydrothermal vents do use an alternate energy source. Possibly a different temperature range too, can’t remember.
As for life on other planets, I think it’s only found on a fairly small fraction of stellar systems. Perhaps only one in a few hundred. I’d elaborate but I have another life form sitting in my lap that makes it hard type right now.
Not only this, but any extraterrestrial life that might be encountered will be so bizarre (morphology, biochemistry, etc.,), that we might not initially even recognize it as Life.
When we actually look it appears most stars have planets
The less common case of planets of the right size in the right orbit existing with the right materials may be unlikely but will happen.
“Life” increases the amount of information in a system and thus is tied to entropy.
Given the example of the Earth, and how quickly life developed it is highly unlikely it did not also happen in other places.
Unless we can identify some property that makes the Earth unique in the entire universe there is life other places.
IMHO simple life is probably common when the conditions are correct
Other realities in our current understanding of physics will make it extremely hard to detect or interact with any of these other locations where life arose.
Most likely, almost all if not all forms of life will be water based.
I fully expect simple forms of “life” to be discovered on the moons of our solar systems gas giants
Thus we will never really know outside of our own solar system.
Why rule out chemistry with open systems, organized into cells, having a life cycle, undergoing metabolism, capable of growth and adaption to its environment, responding to stimuli, reproducing and evolving on Titan with methane and other hydrocarbons as the liquid solvent? Slowly.
The wanting life to exist elsewhere is all well and good, but wanting it is not enough to conclude it probably exists. The existence of life that happens at the same time as our existence is probably naive, for example, given a near-infinity of time, both past and present, for that non-earth life to make its appearance. Perhaps we need to expand our frame of reference.