P ?= NP is IMO way more significant for a start, to say nothing of questions about consciousness, fusion energy, ways to explore and colonise space, ...
This tells you nothing unless you also know the probability of (intelligent) life emerging on a planet. As far as we can tell it could be very low, and earth could very well be a unique combination of factors that allows it. Remember, there are many more possible deck of 52 cards than there are planets in the universe.
In that case we can't treat our existence as independent of the existence of other nearby civilizations.
So then.. maybe only the civilizations that aren't expansionist survive? Or everyone changes their mind and no one is expansionist by the time they get the right tech? Or maybe it's physically impossible to build von Neumann probes for some reason we don't yet understand? Or who knows what else. In any case, it's got to be zero in the history of our galaxy.
Also don't forget that the purpose of the probes is exploration and/or resource harvesting. For exploration you only need a handful of probes at each star system and they may depart after completing their survey which would result in a very small footprint. For resource extraction you need some means of transporting the resources back to where they will be used in a timely manner which puts limits on the effective distance at which they can operate.
A civilization may even decide that it's pointless to explore the entire galaxy this way since it would take millions of years to gather and transmit the information, what government do you know of that's capable of planning over that kind of timescale?
That said, it only takes a tiny fraction of their civilization to do it, for it to happen.
1) The idea is that we will do it, not that we have done it already. (How does something we will do in the future affect what we see today? It doesn't, at least not causally. It's just that some civilization had to be first in the neighboorhod, and that civilization will be the one to preempt the others, at least according to this model. So it's more of a probabilistic conditioning effect than a causal effect: conditional on existing, that means no one preempted us, which means we're the first, which means we'll preempt everyone else.)
2) The preemption happens well before the other civilizations come into existence. For example, we might deplete their stars of energy so that evolution doesn't happen at all on their planet.
Interesting. That's a point I haven't heard before. Or perhaps it's my lucky 10,000 day. :-)
Although our path through the galaxy is somewhat unique. Stars don't really move in unison in the greater timescales, but more like slip past each other. Assuming Sol was born as a binary star, its sibling could be other side of the galaxy by now.
Another thought is that if WE do expand to the stars, how long until our distant ancestors aren't really the same civilization anymore, but something completely alien to each other? Evolution could take some rather unexpected steps in the long run.
Rather, it refers to those stars which are within reach of us, now, in a timescale that is short relative to the typical interval between births of civilizations that distance apart. That could be anything from a corner of a galaxy to a galactic supercluster, depending on the speed with which civilizations can expand and the frequency with which new ones arise in the universe.
Note that if civilizations expand at sufficiently close to the speed of light, then there is only a tiny window of time between when their light arrives and when their colony ships do. So under this model, it is quite unlikely that a new civilization waking up for the first time would look around and see anyone. Most likely, either the light from those other civilizations hasn't yet gotten here, in which case we see nothing, or their colony ships have already gotten here, in which case we wouldn't be born in the first place.
If a civilization doesn't have FTL then expansion beyond their solar system seems unlikely. Yes, it is still possible with sub-light travel, but then you run into the problem of motivation.
When limited to sub-light speed trade between colonies and the home system is so slow that you probably can't usefully import resources from the colony systems.
When you are stuck with sub-light, colonizing another system (unless perhaps you are in a place with a lot of stars close together) is more accurately described as spending a whole lot of effort to establish another system that then won't really have much interaction with or effect on your system.
Even the old classic of kicking out your undesirables who then go on to start a new civilization doesn't really work, because it is so expensive. If you dislike them so much that exile is the only answer and you don't have someplace in your system to exile them to you are far more likely to just kill them.
> When limited to sub-light speed trade between colonies and the home system is so slow that you probably can't usefully import resources from the colony systems.
I mean this seems to disregard our entire history as a species. There have always been "others" within a population that seek, above anything else, to find a new place to go in order to live life they way they want to.
We are also moving into an age where data and knowledge are raising to supreme importance. Both of these things can be transported at the speed of light, so a multi-solar system civilization that is able to increase is total resources available to acquire new information and knowledge will be at an advantage. Then, of course, there is the desire to preserve the human species as a whole by "spreading our seeds" so to speak.
If the energy and time requirements are great enough, space between solar systems will work as the same sort of barrier space does for the rest of life on Earth.
Sure, but those who have successfully done that have either went to a place near enough that they could take all the food and other supplies they would need during the trip there with them, or have went to a place where food and other resources were available on the way.
I can't think of any human group that did a migration that had to cross a span that provided no food or drinkable water and was too long for them to cross on what food and water they could carry with them.
With sub-light migration to other solar systems we are talking about crossing empty spans that will take several lifetimes to cross. There are ways to deal with that, but they are likely to be major undertakings that require a heck of a lot of resources so that to do it you need widespread support from the people who aren't going.
My guess is that you'll need a pitch much stronger than "We want to go someplace to live our way" (especially since the people who leave won't be the ones who arrive at their destination--it will be their descendants).
But the region we can observe is definitely finite.
What we can causally affect (light cone) is a subset of that.
And where we can travel given the Ultimate Technology is a small subset of the previous.
Life is not only probable, it's inevitable. Given the proper conditions, it's just a matter of time. And the same happens with intelligent life, it just needs more time without being hit by a meteor.
Given the proper conditions, that is. A planet that is just a ball of magma won't see life (as we know it) until it cools down.
The Rare Earth solution to the Fermi Paradox is as good a guess as any. Life of some kind might be relatively common, but intelligent life could still be really rare. We are the only species on Earth in 3.5 billion years to make radio telescopes and spacecraft.
On other worlds, it might never happen because of the thousand different factors that led to hominid evolution which might be different elsewhere. For example, If the non-avian dinosaurs hadn't gone extinct from a large meteor impact, who knows whether any technological civilization would have ever formed. At any rate, mammalian evolution would have gone differently, and it's anyone's guess whether some non-hominid intelligent species would have evolved instead. They didn't during the age of the dinosaurs.
We don't even know whether multicellular life is a low probability event. Maybe Cambrian explosions don't happen very often.
There's no inevitability here, only unknown probabilities.
FWIW, the actual paper does not put it like that. It instead calls it "one of the most profound and fundamental questions posed to science". That seems reasonable.
> Given the number of stars out there, it seems wildly improbable that we are alone, and if we're not then it's anyway going to be basically impossible to communicate with them due to speed of light limitations.
Don't you find it fascinating that we think it's wildly improbable that we are alone, yet have not been able to find other life? I certainly do.
Ignoring the huge philosophical implications intelligent life elsewhere would have, it would also provide some very useful bounds on a bunch of the quantities involved in e.g. Drake's estimate. It would also offer some clues as to whether or not a great filter is likely, and wheter or not it lies ahead of us or behind us. Surely massively important!
> P ?= NP is IMO way more significant for a start
Important, yes, but not a scientific question (it is a mathematical one).
> to say nothing of questions about consciousness, fusion energy, ways to explore and colonise space, ...
A complete understanding of consciousness would also be monumentally important, I agree. But fusion and space exploration? Great, but surely "just" (huge and important) technological advances, rather than fundamental scientific questions?
Given that we can scarcely communicate with a chimpanzee, our nearest living relative, nor fully comprehend how any other species on Earth communicates (those which evolved under the same conditions that we did), I find it totally unsurprising that we're unable to communicate with aliens.
That's as much as we can manage with chimpanzees - our immediate relatives, who we have physical contact with.
Humans scarcely care how other earth-bound species communicate enough to identify it as communication - how do insects and plants and fungi communicate? What information is whale song (mammal) transmitting? Is the 52 Hz whale communicating, or not?
Alien communication will look far more different even than that.
We haven't been looking for very long, and out searches have been very very limited.
In part this has to do with the Fermi Paradox. Are we alone because we're in a protected garden? Alone because the half-life of civilizations is very low? Alone because there is a firewall that takes out all civilizations at a particular level of development (like say climate change)? Maybe if we learn about the firewall we can do something about it? The list of answers to the Fermi Paradox is immense and many of those answers could make a concrete difference to us.
Who is to say that we can't communicate? Some theories of physics might allow for wormholes or something like that (this is not likely at all due to time travel paradoxes, but who knows).
Even just learning about another civilization and measuring the rough properties of the atmosphere of their planet could be a revolution. If we discover that the atmosphere is totally unlike what we have, that a totally new kind of life is possible, we could open up entire new fields of science.
The most obvious way to communicate is to put out basic facts about the universe, like say the energy states of your favorite atoms or something like that. What if their version of the basic facts is thousands of years ahead of ours? Physics works off of very little evidence, a small nudge toward the right answer is all that it would take to change everything.
Even if we can't communicate in a lifetime or two, maybe we can communicate over the span of 200 years. Imagine what could be learned through an exchange with a culture that has followed a totally technological and scientific arc. We could be in a local minima missing really important things about the universe.
We're in a pretty crappy place when it comes to AI. We know how to do some things, but the overall picture of figuring out what intelligence is, we're in the dark about that. We don't even know how to ask the right questions. Access to a totally different intelligence would change that completely.
I could go on from fields like linguistics, to psychology, everything that communicating with an alien species touches upon would be revolutionized. Imagine how chemistry would change if we knew for sure that ammonia-based life was possible? We would invest massive sums and figure it all out, and all it would take is a bit of knowledge about the gross statistics of their atmosphere.
And we're just scratching the surface.
Whales also teach each other new hunting techniques and have other complicated social behaviors.
Without a better understanding of whale language and cognition, I don't think you can safely say they don't engage in a form of scientific inquiry.
[1] https://news.ycombinator.com/item?id=16270270
[2] https://www.orcanation.org/2019/10/10/the-social-intelligenc...
[1] https://www.zmescience.com/science/biology/killer-whale-dolp...
However, it might give us a clue about how hard cross species translation can be.
* alone because there was no need to simulate a second intelligent species
* alone because there was no desire to simulate a second intelligent species
* alone because there were not enough resources to simulate a second intelligent species
On the contrary, bigger brains can be a hindrance, consuming energy for no reproductive benefit.
That is an odd thing. The one that I'm curious about is the drum-banging for spotting (probably highly simple) lifeforms on places like Mars. Given the ability of rocks to hop planets, it's a totally reasonable thing to find I think as you don't even need from-scratch bootstrapping.
I expect it's partly a product of PR departments as you have to keep the public engaged, not unlike the occasional production of aesthetically pleasing images.
It seems to me that it's enough to push for off-planet permanent human settlement. Heck, given the long-term possibilities of AI and von Neumann probes, distance isn't even an unassailable problem, you just have to change your time horizons.
Like in a video game where new areas are rendered as you discover them....
Jill Tartar has talked about how we would need to think about investing in a powerful radio beacon for 60,000 years if we wanted other aliens to know about us. That gives one an ideal of the scale of time and distance SETI is dealing with, assuming their assumptions are more realistic than Fermi's was.
And putting some resources into that research is a good idea, even just for what we learned about our own planet thanks to having a different context.
Or having an interesting question for people to become interested in adjacent research at least.