Until recently we didn’t even know if other stars had any planets. We have a lot more data now, but it rather looks as if Earth-like planets are not very common… certainly not to the extent of some SF universes where they are taken for granted. (Rather a shame, but c’est la vie).
Though this is still skewed by limits of our instruments: what types of planets are easiest to detect.
To take a step back though: how about completely different substrates for intelligence: Hoyle’s Black Cloud, for example?
I can’t cite the future, but I have given my reasoning for my position. If it takes humans 10,000 years to make an SRP, that’s still an eyeblink on cosmic timescales. That’s what I mean by “close”. And that’s ludicrously pessimistic considering the progress we’ve made in mere decades
.Yep this goes back to the root issue.
If we’re interpreting “Where is everybody?” as making the positive claim that there should be lots of advanced ETIs, then of course we can question the assumptions and our work is done. Problem solved.
But what have we solved? Have we reached some greater understanding?
The better interpretation is to see it as: Based only on what we know today, there’s no reason why the night sky couldn’t have been lit up with the evidence of millions of advanced ETIs.
Instead, we don’t see evidence of even one (unless you count seeing our own satellites). And we have no idea why – it could be that multicellular life is vanishingly rare, it could be that civilizations fail before they reach our level. And yes it could be that no-one ever builds anything trivially visible.
It’s a huge unknown, indeed collection of unknowns.
And, seeing it this way, we can also see the progress being made. We can (basically) rule out explanations like “Maybe planets are rare” or “Maybe planets in the habitable zone are rare”.
If we were actually “close” there would be some semblance of a prototype. There is none. Postulating something will will happen 10,000 years in the future, doesn’t equal ‘we are close’, (or, honestly that it will happen at all).
Speculating about the future is not “citing the future”. This is an inherently speculative topic, but for some reason your speculation is fine but mine is not allowed.
I have not tried to attack or ridicule you, so I don’t know why you’re taking the tone that you are on this.
Suggesting that a technology might be 10,000 years away does not entail that we should already have a prototype. If we had a prototype of all necessary functions then we’d likely be a century, if not merely decades away from launching one. Or, if we’re defining prototype more broadly, then we already have produced probes that can land on asteroids and probes which can leave a star system. The first two important steps.
10,000 years is close, because I explicitly stated that I meant close on cosmic timescales (which is relevant to the Fermi paradox). Surely we can agree that 10,000 years is close relative to 13,700,000,000?
I just came across Webb’s book, independently, although I found the earlier version with 50 solutions. It’s absolutely the best treatment of the subject I’ve ever seen. He’s a physicist and understands the science, has read deeply into earlier speculations, and is knowledgeable about the science fiction treatments. Webb sets out each solution, and in a few well-written pages manages to analyze its origin, the reasoning, and the science behind it, and then summaries the available evidence and our ability to gather and evaluate that evidence. (As of 2002, which is before many amazing advances in technology.)
He drops the solutions into three headings: They Are Here; They Exist but Have Not Yet Communicated; and They Don’t Exist. I think they deserve narrower categories than that; I’d love to do a taxonomy of solutions. (Some of his solutions contain multiple variations that I wouldn’t lump together.) Something for every philosophy.
Which I’ve been doing. How many times have I mentioned data points? I’m repeatedly referencing what we know, and letting that data lead me to the most likely conclusion being something I don’t want to be true.
We know that self-replicating systems exist; we are self-replicating systems ourselves. Unless there is something ineffable about life’s ability to replicate, then replication is something that can be done.
Caveats; humans can’t replicate without an entire oxygen-producing biosphere, but life can also replicate in the absence of oxygen, so in theory life could be sent to another suitable world in the galaxy with some prospect of gaining a foothold - an idea put forward by J D Bernal about a hundred years ago.
About the same time Olaf Stapledon suggested the idea of encircling stars with rings of artificial life-bearing artifacts; one of the first expressions of the idea of a Dyson Sphere, as Dyson himself acknowledged. Stapledon anticipated that an industrial civilisation would be necssary to construct such a ring of artifacts; we also know industrial civilisations exist, and are in themselves complex, self-replicating entities.
The idea of self-replicating power-collection swarms contains within itself no technical, philosophical or thermodynamic impossibilities, so the fact that we can’t see any such things is a reflection of the Fermi Paradox itself, and like the FP there are many possible answers. But, as with the FP, we don’t know which solution is correct, or even if there is only one solution.
Perhaps these slightly anomalous interstellar comets (that Avi Loeb is so obsessed with) are fragments of ancient defunct megastructures - I doubt it very much, but it wouldn’t hurt to find out.
I’m open to just about any possibility. I’ve listened to a lot of Loeb’s interviews and lectures - he’s a tad more optimistic than I, but I agree it wouldn’t hurt to find out.
This is frequently brought up in these discussions but to my way of thinking, it’s not a valid comparison. Yes, here on earth humans are self replicating ‘machines’. But it doesn’t necessarily follow that we could build a mechanical version of ourselves that could then build a copy of itself on a distant planet by mining raw materials, smelting, machining, fabricating and assembling a copy, and not only that, build a rocket and somehow process fuel to jet it off to another planet to start the process over again.
That is why I prefer to imagine ‘self-replicating industrial civilisations’ rather than just ‘self-replicating probes’. If our civilisation does not collapse in the next thousand years, I expect that we will build ‘self-replicating industrial civilisations’ on a great many of the planets, moons and free-orbiting objects of our own solar system, and this will give us the experience to learn how to replicate the process around other nearby stars.
This will involve progress in a/ developing autonomous systems and b/ miniaturising the processes involved in an industrial civilisation significantly. If this process of autonomy and miniaturisation follows biological templates, that is fine; at least we know that biological self-replication works, even if the results are sometimes unexpected.
Humans and human minds would be involved, of course - in a variety of ways. But probably not humans as we recognise them nowadays, and almost certainly not vanilla humans like Captain Kirk, sitting in a captain’s chair, giving orders like the captain of a WWII aircraft carrier.
That’s a good jumping off spot for a sci-fi story. Genetically bred tiny humans on a generation ship with miniature machines for replication. To infinity and beyond!
Hmm. Except that there is probably a lower limit to the size of a genetically-engineered human, in order to support our complex minds. Some birds have very smart brains inside relatively small heads - crows and parrots, for instance. Making humans smaller would make interstellar flight just that bit easier. Other very useful adaptations that could make long spaceflights more achievable would be extreme longevity, freefall and hibernation.
Perhaps humans can’t be modified successfully for long term survival in space - this remains to be seen. But I suspect that if humans can’t adapt to interstellar flight and colonisation, then there could be other, more adaptable alien species which can, and these would be the ones we are most likely to meet. So where are they?
I’m going to stick with my previous answer. They are stuck in their home solar system, or at best in a neighboring system if their home star is part of a binary / trinary / etc. system. All their probes and crewed spaceships are inactivated / dead relics, having succumbed to the ravages of interstellar space due to the practical limits of how far technology for things such as shielding against radiation can advance (and that’s just one of a multitude of potential points of failure) no matter how many millions of years a species has to advance.
ETA: There’s also the possibility that the numbers we’re counting on for how likely a solar system is to develop life are smaller than we think. It could be (and my guess is that it’s highly likely) that the solar systems near the galactic center, where the majority of the stars in our galaxy are located, are inhospitable for any kind of life to develop due to their proximity to the black hole at the center of our galaxy. I think it’s also likely that red dwarfs, due to their propensity for damaging solar flares, are also unlikely to host life.
These are all good solutions to the Paradox. Self-repair may have its limits.
Red dwarfs are an interesting factor; most are very active, and would probably be deadly to an Earth-like biosphere; but they are very long-lived stars, and get gradually brighter over time. Hundreds of billions of years from now many red dwarfs will be about as bright as the Sun, and will pour warmth onto the frozen worlds now orbiting them; these icy worlds could melt and develop biospheres of their own, long after our G-type star is dead.
