Here you go.
By saying observations show any kind of planet at any kind of distance, you are implying that all types of planets are being seen. It is true that the gas giant types of planets easier to see are showing up in all kinds of places, but Mars-sized planets, for instance, we have no clue about.
We’re not even close to being able to identify all the planets in one star system, let alone all of them in a lot of star systems, so it is a bit premature to draw conclusions.
There are perfectly rational explanations of these events that involve ordinary geometry, infrared imaging artifacts, camera orientation, and common misinterpretation by pilots of what they are seeing. That is not the same as proof, but it is far more likely than either of the totally made-up options that you offered.
The dark forest theory is interesting (it’s from this great sci-fi novel series “Remembrance of Earth’s Past”).
Essentially the universe is a dark forest, and advanced civilizations are hunters wandering around in the dark. If you hear a sign of life, the best course of action is to kill it before it kills you.
If you wait around to see whether or not it’s hostile, it very well may be too late. If you think there’s any chance of other civilizations being more advanced than your own, then you should try to hide yourself from the rest of the universe.
Outside of science fiction… I think it’s possible we’ve been visited… but any species capable of doing so would be so advanced that we’d basically be the equivilant of ants. There’s no obvious benefit of making themselves known to us, and if they’re trying it’s possible that we can’t even comprehend it.
Maybe there’s some lowly intergalactic entomologist dropping by occasionally to take a few notes that occupy a couple pages in some guide to life in the universe that no one’s arsed to read. How many of the 12,000+ species of ants are you aware of?
It’s the best there is.
Well, the data we have got shows some interesting gaps. The planetology types call them ‘deserts.’ As you say. we haven’t got a good handle on Mars-sized planets, but there are ‘deserts’ between Neptune-sized and Jupiter-sized planets, and a lot more superearths than we expected.
https://www.nasa.gov/sites/default/files/thumbnails/image/fig10-exoplanetdisc-dec14.jpg
Scientifically, I might hypothesize that after a planet gets bigger than Neptune, it’s becomes a dominant gobbler, and gets to be Jupiter or bigger.
But I’m not a planetologist, so I’ll merely speculate that all the super-Neptunes are hiding, or are too smart to be seen as planets, or have vanished to a higher plane.
The problem with the “dark forest” argument is that it assumes that every intelligent species in the galaxy is doing the equivalent of hiding under the bedclothes hoping that the boogeyman goes away. If there’s no boogeyman, it’s pointless. If there is a boogeyman, it’s not a great strategy. Odds are, that if there’s an intelligent species out there that is both close enough and advanced enough to do anything more harmful to you than sending snarky radio messages, hiding from it is not likely to work for long - and they probably know you’re there already. And sooner or later somebody is going to decide that the best solution to the problem is to clear-cut the forest - expand aggressively in all directions and kill off potential rivals before they become a threat.
The problem with the “space is very big” argument is that while the galaxy is very big, it is also very old. The fastest space probe we have yet launched goes at a dizzying 0.00005c. At that speed, it could cross the entire Milky Way in a “mere” 2 billion years. The Milky Way is about 13 billion years old, so a spacefaring species that appeared in a roughly central position about 10% of the galaxy’s age ago could potentially have colonised the entire galaxy by now - without needing FTL or any other exotic physics.
Of course, 100,000-year interstellar transit times are laughably impractical by current human standards. By the standards of an advanced alien species that may have discovered immortality, uploaded its consciousness to self-repairing computers or be sending out solid-state Von Neumann probes, maybe not.
I’ve wondered about those calculations.
How long would a von Neumann probe (or equivalent) need to spend surveying a new system and building up a resource base before it could build up and send out new probes.
It’s probably a fraction of the transit time, but maybe not a very small fraction. At least if it’s living beings doing the building and sending. Maybe an all robot system entirely oriented to duplication could do it in a relatively small fraction of transit time.
Or maybe a von Neumann probe isn’t something that can actually be built.
Why would you think that? There is nothing in the idea that doesn’t already exist in cybernetics science.
So we already have tiny robots that can mine raw asteroids in a vacuum, refine them, and build copies of themselves, including the microchips that control them? Cool. Where can I get one?
We have every single component of such a machine: we have propulsion systems, mining machines, forges, memory and instruction sets, etc. We could build such a machine, just as we could build the space station from 2001.
Nice fake argument, but fundamentally dishonest.
(Just to begin with, you completely made up the word “tiny.” I didn’t say that. Why did you?)
I don’t think they are impossible. I just imagine that are probably very large and complex and would require vast resources to build and fuel copies.
Maybe fewer resources if they really carry along all factories needed, but then vastly larger (and therefore probably slower).
At any rate, probably a good deal bigger than Voyager.
People and their societies could be imagined as von Neumann probe equivalents. But imagine how long it would take your colony to become self sufficient, let alone be ready to build and fuel 10 more colony ships. Maybe not 100,000 years, but whew! Probably the first 100 or 1000 or 10,000 cans you build would simply go to local colonies, while you’re building up your population.
On some other thread in this board, on a similar topic, I saw someone suggest that once a spacefaring race had the capability of living freely enough in space to endure many generations of interstellar travel, upon arrival in a new system they might have precious little interest in terrestrial planets. Maybe that’s the answer. They don’t want our water, our wimmen, or any of our planetary resources. They just want to mine our asteroids and water slide on Saturn’s rings, but otherwise keep a low profile.*
*I guess I would have thought our astronomers could pick up even modest industrial activity in the asteroid belt, but maybe it’s vaster than I imagine. I’m sure there could be a lot hiding in the Kuiper belt, if they can keep their radio noise down.
I’ll throw my opinion in, what the hell.
There is life elsewhere. There is even intelligent life elsewhere, but for a myriad of reasons, we’ll never meet.
Many ppl assume that we’ll discover some magical way to travel near, at, or (far more preferably) beyond the speed of light one day, like in Star Wars or Star Trek. I don’t know that such a thing can exist, even if we suddenly had complete, perfect knowledge of physics and the universe. It simply may never, ever, be possible, and I think the bulk of our dreams for interstellar travel rests on this. Even a four light-year trip to Alpha Centauri has so many issues to overcome, so many possibilities for disaster, that just getting a human crew there seems unlikely, much less bringing them back.
If we get lucky, we may detect intelligent life. Maybe by spotting a Dyson sphere, maybe someone will send out a ton of probes with their version of the Voyager gold records, but we’ll never have an active conversation with it, never meet it. In fact, by the time we discover them, they may already be dead.
TL:DR: My belief in intelligent alien life is based on the sheer vastness of space and unfathomable number of star systems. My belief that we will never meet them is based on the same things.
“In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves.” - Carl Sagan
Currently I’d agree that building von Neumann probes isn’t possible (we might be able to make an expensive, fragile, limited proof-of-concept, but building something that can be shot into space is an issue and expecting it to be viable at the far end of a multi-millennia interstellar voyage is a bigger issue).
But that’s a limitation of 21st-century engineering. The things don’t break any known laws of physics (hell, we know mobile factory-building self-replicating intelligences are possible, because we exist). And we’ve been developing technology for a really short time on a the Galactic scale. We’ve been working with computers for a whole 75 years, and we already have experts talking about the possibility of strong AI in the next 75. It’s a fair bet that our descendants in 2220 - never mind 3020 or 20020 - will have nanoconstructors and fusion reactors and strong AI and probably a bunch of things we don’t even have words for. And even if it takes a million years to get to the point where an interstellar probe is practical, that’s an eyeblink in the history of the Galaxy - or the time it takes a tool-using species to evolve in the first place.
I disagree with the last bit. There’s a difference between us and ants that cannot be handwaved away. We understand the concept of other intelligences that may be far more advanced than ourselves, ants do not. Even if I knew ant language as well as any ant in the world, I could not communicate the concept that I’m a being more advanced than them, their brains could not encompass that idea. Our brains can.
At a minimum, a vast intelligence would be able to learn the scope of our senses and abilities to be able to communicate human level concepts with us. Is it possible they would choose to not communicate, and to keep their visits secret? Yes. But if that’s the case, the aliens wouldn’t be picking up drunk farmers for probing then letting them back out into the world. They wouldn’t be caught by our obvious radar systems and viewed openly by pilots.
Simple, yet instructive, speculation involves trying to estimate how many nearby alien civilizations may be nearby emitting detectable signals, e.g. the Drake equation [it would be surprising if many of you have not seen references to this equation]. And astronomers do look for such signals (in any case there are other reasons to scan the heavens for interesting signals and phenomena).
The trouble is, while such a formula may look impressive, one can extract low as well as high numbers out of it depending on how one massages the parameters, therefore it does not tell you much. Still, it lets you begin to enumerate possible reasons why there are not such signals around: space too big, forms of life too alien to be emitting the kinds of signals included in the search, etc.
You cavemen couldn’t even fly 150 years ago*. 350 years ago you hadn’t even explored your planet yet. 4000 years ago you couldnt make a ****ing NAIL.
And you sit there and have the Space Balls to say “The speed of light can’t be broken.”
I’m kidding of course…the tone that is.
Difference between flight and FTL:
There was doubt as to whether or not man could make an artificial flying machine, there was no doubt as to whether flight was possible.
That is not the case for FTL. Not only are there no natural examples of anything being FTL, we have an extremely rigorously well proven theory that explains why.
Comparing days of ignorance to today is not a useful comparison.
That said, we don’t need FTL to colonize the galaxy and local group. Just time. That is one thing that most people have trouble with, it’s a big hangup for evolution as well, comprehending what can happen when you stop thinking years or decades, but in megayears and eons.
Assuming that we don’t kill ourselves off (probably misplaced optimism), then there is no reason why we wouldn’t spread out as far as we can. You don’t need FTL to grow. If your civilization is just colonizing asteroids and rocks, it will move further and further out, and one day, thousands or tens of thousands of years from now, you will be colonizing a rock that’s a bit closer to another star than to our sun.
It may take millions of years to fill up the galaxy, but millions of years is nothing.
As long as I’m musing…it would sure help the notion that the UFO’s (I’ve discussed) are extraterrestrial if there were no one in them. IOW if the craft themselves were the aliens and there was no organic life inside. That would help explain away the inertia and G-force defying, and would go a ways explaining how slower then light craft arrived here.