I thought the idea that there are gazillions of advanced aliens has been pretty much disproven by the fermi paradox.
If there are gazillion, at least one out of all the diversity out there should have already colonized the entire galaxy and evidence should be plentiful.
There’s a nice analysis of the Fermi paradox out there somewhere that takes into account uncertainties in each of the parameters. As you multiply them together, the uncertainties compound each other. The end result is a big old who knows, rather than a paradox. Our observations are compatible with a really wide variety of realities, many of which include lots of aliens and many of which don’t.
Maybe there has been some sort of accident of scale, like the intergalactic fleet in Hitch Hiker Guide to the Galaxy that arrives to destroy Earth but is eaten by a dog.
There could be a banging ET party going at the Planck scale and we would never know, they might as well be on the other side of the universe.
The problem with this is that mechanics is not scale invariant. This puts bounds on creatures. Unless there's some crazy different way to compute I wouldn't expect a being to be able to have strong cognitive functions and be the size of a fly. They would also have a difficult time building advanced machinery to get to galactic travel scales. Similarly I wouldn't expect a creature the size of a Brontosaurus to become space faring. Because of their sizes they would have to consume significantly more resources to build simple things. A two story house probably couldn't be created out of wood or other basic biological materials making it difficult to transition into even the stone age. They also require higher food because energy requirements aren't linear. But think how much it costs to send a pound to space. Their first to space would be significantly more expensive.
This doesn't mean these things are impossible because maybe there are ways around them, but it certainty shifts the probabilities by quite a bit. Given our current understanding of biology and mechanics it makes it much more probable for creatures to be within the ballpark of our size (let's say crow to elephant?).
I think this is a mistaken way of thinking in general, because you're omitting time. Your assuming that intelligent/thinking/conscious creatures would necessarily function on timelines that make sense to us. If that were true, then what you're saying makes sense - there are real bounds on how fast you can move chemical energy from A to B, for example.
But I see nothing preventing intelligent life from operating on massively longer timescales. This requires, of course, that you believe that intelligence (and maybe consciousness too) is substrate and timescale independent, which may or may not be a big ask depending on where you stand on these issues.
I think this is strange thinking because it breaks our laws of physics. The clock ticks at the same rate in internal reference frames, it is only different when looking at two different frames. But if you're talking about them acting at slower speeds or faster, then that brings along other problems similar to the mechanics ones we discussed (assuming we're not counting that they are in a slower reference frame). It really shifts the probabilities around. Even trees act relatively quickly because forces act fast. You'd have to be in a pretty extreme environment for other things to happen.
As to chemistry, if they are moving faster then that means that they have more thermal energy. That comes with radiative problems (why humans stand) and this is much more difficult the smaller you are because you have less surface area. Which then puts large energy requirements on intake. And then the inverse is true.
The thing is that aliens would still have to follow the laws of physics. There is no reason to expect that wouldn't be true and reasoning otherwise would take some pretty extraordinary evidence and probably win you several Nobel prizes.
consider the range of timescales that humans can have effective control over. We manage to organize subatomic collisions that occur in femto-seconds, and we manage to build things that last thousands of years. All this despite the fact that our own lives are measured in units that are several orders of magnitude smaller or larger.
So I can imagine (just about) an intelligent system that can also effectively build systems operating in time domains orders of magnitude from their own experience/lifetimes. If they were very "slow" then certainly launching objects into orbit may appear almost impossibly fast to them. But it wouldn't be notably different than what we do with particle physics (or even firing a gun), where the timescale of the event is essentially impercetible to us, and far beyond our ability to control with our own bodies.
The other way around is harder, because creating things that last much longer than an individual's lifetime has to fall back on culture, and that seems to evolve (change) much more rapidly. There are very few buildings still in use that are more than a thousand years old, even though the physical construction of such a thing is relatively trivial.
> So I can imagine (just about) an intelligent system that can also effectively build systems operating in time domains orders of magnitude from their own experience/lifetimes.
This isn't the problem I'm getting at. The problem I'm getting at is that it'd be highly unlikely for an intelligent lifeform (or really any) to develop under those extreme conditions. Advancing under other conditions and then developing towards extreme conditions after they have reached a sufficiently advanced state is a different issue.
For extreme conditions like operating at a speed much faster to us (imperceptible) would mean that they would be under high amounts of acceleration than compared to us. Gravity already puts major constraints on humans and for a lifeform to be operating at a rate imperceptible to us we're not talking about 10x or 100x the gravity but more like 10^10^10^10 (or more). Mind you that their internal reference frames (their internal clocks) would operate at a different speed than what we see their clock moving at. Subatomic particles have a difficult time operating at a fraction of that gravitational force. That means you have no building blocks.
What you're not considering is that I've accounted for things like chemical processes and electrical processes not being needed. The problem is that I don't know how you get two particles to change state (at least in non-extreme or destructive ways) under the conditions you're talking about. This isn't about "oh we just don't know" it is that there are some things we do know. We know that lifeforms have to be able to change their state (e.g. you can move your fingers or you can have a thought. These are state changes). We know the basic building blocks of the universe, quarks (or at best strings). There's certain rules these things have to abide by. You can let your imagination run wild but there are still limits of what you can do within this universe. And any being even visiting this universe would still be subject to these rules even if they were from a different universe that had a different set of rules. You can't just trash these rules in the spirit of imagination (which btw testing and updating these rules is what the job of a physicist or really any scientist is. But it is still a convergent process).
Creating things that last longer than an individual's lifetime isn't hard at all. We've done it by accident, they are called artifacts. Nature does it all the time, they are called fossils or just dirt. Trees last longer than human lifetimes. I know you think you're keeping an open mind but instead what you've done is limited it. Operating within the bounds of the rules doesn't have to be a limiting process. There may still be an infinite number of configurations under these rules. But abandoning them makes your search space so open (and open in a way where you wouldn't expect to find solutions) that you can never find what you're looking for. It is like if you're looking for needles in a haystack and arguing that the way to find the needle is to add more hay because the needle is inside the hay.
sorry, the relevant part of the book is in the first few pages of the first chapter, where JBS Haldane discusses the physical limits of mammalian anatomy due to load bearing constraints on bone cross sections and hydraulic implications for a heart that must circulate blood/lymph through a gigantic body, and how all of these and other separate systemic envelopes merge to form what we understand as the "right" sizes for living things etc.
Some portion of this chapter is occasionally excerpted to deflate claims about extraordinarily large or small purported alien creatures, though Haldane was setting up an argument for dynamically limited systems in general.
I thought it might be an interesting skim given the similarities to your comment above.
I haven't, that's pretty cool. You can update my terrible range guesstimate accordingly. Though that doesn't change the main thesis of there being more likely sizes than others.
A possible chink is that civilizations just don't do that -- carpet colonize the whole galaxy, or fill it with their probes to the extent that we seem them all over the place. The Fermi paradox relies on material (probes, colonies) and light (signals).
With the material explained away, the lack signals is much easier to explain in that we haven't listened long and we can only hear very loud signals. (Or maybe advanced civs don't use light and use gravity waves or tachyon beams or whatever, but you don't even need to go that far.) The only way we hear a signal is if it's:
1. loud (high energy) and aimed directly at us, like a tight beam
2. EXTREMELY LOUD and aimed everywhere, isotropically
1 is unlikely since they'd have to know where we are; 2 is unlikely since you're talking about an insane level of energy. If it's the case that civs don't seem to be making Dyson spheres or harvesting whole galaxies for energy, being able to throw around that kind of power is prohibitively expensive. In both these cases, the inverse square law applies (for every unit x of distance, the light's x² less bright). Ironically, that means we're more likely to detect signals from an improbably close civilization (like 4 light years next door, in Alpha Centuari), than from farther away -- and even then, by a chance sweep of an umodulated asteroid scanning beam[0] or something, if we happened to be paying attention at the time.
> A possible chink is that civilizations just don't do that -- carpet colonize the whole galaxy, or fill it with their probes to the extent that we seem them all over the place
This assumes that there are gazillons of alien civs yet somehow they all come to the same decision. That's much less likely than gazillions of alien civs all make different decisions and it only takes a single one to make the replicating probs or try to colonize.
Do you know if about any simulations of what it would look like if there were alien radio operators?
If there were 50 other Earths scattered around the galaxy (ones that have been broadcasting like us but for longer) should the first television have imnediately picked up interstellar "I Love Lucy" or would it be faint anomalies from SETI? Somewhere in between?
The inverse square law says no [0]. Even relatively high powered transmitters aren't detectable for an Arecibo-class antenna more than a few AU from Earth. If you want a signal detected light years away you need it to be highly directional. An isotropic radiator emitting enough power to be detected light years away is called a star.
So any SETI signals we might detect would almost certainly need to be intentional. That doesn't mean they would need to be responses to something we've broadcast just the sender was aiming their transmitter towards the solar system and sent a signal.
Paradoxes are paradoxes precisely because they fail to disprove two contradictory claims.
For the Fermi paradox, the paradox is that the immensity of the universe leading to life seems obvious, yet the complete absence of that life around us seems to show it's not there. So it disproves nothing, but actually highlights the difficulty of disproving either claim given the other.
I never much liked this being called a paradox since it has so many built in assumptions, most of them centered around any given, theoretical alien civilization resembling a human civilization in any way. It's a limitation of what we know for sure, since there's certainly no rule that civilization elsewhere should resemble civilization on Earth. That's an acceptable limitation, it's difficult to notice things you don't know you should notice, but it's a limitation nonetheless.
Of course, it's also possible for civilizations to be so far away that we will like never detect them due to the inverse square law. They could even be in parts of the universe we can't observe.
According to the Chinese science fiction author Liu Cixin the Fermi paradox is solved by the certainty that if an alien civilization announces its presence to the rest of the universe, one of the gazillions of other advanced alien civilizations is sure to destroy it. So they keep quiet.
That would imply the laws of physics somehow dictate the self-manifestation or creation of intelligent clouds of elements (e.g. humans) who by their vary quantum waveform / nature are violent and want to destroy other clouds of elements even if the cost involves harvesting energy from your only local star.
The books and all are nice but the Dark Forest Theory doesn't hold agains much scrutiny. Among other reasons because if that were true we would be already dead.
Why is that? Let's say we've emitted since about 100 years. They are bound by lightspeed like we are. Our wavefront hasn't reached them so far, OR it has, and they are about 50 lightyears away, busy building a slow annihilation fleet, arriving here anytime about 100 years from now, depending on how high up to lightspeed they can go?
Nonono! Need to have the holy and heroic enforcers of the righteous path embedded and experience it with full sensorium, to conserve the glory of it for all eternity, and bring it back to be rememberd as it really happened(TM)!
I mean - it's called Dark Forest, but if you will look at any documentary, even dark forest is full of life. You will hear crickets, you will hear owls, you may see fireflies.
The theory has catchy name, but even the earth's nature disproves it.
If you read the three books, you realize that the true message is that if you're considered a possible threat to an advanced species, they'll annihilate you, otherwise you'll be left alone. Maybe every other species which knows about us knows we can't even leave our own planet/moon right now, the most we can do is send useless robots to other planets over 30 years.
I haven't read the third book so maybe they expanded on it, but from the first 2 books the theory seemed different. It is far too dangerous to let a non advanced civilization live because they can quickly develop to an advanced civilization.
That's how I understand it: light speed is so slow and technological progress is so fast that any intelligent species could develop the ability to wipe you out faster than you could realize the threat is coming. Ergo, the only possible way to be safe is to destroy other civilizations as soon as they pop up their heads.
I feel like a lot of so-called solutions to the Fermi paradox fail when they speculate on what "aliens" would do. Would they seal us off and make a zoo, or find it morally wrong to contact us, etc, etc. It's bold to assume a single policy, since there would likely be multiple alien civilizations, or multiple factions even if there is only one.
So I give this one more credit in that once you have reached 100% understanding of physics, you will know whether this premise true or not true and it more or less dictates that you answer it if it is true. However, I'm not convinced that with 100% knowledge of physics you would find yourself so vulnerable. And even if you were, it still seems various forms of containment would be just as effective as a genocidal attack.
This one kind of works because it only takes one civilisation to block us and keep the others out.
> once you have reached 100% understanding of physics, you will know whether this premise true or not true
How does understanding physics give you the certainty?
As a solution to the paradox that would assume that all civilisations are extremely xenophobic and also always assume that collaboration is impossible.
BTW: my current belief is that most likely life is just super-rare (phosphorus problem, and way too many required variables) and also that colonising a galaxy is probably a sub-optimal solution for overpopulation.
Friends trump enemies. Survival of any individual is maximized when working with others. Whether that individual is a cell, a multicellular lifeform, a country, or a multi-system species. Dominating all others is a poor bet compared to being friendly.
Every advancing civilization will eventually create an internet. Once they do that, interstellar travel is off the table. Advanced civilizations stay closely packed because they cannot tolerate latency once they get a taste for near instant communication.
Why is FTL necessary for interstellar travel? If you could go even 1% c then you could make journies that are multiple light years on the scale of centuries. It’s not until 50% c does time dilation start playing a significant role, but it would allow making a 10 l-yr journey in 17 years.
Nature doesn’t care if we think there should be aliens or FTL travel. Nature doesn’t like casualty violated and that means we’re all going to be following its rules on the speed of causality. There are no cosmic-scale sentient forces that can shape space-time near us or else we would have noticed in observations decades ago.
I disagree, I think it probably would for humans.. but what about other advanced organisms? Maybe they have very long lives. Maybe their biology is more conducive to 'suspended animation' or some other form of hibernation. Maybe they've digitized their minds and can suspend execution of their thought processes for tens of thousands of years. Maybe their social traits (ant like hives perhaps?) make generation ships feasible while they would collapse into strive for humans.
If there are gazillion, at least one out of all the diversity out there should have already colonized the entire galaxy and evidence should be plentiful.