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 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.
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?).
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.
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.
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.
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.
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.
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.
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?
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.
[0] https://web.archive.org/web/20140719094337/http://www.comput...
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.
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.
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.
The theory has catchy name, but even the earth's nature disproves it.
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.
Applied to a forest on earth, you'd have to make the animals are extremely slow.
It's an interesting idea, but it raises the reasonable (IMHO) question, "Why would they bother?"
It seems like an awfully big investment of resources for actions which wouldn't be of real benefit to them.
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.
Sadly, I could see it. Some billionaire somewhere wants "The Best" latency numbers and wants it on their yacht...