This is a compelling theory, especially the implication that humans are early. I do wonder whether we should see the evidence of spheres of growing alien influence out in the stars, but instead we see a highly uniform universe in all directions.
This would indicate a few possibilities:
1. Expanding alien civilizations are relatively low impact and don't collect all of the energy of stars in ways that are visible to our current telescopes.
2. We are a very early civilization, civs are fairly rare, and we're relatively alone in the parts of the universe that we can see. Civs that are expanding in a grabby fashion started less recently in years than their distance in light years.
3. Aliens expand at close to the speed of light, so there are a lot out there but we won't see them until they're almost here.
4. Something that we have already noticed is actually evidence of grabby aliens, but it is happening in every direction so we assume that it is a natural phenomenon, because it is so uniform.
At the very least, it seems likely that we either we are alone in the galaxy, or expansion is very slow. The idea of "expanding in a bubble of influence close to the speed of light" seems implausible to me, just because of the vast amounts of energy required to accelerate and decelerate to relativistic speeds, not to mention protecting the cargo in transit--when you're flying at .9c, almost every other piece of matter in the universe is flying towards you at you at .9c. Accelerating tiny nanomachine von Neumann probes might be a solution, but how would they decelerate enough to not be destroyed on arrival?
5. Controlled transportation between the stars, sufficient for colonization, is sufficiently impractical that there are no grabby aliens within our light-cone.
That itself would be quite interesting though, because based on what we know now it's merely difficult, not impossible with reasonably foreseeable technological improvements.
The dynamics which would make it impossible on any known timespan don't seem currently observable.
I think a huge factor you don't account for here is that some of these technological improvements might imply a great-filter that we really haven't passed yet as humans, and the negative effects would affect most similarly expansionist and competitive races alike us since it might be questionable if there would be enough pressure on a non-competitive race to expand rather than just conserve local resources.
Just with state-controlled nuclear weapons we've been on the brink of extinction a couple of times already, the energy levels required for star-travel implies this kind of destructive power being in the hands of even more people (and by necessity more or less out of control of the nation states). A commercial airliner took down WTC, a starship would be an WMD capable of taking out a city (or more).
One implication of this is that there's a chance that we've already invented practical fusion power, but if it's trivial to miniaturize AND weaponize then people in control of it have decided to withhold it to avoid every weird terrorist group creating one.
You might want to check the physics on your assertion that a starship could take out a city. It’d have to be designed to do so otherwise it would just vaporize as it entered the atmosphere at the velocity you’d need for that kind of impact.
I haven't done any calculations (since we don't have any feasible crafts for interstellar travel that's irrelevant really), but considering it for a few minutes I'd say there's 3 increasingly likely ways around that.
1: Considering the amount of rocket fuel we need to leave earths atmosphere and reach the Moon, people have been proposing nuclear rockets to reach Mars. That's still within the solar system, reaching another star requires magnitudes more energy, even more so to accomplish enough acceleration to reach another star within a persons lifetime. Such a mode of energy generation not having an explosive failure more feels unlikely (thus making it blow up in a dock is enough).
2: Barring option 1, reaching fractional light speeds, would not a ship need enormously more capable shields than anything today to safeguard humans? The Tunguska event(3-5 mt) was at "just" 27km/s of a 50 meter object.
3: Speaking of Tunguska, even if the ship itself would lack such shields (however a human would be expected to survive w/o one), a ship capable of interstellar travel should be able to push out a rock and then accelerate it back to earth to create a Tunguska (or larger) event at a target location.
The core issue is the energy levels required(1), converting them to something destructive is usually within grasp of less intelligent people than those that research the advances that make them available.
If we’re talking specifically about interstellar craft with enough shielding to survive an uncontrolled reentry at high velocity then what the heck are those going to be doing near a planet? Sublight travel would have to be performed by craft large enough to support the crew for years if not decades or generations. You’re not going to want to maneuver that much mass into orbit around a planet. They’d be better off parked in a trojan orbit and letting smaller craft move people and supplies back and forth You might as well try to hijack an aircraft carrier and fat chance of surprising anyone if you could pull it off.
To get a ship to hit the ground at the velocity you’re talking about a large chunk of it would need to be solid steel like a bullet basically. Space craft aren’t built like that, they need to be mostly empty space for storing propellant and people. A reactor and its shielding might survive but that’s on the scale of 5 - 10 meters and it’s still not 100% solid so it doesn’t compare to a large metallic asteroid.
Throwing rocks at a planet might work but you need the right equipment and expertise to bullseye a planet from 100 million miles away and if anyone saw you do it they could take their time intercepting the rock.
If you assume FTL travel will never be developed then distance and time are simple limiting factors. How do you keep a cohesive civilization going when communication takes 200 years? Or even just 20? Here on Earth entirely new languages and cultures arose across distances that wouldn’t even cross a state line when communication was limited to a small handful of travellers and merchants. Any colony further away than 5ly would quickly diverge. I’m pulling that number out of my hat but I’m sure you could figure out the effect of time spent in journey on willingness to travel. Not many people would commit significant chunks of their lives to interstellar business trips. Radio communications won’t solve it either since they’d be out of date and essentially one way if it took decades to get a response. No I think any interstellar colonization effort would immediately create competing civilizations distinct from their homeworld.
Consider a colony of bacteria multiplying by splitting. Each new pair of cells is independent and do not cooperate. Some die, some stay put. Nonetheless, the “colony” spreads and explores new territory with zero coordination of these activities. Certainly not an intelligent centralised leadership!
Even if our first interstellar colonies diverge immediately and some even turn into reclusive hermits, some may expand, repeating the cycle.
Hard to say what would happen but I think we still need to avoid the assumption that each star system remains relatively static especially over very long periods of time. You also need to consider the purpose behind colonization, if it is to spread the existence of your civilization to new worlds then no one says those worlds must be uninhabited.
We barely knew about flight in air, or germs on hands, sent even small objects in to space in extremely recent history.
Hand waving away “we can’t travel through stars” because we currently don’t get it, seems like the weakest way to discuss the topic.
You/we can’t imagine it; so it must be impossible or in practically difficult? What if it turns out to be extremely easy, we’re just extremely small or extremely uninteresting? Those are far more likely topics than we already have the answers and have decided it’s not possible.
? Did you read the original post? On grabby aliens?
This whole discussion is about being 'early'.
Not sure you are making a point.
Edit:
The original post discusses below light speed transportation. 25% speed of light is used in the estimates.
But guess I agree, if no aliens including us, never-ever with infinite time ever develop transportation that can get up to some fraction of light speed. Then maybe no colonization ever happens, and the grabby guys stay in their system.
“Alas, there's a fifth possibility” was my comment, and I made it because the discussion was excluding the possibility, despite it being explicitly discussed in the paper.
“We can't see any evidence because there is nothing there to see” is a possibility, grabby aliens _requires_ significant-fraction-of-C travel for the argument to hold, and it's entirely possible that it's just impractical-to-the-point-of-impossibility. (That's why I quoted it in another comment).
Yes, it's possible that we're early. It's equally possible that we're “early” because there's no concert: _everybody_ is early in a universe where the band never gets on stage and it turns out that nobody bothers colonizing the universe due to the cost and lack of benefits.
See also: “Please don't comment on whether someone read an article. "Did you even read the article? It mentions that" can be shortened to "The article mentions that".” https://news.ycombinator.com/newsguidelines.html
And I can ask for clarification concerning if you read the original post, since your objection/point was already covered.
Did you read it and simply making some additional argument against it, or did you miss it entirely?
"5. Controlled transportation between the stars, sufficient for colonization, is sufficiently impractical that there are no grabby aliens within our light-cone.
"
This is covered in the other points of the theory? So should I assume you read it?
"The universe isn't a rock concert, “we're here too early” is not the only possible reason why there's no band on the stage.
"
Even if interstellar travel is impractical, an advanced expansionist civ would be interested in building megastructures. And since there is no stealth in space (unless you can somehow mask heat), they should be observable.
Ofc there are explanations for that part of the paradox as well, but the impractical travel theory doesn't cover it.
> no stealth in space (unless you can somehow mask heat)
I know two things.
1. We are now already using heat mask measures, even when we are very young civ in terms of Kardashev scale. We already use simple slit heat emitters in military tech (many Stealth planes have slit nozzles and for example, Leopard tanks also use slit exhaust for same reason).
2. Even we now know about possibility of laser heat, which could emit heat directly with very high focus.
In conclusion, idea is, to surround whole civ with heat mask blanket, and make all heat exhausts directly focused on directions, where now observer expected.
Second, looks like our development now is very slow, because it should be on early stages (Kardashev scale), and old civ's should know this.
And I now support theory, that we are fortunate to be far enough, so stronger civ's are not interested in spending resources to limit our development.
I even consider might be exists some preservation pact between Big civ's, to avoid touch young civ's, for some purposes like scientific, or arts. So yes, basically, I support Zoo theory.
> In conclusion, idea is, to surround whole civ with heat mask blanket, and make all heat exhausts directly focused on directions, where now observer expected.
Although focussing emissions (not really a blanket) is possible, not only would some specific civilisation have to actually do that, it would have to be a common enough choice that every example we would otherwise have been able to see actually does choose to do that that — this gets increasingly difficult the more such examples there are: if a civilisation can build a Dyson swarm, what are they afraid of that they would want to hide? Even if one civilisation has a reason, everyone has to make this decision, regardless of how many (or few) "everyone" is.
"Dark forest" is a bad reason, as everyone with a Dyson swarm will have been able to know your planet existed and had life on it even when it was all single-cell species; a star winking out of existence is noteworthy, and easily noticed[0].
One Dyson swarm is enough to directly colonise a high percentage of all galaxies that aren't beyond the "reachable horizon"[1] of the universe. As soon as we can make artificial self-replicating machines (we know such machines can be made because all life is self-replicating nano-machines, we just don't know enough to do it completely from scratch yet), this would take us about 31 years[2] to make such a swarm.
> this would take us about 31 years[2] to make such a swarm
They assume, when have already working general AI technology and it have some limited size (volume-mass-energy consumption).
Unfortunately, we still not have GAI and even cannot predict, how large will be first practical unit.
Must admit, looks like we very close to do it, but from history of previous great technical inventions, some things takes decades to achieve production status and was repeatedly reinvented in some years after another inventor fail.
General AI is unnecessary. Bacteria do not possess this trait, and yet reproduce themselves, some in as little as 30 minutes.
It is also possible to have a large system where humans are just a component, if this were necessary. The human-machine ratio is a function of how close the automation you have is to what you need.
> Bacteria do not possess this trait, and yet reproduce themselves
If you programmer, you should know from experience or from learn, that in complex system possible just two ways to achieve reliable execution.
1. Brute force, just test as many possible scenarios as could, 99.999% is better than 99.99%, and make script for each scenario.
2. Smart, run system when tested somewhere between 70..90% and make some sort of insurance, so when happen non-tested scenario and all failing, you will pay (compensate) for harm, and make additions.
That is. Bacteria lives in comfortable environment (mostly in liquid water drop), and spent billions of slightly modified reproductions, to make solutions for all possible scenarios. You may hear, DNA of simplest bacteria are more than Million pairs, that's because of number of scenarios it successfully survive.
Space is much less comfortable environment than liquid water, it have wide range of possible parameters, I even not sure if exists some structure, which could survive in all possible space environments, so need some adaptation mechanisms, to change structure, and best is consciousness AI, which could make smart predictions of causes and reasons, and control all these machinery.
And also it will have memory, to repeat moves which helps to survive when something similar happens earlier.
> If you programmer, you should know from experience or from learn, that in complex system possible just two ways to achieve reliable execution.
Irrelevant. A self-replicating system does not need to be highly reliable. Look to the past, any time over 200 years ago most families were a dozen kids because most didn't reach adulthood.
> That is. Bacteria lives in comfortable environment (mostly in liquid water drop), and spent billions of slightly modified reproductions, to make solutions for all possible scenarios. You may hear, DNA of simplest bacteria are more than Million pairs, that's because of number of scenarios it successfully survive.
False. Bacterial environments are hostile because other bacteria fight them for the same resources, including predation. Many chemicals are hazardous even in small quantities. Internal chemistry requires water in liquid form, yet there's only a narrow range of temperatures where water is liquid, and worse the chemical processes change rate significantly even within that range.
Also irrelevant, we've been using simulated evolution as a form of AI for ages already. It's not new or novel. I implemented a version of this in 30 minutes over a decade ago just to prove a point. A million bases is trivial to store, so is a billion or a trillion.
> Space is much less comfortable environment than liquid water, it have wide range of possible parameters, I even not sure if exists some structure, which could survive in all possible space environments, so need some adaptation mechanisms, to change structure, and best is consciousness AI, which could make smart predictions of causes and reasons, and control all these machinery. And also it will have memory, to repeat moves which helps to survive when something similar happens earlier.
Also false.
1. Space has far fewer parameters than water.
2. One does not need to make a single machine to survive "all possible space environments" to do this, just our solar system at 0.47-0.31 AU from the sun. We already have that, we sent probes there.
3. Consciousness is not necessary for any of that. Neither is episodic memory (though that is trivial to implement). Bacteria exist and do these things well enough with mere DNA.
> Look to the past, any time over 200 years ago most families were a dozen kids because most didn't reach adulthood.
Do you know mathematics? Calculate, how slow will become your Dyson swarm, if for example only 1/20 will survive?
BTW, you may hear about baby-boomers, and they are exactly caused by much improved medicine, now in EU survive near 100% children.
Calculated? Ok, now calculate, how much suffer probability of overall success, because limited resources does not accept to make 20 turns to achieve 1 successful?
> 2. One does not need to make a single machine to survive "all possible space environments" to do this, just our solar system at 0.47-0.31 AU from the sun. We already have that, we sent probes there.
Well, now I see you are just overweening human, but without real knowledge. Solar system is itself have wide parameters spectrum, but is is also significantly different from other stars environments.
> Bacteria exist
Bacteria have sacrificed billions lives, to gather information, to achieve current success rate.
But must admit, I will consider idea you suggest me, about send hopeless missions, to just gather info, and I'm sure you also lazy, so I'll myself calculate success rate for each sacrifice rate.
> Do you know mathematics? Calculate, how slow will become your Dyson swarm, if for example only 1/20 will survive?
It means the real reproduction time is t/f, where t is the time it takes to make a single unit and f is the fraction of units which survive to further reproduction. For 1 in 20 surviving, that means the real reproduction time is 20t.
Some bacteria take 30 minutes for a single reproduction, so that with a 1/20 success rate would be an effective population doubling every 10 hours. An E. coli cell weighs 1 pg, and this is only a factor of 2^128 from the planet Mercury. These random example numbers would therefore be able to consume the entire planet in 53.32 days. At this level, almost all the time (97%) is spent on waiting for the solar panels to supply enough to get the stuff from the planet's surface to solar orbit.
> Calculated? Ok, now calculate, how much suffer probability of overall success, because limited resources does not accept to make 20 turns to achieve 1 successful?
I have no idea what point you're even trying to make here.
We know we don't need to worry about your 1/20 random example for humans because we know ourselves; only the machines need this consideration. That's a number which you made up, and your own complete fiction is what you're now trying to use for an example that I don't understand.
> Well, now I see you are just overweening human, but without real knowledge. Solar system is itself have wide parameters spectrum, but is is also significantly different from other stars environments.
Completely irrelevant. I don't even know what point you think you're making. I linked you to a specific plan to build a Dyson swarm specifically in our solar system at the orbit of Mercury. The rest of the universe is irrelevant to this part of the plan, for exactly the same reason and in exactly the same way that it is irrelevant to bacteria on Earth that the rest of the universe exists.
What you do with your Dyson swarm (including colonising the universe) only matters after you've built your Dyson swarm. Building one is fast the moment von Neumann machines can be engineered rather than grown, and give you such an incomprehensibly large industrial and resource base to work from that comparing it to what we have access to today is more extreme than asking a single pre-writing cave painter to imagine our current entire world.
> Bacteria have sacrificed billions lives, to gather information, to achieve current success rate.
BTW if you really know, you could make GAI for some reasonable amount of money, or you know people, who have this knowledge, I know few very serious people, who want to invest into such thing and have money.
You're implying we'd easily see megastructures. Believe it or not, there's many more stars we haven't inspected than have. And our telescopes suck too much to see all but the largest megastructures, which you're assuming it would make rational sense to build in the first place. There can be better things for an economy to spend its (always finite) resources on.
> which you're assuming it would make rational sense to build
Yes I mean why not. If you are an expansionist advanced civ, travel is impractical and you have enought time and resources then what else is there to do?
Obviously there are explanations "why not" (as I said), but insterstellar travel unavailability is not one of them.
A hypothetical megastructure Dyson's sphere would not radiate heat.
And I'm not so sure that you can apply the stealth principle here. Stealth inhibits active measurement and astronomical measurements are passive. We have sensor resolution and we have a mass of data to sift through - each time sensor generation or data processing advances, we see stuff we haven't seen before.
The data is analyzed as a dynamic system. Radar just looks at a bounce. If you setup radar incorrectly you might get false hits and no returns on valid targets. If you use a wrong model in analysis of astronomical data you're never getting anywhere close to a correct result.
A Dyson's sphere is a device to convert high frequency photons (visible light and uv) to low frequency photons (radiated “heat”). A sufficiently deep stack of shells can bring the temperature of the radiated light closer to the temperature of the cosmic background radiation, but it absolutely will radiate.
The question isn't whether Dyson speheres radiate, the question is can we detect an artificial megastructure and my answer is no, based on the hypothetical Dyson design.
That is physically impossible unless there is new physics in that hypothetical design. All physical objects radiate heat and a Dyson sphere in particular would be trivial to detect. You look take a picture of the sky in infrared and in the visible spectrum. If you find an infrared source but no associated visible star you’ve got a strong candidate for being a Dyson sphere. Such searches have actually been conducted.
Other megastructures might be discovered through the same methods as exoplanets.
Yes, but a Dyson sphere, even around a red dwarf, would be far more luminous in the infrared than a brown dwarf. It would also have a different spectrographic signature, and importantly its heat distribution would appear artificial.
Rough calculation get's me a dyson sphere big enough to bring the black body radiation of the sun down to ~4k being hundreds of times the orbit of pluto. At that point it's actually an interesting question of where you get all the mass for the nesting shells.
> A hypothetical megastructure Dyson's sphere would not radiate heat
Could you elaborate why not? All current technology I know of has an efficiency of <100%, with waste energy being lost as heat (which in space would be radiated away in the infrared spectrum). Why would this not be the case for a hypothetical dyson sphere or swarm?
There are many middle possibilities between that and aliens expanding at c.
Expansion at c is very unlikely. Insane things happen when you approach c, like the cosmic microwave background transforming into a gamma ray laser aimed at your head and collisions with microscopic particles destroying you. It may be that travel close to c is so hard as to be effectively impossible.
I’ve read that speeds up to about 30% the speed of light are “thinkable” with currently known physics plus advances like compact fusion reactors. Think something that looks like the Epstein Drive in The Expanse or the ships from Avatar.
These models provide indirect evidence against the existence of FTL travel. If FTL exists it means we really have to be extremely early, maybe even the first in our galactic cluster. Otherwise someone would have visited at least.
I also think if someone has visited, such as if some tiny number of UFOs are actually of ET origin, it means we are probably incredibly lucky to have neighbors that aren’t “reapers” in the dark forest sense. It’d be funny if our galaxy is actually full of aliens and we lucked out and are camped next to some superintelligence that is both benevolent and powerful enough to fight off anyone who isn’t. So hey if they’re taking our cattle maybe that’s a pretty small price to pay.
Lightsail seems sufficiently practical if you don't care about being fast. You basically directly exploit energy of the stars you are traveling between.
The argument is premised on grabby aliens being fast enough to explain why we don't see their expansion; grabby aliens that don't care about being fast would have showed up _long_ ago.
Yeah, it's like we're playing cosmic detective trying to figure out if there's anyone else out there in the universe. The fact that we haven't seen any clear signs of alien civilizations doing their thing is kind of mind-boggling. It's like, are they just really subtle about it, or are we just super early to the party?
When you mine asteroids in orbit on a large scale around your star, the released dust/debris would form an IR halo around the star that would be very easy to detect and reveal your presence but we dont see any of it.
Your point on missing IR halos is valid, but don't overlook anomalies like Tabby's Star (KIC 8462852) [0]. Its odd dimming led to theories about alien megastructures like Dyson Spheres, though dust or comets are possible explanations. Still, Tabby's Star highlights the difficulty in excluding advanced alien activities with our current tech. [1]
This person [1] ran a data search for stars with a similar light profile (“slow dippers”) to Tabby/Boyajian’s Star, and claims to have found a cluster of similar stars in the region. But the results are not particularly high confidence and are probably just data artifacts.
I don’t think we’re going to build rock crushers in space. With all that available energy it’d make more sense to just throw the whole rock into a smelter and fractionate the elements as they boil off. Why waste the slag either? You need all the material you can get so hang on to it and use it as ballast or extract the carbon and silicon from it. It’s more likely that we don’t see waste because there isn’t any, a dollar saved is a dollar earned.
My money is on option 2 with the key factor being that complex, intelligent life takes a long time to develop. Our empirical data (of sample size one) indicates that it takes multiple billions of years to go from single celled life to even quite simple multi-celled life. If we got lucky with that, the average could easily be longer than the age of the universe.
The problem with option 3 is that even a small drop below light speed becomes a large multiplier when looking at galactic and intergalactic distances. Let's say you can manage 0.5 c (pushing far beyond any current physical understanding of what is possible), that means we would have up to a 40,000 year heads up on an approaching galactic civilization. Even if it was 0.9c we would have up to 8,000 years notice. Even with something crazy like direct antimatter - matter conversion the amount of energy to bring a ship to that kind of speed would be a gigantic beacon in the night sky. Barring science fiction we can be relatively confident none are on their way right now.
Given that the universe is 13.8 billion years old, 40,000 years is nothing.
The presumption that other putative galactic civilizations start at nearly exactly the same time as us is implausible, especially considering more than 9 billion years passed before the solar system even formed.
Sure, but we'd see the markers on timescales relevant to us. The gap between the light cone and actual velocity is the critical difference between a kugelblitz and an invasion: you could conceivably conceal the former but not the latter.
I'm pointing out that any scenario that requires this synchronization is inherently implausible. So if we don't see the markers, trying to say it's because there are lots of civilizations but they just happened to pop up in synchrony with us is not a plausible theory.
> 4. Something that we have already noticed is actually evidence of grabby aliens, but it is happening in every direction so we assume that it is a natural phenomenon, because it is so uniform
* Brown dwarfs: These are objects with masses too small to ignite nuclear fusion in their cores and shine like stars. However, they are still warm enough to emit infrared radiation.
* There are rogue planet candidates that do not belong to a solar system.
Aliens collecting all the light/electromagnetic radiation from stars would be an interesting way to get dark matter. That's one place it could fit.
And, if our theories are right, we're at 4.9% regular matter and 26.8% dark matter, so dark matter is five times as much as regular matter, so that's a lot of aliens...
Dark matter isn't non-luminous matter. It's matter that only interacts gravitationally, but not electromagnetically. This means it doesn't undergo collisions and can't shed angular momentum. It forms a diffuse, largely uniform cloud throughout galaxies. The result is that galaxies are more dense further from the galactic core than we would predict from luminous matter alone.
It's clearly confirmed that galaxies don't obey the known laws of quantum electrodynamics (QED) + general relativity (GR) if we assume they are made entirely of Standard Model particles. So, either QED is wrong (extremely unlikely) or GR is wrong (unlikely) or there is some matter that is not in the Standard Model (plausible).
Dark matter corresponds to option 3 - and there are observations that conform some models of dark matter distribution that match quite well between different galaxies. There are other theories as well, such as MOND (modified Newtonian gravity) that explore option 2 (GR is wrong).
Still, whatever the theory, it's clear that what is not happening is "aliens someone consuming all of the EM radiation from some stars". With anything resembling currently known physics, it's impossible to "consume" EM radiation in this way. Electric charge is always conserved, electrons and quarks don't disappear just because they move around, even with something like controlled fusion. A Dyson sphere would be an extremely hot visible object, not some dark point.
> So, either QED is wrong (extremely unlikely) or GR is wrong (unlikely)
Not my area, but I thought both were known to be incomplete? Q because it presumes a flat spacetime; R because it predicts the formation of singularities that the maths used to develop it assume don't exist?
I think the general belief is that it will turn out that space time is actually approximately flat at small levels, so that QED will be essentially exactly correct, while GR will turn out not to apply past a certain small scale.
5. Grabby aliens do not exist because the universe is a dark forest and any detectable signs of life result in anonymous relativistic snowflake bombardment.
There are electromagnetic waves reaching the earth from this galaxy which were emitted anywhere from 80,000 years ago to an instant ago, and everywhen in between. Practically all alien races among the hundreds of billions of solar systems would have to have been electromagnetically silent for a minimum of 80 thousand years for us not to see them.
If you include other galaxies, then they would've had to have been silent since the beginning of time.
Also, non-living matter spontaneously forms into living matter by no known mechanism.
If you're going to believe something religiously, make it something less trivial than muh aliens.
Okay, so you imagine a galaxy-wide communist society in which everyone is successfully prevented from emitting any unencrypted signal from so much as a Dyson refrigerator, for tens of thousands of years at a time.
No, I imagine them doing exactly the same thing we are: using more and more efficient methods of communication as we develop them. Compressing and encoding data, focusing our transmissions where they need to be instead of blasting at max power in all directions, using the most effective form of transmission for the purpose whether it’s laser, microwaves, specific wavelengths of radio, or hard line connections for planet side comms. Signals decay very rapidly over distance so unless you have a very good reason to build a gigantic transmitter capable of reaching beyond a few light years in all directions you’re not going to just accidentally wind up communicating with a random star 100ly away.
Oh, yeah, because zero of the roughly 5 quintillion aliens which the Milky Way could comfortably support have hobbies (very primitive) and none would ever use a cheap and effective terraforming unit or dyson sphere even once in 80 thousand years when they could use a more expensive one which mimics pure blackbody radiation
even in war (or are they pacifist communists), they would never emit a signal for any reason on any of the multiple trillions of planets during this 80,000 year period. not even from a bomb.
yes, yes; this all makes sense -- I have done the math.
maybe all 5 quintillion aliens are being hunted by equally non-emitting terminators and they don't want to give themselves away and also they want to save energy
directional communication makes sense when you have only two planets. if you have an entire solar system (or the entire galaxy) it's a dumb idea to eschew simple omnidirectional devices
You should really look into basic probability calculation LOL. If you have to come up with like nine different copes like "alien population in Milky Way is low" AND "aliens are relatively low technology with no Dyson spheres and limited terraforming" AND "aliens by mere chance don't exist within this arm of the Milky Way (except for us)" AND "zero aliens which do exist have tried deliberately signalling to the rest of the galaxy despite humans having done this nearly continuously since they developed the means" AND AND AND
Like just throw in the towel bro. You're adding epicycles on top of epicycles when the answer is right in front of you. You're just too stubborn to admit you were wrong.
Who are you responding to? I gave one reason and it’s called the inverse square law. The distances we’re talking about are unimaginably huge so the chances of any signal reaching us is practically zero unless it’s close by (within a few hundred light years) and intentionally directed at us with sufficient power.
Despite all your bluster you obviously have no idea what you’re talking about if you think exoplanet detection techniques can tell us if there is even a single radio transmitter on that planet.
you literally think that aliens are all so primitive and just happen to be completely absent from anywhere within 5000 light-years despite that being so statistically improbable it's laughable.
that every alien race just happens to either be on the opposite side of the galactic core or they all abide by the Georgia Guidestones and live primitive one-planet lifestyles.
how many copes do you need, honestly? either that or some people are literally incapable of grasping basic statistics.
by the way, how would you have felt if you didn't have breakfast this morning?
This would indicate a few possibilities:
1. Expanding alien civilizations are relatively low impact and don't collect all of the energy of stars in ways that are visible to our current telescopes.
2. We are a very early civilization, civs are fairly rare, and we're relatively alone in the parts of the universe that we can see. Civs that are expanding in a grabby fashion started less recently in years than their distance in light years.
3. Aliens expand at close to the speed of light, so there are a lot out there but we won't see them until they're almost here.
4. Something that we have already noticed is actually evidence of grabby aliens, but it is happening in every direction so we assume that it is a natural phenomenon, because it is so uniform.
At the very least, it seems likely that we either we are alone in the galaxy, or expansion is very slow. The idea of "expanding in a bubble of influence close to the speed of light" seems implausible to me, just because of the vast amounts of energy required to accelerate and decelerate to relativistic speeds, not to mention protecting the cargo in transit--when you're flying at .9c, almost every other piece of matter in the universe is flying towards you at you at .9c. Accelerating tiny nanomachine von Neumann probes might be a solution, but how would they decelerate enough to not be destroyed on arrival?
It's all fascinating to think about, at least.