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Researchers Say The Aliens Are Silent Because They Are Extinct (theconversation.com)
HughPickens.com writes: The Conversation reports that according to research by Dr. Charles Lineweaver and Dr. Aditya Chopra, a plausible solution to Fermi's paradox is near universal early extinction of life on exoplanets, which they have named the Gaian Bottleneck. "The universe is probably filled with habitable planets, so many scientists think it should be teeming with aliens," says Chopra. "The mystery of why we haven't yet found signs of aliens may have less to do with the likelihood of the origin of life or intelligence and have more to do with the rarity of the rapid emergence of biological regulation of feedback cycles on planetary surfaces." According to the researchers, most early planetary environments are unstable. To produce a habitable planet, life forms need to regulate greenhouse gases such as water and carbon dioxide to keep surface temperatures stable. About four billion years ago, Earth, Venus and Mars may have all been habitable. However, a billion years or so after formation, Venus turned into a hothouse and Mars froze into an icebox. Even if wet rocky Earth-like planets are in the "Goldilocks Zone" of their host stars, it seems that runaway freezing or heating may be their default fate. Large impactors and huge variation in the amounts of water and greenhouse gases can also induce positive feedback cycles that push planets away from habitable conditions. The difference on Earth may be that as soon as life became widespread on our planet, the earliest metabolisms began to modulate the greenhouse gas composition of the atmosphere. "The emergence of life's ability to regulate initially non-biological feedback mechanisms could be the most significant factor responsible for life's persistence on Earth, conclude Lineweaver and Chopra. "Even if life does emerge on a planet, it rarely evolves quickly enough to regulate greenhouse gases, and thereby keep surface temperatures compatible with liquid water and habitability."
A good theory I read about somewhere is that the reason we can not find evidence is simply to do with technology either other alien cultures at the point in time we are witnessing there systems have not developed the technology that we can detect or they have moved beyond the need to blast everything in the entire em spectrum out to space.
How many years have we been detectable by other races and how many years left until our technology gets efficient enough that any trace of our race gets hidden by been simply cleaner with our em pollution.
Will we cease to exist to other races out there when we become undetectable?
They can be built around any reasonably stable star (especially very long-lived red dwarfs) which has some rubble to rebuild into spacious habitations. No need to seek a proper star or habitable/terraformable planet. No need to genetically warp ourselves or live in underground tunnels like morlocks. The Colonies provide the perfect living conditions for the builder species.
Communication networks are likely via line-of-sight laser or some means we can't comprehend, so there's no transmissions for us to pick up. Hundreds of millions in number around each star, they're still too wispy to show up at distance as much more than asteroid fields or protoplanet belts. Being self-sufficient, it's no big deal when one colony decides to make the long, slow journey to the next uninhabited star. There, they get busy populating the colonies pre-built by robots sent ahead. The universe is old enough that there has been time for every star in the galaxy to be homesteaded by now.
We can get started by dismantling our own moon for material, moving on to Mercury and Mars's moons (planets are too big and unhealthy for our biology) until all of the available floating rock has been utilized. The colonies aren't made of girders and sheet steel. They're built by sintering crushed rock in the beam of focused sunlight, building up the superstructure like a gargantuan 3D printer. To simplify energy collection, the second or third generation of colonies are probably towed close to the sun, to minimize the size of PV panels needed.
I think there are two other points to consider: First, life and even intelligent life does not necessarily mean technology, or technology at an industrial scale. Maybe just THIS is very, very rare, with civilisations going this way separated by enormous gulfs of time and space. And maybe the universe is full of planets with aliens that have some sophisticated culture, but not at an technological scale that would lead to us being able to detect them.
Then there's the bottleneck of how long a species can sustain a lifestyle of full-scale industrial technology. Without forking out into space as soon as they can resources will be depleted very soon and then it's too late. Either that culture will end then or will (have to) become much more efficient and low-key, which again lowers the chances of us detecting anything.
I mean, one very useful aspect of thinking about this is thinking about what is going on here, not there. How long can we sustain this and what do we have to do to sustain it? Maybe we will learn how things tend to go with industrial-scale technological civilisations very quickly, even if too late...
Except that it ignores subsurface oceans, which seem to be quite stable over long timeperiods and quite likely to be very abundant in the universe.
Sure, a species evolved to an undersea environment faces challenges in getting to their surface and beyond... but if we can get out of this deep gravity well after such a (geologically) short period of time after our species' evolution, sentient species in subsurface oceans with hundreds of millions or billion years on their "hands" would surely deal with the technical difficulties.
And of course there's also the possibility of LNAWKI, but let's just stick with LAWKI for now.
My personal suspicion is that a wide variety of factors work together to keep complex life rather rare on a per-planet basis, great distances dilute any signals from any that do achieve sentience, and the speed of light and difficulty of propagating a civilization outward at near that limit keeps the vast majority far away. Basically, rarity + dilution. But that's just my suspicion.
Maybe, but I can barely make out what you're saying because your horse is too high.
My personal theory is that the most likely thing for any intelligent and technologically capable alien race to be doing is exactly what *we* are doing. Listen, and with a small budget - so only listening to a very small part of the spectrum from a tiny part of the sky. That golden record on voyager 1 is about the last major attempt we made at sending anything and it wasn't a very sensible one.
But if that was what economics led to here, why would we assume it would have other outcomes elsewhere ? Literally the only experimental sample of a technologically capable space-faring race we have - did this one.
So it's perfectly likely that there dozens of alien races within easy communications range of us all making a half-hearted attempt at listening and waiting for one of the others to talk first. All of them, in fact, hoping the outsource the expense of sending high-powered signals into a void where you don't know if anybody is listening, don't know if anybody who was listening would be able to understand it and don't even know in which direction to aim - to one of the others.
Exactly because sending messages is so incredibly difficult technically, and expensive, they may all have opted to just listen instead and, like us, hope that one of the others will figure out transmission first so they can justify the budget to build a transmitter to reply with.
Unicode killed the ASCII-art *
Even if we're not, look at our development. Even if another civilization was on par with us, they could not even communicate with us if they wanted.
Whenever the topic gets to alien life forms, everyone assumes that the aliens must be advanced compared to us and have mastered interstellar, maybe even intergalactic, travel. Says who? Who says it's even possible to do this akin to various SciFi movies? What if the aliens would have to use newtonian physics to get here? Even if they developed 20 LJ away their journey would take centuries.
Our development from "duh, me make fire" to "duh, remote control is broken, need new TV" took about 10,000 years. And we're still in no position whatsoever to fly to any other star than our own. Hell, even reaching the next planet is something we've been working on for half a century now. And every time we actually manage to get a non-manned robot there on a one way trip we celebrate it hugely. What makes us think that anyone else in this universe is actually so far ahead of us to be able to fly about between the stars AND have the hubris to assume that someone this advanced would actually want to have anything to do with us?
We used to have a Bill of Rights. Now, with the rights gone, all we have left is the bill.