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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."
It's a fucking good reason to be silent, I admit.
Achille Talon
Hop!
Yep, it's the distance.
And whatever constitutes "teeming with aliens". Is that 10 planets per galaxy? 100? 1,000?
And the time involved. How long ago did life start on Earth? How many mass extinctions have there been? Would ANY of those have been detected by aliens on their home planet using technology equivalent to ours?
The Fermi "paradox" is based upon alien expansion. Which is, in turn, based upon tech advances that we don't have.
The galaxy could be "teeming with aliens" that we cannot detect and that we cannot reach with our technology. Nor can they detect us or reach us.
'Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us.'
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.
Just some of the things that had to happen for us to be where we are now:
1) Life had to evolve
2) Multicelluar life had to evolve (this took a billion years after life itself arose so is probably not a forgone conclusion)
3) Life had to climb out of the oceans (dolphins might be smart but they won't be building any rockets with their flippers anytime soon)
4) Suitable intelligence had to evolve. Had it not been for the asteroid the dinosaurs would still be in charge.
5) Humans had to survive numerous climate changes and if the genetics is to be believed we almost died out and everyone today comes from a very small population who made it.
6) Farming had to be created to allow people to do something other than hunting and gathering.
7) For the industrial revolution plenty of freely available energy had to be lying around near the surface - ie coal. You can't melt iron with wood fires.
8) Someone had to invent radio.
I'm sure there are dozens of other things that could fit inbetween those points but my basic point is that a technological civilisation than can broadcast information out from his own planey is very VERY unlikely. IMO we could well be the only one surrounded by planets full of the equivalents of bacteria and jellyfish but little more.
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...
Or National Enquirer ?
Monty Python
Maybe the aliens aren't quite dead yet . . . they are merely resting?
Tired and shagged out after a long squawk . . . ?
Or it's intern-planetary censorship . . . their governments are blocking them from contacting us . . . ?
Schroedinger's Brexit: The UK is both in and out of the EU at the same time!
It's the phrasing used. "[life] rarely evolves quickly enough to regulate greenhouse gases" implies that the origin of life on exoplanets been observed often enough for us to to determine that the probability of it evolving to regulate greenhouse gasses is low. We can't even prove how life began on earth, so we sure as hell can't determine the probability for it occurring and evolving on a planet light years away from us.
We don't even have the Concorde anymore, or the SR-71, in some ways we've gone backwards.
The only way in which the Concorde and SR-71 were not primitive is that they were fast. But the mindset of burning up that much fuel so that Rod Stewart can get a haircut in another country and still wind up looking like an aged lesbian or so that we can spy on another country so that we can more effectively wage a cold war against them is seriously fucking backwards.
Getting rid of the Concorde and the SR-71 might seem technologically backwards, but in fact, it is a huge step in the correct direction. Do you seriously suggest that advanced aliens would be flying around at supersonic speeds for no good reason? How inefficient.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
Supersonic in interstellar/interplanetary terms would be like going cross country on a push bike
In space, no one can hear you trying to exceed the speed of sound.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
For four billion years, life on Earth was microscopic blobs of goo.
Then 600 million years ago - BAM - complex life emerged pretty much in the blink of an eye.
We have no idea how likely that transition to complex life 600 million years ago was - we have a sample size of ONE.
Now go back an read my first sentence: For four billion years, life on Earth was microscopic blobs of goo.
That four billion years was about half the expected lifetime of the Earth. The probability that complex life evolves may very well be infinitesimally small. WE DON'T KNOW.
Believing the universe must be teeming with intelligence is based on nothing more than faith.
In space, a snail can exceed the speed of sound.
- Don't do what I do, it's probably not healthy nor safe. -
>To get a technological head start and a head start out in space an alien species would been part of an evolutionary process that skipped whatever their equivalent of dinosaurs would have been and gone directly to intelligent life capable of technology.
Firstly - why not ? We have no proof that there were NOT technologically advanced dinosaurs, at best we have strong reason to doubt there were spacefaring dinosaurs. You are underestimating just how massive an amount of deep time 65-million years was. Dinosaurs could have built cities five times bigger than New York and not a shred would have survived for us to find. If we go extinct tomorrow, it's unlikely that in 10-million years there will be any evidence whatsoever that we existed - except maybe a few primate fossils, even our best mummies can't make it that far. A hundred million ? Not a chance, by that point even our satelites would have decayed and crashed. The last evidence of our existence that may be around would be the bits of junk Apollo left on the moon and any future paleontologists (whether evolved here or elsewhere) that found that evidence would mostly wonder what the hell a Richard M. Nixon was... think about it, they would not even be sure whether it was left there by an earth-born species that reached the moon - or a long-lost lunar species that had a great council to end a war at that spot.
Secondly - your argument is flawed because that's not how time works, time is relative and doesn't happen at a constant rate. Planets that rotate their stars slower have physically existed longer than ones that move slower. So two planets around the same star, in different orbits, which orbit in the same timeframe, that formed together at the same time - the outer one will be significantly younger because time slows down as you speed up. It may be a matter of seconds per rotation - but there's been many billions of rotations for those to add up. And planets around more massive stars are regardless of when they formed relative to the big-bang, have had less time pass on them than those around smaller stars - because time slows down near bigger gravity wells.
The amount of "time" that passed on the surface of a planet is only very vaguely connected to the age of the universe and even to the age of that planet (which we measure relative to the age of the universe). The one decidedly does not offer any indications of the other. The only reason they happen to be the same on earth is because we happen to measure "years" by the time it takes our planet to rotate, but Jupiter formed at the same time as Earth did - and quite a lot less time has passed on Jupiter than on Earth. Even less have passed on the sun.
This is, actually, one reason why - if there is life on Io or Europa - that life is likely to be "bacterial" rather than fishes - those moons circle a massive planet, any life there has had significantly less time to evolve than life on earth has had. No, I don't feel like doing the math to figure out how much.
Unicode killed the ASCII-art *
Even if there were advanced civilizations on only 1% of all the planets, that would still be millions or more.
To believe there are no other advanced civilizations out there, that they are somehow obligated to come pay us a visit, or that they blew themselves up, is pretty fucking arrogant of us.
When you move into a new neighborhood and the neighbors don't come to visit you, that doesn't mean they don't exist
When Fascism comes to America, it will call itself Anti-Fascism, and tell you to give up your guns.
I think you're missing the point.
An alien civilisation with a mere few hundred years head start on humanity would probably have technology that was nearly magical to us if we were to meet them today.
Stretch that out to a few tens of thousands of years - still utterly irrelevant on a timescale measured in billions of years - and you've easily got the kind of civilisation the OP was talking about. Undetectable by us and completely uninterested in us.
From memory, even with the technology we have today we could colonise the entire galaxy in a million years. Not that I think any civilisation could remain stable for that long, but consider it in the context of the mere hundreds or thousands of years "head start" required as discussed earlier.
One thing to bear in mind is that life here existed in the form of anaerobic bacteria for a staggeringly long time. Photosynthesis began as a way to split hydrogen sulphide into useful hydrogen ions and a useless waste product of elemental sulphur, which was also usefully inert. Early photosynthesis therefore didn't require much in the way of biochemical sophistication to operate; the waste sulphur is where some large sulphur deposits originated.
That changed with a mutation which let the photosynthesis split not hydrogen sulphide, but water into useful hydrogen and (to anaerobic bacteria) highly toxic and dangerous oxygen. That initially wasn't all that big a problem to early water-splitters; the oceans they were in were rich in iron-II salts which readily absorbed oxygen to become insoluble iron-III salts (this is where the banded iron rock formations come from).
Everything changed when most of the iron-II in solution in the early earth's oceans was used up. Oxygen levels slowly rose, and virtually all bacterial species either adapted or went extinct. Oxygen is toxic to most bacteria.
I would hypothesise that most alien worlds either never make the switch from anaerobic atmosphere to aerobic one, or fail to establish a homeostatic oxygen-nitrogen atmosphere quickly enough and effectively enough to become self-regulating.
True but usually you can see some signs that there are neighbours there such as hearing their car or the music they are playing. In our case we have not heard anything so either we are not listening in the right way, they make practically no 'noise' or they don't exist at least close by.
When humans first invented radio, we broadcast strong simple signals because our technology was primitive. These signals would be detectable from very long distances away. But we are rapidly moving to much weaker and complex transmissions. This has the benefit of using far less power, and has much greater bandwidth. But it also makes the signal harder to detect and almost indistinguishable from background noise. There was only a 150 year window from when we started to transmit, and when our transmissions became indistinguishable from static. Compared to the age of the Universe, that window was a very tiny blip.
wild, speculation like this is a waste of time
Wasting time on wild speculation is the whole point of Slashdot.
even with the technology we have today we could colonise the entire galaxy in a million years
No we could not. The milkyway has a diameter of about 100,000 light years, give or take.
To fly every where you would need at least 0.1c and may not be to far at the edge, which unfortunately is the case for the solar system.
With our technology we have no means to accelerate and decelerate a space ship with life on it to 0.1c.
You probably could "seed" the whole galaxy in 10 - 100 million years, but not in 1 million.
And bottom line: why would anyone really want to do that? Except for the curiousity like "wow lets dive as deep as we can and look what is there" there never will be a big appeal to space for most of the humans.
Would i like to go out visit the next star system? Yes, absolutely.
Would I like to go out to the next star system on a journey that will take so long that I definitely die on the way before we reach the destination? Absolutely not. There are much more fun activities I can do here on earth than on a what ever luxuries it might have, space ship.
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
You are underestimating just how massive an amount of deep time 65-million years was.
What would a radioactive waste storage look like in a 100M years? Ridiculously stable. Dry. Sealed from elements. Even if it literally just disintegrated in place, the odd mix and ratios of remaining isotopes at the site, surrounded by solid geologically stable rock millions of years older... would clearly suggest something unnatural.
Or perhaps a lego mini-fig -- tey'll soon outnumber humans after all.
http://xkcd.com/1281/
Surely bunches of those highly stable bits of plastic will find themselves some place safe to hide... preserved in amber, or tarpits, or trapped in some glacier, at the bottom of the ocean, or in a salt mine... there are billions of them, so probably all of those things will happen.
And we have things like modern jewelry. Laser engraved diamonds, set in platinum bands. Stored inside fire proof safes... some which would end up buried in stable places... even bunkers. What's 65 million years going to do to that?
Secondly - your argument is flawed because that's not how time works, time is relative and doesn't happen at a constant rate. Planets that rotate their stars slower have physically existed longer than ones that move slower. So two planets around the same star, in different orbits, which orbit in the same timeframe, that formed together at the same time - the outer one will be significantly younger because time slows down as you speed up. It may be a matter of seconds per rotation - but there's been many billions of rotations for those to add up.
Ok... so lets put some figures into those numbers ... say 11 seconds for "a matter of seconds". And how about 4.6 billion for for "many billions" as that's the age of our solar system measured from earth's perspective at least.
11 seconds x 4.6 billion rotations = 1603 years. I don't think we need to worry too much about relative ages of the planets.
This is, actually, one reason why - if there is life on Io or Europa - that life is likely to be "bacterial" rather than fishes - those moons circle a massive planet, any life there has had significantly less time to evolve than life on earth has had. No, I don't feel like doing the math to figure out how much.
You really think its going to be billions of years though? I'm pretty skeptical. Maybe you should do the math.