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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!
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 surface
Monty Python
.. I mean It's the distance .. the distance
err
"Even if life does emerge on a planet, it rarely evolves quickly enough to regulate greenhouse gases......"
Rarely? What is the sample size for the statistics?
'Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us.'
Coupled with the odds of being alive and intelligent at the right time ...) long enough.
and putting in the resources to make one noticeable (large laser irradiating the sun, dyson sphere,
I'm not really that surprised there is yet another plausible factor that makes it hard.
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 ?
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.
You forgot the Soviet Russia, no?
where meme forgets you?
Wanna buy a shirt?
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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.
Exploring Earth is a bit like using a toothbrush. Once someone else has done it, you kinda don't wanna do it anymore.
We used to have a Bill of Rights. Now, with the rights gone, all we have left is the bill.
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.
Consider this: particle physics shows us that entangled observation (not to be confused with human or intelligent observation) ties past and future events together into a causative vector of influence.
Extrapolating from this using entangled observation similar to Einstein-Rosen bridges between quantum events suggests (mathematically) that there is a correlation between frames of references in real-space once a chain of events is initiated.
This would have the effect of linking independent causative frames such that the 'arrow of time' would diverge, probabilistically, between relative frames.
Or, attempting to explain this analogically:
The light from a distant star contains a tremendous amount of observable information about a star, and a limited amount of information about exoplanets (Doppler shift, chronographic direct imaging, etc...). As technology advances, however, it should be possible to tease out (observe) direct evidence of extrasolar life from this meager data due changes over time to how life changes a planetary atmosphere (specific to biome, but similar divergence vectors).
Depending on how one interprets causative entangled observation, this could actually have a strong anthropic effect on life. Evidence that alien life, intelligent or not, exists on an exoplanet would strongly influence the actions of any intelligent species towards visiting and exploring the planet. This would be very close to a strong motivational influence towards any intelligent social network, yielding a high probability outcome of events.
Depending on distance between planets and assuming that technological development is generally rapid, there becomes a high probability chance that any technological species would, inadvertently, directly affect the development (probably adversely) of all emergent evolutionary biomes within observational range.
As a species matures, they would probably realize this at some point, and take one of two divergent vectors: Some level of apathy (no empathy, just settle habitable planets or destroy competition) or avoidance (let them develop, don't interfere). Extrapolating those two motivational vectors, it's likely that there are those that would visit for nefarious reasons, and likely that there are those that would seek to prevent that type of interference due to social morays based on the above principles.
My $0.02 will always be worth more than your â0.02, so
Say you have two antennas, one sitting 1 mile from a 100kW (maximum allowed power for radio in the US) radio broadcast tower and one sitting on a relatively close planet 100 lightyears away. The ratio of the difference in intensity will be 2.9E-30. In other words, only a handful of photons actually reach the antenna placed on the exoplanet, certainly not enough to generate any kind of recognizable signal. THERE IS NO PARADOX. We're simply too far away.
In addition to that, the earth is becoming radio silent as we shift from broadcast towers to low power communication and internet. It's pretty likely aliens would do the same thing, meaning there will be only brief periods of radio emanating from worlds where intelligent life forms. We've only been listening for a couple decades. Pretty unlikely that our period of listening would coincide with an alien world's period of broadcast and that we would actually be close enough to collect any signal.
I submit that there is no paradox here. It's all a consequence of being too far apart, radio signals attenuating (inverse square law), and brief periods of popularity for mass broadcast technologies followed by radio silence as internet/other tech replaces it. Makes total sense.