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Fraser
2016-Jan-22, 11:40 PM
http://www.universetoday.com/wp-content/uploads/2014/05/Kepler186f.jpg
In 1950, physicist Enrico Fermi raised a very important question about the Universe and the existence of extra-terrestrial life. Given the size and age of the Universe, he stated, and the statistical probability of life emerging in other solar systems, why is it that humanity has not seen any indications of intelligence life in the cosmos? This query, known as the Fermi Paradox (http://www.universetoday.com/103061/where-are-all-the-aliens/), continues to haunt us to this day.
If, indeed, there are billions of star systems in our galaxy, and the conditions needed for life are not so rare, then where are all the aliens? According to a recent paper (http://online.liebertpub.com/doi/abs/10.1089/ast.2015.1387?journalCode=ast) by researchers at Australian National University's Research School of Earth Sciences., the answer may be simple: they're all dead. In what the research teams calls the "Gaian Bottleneck", the solution to this paradox may be that life is so fragile that most of it simply doesn't make it.
To put this in perspective, let's first consider some of the numbers. As of the penning of this article, scientists have discovered a total of 2049 planets in 1297 planetary systems (http://exoplanet.eu/catalog/), including 507 multiple planetary systems. In addition, a report issued in 2013 (http://www.pnas.org/content/110/48/19273.abstract) by the Proceedings of the National Academy of Sciences of the USA indicated that, based on Kepler mission data, there could be as many as 40 billion Earth-sized planets orbiting in the habitable zones of Sun-like stars and red dwarfs within the Milky Way, and that 11 billion of these may be orbiting Sun-like stars.
So really, there should be no shortage of alien civilizations out there. And given that some scientists estimate that our galaxy is 16*billion years old, there's been no shortage of time for some of that life to evolve and crate all the necessary technology to reach out and find us. But according to Dr Aditya Chopra, the lead author on the ANU paper, one needs take into account that the evolutionary process is filled with its share of hurdles.
"Early life is fragile, so we believe it rarely evolves quickly enough to survive," he says. "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."
Consider our Solar System. We all know that planet Earth has all the right elements to give rise to life as we know it. It sits within the Sun's so-called "Goldilocks Zone" (aka. habitable zone (http://www.universetoday.com/120982/what-is-the-habitable-zone/)), it has liquid water on its surface, an atmosphere, and a magnetosphere to protect this atmosphere and ensure that life on the surface isn't exposed to too much radiation. As such, Earth is the only place in our Solar System where life is known to thrive.
But what about Venus and Mars? Both of these planets sit within the Sun's Goldilocks Zone and are believed to have had microbial life on them at one time. But roughly 3 billion years ago, when life on Earth was beginning to convert the Earth's primordial atmosphere by producing oxygen, Venus and Mars both underwent cataclysmic change.
Whereas Venus experienced a runaway Greenhouse Effect and became the hot, hostile world it is today, Mars lost its atmosphere and surface water and became the cold, desiccated place it is today. So whereas Earth's microbial life played a key role in stabilizing our environment, any lifeforms on Venus and Mars would have been wiped out by the sudden temperature extremes.
https://youtu.be/k9uAPAezbis
In other words, when considering the likelihood of life in the cosmos, we need to look beyond the mere statistics and consider whether or not it may come down to an "emergence bottleneck". Essentially, those planets where lifeforms fail to emerge quickly enough, thus stabilizing the planet and paving the way for more life, will be doomed to remain uninhabited.
In their report, "The Case for a Gaian Bottleneck: The Biology of Habitability (http://adi.life/pubs/ChopraLineweaver2016.pdf)" - which appears in the first issue of Astrobiology for 2016 - Dr. Chopra and his associates summarize their argument as follows:

If life emerges on a planet, it only rarely evolves quickly enough to regulate greenhouse gases and albedo, thereby maintaining surface temperatures compatible with liquid water and habitability. Such a Gaian bottleneck suggests that (i) extinction is the cosmic default for most life that has ever emerged on the surfaces of wet rocky planets in the Universe and (ii) rocky planets need to be inhabited to remain habitable.
While potentially depressing, this theory does offer a resolution to the Fermi Paradox. Given the sheer number of warm, wet terrestrial planets (http://www.universetoday.com/50289/terrestrial-planet/) in the Milky Way Galaxy, there ought to be at least a few thousand civilizations kicking around. And of those, surely there are a few who have climbed their way up the Kardashev Scale (http://futurism.com/the-kardashev-scale-type-i-ii-iii-iv-v-civilization/) and built something like a Dyson Sphere (http://www.universetoday.com/104919/what-is-a-dyson-sphere/), or at least some flying saucers!
And yet, not only have we not detected any signs of life in other solar systems, but the Search for Extra Terrestrial Intelligence (http://www.seti.org/) (SETI) hasn't detecting any radio waves from other star systems since its inception. The only possible explanations for this are that either life is far more rare than we think, or that we aren't looking in the right places. In the former case, an emergence bottleneck may be the reason why life has been so hard to find.
But if the latter possibility should be the case, it means our methodology needs to change. So far, all of our searches have been for the "low-hanging fruit" of alien life - looking for signs of it on warm, watery planets like our own. Perhaps life does exist out there, but in more complex and exotic forms that we have yet to consider.* Or, as is often suggested, it is possible that extra-terrestrial life is taking great pains to avoid us.
Regardless, Fermi's Paradox has endured for over 50 years, and will continue to endure until such time that we make contact with an extra-terrestrial civilization. In the meantime, all we can do is speculate. To quote Arthur C. Clarke, "Two possibilities exist: either we are alone in the Universe or we are not. Both are equally terrifying."
Further Reading: ANU (http://www.anu.edu.au/news/all-news/the-aliens-are-silent-because-they-are-extinct), Astrobiology (http://online.liebertpub.com/doi/abs/10.1089/ast.2015.1387?journalCode=ast)
The post Why Haven’t We Heard From All The Aliens? Because They’re All Dead! (http://www.universetoday.com/127032/127032/) appeared first on Universe Today (http://www.universetoday.com).


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Ross 54
2016-Jan-23, 04:16 PM
The comparison evoked, of Venus, Earth, and Mars doesn't seem all that discouraging for the prospects of life, even intelligent life, elsewhere. If one of three planets in our Star's habitable zone managed to host complex life and a stable environment, what basis do we have for deciding that this proportion couldn't apply to other star systems, too?

Spacedude
2016-Jan-23, 05:52 PM
I give the so-called Fermi paradox a 50/50 chance of being just as much as an illusion as any ufo sighting.

DaveC426913
2016-Jan-24, 03:57 PM
I give the so-called Fermi paradox a 50/50 chance of being just as much as an illusion as any ufo sighting.

How is it an illusion? It is simply a logical argument. Do you find fault with one of the premises?

1. The Sun is a typical star, and there are billions of stars in the galaxy, including many billions of years older than Earth.
2. With high probability, some of these stars will have Earth-like planets, and if the Earth is typical, some might develop intelligent life.
3. Some of these civilizations might develop interstellar travel, a step the Earth is investigating now.
4. Even at the slow pace of currently envisioned interstellar travel, the Milky Way galaxy could be completely traversed in about a million years.
5. According to this line of thinking, the Earth should already have been visited by extraterrestrial aliens.
C: Where is everybody?

Spacedude
2016-Jan-25, 09:08 PM
How is it an illusion? It is simply a logical argument. Do you find fault with one of the premises?

1. The Sun is a typical star, and there are billions of stars in the galaxy, including many billions of years older than Earth.
2. With high probability, some of these stars will have Earth-like planets, and if the Earth is typical, some might develop intelligent life.
3. Some of these civilizations might develop interstellar travel, a step the Earth is investigating now.
4. Even at the slow pace of currently envisioned interstellar travel, the Milky Way galaxy could be completely traversed in about a million years.
5. According to this line of thinking, the Earth should already have been visited by extraterrestrial aliens.
C: Where is everybody?

It's just my personal opinion of course Dave, but I've been interested in the topic since the 1950s and it was in 1950 when Fermi brought up his paradox. He died just 4 yeras later in 54' and I have to wonder if he were still alive today would he have softened or hardened his stance by now. The 1-5 list you posted is quite reasonable to assume and of course via several other related threads here we have heard the long list of reasons why "C" still goes unanswered. One main reason is that we require 100% proof for this particular topic because 99.9% is not enough nor will ever be enough. The only way to obtain 100% is via direct ET contact annoucing themselves to the world or our governments to make the annoucement (neither of which appears to be happening). As long as we continue to pigeon hole ufo eye witnesses into these 3 categories :
1- Misidentifying natural or manmade objects
2 - Hoaxes / Lies
3 - Delusional
We will refuse to take them seriously and will continue reject a 4th category :
4 - Witnesses accurately described their experiences, particularly the 2nd, 3rd, and 4th kinds.
But even then we would still find some reason to find a dash of doubt in their account, and that's all it takes to debunk any account, a small whiff of doubt. It's what we (as scientists) do, we need 100% confirmation and that will be hard to come by regarding this topic. Take the recent thread on the Ariel case, the main auguement is that it involved children, if it involved adults it wouldn't make any difference. No witness could ever prove what they saw is a real bonifide ufo from another world. So that's why I say the Fermi's paradox could be just as much as an illusion as ufo reports, at least 99% of them anyways. To summarize, my position isn't defendable and it's just an opinion.

John Mendenhall
2016-Jan-26, 01:28 AM
Almost everyone in Western societies is carrying around a phone with a pretty good camera in it, and we still can't get a good picture of a UFO by multiple educated observors at the samr time and place?

DaveC426913
2016-Jan-26, 01:49 AM
https://imgs.xkcd.com/comics/settled.png
https://xkcd.com/1235/
:)

citpeks
2016-Jan-26, 05:40 AM
We are very fortunate to live in an environment with an oxygen atmosphere where we can build fires to smelt metals and create extraordinary technology. Another lucky break is that we have dexterous hands and inquisitive minds to create that technology.

If we lived in a water world like the dolphins, could we have achieved this? Dolphins may be as intelligent as we are, but they cannot manipulate objects efficiently or develop the technology for interstellar communication while living in their watery environment. Most of our electronic devices fail when submerged in water. I have lost a video camera and a cell phone to small spills of water and sodas.

Not every intelligent life form has the capability of announcing its presence by broadcasting into the cosmos. There is also the possibility that they already announced it, but we missed it because we were not listening. Or perhaps they will announce it after our species is extinct.

John Mendenhall
2016-Jan-26, 08:58 AM
Yes, thanks, Dave. And revealed some shocking things about ordinary human conduct.

John Mendenhall
2016-Jan-26, 09:16 AM
We are very fortunate to live in an environment with an oxygen atmosphere where we can build fires to smelt metals and create extraordinary technology. Another lucky break is that we have dexterous hands and inquisitive minds to create that technology.

If we lived in a water world like the dolphins, could we have achieved this? Dolphins may be as intelligent as we are, but they cannot manipulate objects efficiently or develop the technology for interstellar communication while living in their watery environment. Most of our electronic devices fail when submerged in water. I have lost a video camera and a cell phone to small spills of water and sodas.

Not every intelligent life form has the capability of announcing its presence by broadcasting into the cosmos. There is also the possibility that they already announced it, but we missed it because we were not listening. Or perhaps they will announce it after our species is extinct.

Good points, skeptic.

Spacedude
2016-Jan-26, 03:29 PM
Do you really and truly believe that better ufo pictures are going to change anything? Let me play the role of a debunker for a moment (easiest job on the planet). Let's say that 3 people with cell phones take pics from 3 different angles of some strange craft flying over a major city. The immediate public reaction is surprise, confusion, and amazement (typical in ufo encounters). The "craft" appears strange and unfamiliar provoking thoughts of an alien spaceship. After the initial response then questions start to come up casting the needed bit of doubt required to let the air out of this balloon (perhaps it is a disk shaped balloon?). Could this be a hoax? Maybe a fancy drone? Perhaps a secret experimental military aircraft that lost control and drifted over a populated area? Did any of the witnesses have a past interest in ufos? No one saw an actual alien so maybe we're jumping to conclusions rather than a simple explanation (the famed Occum's razor fall back). These are just simple examples of what's to follow just as it has been during the past 60+ years of the modern ufo era. Good luck with pics, only direct ET contact or a government annoucement would hold water in this leaky bucket.

John Mendenhall
2016-Jan-26, 04:46 PM
How about 1000's of od witnesses and 100's of pictures? Consider the photo and videos of the Russian meteot. And all the surveillance cameras.

IMHO,the UFO folks have no case for no photos.

Spacedude
2016-Jan-26, 05:01 PM
Nor will they ever.
Public acceptance of a meteor is much more likely and reasonable than public acceptance of an alien space craft entering the atmosphere. The burden of proof far exceeds pictures no matter how many were taken of a strange object streaking across the sky. Besides, there was more physical evidence supporting the meteor explaination.

DaveC426913
2016-Jan-26, 09:25 PM
Public acceptance of a meteor is much more likely and reasonable than public acceptance of an alien space craft entering the atmosphere. The burden of proof far exceeds pictures no matter how many were taken of a strange object streaking across the sky. Besides, there was more physical evidence supporting the meteor explaination.

You're missing the point.

With the vast majority of the population having instant access to a camera (literally, at their fingertips every waking moment), it is not an issue of merely better pictures, it is an issue of we should see a thousand-fold or ten-thousand-fold increase in sightings. Good, bad, whatever - the sheer number of reports piling up should in-and-of-itself result in an irrefutable mountain of sightings. We should be virtually inundated with images.

There is only one scenario where a thousand-fold increase in chances will result in a zero increase in events:
1000 x 0 = 0.

The logic is virtually inescapable.

DaveC426913
2016-Jan-26, 09:32 PM
I would suggest we get back on-topic. It sorta went off the rails halfway through post 5.

The thread is about alien civilizations in the galaxy, not about UFO sightings on Earth.

Swift
2016-Jan-26, 09:37 PM
I would suggest we get back on-topic. It sorta went off the rails halfway through post 5.

The thread is about alien civilizations in the galaxy, not about UFO sightings on Earth.
As DaveC426913 said. Let's drop the UFO sighting discussion.

Spacedude
2016-Jan-26, 10:17 PM
The Fermi paradox continues to haunt us until this day. If, indeed, there are billions of star systems in our galaxy, and the conditions needed for life are not so rare, then where are all the aliens?

Alright, I can take a hint :) this topic never goes anywhere anyways. But I disagree that the two topics are not related. The quote above is from the original post, and to ignor the obvious is to ignor the obvious. It's not apples and oranges, it's more of a fruit salad.