What's the probability of extraterrestrial life?

I'm not talking about possibility, I'm talking about probabilities as to what's most likely and what's less likely based on the available evidence.

A possibility doesn't need evidence. So you can say it's a chinese lantern, everyone is hallucinating or it's a flying shoe. A probability based on the available evidence needs some evidence so it can be weighed as to what's most likely and what's less likely.

When I look at the available evidence, I break it down this way.

90% - extraterrestrial/extradimensional. I say this because of the overwhelming evidence that has been investigated over the years. You also have liquid water on Mars, the moon and other places they are looking at. Extremophiles and over a billion earth like planets. It's getting harder and harder to deny the obvious. I also mix extraterrestrial and extradimensional but I give extraterrestrial a little more weight. Once we confirm extra dimensions then extra dimensional will shoot up even further.

7% - Time Travelers. I don't think these are time travelers from a future earth because of the grandfathers paradox. I think parallel universes explains this very well. If you went back in time and killed your grandfather a universe would branch off where your parents were never born but that wouldn't change the universe that you originated from. Maybe some are time travelers from parallel universes.

3% - Everyone is lying and hallucinating. This is silly but I don't like speaking in absolutes. This will drop to 1% when NASA announces the discovery of microbial life on another planet.

So I'm curious, has anyone else weighed the avalable evidence as to what's most likely and what's less likely? Not what's possible but what's probable based on the available evidence.

Also, probable means:

1 : supported by evidence strong enough to establish presumption but not proof

I say this before someone comes in and says prove this or where's the proof.

[edit on 27-11-2009 by Matrix Rising]

reply to post by Matrix Rising

When I look at the available evidence, I break it down this way.

Given available evidence we have one data point.

We can't even say whether the cat in the box on the lab bench is dead or alive let alone whether there is life out there.

Hell. Some of my friends don't think there is life here - it is all god's dream and nothing else is real.

As to your probability on extraterrestial life look up the drak equation. Its pretty neat as far as alien probabilities go.

reply to post by Matrix Rising


You might find this article helpful when doing your calculations:

New theory suggests that we may not be alone after all

And the companion thread within which you might find some worthy comments/opinions.
www.abovetopsecret.com...

from the number of galaxies and the number of planets within those galaxies ... i would think its statistically improbable if not impossible that we are alone.

Here is a very extensive Wikipedia article on the Drake Equation:

The Drake Equation

Very interesting, I skipped over the heavy math portion of course, then found this quote by Michael Crichton criticizing the equation. Also interesting.

The problem, of course, is that none of the terms can be known, and most cannot even be estimated. The only way to work the equation is to fill in with guesses. [...] As a result, the Drake equation can have any value from "billions and billions" to zero. An expression that can mean anything means nothing. Speaking precisely, the Drake equation is literally meaningless...

In other words, the equation should work, but we can't fill in enough of the variables to make it.

100%

It is here.

It is there.

It is everywhere.

I am 100% certain of ET life, ranging from bacteria and viruses, to other humans, to all kinds of other insects and animals. There are probably planets with intelligent space faring fish. If you can imagine it, it exists somewhere.

Have you actually looked at the night sky? Have you seen all those other stars? Do you know how many stars are in the galaxy? Do you know how many galaxies there are? I don't, but I know it is more than I can fathom.

en.wikipedia.org...
The Drake equation states that:

N = R* X Fp X Ne X Fl X fi X Fc X L

where:

N is the number of civilizations in our galaxy with which communication might be possible;

and

R* is the average rate of star formation per year in our galaxy
fp is the fraction of those stars that have planets
ne is the average number of planets that can potentially support life per star that has planets
fℓ is the fraction of the above that actually go on to develop life at some point
fi is the fraction of the above that actually go on to develop intelligent life
fc is the fraction of civilizations that develop a technology that releases detectable signs of their existence into space
L is the length of time such civilizations release detectable signals into space.[2]

Another good book I read was Probability 1 by Amir Aczel.

Here's a description of the book.

In a universe infinitely large, what is the probability of intelligent life on another planet? Sounds like a trick question, but for anyone versed in cosmology and statistics, the answer is 1; that is, there must be life on at least one other planet in the universe. This is Amir Aczel's theorem. But, as physicist Enrico Fermi once asked, if that's true, where is everyone? Aczel tackles that paradox after he goes through the statistical calculations for the probability of intelligent life, considering factors such as how many stars are in a galaxy, how many of those stars might be hospitable, how many might have planets, and how many planets might have environments suitable to support life as we know it (or as we don't). Aczel also provides an overview of the relevant developments in astronomy and biology--laying the groundwork to show that the universe's chemistry must add up to life. Whether life was spread through the universe by chunks of debris like ALH84001--the enigmatic meteorite from Mars that contained tantalizing hints of the possibility of life--or arose independently, Aczel is sure it is out there. After teasing readers with scientific history, Probability 1 delivers on its promise to prove Aczel's conjecture through a clearly explained application of known statistical theory to the chaos of the universe.

This was before extremophiles, a billion earth like planets and liquid water on Mars. He makes a good point when he says: the universe's chemistry must add up to life. Also Robert Lanza has a book called Biocentrism where he sees life as a fundamental property of the universe.

I'd be stunned if anyone seriously believed we were the only planet with life in our galaxy alone, let alone the universe. Anyone who thinks that, is clinging to the old axiom that we are the center of all, all-important, etc.. as humans, we've always had a high opinion of ourselves.

The first real question is: Is it possible they can get here?

I'd say yes, of course. Just consider the leaps we've made in 200 years. Where we are not considering ways to travel through the galaxy. We are merely scratching the surface of quantum physics. In 100 years, we will be studying things that right now, we can barely fathom. A civilization with a 1,000, or 10,000, or 100,000 year head start probably has multiple ways to travel across the long distances, in short periods of time.

Then the questions are: Can they find us, and would they bother to be here even if they did?

I'd think if someone can master travel, then finding populated worlds would be hardly a difficult thing. Even with our primitive technology, we can discern if a sun in a star system faar away has planets around it, and they could support life. Finding our planet and even finding out exactly what is here, imo, would not be greatly difficult. Not to mention we've made efforts to point an arrow to our planet and say "Here we are!" Which.. in retrospect, may not have been the brightest idea imo. We can't pick and choose who gets that message. Of course, there is the possibility that our planet, harboring a whole lot of very nice resources, might just be a target for visitors, at least until they see it's covered in life.

Why would they bother to come here if they could get here, and realized we harbored life?

I'd guess a few reasons. One, natural resources. Two, study. Three, because we are obviously sticking our nose into space, and we are also rather warlike. Roswell after all, was near, both time-wise and location wise as well, our first nuclear test. Many sightings have been over nuclear power plants and missile bases, including reports of them interfering with missile tests. If I were a species watching and interstellar neighbor, I think I'd like to know their capabilities, and what was needed to stop any attacks, if they turned hostile.

I see no reason to turn to things like time traveling, dimension hopping, etc. There are a TON of planets that could have life. And probably do. And that makes more sense than anything else, even if people don't want to believe it. They want to be the old Sumerians, where even though they were bright and clever, creating law and writing, they firmly believed that their land was on a solitary island, held up by giant turtles, and they were the only thing in the entire universe. Such was their mindset, and such are still many others.

Without the math to back it up, there are x number of habitable planets in the Universe so I would say the probability is much higher than the chance of finding intelligent life on Earth.

I certainly find it impossible we are the only life in the universe. What is interesting, doesn't matter what theory of creation you believe in (if we mark theology as an exception, the universe could have been created by the Bing Bang, the Multiverses Theory, expansionism, and probably a few others), it is impossible we are the only life.

We have observed many UFO cases, many of them posted here. A good percentage of them were confirmed to be hoaxes, others only have theories and speculations but no real answers whatsoever, so they probably do visit us, and they probably do live amongst us. At the end, everything that exists as an everything has one common seed, which is either a creationism theory or an "always there" theory.

I would be surprised if someday we find a real Alien corpse and someone uses Darwin's Common Trunk (I think that's what is called in English? ^^ theory and we end up having much in common. Sounds highly logical, IMHO.

my score: 100%

Why? on the quantum level , the substance is designed to self-organise and develope life. What happened on Earth happened to a very large number of pther planets.

Now - think about us -the humans - used to be like 1000 years ago. Then think , one civilisation would have 1000000 years in advance . Well, that civilisation would have the tech and the time to spread across the universe , and populate prity much every habitable planet.

What is my point? well, even if the probability for intelligent life seems very very low, someone already managed to spread across the galaxy and why not across the universe.

What is the probability to win the lottery? well, small. Yet someone wins nearly every week. Same with life. And given enough time.. we can assume it is everywhere.

My theory!

And now - why do we debate their existance ? well.. after we will manage to understand the human DNA i am sure we will be able to engineer smarter kids, right? also , our computers in thousands of years will begin to morphe with us . I mean.. future quantum cumputers with inimmaginable power, just part of the brain. Then the intelligence will be so great, that present day humans will not even unerstand their presence.

I remember Dr. Kaku (is this spelled right) making this comparation with a collony of ants (we the humans) , and a highway next to the collony. Would they understand the highway?




[edit on 28-11-2009 by Romanian]

Originally posted by Matrix Rising

We need to know what you mean by 'life' before going any further. We tend to classify life from what is generally accepted as 'alive' on this planet but it could take many other forms.

Carbon based protein processing life as we know it may be the exception rather than the rule.

I would ask, what is the definition of "life"

If you were to define life as physical life that breathes, eats, reproduces etc. I would say that the chances for extraterrestrial life is 99.9999%
with the chances for intelligent (meaning equal to or greater than humans) being 95% (these guesses are based on our current limited ability as humans, too find it)

If you define life as consciousness, or a living awareness that encompasses existence, than the answer is without a doubt 100%

I don't remember the source but there was an astronomer that did calculations based off of our current known Universe and came to the conclusion that something between 36,000 and 180,000 intelligent civilisations could possibly exist. Given the vastness of our Universe, that's not a lot but the equation was really speculative in that it only proposed 1 earth like planet suitable for habitation in every 100million planets. or maybe 1 billion planets...I'm not sure...I wish I could find that article......

There is no probability of of E.T. All scientists who know the vastness of space will agree that there is extraterrestrial life. In just this Universe the chance of there being no life other then on Earth, at this very moment is greater than a billion a to one. Then, our current theory which says that space is infinite and there are multiple to infinite universes proves there is life. If space is infinite than there is an infinite amount of life.

I would say that the odds are in favor of life elsewhere in the Universe. If you stated that we were the only form of life in the entire Universe and if that were true, that would be utterly amazing. Just think, out of billions and billions of different star systems in this galaxy, we would have the only planet with life on it. Then if you factor in the fact that there are billions and billions of galaxies out there with just as many star systems, the fact that only this one planet has life would be utterly amazing. I find it more interesting to speculate on what are the odds that an intelligent civilization could survive past the point where we're at where the means to easily destroy our civilization is present.

I took an Astronomy class before and the teacher talked about the subject about the odds of life elsewhere in the galaxy. I'll give an example.

Out of the billions of planets in this galaxy, if you said only 1 out of 20 would be in a preferred zone where water could exist that could narrow the possibility from say 20 billion planets to 1 billion planets in this galaxy.

Then if you said that only one of out 3 of those planets had a stable enough orbit, then the number would drop to 333 million planets. If you further said that only half of those had a sufficient amount of water, then you could drop the number to about 166 million planets.

If you said that most planets required a rare collision with a similar Earth moon size object to collide and orbit the planet and said that chance was one in a million chance, then you are suddenly down to only 166 planets in this galaxy. If you said that only a quarter of planets with life developed into intelligent life, you would be down to around 42 planets in this galaxy with intelligent life.

If you said that a civilization only had a 1 in 4 chance of surviving past the time when they discovered how to easily blow themselves up, then you are down to only around 10 advanced civilizations in this galaxy. If you multiply these odds by billions of galaxies, you have many billions of advanced civilizations scattered around.

However if your odds of a Earth moon size object colliding and going into orbit around the planet were more like a billion to one odds and all the other odds stayed the same, we may have the only planet with intelligent life in this galaxy and many many more. With billions of galaxies, the odds still favor another Earth moon like system out there somewhere.

Intelligent life in the Universe other than Earth: 100%

Intelligent life that has visited Earth from other planets: 100%

Intelligent life on Earth: Questionable!

Intelligence of anyone who in the face of all the evidence in favor of visitation by beings from other civilizations/dimensions, denies all of it:Knuckle Dragging

In all seriousness, if the state of advanced civilizations on Earth is any indication of how things are on other planets in the universe then it does bring into question the presence of a supreme being that created it.

At an interstellar conference of civilizations, I would hang my head in shame.

Originally posted by Agree2Disagree
I don't remember the source but there was an astronomer that did calculations based off of our current known Universe ......

I think you are talking about the Drake Equation which is mentioned a couple of times above in this thread, with a link provided.

Originally posted by orionthehunter

hm.. as far as i understood . the number of stars harbouring planets is far greater than 20 billions in the galaxy.

Our galaxy has 200 billion stars, and it looks like evry star actually has an entire planetary system. I would say there are at least 100 billion planets that can harbour life in our galaxy.

[edit on 28-11-2009 by Romanian]