Intelligent life other than on Earth

[jackwhirl]

Certain that intelligent life has existed in at least 2 locations during the entire history of the universe... If the Earth is the only host for intelligent life in all of history and it turns out it's cyclic, even then we can be certain that it also occurs at least twice with an infinite number of cycles.

I don't think I understand what you mean here, but the wording reminds me of an article I read that applied the Zero-One-Infinity rule to astrobiology. I think it was in Time, but all I could find was this blog post that talks about the article.

Zero-One-Infinity in Astrobiology

Applying the zero-one-infinity rule to the search for alien life is, in my opinion, brilliant. How many locations in the universe can support life? There are really only three answers:

• Life cannot exist anywhere in the universe (zero).
• Life can exist only on Earth; Earth is a very special exception in a universe where life is otherwise not allowed (one).
• Life can exist in an unlimited number of locations in the universe (infinity).

We already know the zero proposition is false.

There was a time (I remember it well) when many a scientist argued that Earth must be an exception: the one and only place in the universe where life could exist. Occasionally, I still hear people try to argue this.

All it would take is to find a second life-bearing world to prove the one proposition wrong (I’m looking at you, Europa). Because once we know about two living worlds, how could anyone argue that there can’t be three? Or four? Or thirty-eight? Or however many the universe feels like having?

Is that what you were trying to express?

 

[George Jones]

Intelligent life on Earth? Some people agree with the last few lines of

 

[Noisy Rhysling]

Certain that intelligent life has existed in at least 2 locations during the entire history of the universe... If the Earth is the only host for intelligent life in all of history and it turns out it's cyclic, even then we can be certain that it also occurs at least twice with an infinite number of cycles.

"...at least 2 locations during the entire history of the universe..."

Los Angeles and New York?

 

[Fervent Freyja]

"...at least 2 locations during the entire history of the universe..."

Los Angeles and New York?

I refuse to believe that the molecular complexity which drove the formation of intelligent life at Earth hasn't, doesn't, or won't exist in numerous locations elsewhere. The Earth cannot be the most special place in the universe- that's old school logic! I have found no evidence that suggests Earth is some sort of preferred location in the universe. Okay, I better stop before my nihilistic thinking gets me into trouble on here...

 

[stoomart]

The Earth cannot be the most special place in the universe- that's old school logic!

I'd say ideas like flat Earth and Earth as the center of the solar system or universe are old school logic, but choosing between naturalism and creationism is more of a philosphical preference.

 

[Fervent Freyja]

I'd say ideas like flat Earth and Earth as the center of the solar system or universe are old school logic, but choosing between naturalism and creationism is more of a philosphical preference.

No, believing we are the most special in the universe is the old logical flaw found at the foundation of every concept you described.

 

[MarkFL]

I refuse to believe that the molecular complexity which drove the formation of intelligent life at Earth hasn't, doesn't, or won't exist in numerous locations elsewhere. The Earth cannot be the most special place in the universe- that's old school logic! I have found no evidence that suggests Earth is some sort of preferred location in the universe. Okay, I better stop before my nihilistic thinking gets me into trouble on here...

I feel very much the same way you do. Intelligent life may very well turn out to be very rare, but in an observable universe with as many implied star systems as ours, even 1 in a trillion (just to arbitrarily pick a fairly large number) would be very numerous in absolute terms.

I too see no compelling evidence whatsoever that Earth has to be unique with regards to intelligent life in the entire universe. It happened here because the laws of nature allow it, and the conditions were conducive. I find it virtually impossible to think there are no other places in the universe where conditions aren't also conducive.

 

[stefanbanev]

Apparently Impossible... who is a judge about intelligence, the one who claims to posses such quality ;o) The ability to foresee/recognize the danger and to arrange the countermeasure is the most basic property of life. Who does it better those prevail so, no surprise that natural selection favors such quality... from the chemistry on the membranes of microbes to the specialized organs to process outside information is inevitable evolutionary trend and the claim that from some particular level it becomes "intelligence" is not quite intelligent ;o) it is a continuum and it exhibits an Exponential growth so, the probability to contact another "intelligence" is getting lower for more evolved "intelligence" because the contact is possible for relatively close levels (like human/monkey for example); due to the exponent the window of opportunity is getting smaller and smaller; thus, the more evolved the more lonely ... ;o)

 

[Noisy Rhysling]

I refuse to believe that the molecular complexity which drove the formation of intelligent life at Earth hasn't, doesn't, or won't exist in numerous locations elsewhere. The Earth cannot be the most special place in the universe- that's old school logic! I have found no evidence that suggests Earth is some sort of preferred location in the universe. Okay, I better stop before my nihilistic thinking gets me into trouble on here...

The evidence for either case is too small to make a definitive statement. Opinions are fine, especially when stating that up front. "Certain" isn't possible, "I hope" would be fine.

 

[Buzz Bloom]

I think the question as phrased is flawed in the same way as in the other recent thread:

https://www.physicsforums.com/threads/do-you-think-et-life-exists-elsewhere.931857/ .​

As I posted in the other thread, #47,

Since the current best cosmological models of the universe indicate that the universe is infinite, then I think the following maxim is applicable: If something can happen once, then it can happen again.​

I would suggest an alternative question restricting the scope to one or more of the following:

The observable universe.
The super-cluster in which the Milky Way exists.
The cluster in which the Milky Way exists.
The Milky Way.​

 

[Buzz Bloom]

I have found no evidence that suggests Earth is some sort of preferred location in the universe.

Hi Freyja:

I made the following comment in post #47 of the thread cited in my post above.

However, regarding the Milky Way having life other than that on Earth, or any other randomly chosen galaxy, my guess is "maybe, but probably not." My reasoning is admittedly based on a controversial premise. I believe that our oversized moon played a necessary (but not necessarily sufficient) role in the pre-life chemistry that led to life, and that such a moon happens extremely rarely.​

I do not have references on hand about the possibility that the Earth's moon was a necessary factor to life evolving from non-life here, but I recall some discussion in MIT's Technology Review from at least 20 years ago. I also recall other published discussions over the years presenting a variety of different reasons supporting the idea that our moon might have been essential. I have also tried unsuccessfully to track down an estimate of the likelihood that Earth would by chance obtain it's oversized moon, but I get an impression from various readings (which I cannot now cite) that the likelihood is extremely small. Thus, I would not be surprised if some reliable researcher someday says that it is very likely that in the Milky Way only the Earth is a planet both capable of having liquid water and also having a large moon like our moon.

Regards,
Buzz