Alex_Krycek

Carl Sagan on Alien Life

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Carl Sagan once argued about the improbability of aliens having visited Earth.  He cited two main reasons: 

  • 1.  the vast distances aliens would have to travel to get to Earth would be an almost insurmountable obstacle
  • 2.  the vast amount of time that separates civilizations during their rise and fall would make it unlikely that any intelligent civilizations would exist simultaneously

On the other hand, Sagan has argued that he believes alien life is inevitable due to the vast numbers of planets and star systems that exist in the universe; he just doesn't think that intelligent beings have visited Earth, for the aforementioned reasons.

I propose a counter argument. 

First, to agree with Sagan's general view of extraterrestrial life, the vast number of stars in our own galaxy alone makes it likely that some form of life does exist.  These star systems undoubtedly contain billions of viable exoplanets.  Even in our own solar system, planets such as Mars have been found to have water, and Europa, one of Jupiter's moons, is thought to have subterranean frozen seas.  Is our own planet special?  Probably not.

Second, Sagan's point that civilizations would exist at different intervals, divorced from one another over eons of time, assumes one thing: that all intelligent civilizations would behave like Earth's.  That is, all civilizations would rise and fall, as those on Earth do, and would eventually end in extinction within a relatively short time.  But what if this isn't the case?  What if other intelligent species establish equilibrium or harmony on their planet and can exist indefinitely, through the wise marshaling of resources and lack of egoistic competition?  Why should we assume that all intelligent civilizations behave as haphazardly and ignorantly as human civilization does?

Continuing this idea, if another species did reach evolutionary equilibrium, where it continued to progress technologically (and perhaps biologically also) but without inter-species conflict or discord, then that species could theoretically exist indefinitely - for hundreds of millions of years, (barring the lack of some existential catastrophe like a meteor strike). 

Further, if the species was continuing to develop technological as human do, then their capability for traversing the vast distances of space would exponentially increase also.  With each passing milenia of stable progress an intelligent alien species would be more equipped to traverse the galaxy.  It has taken human beings roughly 250,000 - 300,000 years to progress from a nomadic state to that of (limited) space explorers, but what would our technology look like if we steadily progressed without self inflicted anihilation for another 250,000 years?

So the idea that an intelligent species could only exist for a short time is an assumption I don't think is 100% true.  And IF that species is able to progressively develop their technology over eons without interruption, then who is to say that the vast distances of space would be any barrier?  Additionally, how many star systems are there in our galaxy alone?  Dr. Sten Odenwald, astronomer for NASA, writes in the Huffington Post that there are between 100 billion and 1 trillion stars in the Milky Way.  At least 100 billions star systems, right in our own galactic neighborhood.

Finally, there is the fact that the Earth is 4.5 billion year old, and has been inhabitable (with breathable air, water, and a viable food source) for 650 million years.  Given these time frames, an alien species could definitely have evolved enough to venture out to explore its neighboring star systems and could have visited Earth already.  So, while I agree with Sagan's view that alien life is more or less inevitable, I don't think that vast time or distance necessarily negate the possibility of aliens having visited Earth.     

Thoughts? 

 

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Posted (edited)

Don't forget about all the galaxies we can't and never will see!

also I've read that 90% of the galaxies we can see have already passed the point of no return and are not really there anymore (past the edge of the visible universe where it's faster than light)

Maybe the above point would be a good motivator to leave your galaxy. Even travelling at slow speeds you would still have enough time to get here. 

I think alien life will more like the Heptpods in the film Arrival than green menIMG_1302.thumb.JPG.fe4ce2e11624f03eb8291de01f2f13f9.JPG

Edited by Curious layman

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2 hours ago, Alex_Krycek said:

Second, Sagan's point that civilizations would exist at different intervals, divorced from one another over eons of time, assumes one thing: that all intelligent civilizations would behave like Earth's.  That is, all civilizations would rise and fall, as those on Earth do, and would eventually end in extinction within a relatively short time.  But what if this isn't the case?  What if other intelligent species establish equilibrium or harmony on their planet and can exist indefinitely, through the wise marshaling of resources and lack of egoistic competition?  Why should we assume that all intelligent civilizations behave as haphazardly and ignorantly as human civilization does?

I find that argument very unlikely. Our intelligence emerged from being predators outsmarting our prey. That drive has kept us going for millennia and can be seen in the way we compete. Without that aggressive drive, we would probably never have evolved to our current state.

So, I argue that aggression/competition is a key element in any emergence of advanced civilisation. You can't have one without the other. And thereby you can't have have a peaceful, non-aggressive, advanced civilisation.

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Posted (edited)

Time and distance certainly do not necessarily prohibit inter planetary/stellar/galactic  contact, but it damn well makes it much harder and unlikely in many circumstances, assuming the logical assumption that the laws of physics apply everywhere.

Of course the main aspect of what Carl has always said, is that one of mankind's most enduring and inspiring questions, is are we alone? Like Carl who I see as an incredible educator, while the likelyhood of life elsewhere is very probable, as yet we do not have any evidence of any life existing off the Earth. And while Carl also agrees that Aliens could well have visited Earth at some time in the past, we have no evidence of such visitations.

Edited by beecee

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IMHO the motivations and appearance of aliens is difficult, to say the least, to try and speculate about these things is, if not a waste of time, really meaningless. We seem to be stuck on the Star Trek\Star Wars mind set where all aliens are more or less humanoid and all planets are more or less mirror images of Earth. Assuming that the laws of physics are as we see them it seems unlikely that star ship will make direct voyages to a star and colonise planets.Of course if we find a way to prolong our life span and or change our perception of time such voyages might be possible. 

But it would seem that slow boats or generational ship would be much more likely. After living their lives on a generational  ships the people on board might think that planets with uncontrolled weather and, wild dangerous animals, and various gravity and gases unlike the controlled environment of the spacecraft might be less than optimal. Using local materials to build new spaceships would look like the logical choice.

In fact I would think that all the material in our own solar system would be used to make habitats instead of starships. Of course such habitats could be converted to starships if the need arose. 

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7 hours ago, Moontanman said:

Assuming that the laws of physics are as we see them it seems unlikely that star ship will make direct voyages to a star and colonise planets.Of course if we find a way to prolong our life span and or change our perception of time such voyages might be possible. 

But it would seem that slow boats or generational ship would be much more likely. After living their lives on a generational  ships the people on board might think that planets with uncontrolled weather and, wild dangerous animals, and various gravity and gases unlike the controlled environment of the spacecraft might be less than optimal. Using local materials to build new spaceships would look like the logical choice.

In fact I would think that all the material in our own solar system would be used to make habitats instead of starships. Of course such habitats could be converted to starships if the need arose.

Well, think of it this way.  Science is always evolving.  Our understanding of the laws of physics is always expanding.  200 years ago the concept of air travel would have seemed ludicrous, due in large part to their limited understanding of physics and preconceptions about what technology is capable of.  The idea of jet propulsion (or even the concept of lift) would have seemed impossible except to the imaginative few.  I think it's the same way with space travel.  We're stuck in the box of the combustion engine: burn fuel, move forward.  But if our understanding of physics changed; for example, if we learned how to manipulate gravity (or even space-time itself), then this discovery would make the vast distances of space irrelevant.  It would be a game-changer in the same way that the airplane revolutionized travel on Earth.
 

Quote

 

I find that argument very unlikely. Our intelligence emerged from being predators outsmarting our prey. That drive has kept us going for millennia and can be seen in the way we compete. Without that aggressive drive, we would probably never have evolved to our current state.

So, I argue that aggression/competition is a key element in any emergence of advanced civilisation. You can't have one without the other. And thereby you can't have have a peaceful, non-aggressive, advanced civilisation.

 

I fundamentally disagree with your definition of intelligence.  I see intelligence as something that trascends petty competition and animalistic aggression.  Think of the most intelligent people on Earth: inventors, prodigious musicians, engineers, or brilliant architects.  Are they driven by aggression and competition?  At some lower level, perhaps - but most just want to pursue their art.  At some point intelligence transcends the predator / prey dynamic that you described, becoming instead a benign creative mindset with the end goal of harmony and peace.  Would an intelligent human being want to destroy the environment, for example?  Or would they want to preserve it indefinitely?  The aggressive, self interested humans are the ones destroying the environment, cashing in for a quick buck with no regard for the future.  Is that intelligent behavior?  I don't think so.

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On 6/27/2019 at 4:56 PM, Curious layman said:

I think alien life will more like the Heptpods in the film Arrival than green men

Arrival is a terrific movie.  The sequence where the helicopter first approaches the alien craft, and the subsequent entrance of the scientists into the craft, is one of the best in cinematic history, in my view.

Another point about a potential alien presence is how sparsely populated most of the world is.  The vast majority of people live in densely populated urban areas.  If there were extra-terrestrials visiting us, it would be fairly easy to avoid people. 

This interactive map shows just how much unpopulated space there is on the Earth: http://luminocity3d.org/WorldPopDen/#5/49.196/6.702

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On 6/27/2019 at 12:08 PM, QuantumT said:

I find that argument very unlikely. Our intelligence emerged from being predators outsmarting our prey.

I disagree. Lots of top-tier predators outsmart their prey without getting any smarter about it. Our intelligence emerged primarily because of the combined effects of cooking our food, tool use, agriculture/animal husbandry, great communication/cooperation, and having the time to specialize in pursuits OTHER than hunting and gathering. 

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