The Fermi Paradox - Where is Everybody?

[StarMountainKid]

I think we also have to factor in the liklihood of of the evolution of an intelligent, technologically capable species on any suitable planet. By technologically capable I mean able to manipulate objects. I would think a bipedal species with hands with fingers, or some like arrangement, would be a necessity.

If humans had not evolved from apes, what other earth species could or would evolve with this capability? I understand that on other earth-like planets evolution may result in different species than on earth, but it seems to me whatever the evolutionary direction it may take, something similar to human-like physiology may be required for the creation of technology.

I think if we look back on the evolutionary history of earth, it is mere chance that humans evolved at all. Just because there are so man earth-like planets in the galaxy, or planets where life may evolve to some complexity, the evolution of an intelligent, technologically capable species may be rare indeed.

[bison]

There are, by various scientific reckonings, 400 million, 8 billion, 40 billion, or 60 billion habitable planets in the galaxy. Let's take the lowest of these figures. If only one in a million habitable planets produced a star-traveling civilization, that would make 400 of them in the galaxy. Many of these could be expected to be millions or billions of years our senior. If any one of these expanded its territory, as life is very often prone to do, it could have filled the galaxy a very long time ago, traveling at well below the speed of light.

[spacecowboy342]

There are, by various scientific reckonings, 400 million, 8 billion, 40 billion, or 60 billion habitable planets in the galaxy. Let's take the lowest of these figures. If only one in a million habitable planets produced a star-traveling civilization, that would make 400 of them in the galaxy. Many of these could be expected to be millions or billions of years our senior. If any one of these expanded its territory, as life is very often prone to do, it could have filled the galaxy a very long time ago, traveling at well below the speed of light.

And if 1 in a trillion trillion are inhabited, we are alone. Any figure you use is arbitrary. All we know is we haven't discovered others yet

[bison]

I thought the 'one in a million' figure quite conservative, and true to the spirit of the idea that intelligent life is very rare. Its possible that intelligent life is found on one in a thousand habitable planets. Even this figure would make it rare.

Thinking ourselves the only intelligent life in the galaxy seems rather like the various ways past generations imagined that they occupied a unique position.

Several early civilizations thought themselves at the center of a flat plane. Even when the Earth was known to be a sphere, it was still considered the center of the universe, and the only real world.

It was eventually understood that Sun was the center of our solar system, and that the wandering stars called planets were substantial worlds. Even then, it was seriously believed that planets around other stars were extremely rare. It was held that the planets of our solar system owed their existence to a very rare accident.

Every one of these assumptions has turned to dust, in light of newer, better knowledge. We may repeat their error, if we imagine that we are the only example of intelligent life in our entire galaxy

[Waspie_Dwarf]

I thought the 'one in a million' figure quite conservative

Based on what evidence?

Given that the total number of planets other than Earth know to have life is exactly zero any figure you provide is pure guess work. If a number is pure guess work then a claim that it is conservative is nonsense.

If I understand him correctly spacecowboy was not making a case for us being alone, he was making a case that if you just invent a number out of thin air (as you have done) you can make any case you want. That is not a scientific approach by any stretch of the imagination.

[Lilly]

If I understand him correctly spacecowboy was not making a case for us being alone, he was making a case that if you just invent a number out of thin air (as you have done) you can make any case you want. That is not a scientific approach by any stretch of the imagination.

Anything one concludes without evidence has a name...it's called "guessing". Doesn't matter if one uses math or just wild-azz speculation, it's all guessing until there's some kind of evidence to back it up.

[Frank Merton]

Anything one concludes without evidence has a name...it's called "guessing". Doesn't matter if one uses math or just wild-azz speculation, it's all guessing until there's some kind of evidence to back it up.

Thing is there is quite a lot of evidence, and its all negative so far. To me the most significant is that over a billion years or so the earth was not colonized. Also, there is no sign of the really advanced societies one would perhaps expect of civilizations a million or so years older than ours. Finally, and probably weakest of all, the skies are silent. As with all evidence, it can all be rationalized, but only so far and one begins to lean strongly toward extraterrestrial rarity.

[Waspie_Dwarf]

Thing is there is quite a lot of evidence, and its all negative so far.

You can not extrapolate from a single data point. We have absolutely no idea whether Earth is typical or not.

[spacecowboy342]

Thing is there is quite a lot of evidence, and its all negative so far. To me the most significant is that over a billion years or so the earth was not colonized. Also, there is no sign of the really advanced societies one would perhaps expect of civilizations a million or so years older than ours. Finally, and probably weakest of all, the skies are silent. As with all evidence, it can all be rationalized, but only so far and one begins to lean strongly toward extraterrestrial rarity.

Absence of evidence isn't really evidence

[Frank Merton]

You can not extrapolate from a single data point. We have absolutely no idea whether Earth is typical or not.

I am not extrapolating from a single data point. That statement is outrageous. I am pointing out that absence of evidence is real evidence.

[DefenceMinisterMishkin]

Why would they want to? i mean step back and look at our planet and humans in general.

We're probably the laughing stock of the universe and the butt of many alien jokes.

[Waspie_Dwarf]

The problem with interpreting a single data point is that you can claim almost anything.

Frank claims that the data is negative. Really?

Let's look at it another way:

• Number of planets known to be suitable for life = 1
  
• Number of planets suitable for life where life is known to arisen = 1
  
• Number of planets known to have life where multicellular life evolved = 1
  
• Number of planets known to have multicellular life where technological civilisations arose = 1

Therefore I could conclude that there is a 100% certainty that planets suitable for life will develop a technological civilisation.

Of course this argument, without any other evidence, is nonsense... but no more nonsense than claiming that the evidence is negative.

The reality is that it is not evidence at all.

[Waspie_Dwarf]

I am pointing out that absence of evidence is real evidence.

That is total rubbish. Absence of evidence is NOT evidence of absence. It is illogical to conclude that something you haven't found yet does not exist, especially when you haven't been looking for long.

[Waspie_Dwarf]

I am pointing out that absence of evidence is real evidence.

So there is an absence of evidence is there?

Make up your mind, you were claiming there was a lot of evidence only a few posts ago.

[Lilly]

Since we're currently at a sample of '1' (as Waspie has just pointed out) there's no way to conclude anything negative or positive.

[Frank Merton]

Lack of evidence is evidence. That is how we know there is no Santa Clause among other things. Practically anything can be claimed. The proper maxim is "lack of evidence is not proof."

I strongly object to being accused of saying things I did not say. I did not project from a data set of one, and I have consistently maintained that they probably exist, we just don't know and it is too early to say.

The thing is if the universe is as populated as some projections maintain, we should now have lots of affirmative evidence. We do not. That puts a serious limiting factor on things.

[Frank Merton]

So there is an absence of evidence is there?

Make up your mind, you were claiming there was a lot of evidence only a few posts ago.

You would do well to read wlhat I post more carefully before attacking someone like that./ Right now I am too angry to deal with it carefully, or do you just want to drive me away.

[spacecowboy342]

You would do well to read wlhat I post more carefully before attacking someone like that./ Right now I am too angry to deal with it carefully, or do you just want to drive me away.

There was an absence of evidence for the existence of Pluto until it was discovered. Absence of evidence is evidence of nothing

[Lilly]

The universe is big....very, very, very, very, very, very, very, very, very (need I go on) BIG!

The amount of the universe we've looked at is very, very, very, very, very, very, very, very, very small!

Just because we haven't found any other life as of yet is no indication either way.

Edited July 16, 2014 by Lilly
oops that reversed itself

[+Hammerclaw]

Absolutely right. The galaxy alone is so inconceivably vast, tens of thousands of starfaring civilizations could be plying space between the stars, and never once encounter each other. I think that--if there is an effective means of communicating between planets orbiting distant suns-- radio isn't it. What it might be, I have no clue. I feel like a neolithic savage trying to imagine cell phones.

[StarMountainKid]

All this talk of advanced technological civilizations that travel among the stars seem to me to be putting the cart before the horse. There may be an obvious answer to the Fermi Paradox: given the restrictive laws of physics, there exists no possible technology that allows for such star-faring civilizations.

Faster than light travel may indeed be impossible no matter how advanced a civilization's technology develops. Just assuming that such FTL travel is possible is a big assumption, in my view, and I think it should be considered a real possibility.

The idea of self-duplicating robotic probes colonizing the galaxy is also problematical. As stated in Wiki somewhere, the likelihood of errors in replication of these kinds of probes could end in dysfunction, or even disaster for biological life in the galaxy.

There is some definite probability that some percentage of these robotic probe's replication errors will result in killer probes. Perhaps advanced civilizations come to realize this, and decide it is not a good idea after all.

http://en.wikipedia.org/wiki/Self-replicating_spacecraft#Berserkers

Also see the Wiki on the Fermi Paradox

http://en.wikipedia.org/wiki/Transcension_Hypothesis#They_tend_to_experience_a_technological_singularity

[+Hammerclaw]

All this talk of advanced technological civilizations that travel among the stars seem to me to be putting the cart before the horse. There may be an obvious answer to the Fermi Paradox: given the restrictive laws of physics, there exists no possible technology that allows for such star-faring civilizations.

Faster than light travel may indeed be impossible no matter how advanced a civilization's technology develops. Just assuming that such FTL travel is possible is a big assumption, in my view, and I think it should be considered a real possibility.

The idea of self-duplicating robotic probes colonizing the galaxy is also problematical. As stated in Wiki somewhere, the likelihood of errors in replication of these kinds of probes could end in dysfunction, or even disaster for biological life in the galaxy.

There is some definite probability that some percentage of these robotic probe's replication errors will result in killer probes. Perhaps advanced civilizations come to realize this, and decide it is not a good idea after all.

http://en.wikipedia....raft#Berserkers

Also see the Wiki on the Fermi Paradox

http://en.wikipedia....cal_singularity

What?

[StarMountainKid]

What?

The only confusing part I could find in my post was "Just assuming that such FTL travel is possible is a big assumption, in my view, and I think it should be considered a real possibility."

Sorry. I may be seeing what you mean. I meant to say, faster than light travel may be impossible. When we consider FTL travel a possibility, this is just our assumption. Even the most highly advanced civilizations may not be able to travel faster than the speed of light.

[questionmark]

The only confusing part I could find in my post was "Just assuming that such FTL travel is possible is a big assumption, in my view, and I think it should be considered a real possibility."

Sorry. I may be seeing what you mean. I meant to say, faster than light travel may be impossible. When we consider FTL travel a possibility, this is just our assumption. Even the most highly advanced civilizations may not be able to travel faster than the speed of light.

It could be possible if we are capable of harnessing enough energy, taken the formula e=mc² you will notice that to accelerate a pound of mass to FTL will need more energy than we can possibly produce at this point.

And that formula has been confirmed independently a few times.

[StarMountainKid]

It could be possible if we are capable of harnessing enough energy, taken the formula e=mc² you will notice that to accelerate a pound of mass to FTL will need more energy than we can possibly produce at this point.

It is impossible to accelerate a pound of mass (or any amount of mass) to the speed of light.

I wonder how many planets in the galaxy are inhabited by an intelligent species that is a close neighbor to another star with a planet inhabited by another intelligent species.

Say, close enough that it would be practical to for them to visit each other's planet.