Originally Posted by Erik '73

Rare EarthI believe that there could be thousands or millions of planets in the galaxy that currently have life of some form, but those with the technology to communicate across interstellar distances is extremely rare. I think that there is a inverse relationship between the complexity of life and its galactic abundance. One option not in the poll was technological transcendence. Perhaps after a civilization pass a Technological Singularity, they rapidly acquire the knowledge to leave normal space and transcend to some new reality that we cannot currently comprend or observe. Maybe highly advanced races think it is silly to try to colonize the galaxy when they can create their own "universes" that suit them far better.

Or perhaps they can create portals to other universes that already exist. It has been suggested that a super civilization might do so to escape a dying universe. But perhaps at an earlier stage another universe might have appeal if its physical laws might be less restrictive than ours.

I think we are the aliens. We are Martians that survived a great impact and earth was the mass thrown off. If apes are deprived of light/dark cues, they naturally revert to a Martian day. Who knows there may be other survivors on other masses. See "exploding planet theory".

Book - How To Build A Time Machine The Real Science of Time Travel by Brian Clegg. I won't claim to understand half of the theoretical stuff, but the book is an entertaining read. One does get the impression that time travel - as well as faster than light travel - will require the super technology of a super civilization. There is a chapter called "Intersteller Engineering." There is also a chapter on "Killing Grandfather."

In another galaxy.

A strange planet orbiting a strange variable star inside the orbits of multiple gas giants. The strange planet has a tilted axis, and the degree of tilt is just right.

We are very, very alone.

Originally Posted by SF_Steve_63

A strange planet orbiting a strange variable star inside the orbits of multiple gas giants. The strange planet has a tilted axis, and the degree of tilt is just right.

We are very, very alone.

First of all, "the degree of tilt is just right" is an example of the anthropic principle. The degree of tilt is "just right" because we (and other life-forms on this planet) are just right for this degree of axial tilt.

We don't actually know what the boundary conditions are for the generation of life even in the biochemical form it exists on this planet. It survives here under a wide array of temperatures, salinity, moisture, and chemical environment. Studies are under way to determine whether life once existed on Mars, and if it's found there the probability of life being generated in any given planetary environment will receive a significant boost. And that's before we even consider the possibility of radically different forms of life based on alternative chemical processes.

As I commented earlier in this thread, there are only two potential bottlenecks to the development of intelligent life capable of interstellar travel, setting aside the "slow boat" possibility (which remains a possibility of course). One is the development of life itself. The other is the survival of a species' own intelligence. Given the existence of life and sufficient time, the evolution of intelligence is a near-certainty. Every step along the path to high-tech intelligence on our planet has been taken very quickly once the prerequisites were met.

If we do find evidence of life on Mars, that will pretty strongly indicate that the first bottleneck isn't a bottleneck. It will show that, given conditions within tolerance, life is very likely to occur. If that's true, then given those conditions, so is intelligent life.

It remains to be seen whether intelligent life will tend to self-destruct. That's the other potential bottleneck. Our own achievement of a sustainable society, and retroactive examination of the process by which we did so and how close we came to blowing it, will give us some information on that. (Or, of course, we'll self-destruct, and then it won't.)

Originally Posted by SF_Steve_63

A strange planet orbiting a strange variable star inside the orbits of multiple gas giants. The strange planet has a tilted axis, and the degree of tilt is just right.

We are very, very alone.

Since when is Sol a variable star? It's a pretty typical G Dwarf with moderately high metalicity. It's near the high end of stars that can produce Earth-like planets, though, K Dwarf stars are better, less UV and they live longer.

Most of the "strangeness" of the Earth is the RESULT of life and/or oceans, and the oceans have not evaporated into space because the Ozone Layer, created by life, creates a temperature inversion that keeps water vapor from rising into the statosphere.

Our tilt is nothing special, either, I don't see how a different tilt would impede the development of complex life unless it is extreme (over 60 degrees).

Luna was created by an impact with a proto-planet with 3 times the mass of Mars, but such impacts are very common in young solar systems, all the inner planets were hit by such whoppers. One blasted off much of Mercury's mantle. Another gave Venus it's slow, backward spin. Mars' northern plains may be a gigantic impact basin.

Originally Posted by Brian Rush

First of all, "the degree of tilt is just right" is an example of the anthropic principle. The degree of tilt is "just right" because we (and other life-forms on this planet) are just right for this degree of axial tilt.

We don't actually know what the boundary conditions are for the generation of life even in the biochemical form it exists on this planet. It survives here under a wide array of temperatures, salinity, moisture, and chemical environment. Studies are under way to determine whether life once existed on Mars, and if it's found there the probability of life being generated in any given planetary environment will receive a significant boost. And that's before we even consider the possibility of radically different forms of life based on alternative chemical processes.

As I commented earlier in this thread, there are only two potential bottlenecks to the development of intelligent life capable of interstellar travel, setting aside the "slow boat" possibility (which remains a possibility of course). One is the development of life itself. The other is the survival of a species' own intelligence. Given the existence of life and sufficient time, the evolution of intelligence is a near-certainty. Every step along the path to high-tech intelligence on our planet has been taken very quickly once the prerequisites were met.

If we do find evidence of life on Mars, that will pretty strongly indicate that the first bottleneck isn't a bottleneck. It will show that, given conditions within tolerance, life is very likely to occur. If that's true, then given those conditions, so is intelligent life.

It remains to be seen whether intelligent life will tend to self-destruct. That's the other potential bottleneck. Our own achievement of a sustainable society, and retroactive examination of the process by which we did so and how close we came to blowing it, will give us some information on that. (Or, of course, we'll self-destruct, and then it won't.)

It is certainly an interesting discussion regarding the boundary value problem of defining the operational envelope of life. That said, looking at the empirical data thus far can at least inform our knowledge.

Originally Posted by Odin

Since when is Sol a variable star? It's a pretty typical G Dwarf with moderately high metalicity. It's near the high end of stars that can produce Earth-like planets, though, K Dwarf stars are better, less UV and they live longer.

Most of the "strangeness" of the Earth is the RESULT of life and/or oceans, and the oceans have not evaporated into space because the Ozone Layer, created by life, creates a temperature inversion that keeps water vapor from rising into the statosphere.

Our tilt is nothing special, either, I don't see how a different tilt would impede the development of complex life unless it is extreme (over 60 degrees).

Luna was created by an impact with a proto-planet with 3 times the mass of Mars, but such impacts are very common in young solar systems, all the inner planets were hit by such whoppers. One blasted off much of Mercury's mantle. Another gave Venus it's slow, backward spin. Mars' northern plains may be a gigantic impact basin.

Sol's output of flux outside the visible band is certainly variable. Witness the cycling of the so called solar wind and the even longer period modulation of that oscillation.

Originally Posted by SF_Steve_63

Sol's output of flux outside the visible band is certainly variable. Witness the cycling of the so called solar wind and the even longer period modulation of that oscillation.

All stars have at least a small amount of variability, the sun's is not enough to qualify as a viable star as defined by astrophysicists.

I haven't really paid much attention to this thread, but I think there should be an extra option - the human and the ant. Perhaps any aliens who could contact us are so advanced (think millions of years ahead of us), that we are the equivalent of ants to them. Imagine an ant hill next to an interstate highway - us expecting aliens to land on the White House lawn and say "take us to your leader", is basically as reasonable as ants in an ant colony expecting us to try to contact them and link our civilizations. It's more likely we'll just step on them, or more likely still, just ignore them entirely.

Originally Posted by MK'94

I haven't really paid much attention to this thread, but I think there should be an extra option - the human and the ant. Perhaps any aliens who could contact us are so advanced (think millions of years ahead of us), that we are the equivalent of ants to them. Imagine an ant hill next to an interstate highway - us expecting aliens to land on the White House lawn and say "take us to your leader", is basically as reasonable as ants in an ant colony expecting us to try to contact them and link our civilizations. It's more likely we'll just step on them, or more likely still, just ignore them entirely.

I think it's more likely that the opposite is true, and that there are billions of planets with alien life on it, but that life is more akin to an ant or insect or worm or something, and not intelligent in the same way we define "intelligent" (but perhaps may be intelligent in other ways that we can't comprehend). The odds of aliens evolving in the similar way as we have on earth is probably so low that "intelligent life" as we like to portray them in star trek and other scifi alien stories simply does not exist.

Originally Posted by Gianthogweed

I think it's more likely that the opposite is true, and that there are billions of planets with alien life on it, but that life is more akin to an ant or insect or worm or something, and not intelligent in the same way we define "intelligent" (but perhaps may be intelligent in other ways that we can't comprehend). The odds of aliens evolving in the similar way as we have on earth is probably so low that "intelligent life" as we like to portray them in star trek and other scifi alien stories simply does not exist.

I addressed this a lot earlier in the thread, but I'll reiterate in capsule form.

Intelligence as we know it (a combination of social organization and tool use) is a viable survival strategy. A planetary ecosystem will display ALL viable survival strategies in the course of its evolution, and therefore will display that one as soon as it is able to. The development of intelligence and civilization sufficient to engage in interstellar travel (assuming that's physically possible, i.e. assuming "slow boat" is false) occurs in the following steps:

1. The emergence of life itself.
2. The development of photosynthesis or some other means of producing nutrients.
3. The development of eukaryotic organisms, or the equivalent.
4. The development of metazoans.
5. The development of semi-intelligent life on the order of crows, monkeys, raccoons, etc. -- animals who rely on the intelligent manipulation of their environment to survive.
6. The emergence of an intelligent species on the order of H. sapiens.
7. The development by this species of civilization.
8. The achievement by this species of an ecologically sustainable, peaceful civilization.

As I pointed out in post #11, on the first page of this thread, of these steps the only ones that might possibly be low probability are the first and last. Given life, intelligent life looks like a certainty, at least until it self-destructs. We don't know how probable the emergence of life is given the preconditions for it. We also don't know how likely it is for a civilization to avoid self-destructing as we may be about to do. Unless one or both of these probabilities is low, the universe should have quite a lot of intelligent life in it. In any case, life that never evolves intelligence should be vanishingly rare, if not nonexistent.

Originally Posted by Brian Rush

I addressed this a lot earlier in the thread, but I'll reiterate in capsule form.Intelligence as we know it (a combination of social organization and tool use) is a viable survival strategy. A planetary ecosystem will display ALL viable survival strategies in the course of its evolution, and therefore will display that one as soon as it is able to. The development of intelligence and civilization sufficient to engage in interstellar travel (assuming that's physically possible, i.e. assuming "slow boat" is false) occurs in the following steps:1. The emergence of life itself.2. The development of photosynthesis or some other means of producing nutrients.3. The development of eukaryotic organisms, or the equivalent.4. The development of metazoans.5. The development of semi-intelligent life on the order of crows, monkeys, raccoons, etc. -- animals who rely on the intelligent manipulation of their environment to survive.6. The emergence of an intelligent species on the order of H. sapiens.7. The development by this species of civilization.8. The achievement by this species of an ecologically sustainable, peaceful civilization.As I pointed out in post #11, on the first page of this thread, of these steps the only ones that might possibly be low probability are the first and last. Given life, intelligent life looks like a certainty, at least until it self-destructs. We don't know how probable the emergence of life is given the preconditions for it. We also don't know how likely it is for a civilization to avoid self-destructing as we may be about to do. Unless one or both of these probabilities is low, the universe should have quite a lot of intelligent life in it. In any case, life that never evolves intelligence should be vanishingly rare, if not nonexistent.

I think that's just a narrow-minded, easy-way-out type of thinking. Just because it's a certain way here on earth doesn't really mean a thing.

I'm not sure that a peaceful civilization is a precursor to going interstellar.

It may well be that what's required is a very conquest oriented, highly dominating civilization which first conquers its home planet then moves out from there. It may be that having an "environmental conscience" is actually a self imposed limitation preventing colonization of space.

When Nixon decided to start cutting back NASA, a move no one since has really countered, it was based on the notion that "we have bigger problems here on Earth that need to be solved." Cut back NASA, kicked off the EPA. That was not a coincidence.

ProjectCyclops

Originally Posted by MK'94

I haven't really paid much attention to this thread, but I think there should be an extra option - the human and the ant. Perhaps any aliens who could contact us are so advanced (think millions of years ahead of us), that we are the equivalent of ants to them. Imagine an ant hill next to an interstate highway - us expecting aliens to land on the White House lawn and say "take us to your leader", is basically as reasonable as ants in an ant colony expecting us to try to contact them and link our civilizations. It's more likely we'll just step on them, or more likely still, just ignore them entirely.

Reminds me of G'Kar's talk with Sakai on Babylon 5 about the Walkers of Sigma 957.

Originally Posted by MK'94

I think that's just a narrow-minded, easy-way-out type of thinking. Just because it's a certain way here on earth doesn't really mean a thing.

That depends on which part of it being "a certain way here on Earth" you're talking about. Some parts of what happened here result from what HAVE to be universal principles. One of those universal principles is the way evolution works, and a part of that is that ALL viable survival strategies will have their expressions in a biosphere. Given the existence of a planetary biosphere and a fair amount of time, the emergence of intelligent life is inevitable, because that's a viable survival strategy.

Originally Posted by SF_Steve_63

I'm not sure that a peaceful civilization is a precursor to going interstellar.

It may well be that what's required is a very conquest oriented, highly dominating civilization which first conquers its home planet then moves out from there.

Start with the level of technology we have today, which is less than what is required to achieve interstellar travel. Note the existence of nuclear weapons. Imagine any country exhibiting a conquest-oriented, dominating collective mentality. Project the likely results.

Yes, peace is a prerequisite. A lack of it results in self-destruction. That really ought to be obvious.

Originally Posted by Brian Rush

That depends on which part of it being "a certain way here on Earth" you're talking about. Some parts of what happened here result from what HAVE to be universal principles. One of those universal principles is the way evolution works, and a part of that is that ALL viable survival strategies will have their expressions in a biosphere. Given the existence of a planetary biosphere and a fair amount of time, the emergence of intelligent life is inevitable, because that's a viable survival strategy.

You are making a lot of assumptions when it comes to the evolution of life. The most viable survival strategy, without question, is to stay simple, like bacteria. They have been proven to survive in conditions that more complex life could not, including all the great extinction events in Earth's history. Do you think if life is found on Mars, Europa, or Titan it will be complex, intelligent life? No, it will have to be simple life that can withstand harsh conditions. The same is true for any of the exoplanets that have been discovered so far. If anything, the development of more advanced lifeforms is a couterproductive survival strategy. Humans and other complex life on Earth have been blessed by a stable planet and solar system that has shielded it from destruction, in spite of it NOT being the fittest to survive.

anti-exponential theory

Originally Posted by Brian Rush

Start with the level of technology we have today, which is less than what is required to achieve interstellar travel. Note the existence of nuclear weapons. Imagine any country exhibiting a conquest-oriented, dominating collective mentality. Project the likely results.

Yes, peace is a prerequisite. A lack of it results in self-destruction. That really ought to be obvious.

"There is profound error and harm in the disoriented claims of bourgeois ideologues that there will be no victor in a
thermonuclear world war." - A. S. Milovidov

And in fact, as horrible as that trial would be, the emergent system would be a mean, tough, gritty, pared down one. All notions of utopian belief would have been discredited. Brute force would rule. It would be the antithesis of the current system. Yes, the next 1T could be fairly intense.

Originally Posted by Erik '73

You are making a lot of assumptions when it comes to the evolution of life. The most viable survival strategy, without question

I don't really need to read beyond this.

What the "most viable" survival strategy may be is irrelevant. A planetary biosphere will not exhibit just ONE survival strategy, it will exhibit ALL viable survival strategies. All of them. All at once. It will not choose just one.

Here on Earth, we may find intelligent manipulation of the environment and social organization (H. sapiens, most other primates, and several other species of mammal and bird), but we can also find large predators (big cats, bears, sharks), social organized predators (wolves, etc.), small animals that breed very quickly (rabbits, etc.), small animals with defensive adaptations (turtles, snails, skunks), plants that grow very tall to reach the sunlight (trees), plants that spread laterally through multiple means of reproduction (grasses), and lots and lots of other survival strategies. If it works, it's here.

That's how life operates. That's how evolution works. Life is always trying new things, and anything that works continues in existence. Life doesn't sit around at a conference table and say, "Hmm, let's figure out what the very best survival strategy might be and then all of us will do that and nothing else." Life is not a dictatorship. It's not regimented. It's chaotic. It tries everything.

And that's why intelligent life will be found in any planetary biosphere that's been around a while: because life will try everything, everything that works will last, and that works.

Originally Posted by SF_Steve_63

"There is profound error and harm in the disoriented claims of bourgeois ideologues that there will be no victor in a
thermonuclear world war." - A. S. Milovidov

And in fact, as horrible as that trial would be, the emergent system would be a mean, tough, gritty, pared down one. All notions of utopian belief would have been discredited. Brute force would rule. It would be the antithesis of the current system. Yes, the next 1T could be fairly intense.

A nuclear war to the finish would mean, at best, the end of civilization and, at worst, the extinction of the human species. What characteristics the "winner" might have are irrelevant. It would be in no position to colonize the stars. It would be trying to re-learn how to farm and live in cities -- at best.

Originally Posted by Brian Rush

A nuclear war to the finish would mean, at best, the end of civilization and, at worst, the extinction of the human species. What characteristics the "winner" might have are irrelevant. It would be in no position to colonize the stars. It would be trying to re-learn how to farm and live in cities -- at best.

The most adamant unilateral disarmament advocates who sprung up during the late 1T and really came out during the 2T certainly wanted all of us to believe what you wrote. I used to believe it myself. I no longer do. Believing it sets you up for certain slavery because it prevents any sort of real preparation for the great power geopolitical stage of The Crisis. Un prepared means ready to be conquered.