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View Diary: A Perspective on Life on Earth (74 comments)

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  •  Great diary (11+ / 0-)

    Well written. Just have two points I would put differently:

    Five hundred years ago, Europeans began colonizing the Americas, and the first slaves were taken from Africa to the New World.
    This makes it sound like this was the first time enslaving other humans had occurred to the human mind, when slavery had long been instituted in many parts of the world, non-European parts. I assume you meant just the American experience with slavery, but since it wasn't mentioned in any of the other moments in history to catalog . . . well you see what I mean.
    ife may be common everywhere there is liquid water and carbon in the universe, but sentient life is really hard to get to. It took a lot of near perfect conditions to get to us.
    We only know one kind of sentient life, us. But because we lack knowledge of or experience with any other forms of sentient life in the cosmos, doesn't lead me to think we are the only life form of sentient life possible. We think of "the near perfect conditions to get to us" as incredibly interesting and accidental, because we associate those conditions with sentient life. But it could well be that evolution on other planets, and perhaps in other universes, generally evolves sentient beings as it evolves from simpler life to more complex life in the particular conditions of that landscape. For all our learning about science, we are still very anthropomorphic. I think we are still in for a ton of great surprises brought to us by science.
    •  I doubt we are the only sentient life (11+ / 0-)

      But it is still very likely to be rare. A lot has to go right, and climate plays a big part of it. Time plays the other big part of it. Many stars don't even make it 4.5 billion years without swallowing their inner planets. It is possible that other species can become fully sentient but still lack the ability to manipulate their environment - could a dog or a dolphin develop much technology without the ability to grasp things, or especially if anything under the see can never use fire? Or is tool use a requirement to get brains to develop that last little bit?

      I thought about how the slavery part read, and decided to leave it in anyway. It is something that people need to think about a little more, and that bit of ambiguity catches peoples attention. It really was a remarkable thing, to transplant so many against their will so far into a completely different culture.

      •  Extremely well written diary (5+ / 0-)

        I also agree that we are probably not the only sentient life-  life seems pretty simple to evolve (and inevitable given the tautology which is the theory of evolution.)  The fact that sentient (and by that I think you mean self-reflective) life is relatively rare is irrelevant given the near infinite number of suns and planets.  Multiply a small number by an incredibly large number and you still get a large number!

        Of course, some would rather believe that of all the planets and suns and solar systems and galaxies "he" created, only earth has people.  the rest of the cosmos (even that which we cannot see) was put there for our enjoyment.  And "he" has a specific interest in the outcome of high school football games but is rather uninterested in the devastation caused by earthquakes, fires, volcanoes and epidemics....

        As my father used to say,"We have the best government money can buy."

        by BPARTR on Thu Nov 29, 2012 at 11:17:38 AM PST

        [ Parent ]

        •  I'm not sure if rareness is irrelevant (4+ / 0-)
          Recommended by:
          atana, rovertheoctopus, binkycat, jabney

          It may matter a lot if it happens twice in this galaxy or a hundred times or ten thousand times. I suspect the core of the galaxy is too chaotic, with too much radiation and exploding stars and close encounters between systems. I could be completely off on that, I'm a chemist, not an astrophysicist, but looking at the images of the big clusters towards the center makes me think that it is hard to get a few hundred million years of peace in there without something coming along to change your obit or throw crap at your planet.
          I'm curious now as to how many intersystem encounters are estimated to have occurred in our history. I'm sure someone has to have done a paper or model for it.
          It takes about 250 million years for us to orbit the galaxy once, so we have done it about 18 times since the Sun's ignition.
          In any event, do we meet up with something else, or forever stay isolated? I guess that is why it seems relevant to me. If each galaxy only gets a few shots at this, in a given period of time, we probably ought to try to make the most of it. I mean, we probably ought to anyway, but especially if it is as hard to get to us as it appears to me :)
          I think that we don't have evidence of alien life or visitation does mean we are kind of isolated. If you look at where we are at now, technologically, it is reasonable to assume that within, say, 200 years, we will know which stars have potentially habitable planets without our region of the galaxy. If any other species has even a 1000 year jump on us in terms of scientific development, which is nothing in terms of evolutionary time, they have known for a long time that the Earth exists, and is a prime piece of real estate for visiting and/or colonizing. If we found an Earth-like planet we could reach within a few hundred years, I'm pretty sure we would make the effort.
          Or maybe we are just the first locally of many that may come afterwards. Maybe there are dozens of sentient species still working out agriculture or whacking each other with sticks and flint within a few thousand light years.

          •  Stars don't have to stay at fixed distances (0+ / 0-)

            from the galactic center throughout their lives. The sun's composition is a little higher in metals than other stars in this region, suggesting it may have formed closer to the center and migrated outwards.

          •  Plus, Earth is home (1+ / 0-)
            Recommended by:
            binkycat

            I don't know about you, but I tend to get emotionally invested in places I've been in for a long time, and it's fair to say that I've lived on Earth my whole life, and I want to keep it that way. I've become quite fond of the fauna and foliage we've been neighbors with for hundreds of thousands of years. Maybe one generation, if our species comes out of the incoming changing climate alive, when the Sun is a red giant and set to die out another 4.5 billion years from now, we'll have an eye on a livable planet. For now, I like home. I'm just human!

            "Growth for the sake of growth is the ideology of the cancer cell." ~Edward Abbey ////\\\\ "To be a poor man is hard, but to be a poor race in a land of dollars is the very bottom of hardships." ~W.E.B. DuBois

            by rovertheoctopus on Thu Nov 29, 2012 at 12:55:13 PM PST

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          •  Yes. There may be intelligent life (1+ / 0-)
            Recommended by:
            BPARTR

            elsewhere but it may not be possible for us to interact or even know of its existence because of space-time. The stars we see are like recordings. The light we see is sometimes older than our planet.

            For if there is a sin against life, it consists perhaps not so much in despairing of life as in hoping for another life and in eluding the implacable grandeur of this life. - Albert Camus

            by Anne Elk on Thu Nov 29, 2012 at 02:37:19 PM PST

            [ Parent ]

      •  And the bad news (1+ / 0-)
        Recommended by:
        MillieNeon

        Even if we fix all of the problems we've created there is only about 500 million years left before our aging Sun cooks the planet.  If we screw it up there might not be enough time for intelligent life to evolve again.  

        As others have pointed out long term thinking is not our forte.  Geologic time is beyond our comprehension.  Still, I wonder where we will be in 10^3...10^7 years.  Will there be any trace of us left ?  Will anyone else out there even know we existed ?   Will anyone care.....

      •  I see your point (1+ / 0-)
        Recommended by:
        binkycat
        But it is still very likely to be rare. A lot has to go right, and climate plays a big part of it. Time plays the other big part of it. Many stars don't even make it 4.5 billion years without swallowing their inner planets.
        My point is that even with our newer powerful telescopes, we really know so damn little about this universe. Just as Newtonian physicists thought they'd gotten the foundational laws of physics mostly figured out and then BOOM! Quantum Mechanics opens a whole nother door. And the science evolutions, revolutions, innovations just keep on opening doors. When I say our species may not be the only form that sentient life takes, I didn't mean to imply that on some planets dogs may be sentient.

        Was pointing at the possibility of completely different species -- not even mammals -- that did not evolve on our planet, but evolved somewhere else in the cosmos may be the sentient beings in their world. Maybe some planets have several sentient beings. We don't really know what is possible and how many possible elsewheres are hanging around out there in vast outland.

        When we look out into that humongousness, we gaze through the particular filters that is our current map of the territory based on our current sciences and our current scientific assumptions. (And we have seen that even science has operated on assumptions until it develops the tools and experiments to test those assumptions. And they don't always prove to be accurate assumptions.) And we know the map is not the territory.

        No telling what interesting sentients are part of the cosmic fabric. But then, I must admit, I love the cosmic bar scene in Star Wars.

      •  The question of our rarity is a question of (0+ / 0-)

        statistical probability.  And since we have taken only one very non-random sample in the universe (us), we can't assign a probability to sentient life elsewhere until we either discover it (100%) or never do (something above 0%).  

        I am with you, mattakar, in accepting that the possibility that the sentience required to discuss these topics may be rare indeed.  When the Alvarez father-son team proposed the meteor extinction hypothesis in the early '80s, they also proposed an agent for a posited cycle of mass extinctions: a dim, distant companion star of the sun that they named Nemesis, which every some tens of millions of years would make a close enough approach to the outer bands of the solar system to perturb the outermost objects and send them hurtling in toward us.

        While the meteor impact has pretty clearly been identified (its long-submerged crater lies around the Yucatan and the angled impact is thought to have sent a life-scouring firestorm fanned across what today is North America), Nemesis almost certainly does not exist.  But it makes your point that if we were in a more active galactic spot, we'd probably not be here at all.

        We orbit a solitary sun, not one like our nearest neighboring triplet stars in the Centauri system - or like the majority of linked stars in our galaxy.  We are in the rarefied outer galactic reaches, not the densely packed center where the majority of our galaxy's stars lie.  And we are in a spiral galaxy, not one of the enormous elliptical ones that may not be as hospital to the heavy elements or the multi-billion years of stability that may be necessary to develop sentience.

        And when we look for reasons for that stability closer to home, we may also note that we are an inner rocky planet protected by 4.5 billion years of gravitational object-sweeping by four gaseous giant outer planets, and share our orbit with a pretty hefty moon, allowing our dual system to do a darn good job of sweeping out the inner system (billions of times).  Finally, the collision itself that created that moon which you mentioned redistributed the accreted formative elements of our planet quite explosively, and the tidal effects of that moon may also be an agitating propellant in our story.

        So all in all, if it should turn out that there is sentience elsewhere, that wouldn't surprise since the universe is so large; but it's also young (only 3 times older than our own planet!) so if all these ingredients conspired to make us unique, that wouldn't be so shocking, either.  Hey, like I said below somewhere: great diary.

    •  Slavery was endemic before the (2+ / 0-)
      Recommended by:
      MillieNeon, jabney

      industrial revolution.  Tragically, slavery still exists and there are efforts to end it everywhere, but some humans just love to have complete power over other humans.

      United Citizens beat Citizens United

      by ThirtyFiveUp on Thu Nov 29, 2012 at 06:09:54 PM PST

      [ Parent ]

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