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  • Dan Dredger wrote a new post, Yes, There Have Been Aliens 4 years, 2 months ago

    By Adam Frank
    Last month astronomers from the Kepler spacecraft team announced the discovery of 1,284 new planets, all orbiting stars outside our solar system. The total number of such “exoplanets” confirmed via […]

    • Worth ignoring the catchy title and looking at the article which you can get for free by following the New York Time link. It’s quite short. The abstract covers it nicely:

      In this article, we address the cosmic frequency of technological
      species. Recent advances in exoplanet studies provide strong
      constraints on all astrophysical terms in the Drake equation. Using
      these and modifying the form and intent of the Drake equation, we set
      a firm lower bound on the probability that one or more technological
      species have evolved anywhere and at any time in the history of the
      observable Universe. We find that as long as the probability that a
      habitable zone planet develops a technological species is larger than
      10 to the -24, humanity is not the only time technological
      intelligence has evolved. This constraint has important scientific and
      philosophical consequences.

    • Added to this, Alan, I think we have other major unresolved probabilities. Abiogenesis looks a thermodynamic doddle. Evolution to sophisticated entities a blithe inevitability, but the prokaryote to eukaryote transition, the first step to sophisticated entities remains an unsolved thermodynamically improbable bottle neck.

      Life, given goldylocks planets, is a dead cert. Civilisations a cert given eukaryotes. What we need to better hypothesise and test is the ready creation of eukaryotes (highly thermodynamically unlikey in all models to date) or an alternative path from sponge to civilisation using cooperating prokaryotes or some such.

    • phil rimmer #6
      Jun 12, 2016 at 7:32 am

      Added to this, Alan, I think we have other major unresolved probabilities. Abiogenesis looks a thermodynamic doddle. Evolution to sophisticated entities a blithe inevitability, but the prokaryote to eukaryote transition, the first step to sophisticated entities remains an unsolved thermodynamically improbable bottle neck.

      Life, given goldylocks planets, is a dead cert.

      To expand on my earlier comments, rocky planets and carbon are features of later generation stars, so lacking in the first stars formed from accretion disks of hydrogen and helium.

      These contained no heavy elements, and unless the stars were big enough to go supernova galaxies of such smaller low metalicity stars, would have accretion disks lacking these. Without explosions, any heavy elements would be retained inside the stars where they were formed. There would be no planets with heavy elements. We do not even know if such light elements would be dense enough to form planets in systems as we know them, at all!

      Big heavy galaxies of heavy elements are a product of a much later stage of cosmic evolution, as are the high metalicity stars and accretion disks. – So we can write off large areas of space and time as potential areas of the universe for life, due to a lack of heavy elements and possibly a lack of planets – rocky or otherwise.

    • Alan

      I hastily added goldylocks and should have further qualified it as well. Your point is well taken.

      Life, given late stage goldylocks planets, is a dead cert.

    • I am approached about things like this all the time. I am not as cutting edge nor well read as Alan4 nor Phil
      However, there are a few points that seem to communicate to laymen a proper way of dealing with these types of questions.

      I give you……. “confidence”. I always tell people that I have close to 100% confidence in some ideas and close to 0% confidence in other ideas. I am not at 100% nor 0% on anything. However, to make the point. I have in my hand an orange. I am almost 100% certain that oranges exist.

      I also have a drawing of a unicorn. I am almost 0% certain that they exist. Same with bigfoot, loch Ness monster, yeti, ghosts, spirits, leprechauns, fairies, gnomes, Gollum, bilbo, Freddie Kreuger, the devil and god.

      Now, my confidence that there are aliens somewhere in the universe is high but it starts to erode and dwindle when you start defining it. So, life? Probably. Multicellular life? less probable. Multicellular eukaryotes that have technology? even less probable… All the way down to “visiting earth and crashing into the desert” to which I assign very low probability.

      There are many nuances to the discussion. One I am always fascinated by is the idea the many think aliens would have to be on our scale. Seems arbitrary to assume that alien life needs to be macroscopic to be advanced…. Or that these “beings” would be supermassive and huge…. We anthropomorphize so so much about the discussion…. It seems that we cannot break away from the need for things to be like us . Perhaps viruses are an alien “gift” to us! Perhaps there are living things that are lobbing nano particles around the universe!

    • crookedshoes #10
      Jun 13, 2016 at 1:07 pm

      So, life? Probably. Multicellular life? less probable. Multicellular eukaryotes that have technology? even less probable…

      I think there are various possibilities.
      Earth-like planets in solar system habitable zones, in galactic habitable zones, orbiting suitable star types, and maintaining suitable climate and temperature ranges over enough years, would seem to be likely to be very rare.

      On the other hand, high metalicity gas clouds which produce the right types of stars and planets, are likely to produce clusters of similar stars and planets of similar composition, in their localities.
      This could lead to very local clusters of stars with habitable planets, but with massive distances in between.

      All the way down to “visiting earth and crashing into the desert” to which I assign very low probability.

      If we look at Earth type life forms, there are many multicellular organisms on Earth which are many times more suitable to survive the rigours of space travel than the human body. – Resistance to impacts, G-forces, pressure, changes of pressure, radiation, hibernation capability, – to mention but a few!

      As I understand it however, our Sun has migrated a long way from its formation cluster, into quieter parts of our galaxy.

    • Even before this, I’d thought it a near certainty that a civilisation other than ours has/does/will exist somewhere in the universe. The number of stars is just so large, and the life of the universe so long (if indeed it will ever end), that even if intelligent life is rare in all of space time, there is still likely to be (have been/will be) quite a lot of it. The downside if you’re looking for contact with other civilisations is, if any such civilisation is contemporary with us, it’s likely to be so far away as to make contact unlikely.

    • It’s good to see the error bars reducing on the terms of the Drake Equation.

      There is still plenty of scope to promote your personal preference, complex life is rare or commonplace.

      I prefer commonplace. Some people prefer rare. As long as people with both preferences continue to dig away at the actual evidence, and work to gather more, we’ll continue to narrow down those error bars, and one day, maybe, one side will have to admit to being mistaken. Until then, there’s plenty of discovering still to be done. Happy times.

    • Well perhaps more advanced civilisations existed on this very earth where all life is thought to have originated, but the very universe itself is a living thing and the diversity of its living contents all share similar attributes which lends itself to the feasibility that other living things elsewhere may also possess eyes and what have you and have similar difficulties in what amounts to a statistical universe where people and things are dying for all kinds of disturbing reasons. The universe?! Just one multi-cosmic orifice or so called ‘mouth’ of a god no-one knows nothing about. So it is in that sense that god exists though only to the confused. Me, still trying to understand and happily never and always will in a synonymous vein. It is a brave and stupid thing to allude to the loose term ‘alien’ like ‘chink’ ‘paki’ ‘nigger’ or ‘Jap’. There are no such things as aliens, but there is life out there, but more importantly it is right here, rooting and tooting with real people all quarrelling with one another on this beautiful wee baby emerald earth spinning silently in the shiny vinyl void. I base my ontological observations on a preponderance of research, so it you want the truth then you’d better get reading I was once advised. So I did and so there you go, that is only partly what I think and so there you go.