Yes, There Have Been Aliens

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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 Kepler and other methods now stands at more than 3,000.

This represents a revolution in planetary knowledge. A decade or so ago the discovery of even a single new exoplanet was big news. Not anymore. Improvements in astronomical observation technology have moved us from retail to wholesale planet discovery. We now know, for example, that every star in the sky likely hosts at least one planet.

But planets are only the beginning of the story. What everyone wants to know is whether any of these worlds has aliens living on it. Does our newfound knowledge of planets bring us any closer to answering that question?


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17 COMMENTS

  1. 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.

  2. @OP link – But our new planetary knowledge has removed some of the uncertainty from this debate. Three of the seven terms in Drake’s equation are now known.

    That does leave rather large margins of uncertainty! – Especially as two of the three terms are doubtful, despite the author’s assertions.

    We know the number of stars born each year.

    Yep! Very approximately.

    We know that the percentage of stars hosting planets is about 100.

    No we don’t!
    We know accretion disks CAN form stars and planets together, but we don’t know if any planets or rocky planets form around low metalicity stars, if planetesimals can form rocky planets in all cases, or if all stars retain their planets.

    And we also know that about 20 to 25 percent of those planets are in the right place for life to form.

    No we don’t!
    We have to take into account GALACTIC HABITABLE ZONES as well as planetary habitable zones. – Not to mention features like effects of synchronous tidal locking on climate!
    Much of our Milky-way Galaxy is extremely hostile.
    Other spiral galaxies may be similar, but there are many other structures in other galaxies.

    http://astro.unl.edu/naap/habitablezones/ghz.html
    The Galactic Habitable Zone (hereafter GHZ) extends the idea of a CHZ to describe the regions of the Milky Way Galaxy where conditions are not inhospitable to the development of complex life. The basic idea is that a number of physical processes that may either favor or hinder the developement of intelligent life depend strongly upon location (and era) in the Milky Way.

    This puts us in a position, for the first time, to say something definitive about extraterrestrial civilizations — if we ask the right question.

    Nope!
    It puts us in a position to say something speculative about the possibilities of life evolving, or the possible conditions needed for the early chemistry of life, occurring on a statistically predictable tiny percentage planets which share features with our rare Earth-Moon system!

    There may however, be many more planets which are CAPABLE of sustaining imported life over a shorter time scale, than that needed for life to evolve in situ!

  3. @OP – And we also know that about 20 to 25 percent of those planets are in the right place for life to form.

    This is nonsense!

    http://www.astrobio.net/news-exclusive/galactic-habitable-zones/

    Galactic Habitable Zones
    May 18, 2001

    Our Milky Way Galaxy is unusual in that it is one of the most massive galaxies in the nearby universe. Our Solar System also seems to have qualities that make it rather unique. According to Guillermo Gonzalez, Assistant Professor of Astronomy at the University of Washington, these qualities make the Sun one of the few stars in the Galaxy capable of supporting complex life.

    A Spiral Galaxy. The sun keeps out of the way of the galaxies spiral arms which contain disruptive gravitational forces and radiation.

    For one thing, the Sun is composed of the right amount of “metals.” (Astronomers refer to all elements heavier than hydrogen and helium as “metals.”) Moreover, the Sun’s circular orbit about the galactic center is just right; through a combination of factors it manages to keep out of the way of the Galaxy’s dangerous spiral arms. Our Solar System is also far enough away from the galactic center to not have to worry about disruptive gravitational forces or too much radiation.

    When all of these factors occur together, they create a region of space that Gonzalez calls a “Galactic Habitable Zone.” Gonzalez believes every form of life on our planet – from the simplest bacteria to the most complex animal – owes its existence to the balance of these unique conditions.

    Because of this, states Gonzalez, “I believe both simple life and complex life are very rare, but complex life, like us, is probably unique in the observable Universe.”

  4. mmurray #1
    Jun 12, 2016 at 3:46 am

    Worth ignoring the catchy title and looking at the article which you can get for free by following the New York Time link.

    http://online.liebertpub.com/doi/full/10.1089/AST.2015.1418

    They seem to skip over the key features of the basics for life to form and exist long enough to evolve complexity, and concentrate on technical advancement of civilisations.
    This appears to be based on an assumption of goldilocks zones in solar-systems like ours during Earth’s history, while ignoring key planetary and galactic features.

  5. 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.

  6. 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.

  7. 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.

  8. phil rimmer #8
    Jun 12, 2016 at 8:21 am

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

    I think there is a high probability of abiogenesis on late stage goldilocks planets – particularly those with large moons like ours, which stabilise the plant’s axis.

    The numbers in the OP are ridiculously high, if we take into account the evolution of galaxies, the diversity of types of galaxy, galactic goldilocks zones, star types, and sizes and types of planets, and planetary system goldilocks zones for various star types.

    https://en.wikipedia.org/wiki/Hertzsprung%E2%80%93Russell_diagram

  9. 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!

  10. 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.

  11. 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.

  12. The OP on this other discussion, explains why it would be a very bad idea to try to live on a planet in a star system near the super-massive black hole at the centre of a galaxy! ie. In an uninhabitable zone!!!

    https://www.richarddawkins.net/2016/06/how-did-supermassive-black-holes-get-so-well-supermassive/
    Supermassive black holes are a bit of a problem.

    Well, some of them power the most luminous objects in the Universe, spewing out high-energy radiation and matter at close to the speed of light, probably sterilizing all of space for thousands of light-years around them. So if you’re too close, yeah, they’re more than a bit of a problem.

  13. 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.

  14. 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.

  15. Joseph #15
    Jun 15, 2016 at 5:10 am

    It is a brave and stupid thing to allude to the loose term ‘alien’ like ‘chink’ ‘paki’ ‘nigger’ or ‘Jap’.

    It maybe in vernacular usage, but the dictionary definition makes it clear it is a non-native individual or organism.

    http://dictionary.cambridge.org/us/dictionary/english/alien

    a person who lives in a country but is not a citizen (= member of a country with specific rights)
    › An alien is also a creature from a planet other than Earth.

    Biologists use the term “alien” all the time, to describe species which have been imported to new lands, away from their native habitats.

    There are no such things as aliens, but there is life out there,

    We do not know for certain. but given the size of the universe, our knowledge of the chemistry of abiogenesis suggests there could be life on a few other planets or moons.

    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.

    It is always useful to gives quotes or citations of sources, when referring to research.

    Some of the links I have given, give key information on recent discoveries.

  16. Proxima Centauri , at about 4¼ light years from our Sun, is one of the nearest stars to the Solar System.

    http://www.bbc.co.uk/news/science-environment-37167390

    Neighbouring star Proxima Centauri has Earth-sized planet
    Scientists say their investigations of the closest star, Proxima Centauri, show it to have an Earth-sized planet orbiting about it.

    What is more, this rocky globe is moving in a zone that would make liquid water on its surface a possibility.

    “For sure, to go there right now is science fiction, but people are thinking about it and it’s no longer just an academic exercise to imagine we could send a probe there one day,” said Guillem Anglada-Escudé whose “Pale Red Dot” team reports the existence of the new world in the journal Nature.

    Simply identifying the world, catalogued as “Proxima b”, was a considerable challenge.

    It was made possible through the use of an ultra-precise instrument called HARPS.

    This spectrograph, attached to a 3.6m telescope in Chile, detects the very slight wobble induced in a star when circled by a gravitationally bound planet.

    Its data suggests Proxima b has a minimum mass 1.3 times that of Earth and orbits at a distance of about 7.5 million km from the star, taking 11.2 days to complete one revolution.

    If there are lifeforms on Proxima b – even simple microbes – they may find the going rather tough, however.

    Red dwarfs are very active. They tend to throw out big flares that would bombard a nearby planet with energetic particles. The X-ray emission is much more intense as well.

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