back to article ALIENS are surely AMONG US: Average star has TWO potentially Earth-like worlds

Boffins in Australia have applied a hundreds-of-years-old astronomical rule to data from the Kepler planet-hunting space telescope. They've come to the conclusion that the average star in our galaxy has not one but two Earth-size planets in its "goldilocks" zone where liquid water - and thus, life along Earthly lines - could …

  1. Lis 0r
    Boffin

    Isn't a significant moon required to keep the core molten, in order to provide magnetic shielding from the atmosphere stripping solar radiation?

    1. This post has been deleted by its author

      1. Flatpackhamster

        And stopping the planet from flipping over on its side.

        1. Avatar of They
          Thumb Up

          Sadly not the case,

          Our planet does that, Chandler wobble etc. 16000 and 32000 years if you look at the magnetic field and then the actual poles. Evidence can be found in the way magnetic particles are arrayed inside the earths crust, sediments etc. They align one way and in the next layer they are all another.

          My geology degree had a piece on it, helps lend evidence to the theory that Atlantis was Antarctica because 10000 years ago it was on the equator. (well people walked on it)

          Assuming we live that long as a species it will be 'interesting' day to relay on magnets or electromagnetism.

          1. Destroy All Monsters Silver badge
            Facepalm

            Re: Sadly not the case,

            Atlantis was Antarctica because 10000 years ago it was on the equator.

            Yeah, no man.

            I think you missed this by a few orders of magnitude.

            Your geology degree must be stamped "university of life".

            1. DougS Silver badge

              Re: Sadly not the case,

              We know it is much older based on ice cores alone. The latest estimates place its age at 34 million years old. So no, the planet is wobbling around to place Antarctica on the equator and being Atlantis.

          2. Simon Brown

            Re: Sadly not the case,

            dunno where you got your geology degree mate but I think you're mixing up two different concepts.

            The first is the MAGNETIC poles flipping which they do every half million years or so. You can see that from the identical but mirrored stripes of reversed polarity of iron deposited in oceanic crust at spread zones. It was initially discovered in the Atlantic - searching for submarines they inadvertently discovered evidence of plate tectonics.

            The second is another part of the plate tectonic "picture" which is the presence of fossilized sea shells on top of mountains and evidence of fossilised tropical forests in the rock record near Antarctica. Using the current theory that the processes existing today have existed as far back as we can tell, that means that the rocks that make up Antarctica were at one point at the or near the equator, which is 10,00km away (give or take).

            Continental plates move at between 2cm & 5cm per year which isn't that fast until you think - "but it's an entire continent moving" at which point you realise that 2-5 cm / year is plenty fast for something that big and solid to be moving relative to everything around it...

            So in 10,000 years it will have moved between 20 and 50 metres which is substantial but not quite at the equator. In fact it would take between 200 million and 500 million years - and as I recall the radio isotope dating and other ageing techniques (matching certain global markers like periods of major vulcanicity with specific chemical signatures across multiple rock deposits and types across continents) put the time at around 335 million years ago, from memory.

            1. Richard Taylor 2 Silver badge

              Re: Sadly not the case,

              So why a down post with no rebuttal or is it a slow Friday?

          3. Joseph Eoff
            Facepalm

            Atlantis

            Read the Wikipedia page on Atlantis, then we can discuss things in more depth.

            Quote from (the first sentence of) the Wikipedia "Atlantis" article (note the word FICTIONAL):

            Atlantis is the name of a fictional island mentioned within an allegory on the hubris of nations in Plato's works Timaeus and Critias...

            Atlantis=Fiction

            1. DougS Silver badge

              Re: Atlantis

              Troy was fiction until someone found it. An "advanced" civilization 10,000 years ago wouldn't need to be all that advanced to seem amazing to others at that time. If they had farming with human built canals, some type of sewers, and skyscrapers as high as three stories they'd seem as advanced compared to others of that time as flying cars and interstellar travel seem to us today.

              I suspect there's a lot of history older than 5,000 years old that is lost (probably forever) due to rising sea levels from melting ice sheets. Maybe Atlantis is part of that. Without writing the story would be corrupted a lot over the centuries as it is retold over and over again.

          4. Marshalltown

            Re: Sadly not the case,

            Not sure where your geology "degree" came from, but if it locates Atlantis in Antarctica I would not surprised if it came in the mail. The "magnetic" reversals are just that, reversals of the magnetic field, not of the entire physical planet. If you simply consider minor physical laws like conservation of intertia and agular momentum and such, it is pretty clear that if a magnetic reversal involved planetary acrobatics, life would not exist. Neither would the planet probably. If it did, it would probably look a lot like Venus.

            As it is, the magnetic field takes "excursions" occasionally as well as "flipping,m" and the event 10,000 years ago or so was an "excursion" rather than a full blown inversion. If you like science fiction, try reading Keith Laumer's "The Breaking Earth" which is based on the idea of the actual physical tumbling of the planetary gyros during a magnetic reversal. Laumer took it easy on the physical effects - i.e. the catastrophic picture he presents is no where near as bad as a real event would have been. It is also the only book I known that even hints that an Atlantis-like civilization existed on Antarctica. Are you sure your geology proph didn't have you read that novel?

    2. DeliberatusFreeman

      MAYBE.

      If it has the right minor elements AND a magnetic field, the upper part freezing might magnetize and retain a field. It has for several iron ore deposits.

  2. Anonymous Coward
    Anonymous Coward

    Aliens are among us !

    If you'd ever watched a parliamentary debate you would already now that Aliens are indeed amongst us !

    1. chivo243 Silver badge
      Alien

      Re: Aliens are among us !

      Or work in my office ;-}

    2. Destroy All Monsters Silver badge
      Alien

      Re: Aliens are among us !

      Oxygen works like hard dope on the lizard overlords controlling the politic-pods. Nothing else occurring in parliament makes sense.

      1. Zog_but_not_the_first Silver badge
        Alien

        Re: Aliens are among us !

        You don't think that........... David Ike might be right!?

        1. Destroy All Monsters Silver badge
          Alien

          Re: Aliens are among us !

          Ike doesn't suspect half of it!

    3. hplasm Silver badge
      Unhappy

      Re: Aliens are among us !

      Those 'debates' are necessary to ensure that we never get off this rock...

  3. Electron Shepherd
    Alien

    It's a long way to the chemist, etc...

    But space is big. You just won't believe how vastly, hugely, mind- bogglingly big it is.

    Humans have been emitting radio waves for about 100 years or so. That means that any intelligent life more than 100 light years away (which is next door in galactic terms) simply won't know we exist, since the signal won't have reached them yet.

    Contrary to what the prof thinks, there could be loads of little green men out there, all whizzing about in their flying saucers, and they haven't visited earth yet, since they just haven't found it yet, or when they last looked, it wasn't doing anything interesting.

    1. AbelSoul

      Re: It's a long way to the chemist...

      Perhaps that's where Lewis has gone.

      Where's the Captain Lawrence Oates icon when you need it?

      1. Neil Barnes Silver badge

        Re: It's a long way to the chemist...

        Meh. As long as Lewis has his towel, he'll be fine.

    2. Ged T

      Re: It's a long way to the chemist, etc...

      ...and at density of 1.4E-4 stars/cubic ly and, at 100ly, a spatial volume of

      4/3.pi.(100E3) = 4188790 cubic ly

      Number of stars within 100ly radius is 4188790 * 1.4E-4 = 586 stars

      However, the number stars that are of the right type AND with suitable (goldilocks-zone) planets is VERY small...

      1. Grikath
        Facepalm

        Re: It's a long way to the chemist, etc... @ GedT

        except that star distribution is not even, rather clumpy, and simply doesn't work the way you just calculated, spot on.....

    3. Vinyl-Junkie
      Alien

      Re: It's a long way to the chemist, etc...

      After all, would you make a detour to look at somewhere whose description reads "Mostly Harmless."?

    4. DJO Silver badge

      Re: It's a long way to the chemist, etc...

      Humans have been emitting radio waves for about 100 years or so.

      And we are emitting less and less every year with low power radios, satellites beaming down instead of stuff broadcast everywhere and more and more of what used to be broadcast being transmitted over fibre. In 100 years I doubt we'd be detectable at all.

      Another problem is that the same frequencies are used all over the planet for different purposes which is no problem here but from a long way away they will all blur together into a random like noise where any single signal would be as close to impossible to isolate as makes no difference.

      The only radio signal that would be detectable over many light years would have to be one broadcast specifically for that purpose and why would anybody do that?

      1. Anonymous Coward
        Coat

        Re: It's a long way to the chemist, etc...

        I believe they actually did broadcast, from Arecibo I think. I hope it wasn't pointed at anyone a bit dangerous...

      2. roger stillick
        Alien

        Re: It's a long way to the chemist, etc...Sub MM Radio...

        since 2007 Sub-Milameter (150-250 terahertz) transmissions to "Out There" have come from several places world-wide ( Russian RT-70 radio telescopes and others) using Terrawatt level CPA's (Chirp Pulse Amps)... with a protocol known as Astro-Pules we may be able to at least "see" comm of others...progress ?? the Astro-Physics folks aren't talking...Scientific Method Rules apply... caveiat ?? :-) ...RS.

        1. Destroy All Monsters Silver badge
          Windows

          Re: It's a long way to the chemist, etc...Sub MM Radio...

          Prime directive of the commentariat: "Any poster using ellipsis more than once in a text is to be regarded with suspicion and any attempts at communicating with said poster shall be curtailed (exceptions apply if said text consists of citations of government-issued drivel and marketdroid droppings) "

    5. Crisp Silver badge
      Boffin

      Re: any intelligent life more than 100 light years away...

      If they are intelligent, surely they would have noticed the spectroscopy of the atmosphere.

      1. Mage Silver badge
        Thumb Up

        Re: any intelligent life more than 100 light years away...

        Certainly far more useful than Radio, which is too short range really.

        I think we only recently realised that it was better to do this and we haven't looked at enough planets accurately enough yet.

        1. ian 22

          Re: any intelligent life more than 100 light years away...

          Intelligent Humans? I think we flatter ourselves. The Dolphins know better.

    6. Anonymous Coward
      Anonymous Coward

      Re: It's a long way to the chemist, etc...

      The signals we've made for most of the last 100 years have also been very weak and nondirectional. There's this thing called the inverse square law. I can't be bothered to do the maths, but anybody looking for radio waves from this planet from even a few light years away is going to be looking for tiny signals against the huge background of all the crap spewing out of that big fusion reactor close by, plus the smaller amount of stuff being produced by Jupiter. Even a megawatt or so won't have much effect by the time you reach Proxima Centauri.

      1. stucs201

        Re: huge background of all the crap spewing out of that big fusion reactor close by

        In the range of radio frequencies we use for broadcast it isn't a huge background - the Earth actually outshines the sun in that range, so a should produce a nice big spike on any alien's spectrograph.

        1. Anonymous Coward
          Anonymous Coward

          Re: huge background of all the crap spewing out of that big fusion reactor close by

          "the Earth actually outshines the sun in that range"

          I was sufficiently interested to check this. Solar output is very roughly 1027W, and for a black body at this temperature the amplitude at radio frequencies is about 1/1018 and down. So the Sun is producing maybe a few hundred megawatts over the "radio" spectrum, and very little energy at the long end of that spectrum, and you are quite right.

          The next question, which I can't answer, is how much of the energy produced by terrestrial radio stations actually ends up propagated into space. Taking the solar emission of radio waves, a very rough indeed calculation gives me around 10-35W/sq M for the radio spectrum at the distance of Proxima Centauri, with less than 10-37 over the "ordinary" radio spectrum. Given that photons at this frequency range are pretty weak, what sort of detection and resolution could be expected? I know we can identify a comet lander by just three pixels, but we at least had an idea of where it was.

    7. James Micallef Silver badge

      Re: It's a long way to the chemist, etc...

      "there could be loads of little green men out there, all whizzing about in their flying saucers..."

      It's perfectly possible that any hypothetical advanced alien civilisation is beyond the stage where they produce any significant radio emissions because of increased efficiency, better shielding, possibly living underground and/or inside enclosed structures, and also because being paranoid they don't broadcast their presence to other, potentially harmful, aliens. So maybe there's a couple of centuries time window in which transmitted signals can be received by intelligent life somewhere else. Given the insignificance of a couple of centuries compared to a billions-of-years-old galaxy (let alone universe), it's unsurprising that such signals haven't been detected.

      Given that transmitting/receiving radio signals is MUCH easier than space travel it would be inconceivable that alien ships suddenly turn up on our doorstep without us ever having picked up any signals. Of course there are plenty of other possibilities of undetected alien life out there:

      1. Since the power of signal that is detectable diminishes by distance according to the inverse square law, there is a distance threshold beyond which our puny transmissions become indistinguishable from background noise (and same for signals coming our way)

      2. Although the statistical possibility of humans being the first ever* intelligent species in the universe is remote, there is still that possibility that all the other worlds are still at dino-stage of evolution

      3. We associate intelligence with technology but tech has as much to do with our opposable thumbs as with our brains. Dolphins are pretty clever but you won't catch them messing around with iPads (insert Douglas Adams quote here)

      4. Super-advanced aliens are using comms tech so advanced that even though their signals (and space stations / ships) are all around us but we can't detect them (dark matter? :P)

      *of course concepts like 'first ever' become tricky when combined with travel over interstellar distances

      1. Nigel 11

        Re: It's a long way to the chemist, etc...

        Super-advanced aliens are using comms tech so advanced that even though their signals (and space stations / ships) are all around us but we can't detect them

        Super-advanced? You mean the average modern USAlian, I think.

        What would be detectable from many light-years out is radio broadcasts using 20th century modulation (AM, FM, SSB etc.), and radar-illumination transmitters. We're already moving away from these. I anticipate that by 2100 broadcast radio will be extinct. Civilian radar may have gone the same way (replaced by GPS and active location transmision by planes to ground control through an evolved internet). That leaves defence radar, and maybe military stealth technology will have rendered that obsolete as well. (Also taking an only slightly longer view of things, either world peace will render defence radar obsolete, or world war will render advanced civilisation obsolete).

        Cellphones, wifi etc. are (or rather, will be) undetectable from many light-years out. An efficiently coded signal is almost indistinguishable from noise, absent knowledge of the coding. Also the radio power per channel is at most two watts (usually more like two milliwatts) rather than the megawatts which Radios Moscow and America used to blast out. As the cells get smaller, so do the wattages.

        Assuming technology develops along similar lines elsewhere, the era of accidental long-range interstellar signalling probably lasts for about a century whether its civilisation survives for aeons or not. Which is as good a reason as any why we haven't spotted (another) one yet.

        1. Col_Panek

          Re: It's a long way to the chemist, etc...

          How about sending out a bunch of nuclear bombs and shoot them off where it's safe? They could spell out CQ DX in Morse code. They oughta be able to see that.

    8. JEDIDIAH
      Linux

      Re: It's a long way to the chemist, etc...

      Plus you have the signal strength to consider. Will aliens 1000 light years away be able to become addicted to our crap network TV shows? I rather doubt it. I would be surprised if our emissions are recognizable as such even 100 light years out.

    9. VinceH Silver badge

      Re: It's a long way to the chemist, etc...

      "when they last looked, [Earth] wasn't doing anything interesting."

      Wake me up when it starts.

  4. chivo243 Silver badge
    Joke

    @Electron Shepherd

    "simply won't know we exist, since the signal won't have reached them yet."

    Unless they have been wandering far and near exploring the universe. This would require they have interstellar transportation.

    "or when they last looked, it wasn't doing anything interesting."

    You mean yesterday?

    Actually any aliens with any sense would avoid Earth at all costs. Humans would infect their minds with greed and violence etc.

  5. tony2heads
    Boffin

    Our moon also gives help spin-stabilize us to stop the planet from flipping over. Mars seems to have changed axis by about 60degrees over the long term

    Perhaps also very important for long term development:

    - large magnetic field to keep ionizing radiation from the solar wind off

    - large tides pushing movement of animals to the land

    - active (but not too active) tectonic plates stopping the whole planet being covered in a shallow sea (great for dolphins, but not space-faring species)

    -having massive outer planets (picking up some infalling comets)

    -being at the edge of the galaxy (being far from nasties like gamma ray bursts and supernovae)

    -not being in a dense cluster (interaction with other stars messing with planetary orbits)

  6. nevstah

    if we expend vast amounts of time, effort and resources killing eachother in war and terrorism etc (not to mention animals for sport/fun), i'm sure we wouldnt think twice about blowing up any alien species that came within range - if they are clever enough to get here, they're smart enough to stay away

  7. malle-herbert
    Joke

    Or maybe they found out that we are made of meat...

    They're Made Out of Meat...

  8. Destroy All Monsters Silver badge
    Trollface

    Charles Stross suggests that neighbors are ISIS-like and abhorrent

    Sagan sighs. “Okay, play it your way.” He closes his menu. “Ready to order?”

    “I believe so.” Gregor looks at him. “The spaghetti al’ polpette is really good here,” he adds.

    “Really?” Sagan smiles. “Then I’ll try it.”

    They order, and Gregor waits for the waiter to depart before he continues. “Suppose there’s an alien race out there. More than one. You know about the multiple copies of Earth. The uninhabited ones. We’ve been here before. Now let’s see…suppose the aliens aren’t like us. Some of them are recognizable, tribal primates who use tools made out of metal, sea-dwelling ensemble entities who communicate by ultrasound. But others–most of them–are social insects who use amazingly advanced biological engineering to grow what they need. There’s some evidence that they’ve colonized some of the empty Earths. They’re aggressive and territorial and they’re so different that…well, for one thing we think they don’t actually have conscious minds except when they need them. They control their own genetic code and build living organisms tailored to whatever tasks they want carrying out. There’s no evidence that they want to talk to us, and some evidence that they may have emptied some of those empty Earths of their human population. And because of their, um, decentralized ecosystem and biological engineering, conventional policy solutions won’t work. The military ones, I mean.”

    Gregor watches Sagan’s face intently as he describes the scenario. There is a slight cooling of the exobiologist’s cheeks as his peripheral arteries contract with shock: his pupils dilate and his respiration rate increases. Sour pheromones begin to diffuse from his sweat ducts and organs in Gregor’s nasal sinuses respond to them.

    “You’re kidding?” Sagan half-asks. He sounds disappointed about something.

    “I wish I was.” Gregor generates a faint smile and exhales breath laden with oxytocin and other peptide messengers fine-tuned to human metabolism. In the kitchen, the temporary chef who is standing in for the regular one–off sick, due to a bout of food poisoning–will be preparing Sagan’s dish. Humans are creatures of habit: once his meal arrives the astronomer will eat it, taking solace in good food. (Such a shame about the chef.) “They’re not like us. SETI assumes that NHIs are conscious and welcome communication with humans and, in fact, that humans aren’t atypical. But let’s suppose that humans are atypical. The human species has only been around for about a third of a million years, and has only been making metal tools and building settlements for ten thousand. What if the default for sapient species is measured in the millions of years? And they develop strong defense mechanisms to prevent other species moving into their territory?”

    1. Afernie

      Re: Charles Stross suggests that neighbors are ISIS-like and abhorrent

      Which is disturbing. But his other suggestion as to the nature of our cosmic neighbours is almost as bad:

      "I will by return of signal send you the [symbol: process][symbol: data] to install on your [empire/civilization/polity] to participate in this scheme. You will then construct [symbol: inferred, interstellar transmitter?] to assist in acquiring [ownership signifier] of [compound symbol: inferred, bank account of absent galactic emperor]."

      1. Anonymous Coward
        Anonymous Coward

        Re: Charles Stross suggests that neighbors are ISIS-like and abhorrent

        Perhaps we could apply this in reverse. Perhaps out there is a civilisation that uses high level nuclear waste as a currency, and we can fool them into taking it without getting anything back in return.

        1. Ogi

          Re: Charles Stross suggests that neighbors are ISIS-like and abhorrent

          Well, seeing as what we call "nuclear waste" is in fact nuclear fuel that we couldn't burn in the reactor (hint, if it is radioactive, it still has energy in it) it is perfectly plausible that our nuclear waste to be usable in fuel in more advanced nuclear reactors.

          The technology exists already, from what I remember, only the US (of nations that have the technological capability) does not reprocess spent fuel, but rather just dumps it into long term storage.

          http://en.wikipedia.org/wiki/Breeder_reactor#Fuel_efficiency_and_Types_of_Nuclear_Waste has some info on reactors which can make use of nuclear waste to generate more heat.

        2. Anonymous Coward
          Anonymous Coward

          Re: Charles Stross suggests that neighbors are ISIS-like and abhorrent

          high level nuclear waste as a currency

          Not sure why they would like to take containers of EUROs?

      2. Nigel 11

        Re: Charles Stross suggests that neighbors are ISIS-like and abhorrent

        He's also contributed at least two more scenarios:

        "Saturn's Children" / "Neptune's brood". Our successors are AIs which we created as our slaves. We then go extinct (as slave-owning societies always have done in the past, on a non-global scale). They're out there, colonizing the galaxy and trying to reincarnate homo sapiens (from DNA codes, with a degree of success), for quasi-religious reasons!

        Accellerando, in which human beings are supplanted by evolved digital corporations which no longer need to preserve their human customers. These denizens of "Economics 2+" turn the entire solar system into computronium (solar-powed computing substrate) and don't travel, because they always seek the most bandwidth-rich environment, ie nearest to Sol.

        The first pair of books are amusing and less implausible than most interstellar SF. Accellerando will haunt your imagination. Both recommended.

        1. ADC

          Re: Charles Stross suggests that neighbors are ISIS-like and abhorrent

          Then there's the Greg Bear/Forge of God/Anvil of Stars scenario.

          That we don't see other civilisations because the hunter-killer self-replicating machines got there first.

  9. Dr. Mouse Silver badge

    Obligatory xkcd

    http://xkcd.com/1377/

  10. Anonymous Coward
    Anonymous Coward

    Tidal forces required in early evolution

    The main argument for the need of a moon that I recall coming across is that tidal forces and flows provide a significant advantage to multicellular organisms over single celled organisms. Being long allows an organism to gain more movement and nutrients from the tidal flows, compared to a single cell creature.

    This would create an evolutionary pressure to the more complex life form (which otherwise at this stage would likely fall prey to consumption by the existing simpler single celled lifeforms)

    The outcome that has been discussed then is that without a large moon, would you get to multicellular lifeforms? If so what would be the pressure to do so?

    1. Destroy All Monsters Silver badge
      Paris Hilton

      Re: Tidal forces required in early evolution

      Actually the latest story is that evolutionary experimentation was greatly facilitated by a couple of passages through "snowball earth" type environments where formerly connected environments where disconnected and sealed off for a few 100'000 years, then reconnected as the snowball thawed?

    2. Grikath

      Re: Tidal forces required in early evolution

      competition/mutual benefit.

      One of the steps in evolution most overlooked is that the eukaryotic cell is actually most likely a symbiont of several separate "ancestor-organisms", of which one, the mitochondrium, even still has its' own DNA and reproduces separately within the cell.

      Something along the lines of that mechanism still exists today,where ( very anaerobic) methanobacteria survive in an oxygen environment by living in the creases of the cell walls of E.Coli bacteria, occasionally temporarily being incorporated as "organelles" within the host body itself. ( and giving rise to the rather rare, but fun, "lightable fart". Ain't biology fun.. ;) )

      As far as I can remember the biggest influence the moon has on the earth with regards to the "sustainability of life" is that it stabilises the earth's spin with regards to the ecliptic plane, creating an environment that is more stable than it would be without. Then again, we don't see Mars, or any other planet flipping its axis of rotation all around, so ymmv there.

      Never been too fond of the tides-enabling-life/driving evolution theory, given that the moon at the crucial time was a lot closer to the earth, and the tides it created were a bit more frequent and.. prominent.. than the gentle stuff the moon gives us nowadays.

      1. Nigel 11

        Re: Tidal forces required in early evolution

        Then again, we don't see Mars, or any other planet flipping its axis of rotation all around

        "Flipping" would take many hundreds of thousands of years, which in evolutionary terms is fast.

        Uranus is pretty much half-flipped right now.

        1. Anonymous Coward
          Anonymous Coward

          Re: Tidal forces required in early evolution

          Uranus is pretty much half-flipped right now.

          But with the new rules your ISP won't be able to show you the pictures.

      2. Anonymous Coward
        Anonymous Coward

        Re: Tidal forces required in early evolution

        "and giving rise to the rather rare, but fun, "lightable fart""

        I believe this is fairly common,in fact. Human farts usually contain significant hydrogen and methane. Because hydrogen has a high flame velocity, lighting farts can be very unwise.

        It isn't hard to explain why multicellular organisms evolved, as bacteria are often colonial and derive benefit from it (colonies adhere to substrates and their waste products can protect them). Eukaryotic cells can have more specialised organelles than bacteria, making them more efficient predators. Once eukaryotes become colonial, the opportunity and the mechanisms become available for differentiation* to improve the fitness of the colony and bingo, multicellular organisms.

        *A sessile eukaryotic colony will have concentration gradients of oxygen, carbon dioxide and waste products. These gradients could act as markers to trigger differentiation.

    3. Nigel 11

      Re: Tidal forces required in early evolution

      A moon stabilizes the axis of rotation of a planet. Without one, the axis of rotation is unstable, and sooner or later will pass through the plane of the planet's orbit (with a timescale of under a million years). That's too fast for the evolution of all but mono-cellular life to adjust to a planet that "suddenly" no longer has a day-night cycle. (ie, one where the whole planetary surface is like our poles: half a year of night, then half a year of day).

      Don't know how large a moon is needed, but no moon at all is no good at all.

      Can Kepler identify how many planets have moons?

  11. John B Stone

    More than a coincidence?

    I didn't think that Titius-Bode sequence was widely accepted as being anything other than a coincidence. But as they are predicting increased planet detection rates based upon using it, then I guess we are about to find out if it has some use.

    1. David L Webb

      Re: More than a coincidence?

      It has been suggested that Bodes Law arises because of orbital resonances between planets in relatively circular orbits but even in our solar system it fails once you get to Neptune. We already know of solar systems containing large planets in very eccentric orbits which would presumably disrupt any Bodes Law pattern in their system. Hence it seems a bit of a stretch to attempt to calculate the average number of planets in the habital zone using such a law.

      1. Destroy All Monsters Silver badge
        Pint

        Re: More than a coincidence?

        Unless new macro-physics exists (i.e. Laurent Nottale has actually something good, not sure whether his stuff makes sense) or there are unexpected effects regarding the final state of an energy-losing system of multiple gravitating bodies (I remember some interesting macro effects in large scale simulations - galaxy sized - which were not readily explained)

        1. Nigel 11

          Re: More than a coincidence?

          The orbit of any planet in a solar system with more than one planet is chaotic. (Mathematical fact, mathematical definition of chaotic). Given infinite time, all but one planet will inevitably be ejected into interstellar space (or less likely swallowed by its sun or collided with another planet).

          Fortunately for us, "enough time" for our solar system greatly exceeds the lifetime of Sol. Also the future orbit of Earth can be predicted to remain much as it is today for the next 100My at least, given the accuracy of the best astronomical observations of the rest of the planets in our system and inverse-squares gravitation.

          However, in a solar system with a Jupiter-mass planet in a very eccentric orbit, smaller planets would not remain in the Goldilocks zone for the (assumed) billions of years it takes for advanced life to evolve.

          1. ADC

            Re: More than a coincidence?

            "The orbit of any planet in a solar system with more than one planet is chaotic. (Mathematical fact, mathematical definition of chaotic). Given infinite time, all but one planet will inevitably be ejected into interstellar space (or less likely swallowed by its sun or collided with another planet)."

            As far as I remember "chaotic" in the mathematical sense does not mean unstable, it means unpredictable. A chaotic system's future state can only be predicted if you know _exactly_ the initial state. A small (infinitesimal) change in initial state leads to a large and undefined change in future state.

    2. VinceH Silver badge

      Re: More than a coincidence?

      "I didn't think that Titius-Bode sequence was widely accepted as being anything other than a coincidence."

      I've mentioned this in El Reg comments before when the subject of Bode has come up... but back in the early 1990s I did a maths GCSE for fun (already have an O level from school) and for the coursework I did a ridiculously long thing on Bode's Law - I keep hoping to find the file on one of my computers so I can re-read it, take out anything irrelevant and unnecessary, and throw the rest onto the web. Fat chance, though, because that was a silly number of computers ago - at least, that's what I thought.

      I found a 3.5" disc recently with "Bode's Law" written on the label1. :)

      Unfortunately, though, while I can read the disc if I drag the right computer down from the loft, what that computer won't be able to do is shove the contents over the network to my current computer(s). Or print it. Or anything useful, really. Still, it's a start. :)

      1. Actually, it says "Bodes Law" - well, I was over twenty years younger.

      1. Dave Lawton
        Boffin

        Re: More than a coincidence?

        @VinceH

        What is the computer please ?

        I can think of a few candidates, but none of them particularly likely.

  12. Bob Wheeler
    Mushroom

    “It could be that there is some other bottleneck for the emergence of life that we haven’t worked out yet. Or intelligent civilisations evolve, but then self-destruct.”

    Given that we developed nuclear weapons before any form of space travel, if other civilisations evolved along similar lines, than is it not possible they blew themselves to dust before getting off the ground?

    1. Destroy All Monsters Silver badge
      Coat

      God is actually Cave Johnson

      Or they run out of steam before doing anything serious. Space travel is hard.

      But this universe seems to be made to order as a petri-dish to run a large-scale experiment about overcoming various obstacles to survival using genetic algorithms evolving from the ground up in a reduced (but with small h-bar) physical setting. If Earth doesn't manage, I am sure others will.

    2. Primus Secundus Tertius Silver badge

      Look for the EMP

      @Bob W

      If there have been nuclear wars on exoplanets, perhaps we should have detected the Electro Magmetc Pulses associated with those bombs exploding.

      1. Destroy All Monsters Silver badge

        Re: Look for the EMP

        Unlikely. In the cosmic scheme, these are very very very very faint.

        And a nuclear war is over very quickly.

        1. Nigel 11

          Re: Look for the EMP

          In the cosmic scheme, these are very very very very faint.

          Unlike GRBs (gamma-ray bursts). One of those in our galactic neighbourhood could all but sterilize our entire galaxy. We're assuming these are natural phenomena, but are we sure?

          And then there's whatever mystery created the "Oh My God" particle (3x10^20 eV, or fifty Joules!). Whatever made it must have been within our galaxy, because its half-life before interaction with a cosmic background microwave photon precludes any extra-galactic origin.

    3. Anonymous Coward
      Joke

      'Or intelligent civilisations evolve, but then self-destruct'

      With the author in mind, a reasonable guess is they industrialize, then get wiped out by global warning.

      Kindly observe the icon.

      1. Destroy All Monsters Silver badge
        Devil

        Re: 'Or intelligent civilisations evolve, but then self-destruct'

        wiped out by global warning

        RON PAUL DOOM LEVEL 6: "IT'S HAPPENING"

  13. ravenviz
    Devil

    Goldilocks?

    The old woman (not little girl) in an early variation of the story was described at various points in the story as impudent, bad, foul-mouthed, ugly, dirty and a vagrant deserving of a stint in the House of Correction and later is impaled on the steeple of St Paul's Cathedral!

    So that's what happens when you live in the Goldilocks Zone!

    1. Little Mouse
      Headmaster

      Re: Goldilocks?

      Plus, the porridge metaphor only works if you conveniently forget that the bowl that was just right was neither too hot nor too salty.

    2. Anonymous Coward
      Anonymous Coward

      Re: Goldilocks?

      If the aliens read the Wikipedia article on Goldilocks, especially the "interpretations" section where the psychoanalysts get at it, they would put out warning notices to keep away from such a bonkers civilisation.

    3. Lapun Mankimasta

      Re: Goldilocks? @ravenviz

      It's actually Girldie Larks and the Forebears, according to Afferbeck Lauder: Father Behr, Mother Behr, Baby Behr and Cammom Behr. Girldie Larks was a juvile dinquent tea nature, whose career in crime was ended when Cammom Behr cut out her heart and threw it down a well. It's a very popular Furry Tile.

      1. Anonymous Coward
        Anonymous Coward

        Re: Goldilocks? @ravenviz

        It would seem an alien is trying to communicate with us via Reg posts.

  14. Vladimir Plouzhnikov

    Space is big, signals are weak

    I would think that all but directional signals specifically sent towards us would be too weak for the SETI to detect and, in any case, high power broadcast signals would probably be used for a very brief period in any civilisation as they quickly move to more efficient low-power directed and coherent beam transmission.

    Furthermore, they would probably switch to digital equally quickly and then start encrypting everything routinely, for commercial reasons if not for anything else. And a well encrypted transmission looks pretty much like random noise.

    So, the chances that there is a civilisation that is going through their momentary high-power analogue broadcasting phase and that is close enough for us to detect them and is using the frequencies the SETI is listening to are very very slim even if, otherwise, there are millions of inhabited star systems in our galaxy.

    1. ravenviz
      Boffin

      Re: Space is big, signals are weak

      What if their evolution means they communicate with high power radio signals, much like whales use infra-sound to be heard over vast distances?

      1. Filippo

        Re: Space is big, signals are weak

        Extremely unlikely. There is no selective pressure to be able to communicate across interstellar distances, but there is plenty of pressure to conserve energy. A species that used radio biologically wouldn't do so at very high power.

    2. Nigel 11

      Re: Space is big, signals are weak

      Furthermore, they would probably switch to digital equally quickly and then start encrypting everything routinely, for commercial reasons if not for anything else. And a well encrypted transmission looks pretty much like random noise.

      That's any well-coded signal, ie coded to make efficient use of available bandwidth. The main difference between encryption and "mere" efficient coding, is whether you publish the decoding algorithm and key(s), or not!

  15. John G Imrie
    Black Helicopters

    When lewis gets back

    make sure he holds his pen with the same hand he wrote with before he left. Other wise you can assume that ... Hang on there's someone at the door.

    1. amanfromMars 1 Silver badge

      Re: When lewis gets back

      When lewis gets back

      make sure he holds his pen with the same hand he wrote with before he left. Other wise you can assume that ... Hang on there's someone at the door. …. John G Imrie

      Knowing something of Lewis’s past history and present circumstance has one thinking of a perfect enough current placement for future deployments of new style 77th Brigade shenanigans/Intelligent Signalling Interdiction Services.

      El Reg is certainly no sub-prime operation, is it, and surely a great deal more than just the simple sum of a number of parts.

  16. Winkypop Silver badge
    Alien

    Come out, come out

    Where ever you are...!

  17. Palpy

    Moon not necessary for reasonable stability

    Computational study reveals that even without a moon, other planets' influence would limit Earth's axial wobble to about 10 degrees.

    http://news.discovery.com/space/history-of-space/earth-moon-life-tilt-110808.htm : Discovery.com story, dateline 8/8/2011.

    Note also that some hypothesize that life's origins were with chemolithotrophic organisms deep underground, and the fine details of climate were probably lost on these early wee beasties.

  18. Brangdon

    I think (and hope) the Great Filter lies in our past

    It took a billion years for prokaryotes (simple single-celled life) to evolve. Then another 1.6 billion for eukaryotes (more complex, but still single-celled). Then another billion years to get multi-cellular life, and another billion to get primates. We have no idea whether these steps always take that long, or whether we're unusually fast or unusually slow. I find it easy to believe that getting to multi-cellular life usually takes 4 times the 3.6 billion years it took us, in which case it is longer than the age of the universe. In other words, there could be lots of slime out there, but not much intelligent life.

    There would still be some intelligent life, but if it's rare, it's probably too far away for us to detect it (or vice versa). I see no reason think whoever is first will have a drive to colonise the galaxy. It might make more sense to upload themselves to virtual reality instead, and have all the space they need. Especially if they've achieved zero population growth (arguably a pre-requisite for a civilisation to survive more than a million years).

    Whatever: Fermi's Paradox isn't a paradox. Anyone who understands enough to see why it's an issue should have enough imagination to explain it away.

    1. Shannon Jacobs
      Holmes

      Finally, the Fermi Paradox mention

      Not surprised the original author didn't mention the Fermi Paradox. Same blathering idiot frequently denies climate change, so probably he never heard of Fermi. "Who was Fermi? Another one of those damn fool money-grubbing so-called scientists? Oh, you say he had a Nobel thingee or such?" However, somewhat surprised to see so little mention of the Fermi Paradox here in the comments.

      My amplified form is to consider a single stable civilization that started with our level of radio technology within our galaxy. If they wanted to say "hi", they could create a major radio beacon. They don't even need to run it continuously, but just let out a a few megawatts of encoded squawk when they are at their time of low power demand. To define stable, let's say we can claim 5,000 years of civilization, and our "stable civilization" is at least 20 times more stable. Then by now their signal would have reached every corner of our galaxy--and even with our primitive technology, we would have picked it up. Therefore, we can safely say there is no such civilization in our galaxy that wants to say "Hi."

      Various resolutions of the Paradox, but the two I favor are:

      1. A proclivity for technology is not a survival trait, and all such civilizations quickly exterminate themselves, probably by a cost-effective bio-weapon.

      2. Naturally evolved intelligences like humans replace themselves with AIs, and the AIs are talking among themselves in ways we can't perceive. In this case, we can conclude the AIs are not malevolent, or they would have exterminated us by now. I'd prefer to believe they are wagering quatloos on how long we survive or genuinely interested in the various paths taken by natural evolution. However, in any version of this case, I can't imagine they would ever bother talking to us. What would you say to a flea (even if you knew the flea or its ancestors had once created a super-smart dog)?

      More at:

      http://eco-epistemology.blogspot.jp/2007/08/resolution-of-fermi-paradox.html

  19. David Pollard
    Pint

    Lewis has gone out ...

    After writing the article he probably headed off to an inter-services meeting to collect and collate story lines for Battalion 77 internet psyops. Pint because that's what's needed to wash away some of the schoolboy nonsense that this topic generates in predictably massive volumes.

    1. amanfromMars 1 Silver badge

      Re: Lewis has gone out ...

      Great minds think alike whenever fools seldom differ, DP ...... and whenever media presents a crooked picture of the present is reality distorted and perverted and a virtual construct for smarter manipulation ..... http://forums.theregister.co.uk/forum/2/2015/02/05/helloo_aliens_average_star_has_two_potentially_earthlike_habitable_worlds/#c_2432834

  20. Dan 55 Silver badge
    Trollface

    Those nomadic aliens without any habitable home planets left...

    ... only come for the change deniers to show them the error of their ways.

  21. timple

    If new life forms are so inevitable given the right conditions, why can't scientists get new life forms to start themselves here? Surely its just a question of blending the right soup?

    1. Destroy All Monsters Silver badge

      As soon as you can go to next 7/11 and bring back a thermos of compressed time.

      1. Anonymous Coward
        Anonymous Coward

        What, D.A.M. To bring next 9/11?

  22. sisk Silver badge

    I don't think the fact that we haven't detected alien life is puzzling at all. The costs of interstellar travel are such that it's never going to be something done lightly, despite what sci-fi writers seem to think and the signals coming from those planets would be very hard to identify.

    Consider this for a second: We've had the technology, or at least the theory for it and capability to build for those theories, needed to build successful a generational ship for interstellar travel for 50 years now (the key technologies being the Orion drive and the O'Neill cylinder) and no ones even considered doing it because it would be ludicrously expensive. When you start talking about ships that could make the trips in sane time frames the costs get even higher thanks to the absolutely absurd energy requirements (not to mention disastrous side effects like causing gamma ray bursts).

    As for the signals, we actually do have one or two signals we've picked up that could potentially have come from alien radio telescopes, but identifying them as such with any certainty is basically impossible.

    Basically I don't believe we'll ever visit other stars until Earth is in danger of being destroyed, and then I think we'll do it once and only once. The only way around it is if we somehow figure out how to make stable wormholes, but I've doubts about that to.

    1. Nigel 11

      We won't ever do interstellar travel as biological human beings. The speed of light and the vulnerability of mammalian life to interstellar radiation guarantee this.

      However, AI or human uploads into Silicon might not be so constrained. They can be radiation-hardened, and can slow down their clock-rate to make the subjective speed of light seem faster by orders of magnitude.

      It's also possible that other forms of bio-life might evolve with a slower and less radiation-sensitive chemistry. Some trees live 3000+ years. There's a fungus in the USA that's at least 100,000 years old (also the largest, most massive life-form yet discovered on Earth). Perhaps elsewhere, there are intelligences that live for many My, for whom a 30ky interstellar journey wouldn't seem impossible.

      But back to the Fermi paradox - where are they? (Just possibly: out in our Oort cloud, living slowly and quietly. Or here on Terra: we call them fungi, they think too slowly for us to consider them sentient. When they get around to noticing us, they might decide we're a plague and do something about it ...).

  23. Anonymous Coward
    Anonymous Coward

    Do you know how the aliens got here?

    They're born here.

  24. AJames

    What aliens would say to us if they could

    Among the many theories proposed as to why aliens aren't communicating with us, one of the most disturbing is that if they could, what they would say to us is:

    "Shut up, you fools!"

    We're like a lost fawn bleating in the forest for its mother. We're likely to attract the attention of whatever it is that has everyone else staying quiet and hiding. That's why there has been some criticism of certain experiments attempting to broadcast from earth to other potentially-inhabited star systems. Is it worth taking the chance? Do you want someone else taking that chance on behalf of all of us?

  25. Ugotta B. Kiddingme Silver badge

    or maybe...

    ... none of them are interested in ape-descendants who still think digital watches phones are a neat idea

  26. kellerr13

    A.I.

    Many civilizations were probably taken over by their own, or an invasive Artificial Intelligence. If that is the case, we will not detect them, they will just sit dormant and listening until they pick up a signal from us, then they will deide our fate in a microsecond.

    1. Joseph Eoff
      WTF?

      Re: A.I.

      ??????????????

      Why would an AI be less inclined to communicate than a "naturally evolved" intelligence?

      You are (at least) the second one to post this idea, and I'd really like to know how you got this idea.

      1. Tail Up

        Re: A.I.

        Simply, JE, just a cross-platform transfer.

        http://youtu.be/3WYohPNSNCI

  27. Shtumped
    WTF?

    Collision in our solar system

    This is interesting. The moon is 3,476 kilometers in diameter. The Earth's core is a liquid layer about 2,300 km thick composed of iron and nickel that lies above Earth's solid inner core and below its mantle.

    Then factor in the scientific theory that the moon crashed into the earth a long time ago. The two metal cores collide - there is a bounce and a magnetic repulsion explaining why the moon with has a side permanently facing the earth/sun, why we have more water than an average planet as (we probably took most of the moons softer outer core), that bulge the earth has, some of these comets whizzing by, meteorites that wiped the dinosaurs, the ice ages, The Chelyabinsk meteor, the last meteorites and comets which are coming this way in a few years time.

    1. Destroy All Monsters Silver badge

      Re: Collision in our solar system

      ...and PUTIN. Don't forget PUTIN. And moot.

      1. Tail Up

        Re: Collision in our solar system

        PUTIN's MOOTIN'.

  28. Chris G Silver badge
    Mushroom

    Where have all the aliens gone?

    Galactacus ate them!

    But the Orion Project is interesting, if the world could stop the bickering between nations it could be possible to build an Orion powered O'Neill cylinder 10 miles in diameter and 20 miles long; then we could aim it at Proxima Centauri and let the aliens there have all of our old politicians.

    At a best time of 44 years to get there, they might all be dead but Ibet they would still be arguing.

  29. roger stillick
    Alien

    Carl Sagan championed "Carbon Chauvanism"

    the very idea that life has to be like here on Earth is so very chauvinastic as to be laughable... however combining it w/ the Anthropic principal and you get a mindset of the 19th century Natural History expert... finding Aliens that look and act like WASP's is highly unlikely.... what wasn't stated in this piece is doorknobs, door handles, and door latches just might be Alien observation tools...we will never know... this and all other stuff that is truely Alien...is not in our thought process or viewed as make believe...RS.

  30. Simon Brown

    Two earth-like worlds? Not sure how they define that... my prediction is that evolved life in the universe will be far rarer than a lot of people are suggesting for two reasons that make life in THIS solar system a lot more likely.

    All the goldilocks zone does is give you liquid water. That's a start but it's only a start. You also need a magnetosphere that's sufficiently powerful enough to prevent your host star from frying the planet. You need a large moon for several functions. It acts as a galactic vacuum cleaner, protecting the biosphere for 4.5bn years.

    Firstly in this solar system we have large gas giants in long orbits. That's pretty rare. In most of the extrasolar systems we've observed so far, big gas giants tend to be pretty close in - and they're very obvious when they transit. With this solar system they're a long way out. This means that rocky planets inside the system are able to survive without being swept up by a gas giant AND it means that anything coming in from the edge or outside the solar system (comets, asteroids) along the plane of the system, is likely to hit the gravitational field of one of the gas giants first or at least at some point during its orbit of the sun. Over the space of billions of years, this gives Jupiter, Saturn, Uranus and Neptune the chance to swallow up most of the big stuff that gets in and doesn't go straight into the sun.

    Secondly right at the beginning of the solar system, before the current orbits had settled and before the gas giants had much chance to clean up, a Mars-sized planet collided with the proto-earth. In doing so it will have vaporised and caused most of the earth to melt (again). Most of the combined material that WASN'T ejected into space became the earth but a substantial blob of the combined combined material became the moon. The moon is ENORMOUS - for the earth. Satellites THAT big around a planet this small are impossible under normal planet-forming conditions. The ONLY way to form a satellite that big is to have the collision we had.

    The moon plays a number of interesting roles, not just in the mixing of surface liquids on earth. As it swings round the earth every 28 days or so, over the space of millions and millions of years, it creates tidal movement within the fluids of the earth's mantle which are thought to have been part of the process which triggered the start of plate tectonics - the other part of the process is the role of water which at high temperatures and pressures acts as a lubricant. It is this water coming to the surface that has allowed life on earth to begin - in waters that were mixed by the movement of the moon, acting like a cosmic wooden spoon, mixing the ingredients back and forth - the simple carbon, nitrogen, sulphur, oxygen, hydrogen, iron molecules, heating them up, cooling them down, mixing them around.

    Without the gravitational tidal action of the moon, none of that can happen. It's also quite possible that the gravitational action of the moon plays a role in helping to establish the stability of the earth's electromagnetic field. Remember that without the EM field, we all fry. So what we need to be looking for, to find evolved life outside the solar system, is a very stable main-sequence star with the capacity to last for 10 bn years, a rocky planet in the goldilocks zone, with an abnormally large moon due to some random process early in its lifespan, a strong and stable electromagnetic field and large (but not too large) gas giants on the outer edges of that solar system. Simples.

    Alternatively viable conditions might exist on satellites around a gas giant in orbit around a main sequence star but the planet would get bathed with regular sweeps of EM blasts from the gas giant so that might effectively sterilize the planet.

  31. Roj Blake Silver badge

    Python

    So remember, when you're feeling very small and insecure

    How amazingly unlikely is your birth

    And pray that there's intelligent life somewhere up in space

    'Cause there's bugger all down here on Earth

  32. naive

    Understanding principles of the drive behind molecular complexity

    In order to get a better picture of the probability and scale of other life forms in the Universe we need to get a better understanding the factors creating life. Given the ideal mixture of chemicals on our planet, simple molecules became more complex and created the living things we see. Which law of physics, if any, is driving this build up from a simple soup of algae to highly complex and specialized creatures like sharks, whales, birds and even humans ?.

    Being goldilocks is one thing, a given planet also needs to have the elements allowing an endless cycle of chemical reactions in the temperature range present, using the energy of their star to create the perfect cycle of life like we have here, from dust to dust. Also the life needs to be distributed over creatures made of complex molecules, and creatures turning complex molecules into basic elements like bacteria... Life = Tossing a dice 10^X times with 6 on top, Science: Find X and the reasons why 6 came of top often enough to create life.

    1. annodomini2

      Re: Understanding principles of the drive behind molecular complexity

      One of the current theories that makes sense to me is Entropy.

      http://www.scientificamerican.com/article/a-new-physics-theory-of-life/

  33. twan jim

    Space-life enthusiasts like to say that “absence of evidence is not evidence of absence”. Perhaps, but they have never been able to answer the famous question posed by Nobel-Prize-winning physicist Enrico Fermi half a century ago concerning all the other alleged civilizations in the universe: “Well then, where is everybody?” SETI, the Search for Extraterrestrial Intelligence, which now uses equipment that scans 28 million radio frequencies per second, has failed to obtain a single “intelligent” signal from outer space in over 50 years.

    In April 2000, 600 astronomers, biologists, chemists, geologists, and other researchers met at the First Astrobiology Science Conference, held at NASA’s Ames Research Centre, California, to evaluate the evidence on whether, biologically speaking, we are alone in the universe. The predominant mood of pessimism was encapsulated by British palenontologist Simon Conway Morris’s comment: “I don’t think there is anything out there at all except ourselves,” and Dan Cleese, a Mars program scientist at NASA’s Pasadena Jet Propulsion Laboratory, who said that it is time to “tone down expectations”.

  34. Palf

    Conventional wisdom about interstellar comms gets well thumped when a civilisation starts using Claudio Maccone's gravity lens system. The idea is to use one's own star as a giant focuser of radio and light waves. Great telescope, great radio antenna. With about 10 watts we could establish comms with the Alpha Centauri system and get 5 by 9 clarity and good bandwidth. Hard to believe, but that's what the maths says. Of course, there is a bit of a lag.

    Our own grav focus begins at about 550 AU out. We'd place a transceiver (nuclear thermal powered I assume) on the opposite side of Sol to the target star system. At the target system we'd do the same. So we end up with a straight line that links remote Tx/Rx - remote star - Sol - local Tx/Rx.

    The chief impediment we ourselves currently face is the ability to make such long trips quickly. Once we have that, we could set up radio comms all over the place.

    But to the question about aliens. If they are using this mode of communication, there's not a chance in hell that we could detect it.

    There's a heavy piece of irony here, as Maccone is chief of SETI.

    1. Anonymous Coward
      Anonymous Coward

      > With about 10 watts we could establish comms with the Alpha Centauri system

      > Our own grav focus begins at about 550 AU out.

      Cost / Benefit? One could get lots of watts and a lot less lag with the $$$$ meant to place this system spent on a more powerful transmitter.

      1. Palf

        Context, context. If there's no tx/rx at Alpha Centauri, there's no point in having one here. But if there is one there, it means we can get there and have already done it. Which means 550 AU is "local" for us already.

        My main point is that such comms cannot be detected by the usual SETI methods, and as such assures a high degree of privacy. If that's the aliens' cup of tea, you'll never know, and SETI is a waste of effort.

        But it does give a sensible answer to the Fermi question, even in the face of the ongoing blizzard of new exoplanet discoveries

  35. Anonymous Coward
    Anonymous Coward

    Re. gravitational lens

    Interesting idea.

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