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Space Earth

Complex Life May Be Possible In Only 10% of All Galaxies 307

sciencehabit writes The universe may be a lonelier place than previously thought. Of the estimated 100 billion galaxies in the observable universe, only one in 10 can support complex life like that on Earth, a pair of astrophysicists argues. Everywhere else, stellar explosions known as gamma ray bursts would regularly wipe out any life forms more elaborate than microbes. The detonations also kept the universe lifeless for billions of years after the big bang, the researchers say.
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Complex Life May Be Possible In Only 10% of All Galaxies

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  • Let's do the math (Score:5, Insightful)

    by cat_jesus ( 525334 ) on Monday November 24, 2014 @04:57PM (#48451943)
    10% of infinity is...... hmmm, carry the one...

    Um 7?
    • I think you'll find that the density of life is indeed important to our chances of ever discovering any.

      • by Shatrat ( 855151 )

        If that's what you're worried about, we already know that this particular galaxy supports life. Our chances of finding it in one of the others was astronomically smaller anyway.

      • And if you read TFS they are only talking about life similar to ours; there is nothing saying that in other regions life hasn't evolved to be able to handle those kinds of environments.

        This is exactly why it is impossible to predict the finding of "life" in non-earth environments, there are just too many variables that we don't even know to look for. I.E. life based on something other than carbon, life than can flourish in extremes we could never dream of surviving... be it temperature, pressure, or even ra

    • As far as we know, the Universe is finite.
    • by Kjella ( 173770 )

      Not really, space may be infinite but as far as we know there's a finite amount of energy which by E=mc^2 means a finite amount of mass and since there's a lower bound on the mass of a star and stars to form a galaxy the number of galaxies must be finite.

      • Space is not infinite. It is expanding.

        • Both statements are so arguable as to be nearly meaningless.

          • Only by those who have no fucking idea what they're talking about.

            • Fancy adding a bit of weight to the random abuse? I don't know where Kjella got the idea that as far as we know there's a finite amount of energy around, for one thing. While there may be a finite amount within our horizon, that's a very different thing, since all we need to do is move a few megaparsecs and we've got a slightly different horizon. The statement that there is a finite number of galaxies within our horizon is completely uncontroversial (and indeed obvious, not least since our horizon extends b

    • Re:Let's do the math (Score:5, Informative)

      by JWW ( 79176 ) on Monday November 24, 2014 @05:14PM (#48452089)

      Ummm I think you've confused ridiculously large number with infinity. They are not the same thing.

      • by Saysys ( 976276 )

        Ummm I think you've confused ridiculously large number with infinity. They are not the same thing.

        Clearly you do not understand how calculus works.

      • Depends on who you're asking. I've known physicists to take expressions where infinity is mentioned and substitute 10 because it was "big enough." The frustrating part of course is that they got the right answer. . . .

    • by kuzb ( 724081 )

      There is no real evidence to support an infinite amount of mass. So your "math" has no relevance.

      Of course, when dealing with 100 billion galaxies, 1 in 10 is still really good odds.

      • To anyone currently alive, an infinite universe and one with 100 billion galaxies are indistinguishable. We were previously weighing a practically infinite universe with a practically infinitesimal chance of life, but the numbers seem to have been getting better overall, and the conditions in which life can exist have also expanded considerably.
      • There's no real evidence to support a finite amount of mass.
    • While the Universe may be infinite, the Observable Universe is not infinite (limited by the speed of light).
      The Universe within a radius of a certain number of light-years (and thus of age comparable to our location) is also finite. So considering the galaxies younger than 5 billion years, the number of those galaxies that can be observed (and can contain life that could communicate/meet with us) is finite.

      A quick calculation gives me that the number of galaxies is 170 million. Neglecting very small, dwarf

    • There appears to be an infinity of possible things that could happen evolutionarily.
      But if you look merely at the number of stars in the entire universe, approximately 300 billion billion, that's essentially 10 to the 20th power. That means in order for life to be unique in the universe, all we need are 20 one out of ten possibilities in a row.
  • by Anonymous Coward on Monday November 24, 2014 @04:59PM (#48451967)

    So there are only 10 billion galaxies out there that can support complex life like that on earth? We're practically alone!

    • If you're stranded on a desert island, with no ability to reach another island- you are very much alone. Doesn't matter how many billions of other people there are out there, if you have no chance at reaching or talking to them.

      If this math holds up, the next interstellar island is further away than we thought... and we are likely going to be a very lonely species.

      • If this math holds up, the next interstellar island is further away than we thought... and we are likely going to be a very lonely species.

        This math says pretty much nothing about our neighborhood. Remember, one in ten can just as easily be 1, 1, 0, 0, 0, 0, 0, 0, 0, 0 as 1, 0, 0, 0, 0, 0, 0, 0, 0, 1.

        Even more importantly, this say nothing about our galaxy's likelihood of having life (basically, 100% right now)....

        • This math says pretty much nothing about our neighborhood.

          Yeah, this is the equivalent of using the presumed sterility of the moon to measure the number of people within 1 km of my house. ;)

          Still, from what I've seen of the equations, odds are the median distance between tool-using civilizations is likely well over 100 ly. :(

    • Actually, it's only 17 million. A quick calculation gives me that the number of galaxies within 5 billion light-years is 170 million. Neglecting very small, dwarf galaxies, which are more numerous but have drastically fewer stars, I multiplied the stellar mass density by the comoving volume up to z=0.5.

    • In mathematics "almost" denotes an infinite set minus some finite subset, so if there are only 10 billion galaxies that can support life and the universe is infinite, then the universe is "almost lifeless": infinitely lifeless except some finite subset with potential life.

  • by xaoslaad ( 590527 ) on Monday November 24, 2014 @05:00PM (#48451977)
    I didn't rtfa but if these explosions prevented life for billions of years, does this mean things are settling down? Over the many years will it be possible for life to develop in the other galaxies? Does this make us one of the elder races? If so I feel bad for the universe.
    • Well, eventually there won't be any fusion potential left in the universe, which isn't so grand for life's prospects either.

    • We are only the initial stage of an elder race. Einstein didn't start off with general relativity, he started with addition and multiplication. Don't give up hope yet. The fact that the world is clogged with retards doesn't mean we can't aspire to become the Great Old Ones.

    • In the time between these bursts, maybe a few species got lucky and made it almost to space colonization before getting scrubbed.

      Maybe we're one of them.

      • The stars that are close enough to Earth for a GRB to be dangerous can't produce a GRB. So it's not so much "in between bursts" as being in the right place.

    • by jbolden ( 176878 )

      Yes things are settling down. The universe was much more energetic 10b years ago and will be much less energetic 100b years hence.

  • ...as we know it, screams every sci-fi fan.

    .
  • by Scottingham ( 2036128 ) on Monday November 24, 2014 @05:11PM (#48452067)

    I always like to think that any suitably advanced civilization eventually develops space-drives that can reach appreciable percentages of the speed of light. The time dilation effects would make traversing the galaxy relatively(heh) reasonable. The only hitch is that relative to all other lifeforms not moving at a such a speed would blink in and out of existence in the time it would take them to burp. Our current sliver of space-time is sooo tiny if you think about it like this.

    What if there was a whole...dare I say...confederation of relativistic societies? In order to join you have to catch up. Otherwise you'll be gone in a blink.

    • by HeckRuler ( 1369601 ) on Monday November 24, 2014 @06:54PM (#48452813)

      What if there was a whole...dare I say...confederation of relativistic societies?

      The question would be where are they and where are they going?

      You could probably achieve some meaningful dilation if you orbited a black hole or something. But other than that, presumably the society that can hop around the galaxy still wants to have something to go to. And those locations would experience just as much time as the rest of us. Not that we all experience the same amount. Whole sections of the universe travel at different speeds and times. Like, you know how galaxies are accelerating away from the origin? Yeah, some are moving faster than others. And consequently experience different time dilatation. Dunno what sort of ranges we're talking about. Even at 90% lightspeed, you're only looking at a 1:7 ratio. A 142,000 years as opposed to a million years is still a society-crushing amount of time.

      I'm not sure why you'd want to have a space-faring society that was rushing as fast as they could towards the heat-death of the universe. I guess some people would want to wait and see if anything interesting happened.

    • I always like to think that any suitably advanced civilization eventually develops space-drives that can reach appreciable percentages of the speed of light. The time dilation effects would make traversing the galaxy relatively(heh) reasonable. The only hitch is that relative to all other lifeforms not moving at a such a speed would blink in and out of existence in the time it would take them to burp.

      That's why it isn't useful. You can't use it for anything interesting to anyone but you. So why would anyone do that? There's no real point to moving at near-relativistic speeds because your civilization will be gone by the time you get home from anywhere worth going. After poking around your own solar system, you really need to be able to travel faster than light to achieve anything meaningful by going anyplace. Sending out probes to other places might still be worth it, but if everyone you ever knew will

      • by lgw ( 121541 )

        That's why it isn't useful. You can't use it for anything interesting to anyone but you

        And if the only problem remaining to you in life is boredom?

        So, what would a star moving at near-C look like to the rest of us?

        Get it going fast enough and it would look somewhat like a gamma ray burst, to those directly ahead of it, and be invisible from most directions. But there's probably not enough energy in a star to get it up to that sort of speed, at least with any sort of "stellar engine" anyone has yet imagined.

        • And if the only problem remaining to you in life is boredom?

          You probably just take a several-billion-year nap.

          But there's probably not enough energy in a star to get it up to that sort of speed, at least with any sort of "stellar engine" anyone has yet imagined.

          The energy will have to come from elsewhere, then.

  • "Gamma ray bursts would wipe out any live more complex than microbes".... ...that is, unless life evolved to use radiation as an energy source.

    In other words, a couple of astrophysicists speculate to a degree that's only slightly and unquantifiably less than sheer "wild ass guessing", news at 11.

    • by jandrese ( 485 )
      Or the life lives deep in oceans where it would be protected from the gamma ray bursts.

      The problem with all of these "how much life is in the Universe" answers is that we're trying to extrapolate from a single datapoint (our Solar System). The unknowns outweigh the knowns by a significant margin. In other words, it's mostly a lot of wild ass guesses.
  • by enjar ( 249223 ) on Monday November 24, 2014 @05:16PM (#48452109) Homepage

    If only there hadn't been a Dawn War.

  • by Streetlight ( 1102081 ) on Monday November 24, 2014 @05:26PM (#48452191) Journal
    Most of the galaxies are likely to be so far away that the light - including gamma rays which are made up of high energy photons - has been in transit for billions of years. What's the situation now in those billions of gamma ray emitting galaxies we are now observing in the intervening years since the light was produced? They may have settled down making life possible.
  • Things are even bleaker in other galaxies, the researchers report. Compared with the Milky Way, most galaxies are small and low in metallicity. As a result, 90% of them should have too many long gamma ray bursts to sustain life, they argue. What’s more, for about 5 billion years after the big bang, all galaxies were like that, so long gamma ray bursts would have made life impossible anywhere.

    Wouldn't that also imply that for the first 5 billion years planets in general would be low in metal? So you would have very few planets without iron cores and similer density as Earth. There would be a different chemical mix in most of the universe.

    • Well for the first few hundred million years there's zero metal. Anything* other than hydrogen and helium are only made during a sun exploding. And the quickest dying, hottest stars last hundreds of millions of years. In general, as time goes on, more suns explode making more and more exotic elements like... you know.... carbon and gold.

      *HEY, I'm getting some of that wrong. Turns out elements up to boron could be made by cosmic rays. And gold can only be made in a super-nova. Huh.
      This wikipedia page about t [wikipedia.org]

  • 'Previously thought' has varied quite a bit over time. Since it has been thought to be 1, it's going to be quite difficult for it to be lower than it has ever been previously thought, and 1 in 10 galaxies is higher than most estimates. Skimming TFA, it seems to suggest the problem is that it can't support life if you are too close to a giant explosion in space, and that our universe isn't even in one of the 10% mentioned.

    So, to recap, 90% of galaxies have big explosions that could wipe out life as we k
  • I always despise these reports. They come up with something that life identical to our own - on our world could not stand up against and then say "No life is possible anywhere else".

    No.

    If we didn't have a Van Allen belt, some bright scientist would say no life could survive on earth, because of the radiation.

    Life as we know it evolved to deal with earth. It evolved to live with at atmosphere, with a van allen belt protecting it, with limited meteors strikes (because Jupiter protected us), with our sun

  • It should be 100%, but the Anti-Spiral race keeps killing all other sentient races.

  • Well then, it's a good thing we live in one of the safe ones. I'm going to take a nap, let me know when we can reach the next galaxy,
  • by Dr. Spork ( 142693 ) on Monday November 24, 2014 @05:37PM (#48452271)

    ...the gamma rays would set off a chain of chemical reactions that would destroy the ozone layer in a planet's atmosphere. With that protective gas gone, deadly ultraviolet radiation from a planet’s sun would rain down for months or years

    Yeah, because it's impossible that complex life could be protected by a different (better!) kind of UV shield like... water. From my understanding, it's not exactly rare in the universe.

    • How likely is complex life to evolve under those circumstances? Besides, I got the idea that only microbes with their extremely high radiation resistance would survive even in the deep ocean, as enough would penetrate to kill even things like ocean vent crabs.

  • I am dubious (Score:5, Interesting)

    by mbone ( 558574 ) on Monday November 24, 2014 @05:40PM (#48452303)

    I am dubious that gamma ray bursts are invariably a sentence of doom. The actual mechanism is due to the destruction of the ozone layer due to nitrogen molecules formed in the upper atmosphere; these molecules would "eat" the ozone for maybe 4 - 5 years after a GRB event, but would not (in that sort of lifetime) go from one hemisphere to another. Questions I would have include

    - How many civilizations might form on bodies with very thick atmospheres, far from their Suns? (Venus does not need a ozone layer to keep the UV out, and might be very habitable a few AU out.)
    - How many planets might have very long rotation periods (years), so that the night hemisphere never is subjected to the daytime UV?
    - Are there rotation axis directions and orbital precession constants for planets that would keep GRB radiation mostly in one hemisphere, leaving the other to develop?
    - How many planets might have other special circumstances that protect their ozone (such as a lack of N2 in their atmosphere, or an ozone generating biology in their stratosphere, etc.)

    I am sure that there are others, but even these I think show that, while GRB might be bad for habitability, they need not be fatal. Note, too, that if I was running a Kardashev Type III civilization, one of my action items would be to find any possible GRB progenitors and disarm them. So, in a KIII galaxy, GRB would likely no longer be a problem; maybe that would be a good way to determine the number of KIII galaxies in the universe.

    • Re:I am dubious (Score:4, Interesting)

      by buchner.johannes ( 1139593 ) on Monday November 24, 2014 @06:15PM (#48452535) Homepage Journal

      I can not answer about the deadliness of GRBs, but I think you will find those answers in Phil Plaits book "Death from the Skies!".

      - How many civilizations might form on bodies with very thick atmospheres, far from their Suns? (Venus does not need a ozone layer to keep the UV out, and might be very habitable a few AU out.)

      Yes, insulation is a good idea. But the planet will always radiate as a black body and loose energy, which has to be re-supplied by the suns radiation. The radiation drops with the square of the distance, so rather quickly. These considerations (make-up and size of planets) go into calculations for the habitable zone [wikipedia.org].

      I can also imagine that a GRB comes with considerable photon pressure and might strip the entire atmosphere off a planet, or heat it to a point where it dissipates into space.

      - How many planets might have very long rotation periods (years), so that the night hemisphere never is subjected to the daytime UV?

      I think the rotation of planets around their own axis (spin) is not known outside the solar system. Generally, the spin is generated from formation of planets in the rotating protostellar disk, but interactions and changing orbits may modify the spin (Venus, Uranus).

      - Are there rotation axis directions and orbital precession constants for planets that would keep GRB radiation mostly in one hemisphere, leaving the other to develop?

      If you do not have the problem of heating and evaporation of the atmosphere I mentioned above, then yes, that is probably possible. For example if the GRB goes off from the direction of the spin axis ("below/above the solar system"). This may safe you from one GRB, but since GRBs come randomly from all directions it is not failsafe across many billion years.

      - How many planets might have other special circumstances that protect their ozone (such as a lack of N2 in their atmosphere, or an ozone generating biology in their stratosphere, etc.)

      Not sure. I think it is possible to come up with such scenarios as you stated, but it has to be shown that they are frequent occurrences to be relevant for changing the survival rate of complex life.

  • by djnanite ( 1979686 ) on Monday November 24, 2014 @05:49PM (#48452371) Homepage
    On the plus side, it seems that our galaxy is one of the 10% capable of supporting life.

    So at least we only have to start looking locally...
  • If the environment of such worlds has large amounts of gamma radiation, surely whatever life evolves there will naturally be able to cope with it? Maybe our namby-pamby DNA-based life couldn't survive under those circumstances, but it's probable that there are trillions of alternatives.
  • As I understand it in order to sustain catastrophic, life eradicating damage from a GRB you need to be looking directly down the "barrel of the gun" so to speak, or rather directly in the line of fire emanating from the star's poles. This forms a fairly narrow beam of intense energy that decreases with distance. It doesn't seem that likely to me that 90% of life supporting planets in the universe would find themselves in just this predicament.
  • Of the estimated 100 billion galaxies in the observable universe, only one in 10 can support complex life like that on Earth

    10 percent of 100 billion is still 10 billion galaxies. That's a lot of real estate. Even if you apply all the other characteristics that give rocky planets in the habitable zone of their star billions of years to evolve life. There are features like having a Jupiter in a circular orbit instead of an elliptical orbit or a moon that creates tide pools. That's a lot of habitable plane

    • Carl Sagan talked about it. Look at a planet like Titan. It's got oceans of hydrocarbons. It's far enough from the sun and cold enough to have not developed life, but we can't rule it out. There is simply so many organic molecules there that any life that did exist would be overwhelmed with food.

      But more importantly, in both cosmos version they discuss this very point, even if life is a 1 in a billion or 1 in a trillion chance there are still going to be literally billions of life bearing planets out there

  • These "Astrophysicists" are incredibly short sighted if they think we have any idea as to the variety of life forms that exist throughout the universe from our limited view from our ecosystem on the Planet Earth. Sure -- we might have a pretty good understanding as to some of the life forms we might see in a yellow dwarf star system on a rocky planet with a nitrogen and oxygen based atmosphere -- but who's to say what life forms may exist in other galaxies, or what comprises an organic body or living entit
  • I only had time to skim TFA, but it sounded like they did a strict radial distribution from a GRB source to a potential life-harboring planet. i.e. if there's a GRB of x magnitude and it's within y parsecs of a planet, assume life on that planet is wiped out.

    If I remember, GRBs are focused so most of their energy exits out the rotational poles. If you assume galaxies formed from a cloud of matter spiraling down and clumping together, then the stars and planets in a galaxy will tend to have the same ang
  • We may want to see about relocating...
  • Of course, all of us here are familiar with the Drake equation, something this article certainly applies to.

    But I wonder, has anyone made a serious attempt at coming up with real numbers for the various variables to see what the final number was? Every attempt I've seen thus far at solving the equation either uses very loose figures or doesn't enumerate the variables at all.

    What I'd like to see is someone take the most rigorous numbers we can come up with, narrowing the estimated ranges as best as we ca

  • Does that include ours?
  • It's the simplest life form, and so very, very plentiful.
  • We're pretty sure that most large galaxies have a supermassive black hole in the center. We know that some very-VERY-far away astronomical objects are very active in radio and X-ray output; we call these "quasi-stellar radio objects" or "quasars".

    Is it not at least remotely possible that these facts are related? My physics degree is 30 years old and I have only sort-of kept up with the news, but it seems at least possible that those gamma ray bursts and quasars are symptoms of the formation or expansion

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