Catch up on stories from the past week (and beyond) at the Slashdot story archive

 



Forgot your password?
typodupeerror
Space Stats Science

Astronomers Estimate Milky Way May Have 100 Billion Alien Worlds 294

Posted by samzenpus
from the that's-a-lot-of-away-missions dept.
astroengine writes "Last year, using the exoplanets discovered by the Kepler space telescope as a guide, astronomers took a statistical stab at estimating the number of exoplanets that exist in our galaxy. They came up with at least 50 billion alien worlds. Today, astronomers from the Space Telescope Science Institute (STScI) in Baltimore, Md., and the PLANET (Probing Lensing Anomalies NETwork) collaboration have taken their own stab at the 'galactic exo-planetary estimate' and think there are at least 100 billion worlds knocking around the Milky Way."
This discussion has been archived. No new comments can be posted.

Astronomers Estimate Milky Way May Have 100 Billion Alien Worlds

Comments Filter:
  • by DumbSwede (521261) <slashdotbin@hotmail.com> on Wednesday January 11, 2012 @08:31PM (#38669744) Homepage Journal
    100 Billion is likely too low. Based on a survey of close suns using Doppler shift indicated at least 50% had planetary systems of some sort. I think the future will boost this percentage to 90% or better, probably virtually all suns have some kind of orbiting object that could be termed a planet. Depending on where you draw the line on size this makes for probably more than 2 Trillion alien worlds in the Milky Way alone (which is estimated to have 200-400 billion suns).

    As for examining Kepler Objects of Interest (KOIs) more closely it seems there is little point to single them out. So what if we know they have planets -- everywhere you could point a radio dish there are planets. I am a big supporter of SETI and this is all good news for SETI, but it doesn't do anything to narrow the search.
  • Alien life in the universe that we could encounter, depending on the climactic conditions, gravity and atmosphere would be very different from humans to say the least. They would not be all humanoid races that speak english and can walk and act just like humans, they might be boneless creatures like an octopus or evolved dolphins that pilot ships full of water, or something that we have not even encountered yet. Dolphins show amazing intelligence so it is easy to imagine, that if they evolved over the course of millions of years on a remote planet and developed mathematics and science, they could invent space flight. Star Trek had humanoid aliens as standard, but the science fiction of Larry Niven envisaged quite different creatures such as the puppeteers.

    Not to forget the even stranger aliens in the book Sundiver [wikimedia.org] by David Brin. Discovery channel one time showed a Jupiter sized Earth like planet that had small creatures crawling along its surface that had to eat continually in order to have enough energy to move in the massive gravity. I am not sure if it is possible for such a large planet to form, most large planets that have been discovered are gas giants. But any alien planet we visited could have alien bacteria that we would not have a immunity to and it could be very dangerous if we brought it back to Earth. So any future space exploration would still require caution.

  • by Kittenman (971447) on Wednesday January 11, 2012 @08:58PM (#38669898)
    “Behind every man now alive stand thirty ghosts, for that is the ratio by which the dead outnumber the living. Since the dawn of time, roughly a hundred billion human beings have walked the planet Earth.

    Now this is an interesting number, for by a curious coincidence there are approximately a hundred billion stars in our local universe, the Milky Way. So for every man who has ever lived, in this Universe there shines a star.

    But every one of those stars is a sun, often far more brilliant and glorious than the small, nearby star we call the Sun. And many--perhaps most--of those alien suns have planets circling them. So almost certainly there is enough land in the sky to give every member of the human species, back to the first ape-man, his own private, world-sized heaven--or hell.

    How many of those potential heavens and hells are now inhabited, and by what manner of creatures, we have no way of guessing; the very nearest is a million times farther away than Mars or Venus, those still remote goals of the next generation. But the barriers of distance are crumbling; one day we shall meet our equals, or our masters, among the stars. "

  • by c0lo (1497653) on Wednesday January 11, 2012 @09:00PM (#38669918)

    Alien life in the universe that we could encounter, depending on the climactic conditions, gravity and atmosphere would be very different from humans to say the least. They would not be all humanoid races that speak english and can walk and act just like humans, they might be boneless creatures like an octopus or evolved dolphins that pilot ships full of water, or [...].

    Ships full of water - multiply the difficulties to escape the gravity well by about 1000.
    Imagine developing metallurgy and special ceramics (I reckon these would be needed for at least propulsion) in/under water...

  • by iggymanz (596061) on Wednesday January 11, 2012 @09:01PM (#38669922)

    In a couple years kepler will have sufficient data so we can estimate the number of rocky worlds in habitable zones, that's what is most interesting to me. Once we find such worlds, we'd need to fund the type of probe that can analyze atmosphere, life as we know it does a very detectable transformation. Then step up our optical SETI efforts in those world's directions (they won't use radio waves, sorry microwave SETI dudes....)

  • Re:Fermi Paradox (Score:4, Interesting)

    by DumbSwede (521261) <slashdotbin@hotmail.com> on Wednesday January 11, 2012 @09:14PM (#38670010) Homepage Journal
    I'm not sure why you want to shout Fermi Paradox, it is not an answer but a question.

    20 years or more ago we could have speculated that planetary systems were rare, thus life had few places to evolve on and that could have been a possible solution to the Fermi Paradox -- finding so many worlds deepens the Fermi Paradox.

    Let us hope Fred Saberhagen doesn't have the correct answer to the question with his Berserker series of novels.
  • whatever (Score:3, Interesting)

    by milkmage (795746) on Wednesday January 11, 2012 @09:39PM (#38670166)

    everyone knows they'll ignore us until we have warp capability.

    2 weeks to the Moon?
    9 months to Mars? lol.

  • Re:Fermi Paradox (Score:5, Interesting)

    by wierd_w (1375923) on Wednesday January 11, 2012 @09:45PM (#38670202)

    Or even some clever use of entangled particle pairs. (Simply because we haven't figured out how to use them for comm doesn't mean others haven't.)

    Personally though, I think seti is looking for the wrong things.

    Instead of trying to eavesdrop on the grey aliens ordering space pizza from planet foodcourtia, they should be looking for localized light displacements from known stellar markers, as caused by the huge gravitational eddies that several hypotherical FTL systems would make. Interstellar highways would show up on a sufficiently detailed map of the CBR because of the regular disruptions.

    (This assumes something like an albucare (however you spell his name...) warp drive though, which create a wave of negative spacial curvature behind the vessel, and a synthetic gravity well in front.)

    Our current CBR maps are pretty coarse, since we are dealing with single measurement devices with very wide frequency emmisions, so a highway search would require interferometry to be fruitful. We need to launch about 50 more COBE sats up.

  • by mjwx (966435) on Wednesday January 11, 2012 @09:55PM (#38670244)

    I think the issue is how does this water creature develop fire and metal smelting in the first place (you know bronze and iron age level) - once they have technology working around it is easy, the tricky bit would be developing that technology in the first place.

    You can create fire underwater, it's a different chemical process to on land.

    Besides, you dont need fire for smelting, you simply need heat and there are plenty of active underwater volcano's on earth as well as other heat sources.

    Needless to say, an aquatic civilisation would develop things in radically different ways to the way we have.

  • by Surt (22457) on Wednesday January 11, 2012 @09:58PM (#38670268) Homepage Journal

    It's acknowledged in the article that this is only for 'worlds' about 5x as big as earth and higher.
    The real number, counting everything that would count as a planet in our solar system, may be 5-10X as high.

  • by Bongo (13261) on Thursday January 12, 2012 @04:36AM (#38671846)

    There's also an argument that nature seems to "copy". Once it has done something, it seems to do it again more quickly. Now Star Trek was written to not be so alien looking that the audience couldn't relate to it. And I do get bored with endless forehead-ridge variations. Trek was like that for reasons of TV writing. But humanoids, or things that are sorta upright with four limbs, might be quite common anyway, simply because nature seems to repeat stuff. We might imagine some small change early on in evolution that would have made a very different outcome millions of years later, but life seems also pretty stable, in that, it sorta keeps to a pattern for a long time, then suddenly something changes and the new pattern spreads rapidly, but then it stays the same for a long time, and so on. I don't know if people know why and how patterns in nature spread rapidly. Like, suddenly there is a new species. (I'm not being creationist *spit* *spit* and there is this photocopier-like behaviour which suggests some additional blind and automatic mechanisms which we don't know about, or that we're somehow overestimating how many paths are actually available in the system). It is the "stays the same" and "copies" part that might suggest that alien worlds are similar to Earth. Why? Because Earth isn't special and because nature made it happen here, so we know it can happen, and therefore it is probably happening in a similar way elsewhere. (Of course I wouldn't bet on what aliens look like, but seeing as they're out there across the vast expanse of space, expecting them to be completely different, following a different path, is one view, but expecting them to be very similar, because nature and the universe "likes" to copy stuff, is another.)

  • by tigersha (151319) on Thursday January 12, 2012 @07:27AM (#38672448) Homepage

    Here is a very fine example of an supernova in another galaxy that is visible from earth, but modulating this to carry information would be somewhat challenging.

    http://upload.wikimedia.org/wikipedia/commons/thumb/a/a2/SN1994D.jpg/600px-SN1994D.jpg [wikimedia.org]

    That is one beautiful pic though.

  • by delt0r (999393) on Thursday January 12, 2012 @11:15AM (#38674396)
    Well lets run the numbers shall we.

    Lets listen to Andromeda which is 2.5 million light years away or about 24x10^21 meters away. Lets assume that that the intelligent life in Andromeda only transmit to the closest galaxy, us. Lets also assume we have a perfect quantum efficiency detector at the 1.420GHz "water hole" and that we have zero noise and hence only a photon per second can be considered enough data to rule out anything but ETs. Finally we assume that we have built a 100m radius antenna to capture these photons.

    Ignoring diffraction and the relative orientation of the milky way to Andromeda, we assume they only need the energy to stream that many photons through the milky way disk. The diameter of the milky way is about 100,000 lty so the area is 703x10^39 m^2. We want one photon per second per 100m radius antenna or per 31x10^3. The total number of photons per sec is 22.7x10^36. Each photon has energy E=hv or 937x10^-27J and the total power required is *only* 21x10^12W.

    Obviously there are other losses and diffraction, but the real limit is the noise floor at 1.420GHz. I have no idea what that is, but once we consider shot noise etc we start to see that we need a bit more power than 21TW. However this is not an impossible power level, and is not "life sterilizing" really. But then again its only 2.5 million light years away. In terms of galactic distance, that is just over the fence. Also the guys over at Andromeda have to really want to let others know they are around. Which with the distance involved seems less likely than local civilizations.
  • Re:Sweet (Score:4, Interesting)

    by mcgrew (92797) * on Thursday January 12, 2012 @02:25PM (#38676980) Homepage Journal

    I know you're joking, but you're not going to find any alien species that look anything like human. There are no Romulans, Klingons, nor especially Betazoids. You're probably unlikely to find anything that more than remotely resembles any species from Earth -- look how diverse life here is. We may find intelligent life and not even realise it's alive, let alone intelligent.

    Required reading: Isaac Asimov's What is This Thing Called Love? [wikipedia.org] (originally titled Playboy and the Slime God). I've read a lot of Asimov stories, and I don't think the good doctor (a biochemist) had a single alien that looked human-like, and the story I mentioned gives a clue why.

    Terry Bison's They're Made Out Of Meat (online at Baen Books) is another good one.

    And a thank you to slashdot for waking the muse [slashdot.org] with this topic!

"In the face of entropy and nothingness, you kind of have to pretend it's not there if you want to keep writing good code." -- Karl Lehenbauer

Working...