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Space Science

Milky Way Inhospitable? 351

Posted by Hemos from the the-antropomorphic-galaxy dept.
tdfunk writes "Space.com reports that life in the universe may be more rare than previously thought. In an article published today, Space.com quotes Guillermo Gonzalez, an Iowa State University researcher, who has studied the structure of our galaxy and has concluded that life may not be as common as we may have believed. Apparently, conditions around the Milky Way Galaxy are generally less hospitable than once thought.
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Milky Way Inhospitable? More

Milky Way Inhospitable?

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  • UFOs and Aliens (Score:3, Funny)

    by dasheiff ( 261577 ) on Tuesday May 28, 2002 @05:35PM (#3597904)
    No wonder all the UFOs and Aliens come to Earth, their looking for a place to live and no where else will do.

  • Well Duh (Score:3, Funny)

    by GigsVT ( 208848 ) on Tuesday May 28, 2002 @05:37PM (#3597911) Journal
    99.9999% or more of it is empty space, a near vacuum. What do we pay these scientists for again? :)

  • Many galaxies (Score:3, Insightful)

    by nucal ( 561664 ) on Tuesday May 28, 2002 @05:38PM (#3597929)
    Still, remember how many galaxies there were in some of the Hubble Photos [stsci.edu]? Even if the number of inhabitable planets/galaxy is low, there are still a lot of galaxies out there.

    • Re:Many galaxies (Score:3, Informative)

      by Bonker ( 243350 )
      Our galaxy is around 100k light years across. Assuming we built a craft that traveled .5c, it'd still take over 200k years to cross that... about 20 times longer than human civilization has been around.

      The distance between galaxies is an order of magnitude larger. Even if there was life in the Andromeda galaxy, if they started at the same time we did, we wouldn't meet them for millions and millions of years, assuming sub-light travel.

  • How do we know what is hospitable? (Score:3, Insightful)

    by mini me ( 132455 ) on Tuesday May 28, 2002 @05:39PM (#3597938)
    What if there were life forms on the sun? Or in the milky way. Maybe we, or anything else on earth could not exist in those regions but who's to say something else can't?

    Scientists were suprised when they found life in the hot vents on the sea floor because they thought it was too hot for anything to survive there, yet there was something there. Humans couldn't survive there, but we were never designed to live there. If an organism was native there they would be formed in such a way to be able to withstand what it takes to live there. If they tried to come here maybe they'd die immediatly from something that makes the earth inhospitable to them.

    Also organisms can adapt, and they might be able to adapt way beyond what we have witnessed thus far.
    • What if there were life forms on the sun?

      I'm no biologist or astrophysicist, but frankly that doesn't make any sense. If you have organisms living in the hot vents on the sea floor, fine, but now compare that environment to the Sun. The Sun has no water, no "usable" oxygen, no carbon dioxide, and a hell of a lot of heat (there is oxygen, but it's in the core and even hotter than the outer layers -- it's waste from previous fusion reactions).

      So, as I recall, the surface of the Sun is thousands of degrees Celcius, and I think it was actually above 10,000 degrees. That's enough to obliterate protein structures, among other things, and break "organic chemicals" which we believe are necessary for life. In fact, most materials will be gaseous at that temp... go deeper into the core, and if you manage to sidestep the fusion taking place, you might get a bit crispy from the million degree heat. And did I mention the intense gravitation field, and constant barrage of high intensity energy/particles?

      Life on the Sun is highly unlikely, unless you want to consider the Sun itself a living organism... but of course that's another argument entirely.
  • I think this is going to make the agnostics on slashdot pretty mad...

    oh wait, I think I'm the only one who isn't.

    (I mean that in good fun kids, don't get upset.)
  • Until reading this article, I really believed that at least 25% of the planets in the universe were prime candidates for human life.. This sucks.

  • On a more serious note (Score:4, Interesting)

    by GigsVT ( 208848 ) on Tuesday May 28, 2002 @05:42PM (#3597960) Journal
    We may, it turns out, be very lucky to be here.

    Luck had nothing to do with it, in fact, if you are an intelligent life form, there is a 100% chance you were born on a planet that is capable of supporting intelligent life!

    And besides, suppose there is one planet capable of supporting life per galaxy, taking this researchers findings to the extreme. It is believed there are billions of galaxies. Billions of planets full of life doesn't sound too "alone" to me.
    • yea, you're right. But as cool as it would be to have Billions of intelligent civilizations, if they are in distant galaxies, they might as well be alone without extreme changes in propulsion. Maybe with wormholes, if we don't black-hole ourselves into oblivion before we figure it out...

    • ...because this has to be a joke:

      And besides, suppose there is one planet capable of supporting life per galaxy, taking this researchers findings to the extreme. It is believed there are billions of galaxies. Billions of planets full of life doesn't sound too "alone" to me.

      In other words, "here is a number, and it sounds big to me, so that's a high frequency."

      There are about 400 billion stars and planets in our galaxy alone. Say the average is about 300 billion per galaxy, and 2 billion galaxies, so 600 billion billion stars and planets in the universe (probably a conservative estimate). At 2 billion earth-like planets, that's pretty alone. It's a big universe out there.

    • Billions of planets full of life doesn't sound too "alone" to me.

      Um, that puts the nearest inhabited planet a minimum of 163,000 years of travel away from Earth. That's close enough to "alone" for me.

  • Old news... (Score:5, Insightful)

    by Boulder Geek ( 137307 ) <archer@goldenagewireless.net> on Tuesday May 28, 2002 @05:43PM (#3597971)
    Guillermo is well known for the "Rare Earth" hypothesis, which boils down to the thesis that planets identical to Earth are extremely uncommon. This has even been covered on Slashdot before.

    I don't entirely disagree with Guillermo, but he does make one major blunder, IMHO: He assumes that complex life can only develop on planets with all of the same characteristics as Earth. That sub-hypothesis is not proven.

    Regardless, lets say that a exact Earth analogs occur around one out of a billion stars. That still leaves 100 Earth analogs in the Milky Way alone.

    The real issue for finding ET, IMHO (that sure gets tossed out a lot when discussing life in the Universe ;-) is that time is so much longer than we humans can perceive. Humans have been around in our present form for only a few thousand years, with only a couple of decades when we could be detected by extra terrestrial civilisations. In terms of the age of the Earth that is nothing, and compared to the age of the galaxy it is smaller than nothing. Our window in time is so narrow that it seems unlikely that it actually overlaps with other civilizations.
    • There's a book about this called Rare Earth: Why Complex Life is Uncommon in the Universe, by Peter Ward and Donald Brownlee. As you say, most of the stuff in the article is not new, although as far as I can remember from when I read the Ward and Brownlee book, some of the arguments in this article weren't in the book.
    • Regardless, lets say that a exact Earth analogs occur around one out of a billion stars. That still leaves 100 Earth analogs in the Milky Way alone.

      I believe the point of the article is that most of those billion stars in the Milky Way are not hospitable to carbon based life. Therefore, you would need to only count the stars on the arms of the galaxy (like earth) and then apply your hypothesis.
      • I'm including bulge stars in the billion to one. The thesis is that you need a certain metallicity, radiation level, etc... Rare earthers (gotta love that term ;-) assume that complex life can only be supported on a planet exactly like Earth. Besides, there are more population I stars than pop II in a given spiral anyway.

        The Milky Way has something on the order of 100-200 billion stars in it, and M31 has even more. There are so many stars that even if you toss out half or more, there's still a lot of territory to look at.

        The fact is that we just plain don't know, and won't have any idea on this subject until we get a better handle on how to locate terrestrial planets. In the meantime, I think that its better to keep an open mind than to succumb to the small sample fallacy.
        • The Milky Way has something on the order of 100-200 billion stars in it, and M31 has even more.

          Granted, but if you buy the theory that the article presents, then you automatically throw out the stars that inhabit the core of the galaxy. For any given spiral, that is about 80% of the stars.

          There are so many stars that even if you toss out half or more, there's still a lot of territory to look at.

          Agreed. Now take from the 20% the non-main sequence stars and you have less than 500,000 stars. (Calculations from my own head that are known to be flawed.) This is still a relatively small number and if you go into all of variables in the Drake equation (which I won't) as was pointed out by RovingSlug, you whittle that down to a precious few. While I don't disagree with you, I also don't necessarily agree with alll the rare-earth theories. I do think that life if sufficiently rare that it would be a great leap to assume we will find intelligent life in the near or distant future. Just to put all questions at rest, I believe in a creation, and not every one the tenets of the currently accepted scientific notions regarding the formation of the universe. But I certainly do not dismiss them wholesale either.
      • I believe the point of the article is that most of those billion stars in the Milky Way are not hospitable to carbon based life. Therefore, you would need to only count the stars on the arms of the galaxy (like earth) and then apply your hypothesis.

        Aww man, you beat me to the punch. The other point of contention is his hypothesis is entirely wild. "lets say that a exact Earth analogs occur around one out of a billion stars". Bah, pick "one billion" just because it seems like a big number? Haha. It could just as well be orders of magnitudes off in either direction. One out of a million, then there could be 100 million Earths. One out of a trillion, then best-case, we're the only one.

        That's kind of the whole point of the Drake Equation [pbs.org], to give a better sense of just how far off those estimates are. And, best-case versus worst-case assumptions plugged into the Drake equation are still many orders of magnitude appart. Which means: we just don't know. And the article gives a little more pessimism to those estimates by asserting that R ("The number of suitable stars that form in our galaxy per year") could be much, much lower than most people think.

    • Re:Old news... (Score:5, Interesting)

      by Daniel Dvorkin ( 106857 ) on Tuesday May 28, 2002 @07:04PM (#3598545) Homepage Journal
      Guillermo Gonzalez is also well known as a proponent of "Intelligent Design," the pseudoscientific creationist idea that An Intelligent Designer (read "God") must have made our universe because everything in it is so perfect for human life. (Do a Google search on "Guillermo Gonzalez intelligent design" if you don't believe me.) It's not surprising that ID and Rare Earth-ism go hand in hand; if intelligent life is common in the universe, it makes it less likely that humanity is the product of a Divine Plan -- at least to the degree that the limited minds of ID'ers and other creationists seem to be able to conceive divinity.
      • Guillermo Gonzalez is also well known as a proponent of "Intelligent Design "
        From your later statements referencing "pseodo-science" and "the limited minds of ID'ers" I assume that you believe that Gonzalez's theories are somehow invalidated by this. Of course that is an ad hominem fallacy - his motivation is irrelevent to the validity of his argument. It is an interesting observation about Gonzalez's possible motivation in formulating the rare earth hypothesis but it says nothing at all about whether it's true or not. He may very well be quite wrong, but his reasoning (whatever his motivation to pursue it) seems sound and his argument is convincing. I'm sure there are very convincing counter-arguments but "he's a closet creationist" isn't one of them.

      • Re:Old news... (Score:5, Interesting)

        by IamLarryboy ( 176442 ) on Tuesday May 28, 2002 @11:24PM (#3599842)
        It has been my experience that creationists such as Guillermo Gonzalez can be divided into 3 catagories.

        1) Those that do not know any better. These people believe that God created the earth and everything on it in 6 days because that is what they have always been taught. They are largely ignorant and have no real interest in looking into the facts. These people can be found in almost any church.

        2) Those that believe that God created the earth in 6 days because that is what the bible says and that is good enough for them. These people are completely unwilling to even consider even the consider the possibility that they are wrong. Often they ignore sound science and instead rely on sudo science to try and convince otherse and themselves that they are right and everyone else is wrong. They ignore all contradictory evidence and are as unscientific as can be. Thse people do both thier faith and their theories a disservice. These people can also be found in most any church and are very vocal. Often people beleive that this group are the only proponants of Intelegent design or creationism. An example of this group can be found at www.icr.org

        3) Those that beleive that God created the earth and all life on earth but not neccisarily in 6 days(as we would know them). These people "assume" (they do not really assume rather these they rely on these "assumptions" based on other evidence and experiences) that both the scientific record and the bible are 100% correct. Therefore, there should be complete agreement between the two. If there is an aparent disagrement either the scientific record has been interpreted wrong OR the bible has been misinterpreted or mis translated. This group is generally willing to examine its theories for weakness and to modify its theories to better fit the available facts. This group is as scientific as any evolutionist group and if more creationists were like them perhaps they would not be seen in such a bad light. Unfortunalty, this group is rather small but growing. An example of this group can be found at reasons.org

        Likewise, evolutionists generally fall into one of three parallel groups.

        1) Those that do not know any better. These people believe that man evolved by natural processes because that is what they have always been taught. They are largely ignorant and have no real interest in looking into the facts. These people can be found almost anywhere.

        2) Those that belieleve in evolution because they are unwilling to consider even looking at any evidence that perhaps there is a god. They would rather blindly believe a theory with known problems than consider an alternative. They have evolution taught in schools as fact even though it is only a theory. They do not want children to be taught that some people do not agree with evolution. These people do both their "religion" (atheism/naturalism) and their theory a disservice. These people are very vocal and are just as unsientific as a creationist in group 2. They also can be found most anywhere.

        3) Those that believe in evolution (or some other naturalist theory) because they genuinly believe that it fits the facts. They are willing to look at alternative theories. They are also examine their theories for weekness and are willing to modify their theories to better fit the known facts. These people can be found inside the bona fide scientific community.

        It is a shame that there are so many group 1 & 2 people in this world.

        In conclusion, no theory is pseudoscientific. It only becomes sudoscience once it is conclusivly disproven yet is still passed off as scientific fact.

        • I'm a metallurgist, a computer programmer, and I spend a good bit of time reading about quantum physics, fractal geometry and astronomy becuase I like to. I'm also a fundamentalist Christian, and read and study the Bible, something else I also enjoy.

          I don't claim to understand the mind of God. I'm personally comfortable with the idea that the God I worship - the one that I believe to be an omnipotent, omnipowerful being that exists outside of time and space - had his own reasons for creating, in six days, a universe that looks and in all respects acts as if it were billions of years old. Why? Maybe to give us something to study for a few thousand years. Maybe just to give us something to look at and wonder about in the night sky. In any case, I'm happy to study science on one hand, and argue theology on the other, without feeling the overwhleming need to reconcile what I see as two fundamentally irreconcilable subjects (something both "creationists" and "evolutionists" seem to think is absolutely essential, for some reason.)

          • As LarryBoy noted, that would require that God lie.

            And while you may disagree, I'd rather not believe in a God than believe in a God that chooses to be deceptive in such a fashion.

            Of course, it doesn't reconcile some of the other issues with the Bible, but a large number of those issues are due to faulty translations/interpretations.
      • if intelligent life is common in the universe, it makes it less likely that humanity is the product of a Divine Plan

        Or maybe just that our existence is not the single most important element of said Divine Plan. Perhaps it's this possibility that's the most frightening. Everyone wants to be daddy's favorite child, and it's much easier when you're his only child.

      • Guillermo Gonzalez is also well known as a proponent of "Intelligent Design,"

        Heretic! Off with his head!

        It's not surprising that ID and Rare Earth-ism go hand in hand; if intelligent life is common in the universe, it makes it less likely that humanity is the product of a Divine Plan -- at least to the degree that the limited minds of ID'ers and other creationists seem to be able to conceive divinity.

        Indeed, it is no less surprising that the cyclical universe theory enjoys what can only be described as fanatical desperation on the part of atheist scientists. We can't have the universe being a singular event in time! It's hilarious to me that the evidence in this case supports Gonzales (we haven't seen ET yet), but those who hold forth the standard of pure evidence are capable of stepping outside of the evaluation of evidence to characterize the minds of their opponents as "weak" based purely on their own belief. (again - we haven't seen ET yet.)

      • The theory can be summed up like this: The universe has unimaginable numbers of galaxies with a huge number of stars in each - but there is only one earth with life on it, with man as the crown of creation. And the uniqueness of man proves the existence of god. Because if he had made a second or even more intellegent races somewhere out there, he would stop to exist. No, wait a second, that doesn't make sense...
    • Regardless, lets say that a exact Earth analogs occur around one out of a billion stars. That still leaves 100 Earth analogs in the Milky Way alone.

      Well, okay, let's assume that one out of a billion stars has an Earth like planet. Only about 1 out of 100 of those would be in what he considers a "habitable" zone of the galaxy. I've espoused on this several times here on Slashdot, and since I get to have my soapbox here, I'll do it again. Again I point to this [sciam.com] article, that I think makes excellent points about why there's no other "intelligent" life in this galaxy.

      I don't think that there's no other intelligent life out there, I just think that it averages 1 per galaxy tops. I think the chances of two intelligent species evolving in the same galaxy are incredibly slim, basically on the premise that, before a second species will have the opportunity, their planet will already be colonized.

      And as I'll say over and over again, I very well may be wrong, just as anyone else who espouses on this topic. Working with a statistical sample population of 1 (us), makes it very hard to put statistics, let alone facts, on any of this.

  • Rarity and coincidence (Score:3, Interesting)

    by ParticleGirl ( 197721 ) <{moc.liamg} {ta} {lriGelcitraPtodhsalS}> on Tuesday May 28, 2002 @05:43PM (#3597973) Journal
    The rationale for there being life elsewhere in the universe often goes like this:

    1. There's life here

    2. Well, we seem pretty normal and possible to me!

    3. The universe is a many-splendored thing. There must be other neat planets like this out there.

    4. Since we seen pretty easy to please, there must be life on those other planets!

    People don't realize that it actually works the other way around. If there was going to be intelligent life just one place, well, wherever it was would have the intelligent life! To rephrase: just because we're intelligent and here doesn't mean that there are other intelligent beings elsewhere. That we're intelligent and here means that we've got good conditions for that, here. We (the intelligent life) are here and not on another planet because this planet is uniquely suited to us. About the other potential places that could harbor life-- well, who knows? The universe may be inhospitable. It may be hospitable. The fact of the matter is that we've just managed to find out whether one of our nearest neighbors has water on it. What do we know of the rest of the galaxy, really?
    • Yes, you're asserting the anthropic principle, for which one interpretation is, "The parameters of the universe have consipired to support Human life if for no other reason than if they hadn't, we wouldn't be here to observe them."

      And the argument you're ignoring is the Copernican principle, "We are not unqiue". Assuming the opposite ("we are unique") got astronomers trying to show lots of dumb things (earth at the center of the universe, of the solar system, planetary epicycles, ...).

      So, at a minimum, given the history of science, if you want to show the Earth is unique in the galaxy or the universe, you have to go out and prove it, you can't assume or assert it.

    • What are the odds of intelligent life developing on a planet that has developed a stable biosphere of mega-cellular life? Evolutionary history shows that it was a number of dumb luck environmental factors that happened to line up around the right proto-primates that pushed them on the path towards tool-using sapience. Suffice it to say, it's probably not an everyday occurance.

      Now, if life of any kind is in fact an extreme rarity, to the point where this rock is the only one like it in the cosmos, how amazing is it that it also managed to develop intelligent life as well? If life were common as dirt but intelligence a rarity, then the fairly undeniable fact of our existence is reasonable; it was likely to happen somewhere. But for the coin to land on its edge in the one place in the universe where life existed is stupendous.

      A good analogy would be, what are the odds of someone winning the lottery (i.e., a planet developing intelligence) a) if a zillion people bought tickets (had life already) or b) if one person bought a single ticket? Neither is impossible, and the winner would still have his cash, but one is far, far more likely to be the case than the other.

      What do we know of the rest of the galaxy, really?

      Pretty much zilch. What say we go exploring! I hear Mars is nice this time of year...

  • Sure, for a civilization that is used to ~70 degree weather with nice ocean breezes, it's hard to imagine other life forms residing in these planets. But if we just open up our minds and realize there are living organisms thousands of feet beneath the ocean waves, a place where most scientists would call "less than hospitable", the chances of other life forms existing increase.

    Of course, if my girlfriend showed up to any of these places first, there is no chance any intelligent life forms are left.

    ---
    When you have nothing nice to say, post on slashdot...

  • The same was said of the bottom of the oceans (Score:4, Interesting)

    by DrMegaVolt ( 560884 ) on Tuesday May 28, 2002 @05:46PM (#3597997)
    ... until we went there. The quality of your presumptions weigh heavily in the strength of your hypotheses...

  • Douglas Adams Said it Best (Score:5, Funny)

    by stipe42 ( 305620 ) on Tuesday May 28, 2002 @05:50PM (#3598030)
    The Universe - some information to help you live in it.

    4. Population: None.

    It is known that there are an infinite number of worlds, simply because there in an infinite amount of space for them to be in. However, not every one of them is inhabited. Therefore, there must be a finite number of inhabited worlds. Any finite number divided by infinity is as near to nothing as makes no odds, so the average population of all the planets in the Universe can be said to be zero. From this it follows that the population of the entire universe is also zero, and any people you may meet from time to time are merely the products of a deranged imagination.

    (Douglas Adams, The Hitchhiker's Guide to the Galaxy)
  • All the arguments depend on our knowing how a planetary disk condenses. Yet we keep being surprised by extrasolar planets in sizes and orbits that nobody ever anticipated.

    There's a more subtle argument for the rarity of intelligent life. If it were common, then by now it would have rearranged the galaxy to make it more hospitable. Unless of course they're still trying to finish their environmental impact statement.

  • less hospitable to HUMANS (Score:4, Insightful)

    by jimmcq ( 88033 ) on Tuesday May 28, 2002 @06:01PM (#3598107) Journal
    Why does everybody always assume that life can only form in conditions that are hospitable to humans?

    Who's to say that there aren't other strange forms of life that have evolved to survive in conditions that would be downright hostile to humans?
    • The environment doesn't need to be hospitable to humans. But it probably needs to allow complex molecules to exist for life to form.
      In other words, extreme heat or radiation is probably a bad thing.
      On the other hand, to little of the aforementioned and chemical processes grinds to an halt. That is bad news for any life, no matter how strange.
      Furthermore the environment needs to be reasonably stable, that is, no sudden unpredictable changes (drastic but predictable changes might be ok)

      Anyway, even though this guy makes a few good points, I think he is overly pessimistic. The sheer number of possible locations for eart-like life to form is enough to convince me that it is out there somewhere.
      And probably lots of non-human like life too.
      But the environment has to mesure up to some baseline standard. If you breka up all organic molecules on regular intervals life will have a hard time getting anywhere...

    • Re:less hospitable to HUMANS (Score:4, Insightful)

      by barawn ( 25691 ) on Tuesday May 28, 2002 @07:24PM (#3598690) Homepage
      Because if you think about it, the life that we have (as humans) is, in many ways, analagous to a "minimum-energy solution" to a problem.

      Think about it. Life on Earth begins, fundamentally, with long carbon chains and water cycles. Why carbon? Carbon is the only element that can form arbitrarily long, stable chains. Silicon can form chains - but only short ones. Longer silicon chains break down. There are additional reasons for carbon later, too. Why water? Take a list of molecules, starting from the simplest you can make. That is, H2, LiH, etc. Many of these compounds won't exist, though. Keep going. Water will stick out like a sore thumb when you get to it - because it's the first strong dipole you'll come across that's covalently bonded. The covalence is important because in a liquid form, the molecules are still there, rather than just ions. Ammonia (NH3) is a dipole, but not of the same level as water is. So, a water solution provides literally TONS of bonding possibilities. Hydrogen bonds form all over the place, and you get extremely complex chemicals popping up everywhere.

      The basic requirements for life, in my opinion, would have to be the possibility for many, many combinations of molecules. That's what allows life to exist, really. So carbon/water based life suddenly becomes your 'minimum-energy' solution to generating life.

      The other reasoning here is that if you look at the basic life on Earth, the elements it uses are, well, a little bit "unique" on a stellar scale. The most important elements for life on Earth are undeniably carbon, hydrogen, nitrogen, and oxygen. Without a doubt, you could probably make living objects from just these few elements (probably really basic, but still life). Here's the kicker: hydrogen is the most abundant element in the Universe, and carbon, nitrogen, and oxygen are the elements produced in the second most common stellar nucleosynthesis event, the triple-alpha process (the pp chain is the most common: it turns 4 protons into 1 alpha particle). So flat out, you are NOT going to have carbon somewhere and NOT have water, not for stellar abundance reasons. Temperature-wise, it's possible, so in very bizarre temperature regions, you might get life - I will admit that - but I do consider it unlikely, since high temperature regions don't really allow for molecules to form easily. :)

      That being said, I want to note that I don't agree with the author here: I think he's being exceptionally restrictive. My opinion is all you really need for life is carbon and water. You probably also need nitrogen for variety, but as I've said, where there's carbon and water, you'll have nitrogen as well. Now, the 'livable for humans' bit: I honestly think that anyplace that has carbon, liquid water, and nitrogen could be made livable for humans. You need trace elements (iron, for instance, for hemoglobin), but in general humans recycle them - they don't get 'consumed' - so a well designed colony could probably survive by taking some small amount of trace elements along with them. But as for life developing THERE? I think with the above ingredients, they would find a solution that doesn't use a trace element that they don't have.

      It doesn't matter, really. We have one data point to play with, and we can do whatever we want with it. His instinct says "no life anywhere, it's really complex" my instinct says "life everywhere there's water and carbon: it has this 'knack' for showing up everywhere."
      • I think you are presupposing the existance of human life and showing why it is consistent with a carbon/water system. I don't think you've shown that human life is the minimum-energy solution to that system. It's a little like saying your ears and nose are arranged to support eyeglasses.
    • There are bacteria that live in volcanically-hot jets of water on the ocean floor, would burn a human to death in mere seconds. They thrive.
    • Even better, from the data points we've gathered so far, sentients are able to use tools to adapt their local environments to a state of total comfort. Hell, we have demonstrated the ability to survive in a vacuum, on the bottom of the ocean and on top of the antarctic glacier.

      Even if the Milky Way as a whole is inhospitable for microbes, plants and animals, sentient beings seem able to adapt any hostile environment and thrive in it, so even rare earths mean the possibility of life everywhere.

      Worst case, the population density is a lot lower than in Star Trek or Star Wars. Big deal. That means more real estate for us humans, and fewer non-extremovores trying to colonize Earth.

      I just wish we'd advance our space program a bit faster and set up Von Newmann probes or a permanent offworld base, so our eggs aren't all in one basket.
  • why do they all seem the same sometimes?

    Economist #1: "The economy is going to collapse this quarter!"

    Economist #2: "No! It's on an upswing, you idiot!"

    Dietician #1: "Balanced intake of carbs, protein, and fats is best."

    Dietician #2: "Uh, yeah, sure.. if you want to look like Rosanne. Max protein, don't worry about the fat, and cut down on the carbs."

    Space Scientist #1: "Thousands of life-giving planets are out there. We have the calculations right here. Really."

    Space Scientist #2: "Look, dude, the odds of there being other life-bearing planets are almost nil. We have the calculations right here. Really."

    I mean it in good humor, but as a layman it sure is difficult to tell which of the astronomers and other guessers are on the right track.

    • "Integrity is doing the right thing when nobody is watching you."

      Interesting thought:

      Most religions say to do the right thing because god is watching.

      I guess they assume that people have no integrity, and would never do the right thing when nobody is watching.
      • Of course!

        It's much easier when you're not the ultimate authority for your actions. If there's a source of absolution, ultimately anything is forgivable and you can be absolved of your sins. Of course, the definition of "sin" depends on your society's definition of such, so we're in that whole conundrum of whether all morals are simply conventions society places on individuals as a means of perpetuating the species.

        Believe it or not, that definition of integrity is something I picked up on during my training (in a former life) as an Army officer. Integrity was held (at least by my leadership instructors) as the most important characteristic of an officer. The logic was that if you could be trusted to take responsibility for your actions, you would ultimately take the initiative to ensure that such trust was well-placed.

        Does that mean that all military officers manifest such integrity at all times? :-) Doubtful. But it's a worthy goal to aspire to, I think.

  • What a crock (Score:4, Funny)

    by sharkey ( 16670 ) on Tuesday May 28, 2002 @06:02PM (#3598119)
    A Milky Way is quite hospitable. Leave one on your back porch. It'll be teeming with ant life pretty darn quick.
    • "A Milky Way is quite hospitable. Leave one on your back porch. It'll be teeming with ant life pretty darn quick."

      HAHAHAHAHAHAHAHAHAHA!!!
      HAHAHAHAHAHAHAHAHA!!

      --catching my breath--

      HAHAHAHAHAHAHAHAHAHAHA!!!

      Not the candy bar silly!!! HAHAHAHAHA!

  • Rare Earth (Score:2, Informative)

    by RedCard ( 302122 )

    If this article interests you, I highly suggest that you get (and read) a copy of "Rare Earth" by Ward and Brownlee, Copernicus press.

    In it, they lay out their case for why advanced life is rare in the universe, but simple life may be relatively common. The article that's linked to seems to be a condensed form of the argument set out in Rare Earth.

    Rare Earth goes over planetary habitable zones, galactic habitable zones, and also goes much further on about the necessity of a "benevolent" jupiter-like planet, planetary extinction events, and plate tectonics.

    I think this book was reviewed on slashdot, but I don't feel like looking it up. It's still one of my favourite books.

    BTW: it's not some crackpot theory, either. Ward and Brownlee are both professors at the University of Washington in Seattle and they site 26 pages of scientific references at the back of the book.

    --RC
  • the fact is that we are NOT out there exploring other planets, and that we do not know for a fact that ONLY earth types can support life. We also do NOT know for a fact that earth types are rare, we only suspect as we have no proof through observasion.

  • a galaxy full of germs (Score:5, Insightful)

    by bcrowell ( 177657 ) on Tuesday May 28, 2002 @06:06PM (#3598148) Homepage
    Unfortunately, popular articles, including this one, don't usually do a good job of making the distinction between unicellular and multicellular life. There's every reason to believe that unicellular life is common in our galaxy. Microbes are tough. They can survive and/or permanently adapt to extremes of temperature and chemistry. It's quite possible that even within our solar system, there is unicellular on three different bodies: Earth, Mars, and Europa. When the "rare earth" folks talk about the dangers to life, such as ionizing radiation and comet strikes, those are really more like hazards to multicellular life. An unknown, but probably very big, percentage of the earth's biomass consists of microbes living deep underground or underwater, where they're relatively invulnerable to these things.

    Multicellular life is a whole different story. It's a lot more delicate, and in our planet's geological history, it appears as an afterthought. Germs are and always have been the dominant form of life here.

    Sorry if you're in love with the Star Trek/Star Wars picture, but most likely if our species ever manages to send probes to the nearest 10,000 solar systems, all we'll find is unicellular life. I'll bet your great-great-great-great-great grandkids a six-pack on it!

    • Even a single-cell organism is "multi-bacteria". There are independent forms of the organals of a single cell.

      Something like a sponge is a multi-cell colony that has division of labour, sort of like a city. NS has stories about slugs that in their life fall into intependant cells.

      Ants and bees are multipart animals. Others hold things like trees are colonies of separate plants, with different branches being genetically different. So what is life?

      Life has a nasty habit of starting up anywhere, and given that it's rumoured that some bacteria come from space, where exactly in space *is* that...

    • (* Sorry if you're in love with the Star Trek/Star Wars picture, but most likely if our species ever manages to send probes to the nearest 10,000 solar systems, all we'll find is unicellular life. *)

      Don't you remember that "archeology" episode where Picard's crew found out that most of the humonoid life (Clingons, Romulans, etc.) were *planted* there by some ancient Johny Appleseed?

      If we don't find multicellular life, then simply plant some. A few Monica's here and a few Billy's there, and a few porno tapes and cigars to spark it all, and wazaaam!

    • Sorry if you're in love with the Star Trek/Star Wars picture, but most likely if our species ever manages to send probes to the nearest 10,000 solar systems, all we'll find is unicellular life. I'll bet your great-great-great-great-great grandkids a six-pack on it!

      First, I thought: How do we know that the /. archives of this article will even be readable when your great^5 grandkids are around - or any form of media we use today?

      Then, I thought: If my great^5 grandkids are reading /., I'm going to come back from the grave and smack the shit out of them.
  • Why do I care??? I DONT.

    Why not? Well, all this is just speculative "I thinks" by wannabe astrnomers. If they want us to think what they say is true, then prove it. Oh wait, they cant. They cant prove a negative.

    The main point is that these idiots are trying to get "popularity" by spreading crap. Next week we'll hear about 50% chance life is in next solar system...
  • Here we go...

    Think of the milky way as our "neighborhood". (or, "my network places" for you windows people). I may be slightly innacurate, but I'm nearly sure there are a few billion galaxies in the universe. Just because our neighborhood is a little trashy, doesn't mean the rest of the universe is. In our earth society terms, just as one town may be a slum the town next to it may be very hospitable.

    I base my belief in the existence of alien life on one fact: probability. The universe is far larger than our minds can comprehend... chances are pretty good that there is some life out there, and if you believe in god, than chances are pretty good that alien life can be a lot like us.

  • Gamma ray bursts and the Milky Way (Score:5, Informative)

    by jesterzog ( 189797 ) on Tuesday May 28, 2002 @06:20PM (#3598253) Journal

    Space.com reports that life in the universe may be more rare than previously thought

    I was recently reading up some more on gamma ray bursters, which are a recently discovered thing with explosions (so far only seen a very long way away) that appear to have an amount of energy equivalent to about the rest of the Universe put together.

    There was a paper [lanl.gov] published in 1999 that theoriesed that every gamma ray burst was a galactic scale mass extinction event, and then attempted to extrapolate a rate that they occur locally in the Milky Way, then going on to suggest that because the rate is slowing down, we might be in a transition period for intelligent life appearing. It's all entirely theoretical, but it's an interesting read.

    The good news is "at last we're here". The unfortunate bad news if the theory is correct is that because the last burst is somewhat overdue, we might not be here for much longer.

    For what it's worth, there's a hugely massive star (eta carinae) about 7,000 to 10,000 light years away that's arguably ready to blow some time in the next million years. (If you're in the southern hemisphere it's a really nice thing to look at with binocs or better.) It's on the fringes of the theoretical limits of how massive a star can be, it's gone past the theoretical limits of the maximum amount of light that a star can possibly emit, and it's been suggested as a possible source of a future gamma ray burst in the Milky Way. Really though, nobody's quite sure what's about to happen. On the other hand we should probably be hoping that we're not nearby when it decides to go.

    It's just another theory.

    • I was recently reading up some more on gamma ray bursters, which are a recently discovered thing with explosions (so far only seen a very long way away) that appear to have an amount of energy equivalent to about the rest of the Universe put together.

      Yes. Gamma-bursters are really the biggest bang since the Big Bang and if one was go off anywhere near the Milkyway we would be toast in a matter of milliseconds. But you're forgetting this: Until now we've only seen gamma-bursters really far away from us - which is the same as saying, that we've only seen gamma-bursters really long ago.

      And thats the point: So far we've only observed Gamma-bursters in young galaxies in the early stages of galaxy formation. Not in old galaxies like our own.

      • And thats the point: So far we've only observed Gamma-bursters in young galaxies in the early stages of galaxy formation. Not in old galaxies like our own.

        Yes you can argue that and it's very plausible that they might be a factor of a young Universe. I don't completely agree with the reasoning however, and there are other possibilities.

        Most notably there are so many more far-away galaxies than nearby galaxies. More recent estimations based on the hubble deep field have placed it at possibly 80 billion galaxies [faqs.org], or at least something on that order. Nearly all of them are an incredibly long way away from us.

        Even though there are lots of gamma ray bursters, it's no real surprise that any given event is likely to happen in a far away location from nearly every other point in the Universe. It's already been argued that gamma ray bursts have enough energy that it'll eventually be visible from everywhere no matter how far away it happens. The reason we're seeing so many of them is that we're (arguably) seeing about as far as it's possible to see.

        Under this scenario, it's completely possible that gamma ray bursts happen in older galaxies, too. The only reason we haven't seen them yet is because there aren't enough older galaxies nearby to have justified the probability of it happening while we're here to watch. In an estimated 80 billion galaxies, we're only detecting about one burst per day [nasa.gov], from an entirely random direction.

        If we are seeing every one that happens within these 80 billion galaxies, and if you figure it out on a calculator, a typical galaxy would average a gamma ray burst about every 220 million years... if it was a uniform distribution throughout the life of the Universe.

        Again, it's all theory.

    • If it is 7-10,000 light years away wouldnt that mean that if it went off then it would take at least that many years to get here? If thats the case then im not worried
    • (* that theoriesed that every gamma ray burst was a galactic scale mass extinction event.....For what it's worth, there's a hugely massive star (eta carinae) about 7,000 to 10,000 light years away that's arguably ready to blow some time in the next million years. *)

      I have read speculation that the peak gamma ray bursts tends to be *directional*, probably along the poles of the stars in question. If it happens to be pointing at you, you're toast, otherwise, it is survivable.

      That is why they look so strong even when they are far away. They used to assume that the output was uniform. However, less energy is needed if what we are seeing are simply happenstance pointings in our direction from way far off from these Giant Light-Sabers.

      God is playing Russian Roulette with the Unverse.

      Hmmmm, maybe we can tell whether or not a star's pole(s) are/will facing us by studying fluctation periods or something.

      BTW, ain't Beatlejuice due to go off soon? It is also really big.

      • I have read speculation that the peak gamma ray bursts tends to be *directional*, probably along the poles of the stars in question. If it happens to be pointing at you, you're toast, otherwise, it is survivable.

        You could easily be right, and I think I remember hearing a bit about that. It's hard to get reliable information at the moment because nobody even noticed them until a few years ago. (Within the last decade.) And nobody really has an idea of what they are, except that they're massively huge amounts of energy.

        BTW, ain't Beatlejuice due to go off soon? It is also really big.

        Betelgeuse is getting close to the end of its life and it's expected to go supernova in the next few million years (really big stars only live for tens or hundreds of millions of years, anyway), but it's nowhere near as unusual as eta Carinae. Check out the writeup here [tripod.com]:

        The brightening remains mysterious, however, because the star is thought to be very close to its "Eddington limit," where light exerts so much outward pressure that gravity is just barely able to hold the star together. So any further brightening should produce an outrush of material. But an expanding burst of gas--although still too small to be seen directly--would cool like gas rushing out of a spray can. The cooling would strengthen the star's infrared signal and turn down the ultraviolet. But the full STIS spectra showed just the opposite pattern.

        I guess that more or less demonstrates our present understanding of the Universe. :)

  • this has been discussed numerous times before.... its no biggy...
  • secret transmission to altair command hq stop 15:23:44 gst

    anti-galactic-awareness propaganda mission on terra proceeding swimmingly stop we recommend moving up invasion plans stop all possible intelligent resistance trapped in recursive slashdot thread posting stop sincerely urk!thwoopt-9328 stop ps sorry all your base meme definitely dead stop love to the child-pods fullstop

  • I think it's worth noting that people are merely arguing over how you compute the probability. It's not like it's gone down to zero.

    In fact, we can (almost) safely say that there is likely other intelligent life, since we know the probability is not zero, then the probability that exactly one planet produced intelligent life is really, really, small. Much lower than the probability that there are N such planets.

    Of course, the odds of every discovering (much less communicating) with such life given the distances and the time scales involved makes SETI seem highly quixotic.
  • That's why the really interesting stuff always happens in A Galaxy Far, Far Away.
  • don't you know he's a christian and creationist? It's safe to disregard anything he says.
    • So? He is entitled to his beliefs. If his beliefs automatically bias his research, then how is the research of the scientists with the opposite beliefs biased? In that case I will only believe the research of white male scientists in their mid thirties who like to fish, and play golf.

  • Old theory? (Score:2, Insightful)

    by the bluebrain ( 443451 )
    Beat me with a clue-stick and mod me down, but here's an idea which probably is decades old and has a nifty name:

    Space is rather inhomogeneous in this age. Matter and energy (well, yeah, essentially the same thing) is concentrated in points - stars and surrounding planets - and merrily radiating itself into the great heat sink which is the sky, and into oblivion. Life, as we understand it, but also how we may come to understand it in the future, thrives on the "interface", physically speaking simply slowing down flow of energy toward the heat sink by a very minute bit. For instance - all energy the human race uses is "old energy": either from the sun (food, oil, ...) or good old mother earth (geothermal, the fact that the earth isn't an ice planet, nuclear etc.). This interface is where "Things Happen" - where there is a source of energy on the one side, and a sink on the other. Within such a thin "biosphere", things at least have the possibility of becoming complex - as they have done on earth.
    Now my point is that there are plenty of other places even within the solar system where things have the potential for complexity, moreover steadily so over the millennia necessary for systems as complex as life to develop: the surface of the sun, the surfaces of the inner planets (the outer ones might be too cold), the moons of the gas giants, or the atmospheres of the gas giants themselves.
    So, especially if we include the surface of stars, there are at least as many places in the galaxy where life might occur as there are stars - even more, life we might be capable of recognising as such. Just don't expect SETI to pick up radio signals off the "surface" of stars - I think interference might prove to be a bit of a hindrance there. We might not have very much in common with the majority of conceivable forms of life out there, and thus little to communicate about, but we might at least discover it some day, and recognise it as life.

    Why this post? ... Just a counterpoint to the idea "life = water, carbon , median temperature ~ 20 deg. C, ozone layer against radiation, bla bla".

    I posit that "life (*may*) = some kind of building blocks, plus an energy differential of some kind."

  • So, so arrogant (Score:5, Funny)

    by Comrade Pikachu ( 467844 ) on Tuesday May 28, 2002 @07:09PM (#3598593) Homepage
    Doesn't that assume that the life forms will be something like us? Terry Bisson has a great perspective on this from his short story/play "They're Made Out of Meat":

    "They use the radio waves to talk, but the signals don't come from them. The signals come from machines."
    "So who made the machines? That's who we want to contact."
    "They made the machines. That's what I'm trying to tell you. Meat made the machines."
    "That's ridiculous. How can meat make a machine? You're asking me to believe in sentient meat."
    "I'm not asking you, I'm telling you. These creatures are the only sentient race in the sector and they're made out of meat."
    "Maybe they're like the Orfolei. You know, a carbon-based intelligence that goes through a meat stage."
    "Nope. They're born meat and they die meat. We studied them for several of their life spans, which didn't take too long. Do you have any idea the life span of meat?"
    "Spare me. Okay, maybe they're only part meat. You know, like the Weddilei. A meat head with an electron plasma brain inside."
    "Nope. We thought of that, since they do have meat heads like the Weddilei. But I told you, we probed them. They're meat all the way through."
    "No brain?"
    "Oh, there is a brain all right. It's just that the brain is made out of meat!"
    "So... what does the thinking?"
    "You're not understanding, are you? The brain does the thinking. The meat."
    "Thinking meat! You're asking me to believe in thinking meat!"
    "Yes, thinking meat! Conscious meat! Loving meat. Dreaming meat. The meat is the whole deal! Are you getting the picture?"
    "Omigod. You're serious then. They're made out of meat."
    "Finally, Yes. They are indeed made out meat. And they've been trying to get in touch with us for almost a hundred of their years."

    Read the rest here [setileague.org] (it's very short).
  • I've been complaining about how hard life is here for AGES!
  • For the life of me I can't find the story (I'm pretty sure it was on BBC) but I remember reading about the idea that there is not only solar inhabitable zones, (Places not too warm but not too cold, where earth is) but galactic inhabitable zones as well. The idea is that towards the center of the galaxy life can't arize because there's too much stellar activity and any potential planets are under a constant rain of radiation. Too far out and there's not enough heavy elements to support life.

    Does anybody have a URL for this?
  • I took an astronomy class in which the professor lectured on The Drake Equation. [activemind.com] It struck me as utterly rediculous, and seemed fraught with assumptions about 'life' that would likely have no basis in reality.

    The Drake Equation would make a great title for a science fiction book, though.

  • I see this time and again in scientists. They'll rate a planet by how much like earth it is, and the less like earth, the less likely it is to sustain life.

    I don't buy that. These scientists are still too brainwashed by myths of creation, as if God made living things and searched for a planet that He could stash them on. It seems much more likely that we evolved to best survive on earth. That life is a product of a planet, not simply a consumer that ended up there at the right place at the right time.

    I think it's very arrogant to believe all living things in the universe must be carbon based.

  • Gonzales doesn't justify his conclusions (Score:3, Interesting)

    by i1984 ( 530580 ) on Wednesday May 29, 2002 @02:49AM (#3600578)
    I haven't read any comments that point out one of the severe flaws in the implied logic of the article. Specifically, that Gonzales assumes these characteristics necessarily preclude the frequent formation of earth-like planets. The fact is, however, that such a leap of logic is unjustified. Such a claim requires more detailed explanation of how each of the identified conditions would interact with an actual solar system, down to the climate of the affected planets. We are frequently surprised both in Astronomy and on Earth by the huge impact of seemingly subtle details. The fact that this article offers few (zero) details and utterly lacks careful explorations of the interactions Gonzalez mentions, suggests that his conclusions cannot be taken as more than vague musings.

    It also strikes me that Gonzales may have decided what he wants to believe, and then went looking for justification. The only problem is, he didn't actually find that justification; he just found hints that he selectively presented to bolster his assumption. He says something to the effect of "the galaxy is a scary place, therefore Earth-like planets hardly ever form." That makes for an interesting conversation, but by itself is very far from convincing.

    Until we understand in great detail how planet forming processes & external factors interact, or can exlicitly look for extrasolar Earth-like planets, we can't disprove these assertions. That doesn't,however, mean we should assume, as Gonzales would like us to, that nice planets necessarily can't be common.

    There are, however, hints to believe Earth-like planets could be common. Distant solar systems are, for example, discovered regularly. Unfortunately we don't have the equipment to determine if classicly habitable planets exist in those solar systems. But if we assume the presence of solar systems indicates any likelihood of habitable planets, then there's a hint that habitable planets could be common. It's far from convincing, but no less so than the assertions in this article.

    (As an aside, Gonzalez also ignores the possibility that there may be certain areas of space that make Earth-like planets significantly more likely to form. For example, maybe in some parts of the outer edges of the galaxy one or two Earth like planet are the norm in one-star solar systems. The point is, we don't know and can't fairly assume either way.)
    • Popular science is often dumbed down to the max, and it is really difficult to say whether Gonzales' conclusions are really as unsubstantiated as they appear from the article.

      Just to point out some of the problems:

      1. bombardement by comets/meteorites: He argues that in dense environments, this would be much more serious. However, it has been more serious in the past (known from crater counts on moon). This has depopulated the inner solar system from comets/meteorites long ago. One could argue that dense environments would favour very fast depopulation out to large radii, followed by a much calmer environment than our own solar system. You really can't say anything without solid numerical simulations, which do not exist so far.
      2. spiral arms: according to current wisdom, the spiral arms represent a wave pattern moving with a different speed than the rotation of stars around the galactic centre. This implies that all stars in the galactik disk (including the Sun) cross the arms at regular intervals.
      3. star clusters most probably the Sun has formed in some kind of cluster as well. And while planet frequency in clusters is unknown, the frequency of binary stars is known to be high, although it was thought previously that the environment of massive stars could be hostile for binary star formation ...
  • Maybe unfit for Terran life? But we've never made contact with ANY sort of alien life-form. But I'm guessing for life to thrive in a condition far different from Earth, it will turn up to be far different from life as we know it.

    -Evan
  • The central region of the galaxy, he says, is far to cramped and chaotic to expect Earth-like planets to have much chance of developing and remaining stable. [... Oort cloud ...] Near the center of the galaxy, [...] close encounters between stars would gravitationally boot more of these comets into the inner reaches of a solar system, where the planets would be. Further, because there is a greater concentration of heavy elements -- carbon, iron and other stuff that weighs more than hydrogen and helium -- near the galactic center, Gonzalez said more comets and asteroids would probably develop.

    So what does this prove? We have two "facts" (we actually don't know, but Gonzales tries to prove something here), and Gonzales concludes that constantly a large number of comets and asteroids would rain down on planets, destroing all developing life. No, actually all earth like planets.

    Somebody else might conclude that most of those minor bodies would be send into the system very early on, and actually become part of the still young planets, while later there would be just as little (or even less) impacts from asteroids and comets on the planets as in our system.

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