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Biotech Science

When the Earth Was Purple 278

Posted by kdawson
from the how-violet-was-my-valley dept.
Ollabelle writes "It's always been a bit of a mystery why plants absorb red and blue light, reflecting green, when the sun emits the peak energy of the visible spectrum in the green. A new theory offers one possible answer: that the first chlorophyll-utilizing microbes evolved to exploit the red-and-blue light that older green-absorbing microbes didn't use, eventually out-competing them through greater efficiency and the rise of oxygen."
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When the Earth Was Purple

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  • by Bryan Ischo (893) * on Wednesday April 25, 2007 @03:39AM (#18867511) Homepage
    The article mentions that when looking for life elsewhere in the universe, "We should make sure we don't lock into ideas that are entirely centered on what we see on Earth", suggesting basically that we don't just look for green plants, but accept that plants on other planets could be any color.

    Duh.

    I can't understand people who think that to find life on other planets we have to look for conditions similar to Earth. All of the hubbub over liquid water seems so silly to me. We have *no idea* what life on other planets might be like. I think that the only thing to look for is patterns which we don't believe could occur in nature, suggesting that the anti-entropy force of life might be present.

    Anyway, I'm kind of a skeptic already, I don't think that looking for life outside our galaxy is particularly interesting or useful anyway, considering that the nearest life would be millions of years away by interstellar travel. Even if it's out there, we'll never meet it or communicate with it.
    • by timmarhy (659436) on Wednesday April 25, 2007 @03:44AM (#18867549)
      your just poo pooing other peoples assumptions while making your own in the same breath.
      • Re: (Score:2, Insightful)

        by BakaHoushi (786009)
        And isn't that what much of science is about? "His idea seems wacky. I can't believe it. Of course, I don't have much evidence to prove my ideas, either..." This is why there's a "hypothesis" stage in the scientific method: Because people tend to have guesses or ideas, even if there is no evidence to suggest a result. The difference is, in science, one accepts that their bias is just that: a bias, and that reality will not bend or warp itself to match up with a bias.

        In the case of the GP, he seems to feel t
    • by owlnation (858981) on Wednesday April 25, 2007 @03:48AM (#18867575)

      I can't understand people who think that to find life on other planets we have to look for conditions similar to Earth.
      I guess the simple reason is that people's imaginations have been constrained by TV budgets. Earthlike is cheaper to produce and design, being the reason why the aliens in ST TOS all kind of looked a bit Middle Eastern, and in ST TNG they all had funny foreheads.

      • Re: (Score:2, Interesting)

        by Rob Kaper (5960)
        Sci-fi is a bit broader than just Star Trek, although it is true that for obvious purposes humanoids are the primary choice of alien lifeform in most productions. Maybe that's one reason I liked Farscape so much, compared to other shows it definitely had a high amount of non-humanoid species.
      • by CarpetShark (865376) on Wednesday April 25, 2007 @06:49AM (#18868387)

        I guess the simple reason is that people's imaginations have been constrained by TV budgets.


        Nope. Other shows have tried weird looking aliens. Adults seem to treat them like kids' shows, and lose interest. The thing is... most sci-fi isn't about science or aliens at all; they're just re-tellings of old human stories; those alien stories are just modern versions of ghost/demon/knight stories from millenia ago, that humans find appealing.

        The problem is just that most of us simply CAN'T imagine life from other worlds.
        • That's why I like what I've read (His Master's Voice, Solaris) of Lem's work. He admits that what we encounter "out there" is likely to be largely incomprehensible, and surely won't be able to be just rephrased as another human story.
    • by smilindog2000 (907665) <bill@billrocks.org> on Wednesday April 25, 2007 @03:57AM (#18867601) Homepage
      I agree. I sometimes wonder if there could even be upside-down life under us, at the interface of liquid vs solid rock. What would such life forms think the universe was like? Too bad there's no such evidence in lava-rock :-)
      • Re: (Score:3, Interesting)

        Hey, have you read Thomas Gold's book, THE DEEP BIOSPHERE? He believed that there are micro-organisms; just as you've described, living all through the Earth's crust, that excrete hydrocarbons and thus are the source of natural gas and petroleum. Thus there never was or will be "peak oil"; we'll never run out of "fossil" fuels because they're always being replenished.
        • Re: (Score:3, Insightful)

          by DerekLyons (302214)

          Hey, have you read Thomas Gold's book, THE DEEP BIOSPHERE? He believed that there are micro-organisms; just as you've described, living all through the Earth's crust, that excrete hydrocarbons and thus are the source of natural gas and petroleum. Thus there never was or will be "peak oil"; we'll never run out of "fossil" fuels because they're always being replenished.

          Among other things, Thomas Gold also was convinced that the surface of the moon was a thin fragile crust over deep dust - and that the Apollo

    • Re: (Score:3, Informative)

      Anyway, I'm kind of a skeptic already, I don't think that looking for life outside our galaxy is particularly interesting or useful anyway, considering that the nearest life would be millions of years away by interstellar travel. Even if it's out there, we'll never meet it or communicate with it.

      Who said we were looking for life outside our galaxy?

      We are still on the "looking for life outside our solar system (but inside our galaxy)" stage. We're not even certain that there isn't other life in our solar system, even if it is only bacteria or moulds.

      • What do you mean "only" bacteria or moulds? You're talking about the dominant life on our planet!

        At least in Hollywood, anyhow. Or maybe it's lawn grass, not sure. Which has the better publicity?

    • by Flying pig (925874) on Wednesday April 25, 2007 @04:06AM (#18867651)
      I belive that one reason is that scientists are still trying to defeat, with evidence and reason, the religious fundamentalists who believe we are the only "intelligent" life in the Universe, and on the only planet that supports life. On this argument, which I personally doubt, conclusive evidence that life existed elsewhere in the universe and could make itself known would cause the collapse of fundamentalist religions, to the enormous benefit of the rest of us.

      I don't buy into it because (a) these people aren't rational and (b) taking away their religion could make them worse - they could easily be converted into Stalinists or extreme nationalists. But I am sure that this, as well as the desire to get budget for exploration, is one of the factors in the search for life on Mars, and in SETI.

      Finally, looking for water is not irrelevant. Any practical life form is going to need a solvent and carrier for the various chemicals it needs to get from place to place internally. Water is unique because its strong hydrogen bonding gives it a wide liquid temperature range. Other small molecules which are good solvents also tend to have very low boiling points, meaning that the range of reactions that can take place in them is much more limited. Water has very unusual properties, in fact, that make it more probable that life would evolve on a planet with lots of liquid water than, say, one covered in methane or liquid carbon dioxide.

      • by asninn (1071320)

        I don't buy into it because (a) these people aren't rational and (b) taking away their religion could make them worse - they could easily be converted into Stalinists or extreme nationalists.

        Or, as the case may be, extreme earthists (to coin a new term).

      • by ptaff (165113)

        conclusive evidence that life existed elsewhere in the universe and could make itself known would cause the collapse of fundamentalist religions, to the enormous benefit of the rest of us

        I don't argue that the fundamentalist religion collapse would greatly improve mankind's quality of life.

        But look at the conclusive evidence showing evolution, dismissed by the fundamentalists.

        I really don't believe extraterrestrial light footprints showing presence of life molecules, or even radio communication would

      • by dkf (304284)

        Water has very unusual properties, in fact, that make it more probable that life would evolve on a planet with lots of liquid water than, say, one covered in methane or liquid carbon dioxide.

        Although we believe that to be true, we do not know for sure. We've far too little data in this area to draw any real conclusions yet. Not that I know any way to know when we might have enough; it would require study of a significant fraction of the galaxy for us to start to get some idea of what the real conditions for

        • Re: (Score:3, Informative)

          by GospelHead821 (466923)
          We haven't observed much life, but we do know quite a bit about chemistry. There is good reason to believe that the complexity of life requires delicate chemistry which can be conducted easily in water. This is one of the prime arguments I've heard against silicon-based life, for example. The molecules are too fragile to form chemical constructs analogous to those found in carbon-based life. Likewise, life that does not use water as a solvent would have to overcome some very basic chemical obstacles to
    • by Rob Kaper (5960) on Wednesday April 25, 2007 @04:06AM (#18867655) Homepage

      I can't understand people who think that to find life on other planets we have to look for conditions similar to Earth. All of the hubbub over liquid water seems so silly to me.


      It would be silly to exclude conditions not similar to Earth alltogether, but it is definitely reasonable to focus on conditions that are similar. Other conditions could qualify but that's pure speculation, for the conditions we live in we actually have a proof of concept. I'll take the refined "it works here, so why not elsewhere" over "anything could work" any day.

      Your idea of looking for non-natural patterns is interesting but note that it would very much limit search results to life so intelligent that like ourselves we would consider it above natural. You wouldn't find any microbes on Europe because in our frame of reference they too would be very natural.
      • by Bryan Ischo (893) *
        Those are very good points.

        I think that with respect to your last comment, I think that at a certain level of detail in observation (meaning, once our ability to examine another planet outside our solar system becomes good enough), we'll be able to see even non-intelligent life forms on other planets, just as I would expect that from a far distance, if you could see Earth well enough, you'd be able to see the algae in the oceans (or infer them from other observations), or the forests on the continents.
      • Re: (Score:3, Interesting)

        by rackrent (160690)

        It would be silly to exclude conditions not similar to Earth alltogether, but it is definitely reasonable to focus on conditions that are similar

        While I agree it's arrogant presumption to assume that all "life" must rely on liquid water and similar to life on earth...it's all that we know about and hence, all we have the skills on which to focus. So yes, I agree. We have a decent set of tools to look for life forms that resemble ours, and that's all we have in our toolbox at present. It's natural to cont

      • by at_18 (224304) on Wednesday April 25, 2007 @06:51AM (#18868405) Journal
        Your idea of looking for non-natural patterns is interesting but note that it would very much limit search results to life so intelligent that like ourselves we would consider it above natural.

        Non-natural patters wouldn't be some grid-shaped city. The basic non-natural pattern you can get is chemical non-equilibrium: if let alone, all the Earth oxygen would combine with some rocks and disappear. The presence of oxygen in the Earth atmosphere is a condition far from chemical equilibrium, and inequivocable proof that *something* keeps throwing the chemical balance out.
    • by ResidntGeek (772730) on Wednesday April 25, 2007 @04:09AM (#18867671) Journal
      Looking for liquid water isn't just human arrogance. Water is an effective and stable polar solvent, and there aren't many chemical processes as widely applicable as hydrolysis. In addition, the presence of liquid water indicates temperatures cool enough to allow organic molecules to stay stable, but warm enough to undergo the reactions necessary for life. These things are true throughout the universe, not just here.
      • Re: (Score:3, Interesting)

        by Bryan Ischo (893) *
        I think you're making my point for me. Why does life have to based on processes similar to our own, using chemicals similar to our own, at temperatures similar to Earth? Why can't some substance that is gaseous in Earth conditions be liquid in a colder planet's conditions, and combined with other substances which have different properties than they would on Earth under that planet's conditions, be able to support chemical structures and reactions of a different kind of life?

        Sure, at Earth's temperatures a
        • by ResidntGeek (772730) on Wednesday April 25, 2007 @04:31AM (#18867795) Journal
          The problem boils down to carbon. Of all the elements on the periodic table, there is one (1) which acts like carbon. Other molecules like nitrogen and silicon can form long chains and rings like carbon, but they don't like it. Carbon _loves_ forming itself into complicated molecules that cooperate to reproduce. There might be some non-carbon-based form of life out there, but it's very unlikely, and even if it does exist wouldn't easily evolve to macroscopic scales. It's just so unlikely there's no point looking for it.

          Once you accept that life is carbon-based, the rest follows. All we know about organic chemistry, and the temperatures and conditions it requires for optimum function, apply everywhere. Heat that breaks down carbon chains and makes life unlivable in the lab makes life unlivable on a planet orbiting too close to its sun, too. Water, which is pretty much the ultimate solvent here, allowing acid-base chemistry to exist, hydrolysis and dehydration synthesis to take place, protein microdomains to move diffusively.... it all happens on other planets too. While we shouldn't look for pretty blue centaurs with eye stalks or humans with funny ears, carbon-based life is a pretty good bet fi we're looking for anything.
        • Agreed. It sounded good, until his use of the phrase "necessary for life", at which point the whole thing fell apart.
    • by rucs_hack (784150) on Wednesday April 25, 2007 @04:13AM (#18867705)
      I can't understand people who think that to find life on other planets we have to look for conditions similar to Earth. All of the hubbub over liquid water seems so silly to me. We have *no idea* what life on other planets might be like. I think that the only thing to look for is patterns which we don't believe could occur in nature, suggesting that the anti-entropy force of life might be present.

      That idea comes from the time before we started realising that the nutty Gia concept (of the earth as a living entity) was actually a hypothesis with more than a little proof to back it up. I'd go so far as to say it's a theory.

      Thing is, no matter how far down we drill, we still find life, and no matter how cold or hot or dangerous (to us) an environ we find, there is always life there.

      It's taken a long time for this realisation to permeate through the wider scientific community, and it's a long way from becoming accepted fact for the general public.

      Anyway, I'm kind of a skeptic already, I don't think that looking for life outside our galaxy is particularly interesting or useful anyway, considering that the nearest life would be millions of years away by interstellar travel. Even if it's out there, we'll never meet it or communicate with it.

      Given how many planets exist in our galaxy that are already inconceivably far away, including this new wet planet just 20 light years away (or 4 billion years travel time away at current technology levels that are capable of carrying people), you're right, inter galactic travel is something we shouldn't waste time thinking about.

      Even if we did manage to find a way to do it, we could do little more then explore the minutest fraction of another galaxy. It would be pointless for all but a minority of pioneers willing to take the risk.

      The problem with travel methods that let you go huge distances (wormholes, whatever, jolly fast stuff anyhow) is that they miss all the stuff between you and your destination. That is not the way true exploration works, likely we'd miss lots of interesting things.
      • by tttonyyy (726776)

        The problem with travel methods that let you go huge distances (wormholes, whatever, jolly fast stuff anyhow) is that they miss all the stuff between you and your destination.

        Not to mention stretching you out to a few atoms thick during acceleration. :)

        One day when our conciousness is uploadable to machines, then long distance travel might become possible. Transporting about these Earth-dependant squishy bags of meat is a little pointless - even if we survive the hard-radiation/fast moving debris in space, the native fauna/bacteria/viruses might just finish us off when we get there. I've read War of the Worlds, make sense the other way round too (us as the invaders).

        Assuming,

      • Re: (Score:3, Interesting)

        by Oligonicella (659917)
        "...that the nutty Gia concept (of the earth as a living entity) was actually a hypothesis with more than a little proof to back it up."

        It's the 'acting like a single organism' thing that people don't grab. Me either. I just don't find that more than a little proof. Or any, for that matter. Kindly cite.
    • by emj (15659) on Wednesday April 25, 2007 @05:32AM (#18868009) Homepage Journal

      I think that the only thing to look for is patterns which we don't believe could occur in nature
      Like life?
    • I agree for the most part, except the part about liquid water. Yes, methane or ammonia could also be the enabling solvents for life, and they (the scientists) are aware of this. However, for various reasons water is still the best candidate for said solvent and is quite abundant. Part of the reason is temperature; ammonia and methane are liquid at very low temperatures which has implications about the amount of energy available for life.

      Life *as we know it* is the term they often use. Carbon based life.
    • by thePig (964303)

      Anyway, I'm kind of a skeptic already, I don't think that looking for life outside our galaxy is particularly interesting or useful anyway, considering that the nearest life would be millions of years away by interstellar travel. Even if it's out there, we'll never meet it or communicate with it.

      Not quite. If we were to embark on a journey that long, it would mean we are able to achieve speeds close to c. Now, at that speed, time dilation would really show it's effects. This would mean that even if the distance is millions of light years the traveller might not feel the age. i.e. even if it is millions of light years, the traveller might age in decades/years/months ??

      This means our species would still go on, albeit at a long distance and time away.
      And, I believe that is reason enough to be both in

    • I think that the only thing to look for is patterns which we don't believe could occur in nature.

      Because if you want to understand a process, and you have a fully functional model which uses that process right in front of your eyes, the smart play is to completely ignore that model, right?

      I don't think that looking for life outside our galaxy is particularly interesting or useful anyway, considering that the nearest life would be millions of years away by interstellar travel. Even if it's out there, we'll n
    • by Yvanhoe (564877)
      I can't understand people who think that to find life on other planets we have to look for conditions similar to Earth. All of the hubbub over liquid water seems so silly to me.

      While I agree with you about the main argument, I would like to make a case for liquid water. First, we are looking for carbon-based life. Why ? Because carbon-based chemistry (dubbed organic chemistry) provides an array of possible molecules that is larger than any other element. It allows the most complex strutures and arbitrari
    • First, life occurs in nature. Second, it doesn't have anything to do with anti-entropy.
    • Re: (Score:3, Interesting)

      by Atzanteol (99067)

      I can't understand people who think that to find life on other planets we have to look for conditions similar to Earth.

      I don't think it's that difficult to understand. After all, we *know* that an "Earth-like planet" can sustain life (we have one great example). Why not look for similar planets to see if they do as well? As far as we know it's our best bet. There are a lot of planets to be found, you need to narrow the search somehow...

    • Re: (Score:2, Offtopic)

      by shokk (187512)
      You're looking at it all wrong. We're not really looking for other star races to join in a galactic alliance. We're looking for a new home in the hopes that we won't all be extinct before we've developed the technology to leap to other stars. Ironically, it is the development of this tech that will make this, our first home, the polluted cesspool that no one will want to live on. May God have mercy on any inhabitants of that planet once we get there.
    • by *weasel (174362)

      I can't understand people who think that to find life on other planets we have to look for conditions similar to Earth. All of the hubbub over liquid water seems so silly to me.

      Makes perfect sense to me.

      Liquid water makes a destination quite a bit more useful to us. As you note, intelligent alien life (likely even multicellular life in general) is likely to be very far away. So why shouldn't our early space colonization and exploration efforts be pursued with human needs in mind?

      If alien life happens to e

    • can't understand people who think that to find life on other planets we have to look for conditions similar to Earth. All of the hubbub over liquid water seems so silly to me. We have *no idea* what life on other planets might be like. I think that the only thing to look for is patterns which we don't believe could occur in nature, suggesting that the anti-entropy force of life might be present.

      Please, remind me to *not* hire you as my interplanetary life search scientist. Or chief logic-tition, or finde
    • "All of the hubbub over liquid water seems so silly to me."

      The focus on liquid water is because it is the simplest and one of the most common mediums in the universe that can promote chemical reactions. You can't develop life if molecules can't interact and you need a medium that doesn't directly chemically interfere and can keep things in suspension.
    • Re: (Score:3, Insightful)

      by shaka999 (335100)
      "I can't understand people who think that to find life on other planets we have to look for conditions similar to Earth. All of the hubbub over liquid water seems so silly to me. We have *no idea* what life on other planets might be like. I think that the only thing to look for is patterns which we don't believe could occur in nature, suggesting that the anti-entropy force of life might be present."

      With limited budgets it only makes sense to look for life on Earth-like planets. We KNOW life can exist on an
  • by emj (15659) on Wednesday April 25, 2007 @04:01AM (#18867623) Homepage Journal
    Green is the new purple [penny-arcade.com], completly off topic but a scary resemblance.
  • How about (Score:4, Insightful)

    by Colin Smith (2679) on Wednesday April 25, 2007 @04:07AM (#18867659)
    Specific wavelengths of light are required to kick the electrons in specific molecules into the required energy level... i.e. Plants are green because red & blue light is required for a successful sequence of highly specific chemical reactions.

    It has nothing to do with total levels of energy absorbed from the sun, but the energy produced by the chemical reaction which is triggered by photons. Or, plants are powered by chemicals, not by heat.

     
    • Re: (Score:2, Funny)

      by heinousjay (683506)
      Your chemistry skills are astonishing. I bet you get all the girls.
    • by Flying pig (925874) on Wednesday April 25, 2007 @04:20AM (#18867733)
      Actually, photosynthesis is a complex process involving not one but two photons and some clever quantum effects. You have it exactly the wrong way round. Plants are (usually) green because they have evolved a process which uses two frequency bands of light. Such a mechanism would not have evolved unless either:

      The original form of photosynthesis resulted in a different metabolic pathway which used red or blue light and evolution took care of the rest

      There were some conditions on the Earth at that time which meant that only red and blue light was available at the intensities required.

      There are many possibilities why this might be so, including the nature of the media in which the first synthesising bacteria lived. I suspect the explanation when it is eventually found will be very interesting. However, it is by no means obvious that there is not a much simpler photosynthetic pathway using a single photon absorbtion, and it did not evolve simply because the conditions at the time - the predominant biochemistry of the bacteria and the wavelengths of light falling on them - were not suitable.

      • by Colin Smith (2679)

        and some clever quantum effects.

        All chemical processes involve some clever quantum effects.

        Such a mechanism would not have evolved unless either:

        Or C. The existing blue & red process produces more total energy for the same input than other processes.

        However, it is by no means obvious that there is not a much simpler photosynthetic pathway using a single photon absorbtion, and it did not evolve simply because the conditions at the time - the predominant biochemistry of the bacteria and the wavelengths of light falling on them - were not suitable.

        You seem to be assuming that evolution has in some way stopped. If the pathway you suggest was significantly better, more energy producing then surely there's a pretty good chance that there would be some plants/bacteria out there using it and they should in theory be more successful than the existing green ones.

        • And I was being careless. It is indeed entirely possible that the blue + red reaction is needed to get enough energy, and that perhaps it is a derivative of an earlier blue-only process. The comment on the Register article is interesting - that there are more red photons in sunlight than other types. That means that the yield of a blue + red process could be higher than, say, a yellow + yellow process, because the higher incidence of red photons would make it more probable that the scond step would occur gi
    • Re:How about (Score:5, Insightful)

      by daniel23 (605413) on Wednesday April 25, 2007 @04:27AM (#18867761)
      Your argument, put another way, reads: since plants use chlorophyll and that specific molecule requires energy levels corresponding to red & blue light, things are required to be like they are. This is almost tautologic. The more interesting question would be, why something like chlorophyll evolved to power plants, instead of reactions with a potentially higher gain
      • by Colin Smith (2679)

        This is almost tautologic.

        Almost. Except my argument is that it's the energy production of the specific chemical process which produces the most energy for the plant rather than the amount of energy shining down on the plant.

        i.e.
        It's my argument that chlorophyll produces more energy for less effort than entirely different chemical processes which make use of more abundant wavelengths. Basically, plants are chemical factories which require specific compounds and processes to function, they're not heat engines which can use arbitrary

      • by autophile (640621)

        The more interesting question would be, why something like chlorophyll evolved to power plants, instead of reactions with a potentially higher gain

        Like nuclear fusion!

        Sorry.

        --Rob

    • I'd think there is nothing magical about the frequencies of light being used but it is more of a matter of those are the requencies that happened to work with early protective pigments. Maybe the blues needed to be absoarbed for protective reasons and the energy from that absoarption started to get channeled into a photosynthetic processes.
  • Old news (Score:2, Funny)

    by Timesprout (579035)
    After watching Barney the Dinasoaur I think we were all able to infer that the earth was purple at some point in history.
  • by therufus (677843)
    This is proof that the artist formerly known as the artist formerly known as Prince has been here on earth since the dawn of time!
    • by Vengeance (46019)
      And who ever knew that Jimi Hendrix was actually looking back through time?
      • "Purple scum, in the pond"
        "Lately the spectrum doesn't seem the same"
        "I feel funny, and I don't know why"
        "Excuse me while you turn green and I die..."
    • by njfuzzy (734116)
      In the beginning God made the sea

      But on the 7th day he made me

      He was tryin' to rest y'all when He heard the sound

      Sound like a guitar cold gettin' down

      I tried to bust a high note, but I bust a string

      My God was worried 'til he heard me sing

      My name is Prince and I am funky

      My name is Prince
        the one and only
      hurt me!
  • Red sun (Score:3, Funny)

    by flyingfsck (986395) on Wednesday April 25, 2007 @04:41AM (#18867827)
    Plants originated on a planet where the sun was a different colour (http://news.bbc.co.uk/2/hi/science/nature/6589157 .stm) and the hairdressers and telephone cleaners who colonized earth brought them here...
  • I'm no scientist, so can somebody please explain the relationship between TFA and the article described here:

    Plants may be red and yellow in galactic boonies [theregister.co.uk]

    Frankly, the colour green was easier to understand when I didn't think about it...
  • by aapold (753705) on Wednesday April 25, 2007 @06:12AM (#18868167) Homepage Journal
    All the plants were split into two camps, Green! and Purple! They fought until there was only one kind left.
  • This theory has been around for ages. Is the recent discussion of this because of a new development? I don't see it anywhere.
  • Wrong! (Score:5, Informative)

    by bananaendian (928499) on Wednesday April 25, 2007 @06:58AM (#18868467) Homepage Journal

    It's always been a bit of a mystery why plants absorb red and blue light, reflecting green, when the sun emits the peak energy of the visible spectrum in the green

    No, it doesn't!
    - Solar irradiance at sealevel [newport.com]
    - Absorption-spectrum [uic.edu]

    Solar irradiance at sealevel 'peaks' at 470nm which is exactly where chlorophyl-B absorption peaks. In fact the 'peaking', when put into context, is somewhat vague, since throughout the whole visible spectrum from 400nm - 700nm you have well over 50% of the real watts that you get at the peak 470nm, so an adaptation to a particular wavelenght within it gives at most only a conservative if not marginal advantage.

  • The plants are green because of intelligent painting. The Intelligent Painter, (you know who, but who shall remain nameless due to legal reasons, wink, wink) said I give you green plants for food. [bible.cc]. This unwarranted attack on religion by science is totally unwarranted. Here we are, with a perfectly good explanation of why plants are green. And out of nowhere these scientists come and explain it all in a logical and credible manner. Our God of the Gaps, oops sorry The Intelligent Painter is now diminished by
    • by woolio (927141)
      I just figured that the "intelligent painter" had a monopoly on this section of the universe and decided to paint plants green. It's not like he has much competition...

      Or perhaps he owns patents on many other plant colors. The first green algae/plants were the only ones not smited out of existence.
  • by JayBees (124568) on Wednesday April 25, 2007 @07:59AM (#18868989)
    It's pretty obvious once you know the argument. It's due to light-scattering. There's so much energy in the sky all day that it doesn't matter what color you absorb, there's plenty at any visible wavelength. But during sunset and sunrise there's predominantly red light in the sky, and a green plant would be more efficient at absorbing red light (they're complementary colors) than if the plant were another color. This blog entry goes into it:

    http://blog.myspace.com/index.cfm?fuseaction=blog. view&FriendID=187945&blogMonth=9&blogDay=24&blogYe ar=2006 [myspace.com]

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