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Earth May Harbor a Shadow Biosphere of Alien Life
An anonymous reader sends us to Cosmos Magazine for a speculative article arguing that a 'shadow biosphere' may exist on Earth, unrelated to life as we know it. If such non-carbon-based life were found here at home, it would alter the odds for how common life is elsewhere in the universe, astrobiologists say. "The tools and experiments researchers use to look for new forms of life — such as those on missions to Mars — would not detect biochemistries different from our own, making it easy for scientists to miss alien life, even if [it] was under their noses. ... Scientists are looking in places where life isn't expected — for example, in areas of extreme heat, cold, salt, radiation, dryness, or contaminated streams and rivers. [One researcher] is particularly interested in places that are heavily contaminated with arsenic, which, he suggests, might support forms of life that use arsenic the way life as we know it uses phosphorus."
Not an expert in biology, but unless these contaminated areas have been contaminated for a very long time (read tens of thousands of years), and are quite large, the chances for life to have sprung up seem very, very slim. Current life needed millions of years to gain a firm foothold and start building up complexity. Lucky meteorites aside, starting from zero is bound to be hard.
If the experiment succeeds (here or elsewhere), and something "life-ish" is found, the results will still be tricky to classify. Can a given chemistry lead to increasing complexity, or is it just a dead end? Without hindsight, this seems like a very difficult question.
You both have a point. The question is, where do you draw the line at what is life? Rocks may not have DNA or intelligence, but they do form, change, multiply and there's a recognisable process for destroying them. In a sense, rocks are a lot like the most basic forms of life that ever formed.
Let's be a little more serious now. Rocks around here probably won't ever advance beyond mimicking some very shaky comparisons to the most basic forms of life. But that doesn't stop us wondering if we're just seeing it on too small a scale to make that judgment. Perhaps it's safer to treat rocks as a failed attempt at life, one that happens too slowly to ever get beyond basic chemical reactions and simple molecular structures.
If it weren't for carbon-based life, who knows?
http://www.newscientist.com/article/mg19826533.600-early-life-could-have-relied-on-arsenic-dna.html tried looking up some examples of non carbon based life on earth that I'd heard of but couldn't find any however the ecology of undersea volcanic vents pretty much threw most ideas about heat tolerance and toxins being a problem out of the window.
Build a Man a Fire, and He'll Be Warm for a Day. Set a Man on Fire, and He'll Be Warm for the Rest of His Life.
You both have a point. The question is, where do you draw the line at what is life? Rocks may not have DNA or intelligence, but they do form, change, multiply and there's a recognisable process for destroying them.
Rocks do not have gaseous exchange (breathing) nor reproduce (cracking a rock to make two is _not_ reprodction). However, there is no definition of life that fire cannot meet, which the mule can. In other words, any non-contrived definition of life that includes the mule must also include fire. Here is a very basic explanation: http://simple.wikipedia.org/wiki/Life
It is dangerous to be right when the government is wrong.
we're just seeing it on too small a scale to make that judgment.
specially time-scale.
perhaps they are intelligent, but if you talk to it for days, it can be just a split-second for the rock; and if the rock want's to tell you something, it won't finish the first word before you die of old age (or boredom).
tolkien's ents come to mind..
factor 966971: 966971
You can form chains or rings of around 6 sulphurs (with oxygen), but carbon can be found in chains of 30+ atoms and in multiple ring systems.
It's very difficult to grasp how large the isomer spaces are - and how quickly they grow, but a recent guestimate I made was that if a program (molgen) can enumerate all possible C10H16 molecules in 2 seconds, and all C13H22 in 2 minutes, then it would take 2 days for C18H36 and 1 billion years for C36H72...
Also, there are 25,000 C10s and 9 million C15s. So the sheer number of possible carbon compounds argues that carbon is the only likely candidate.
As the Zen practicioners are indistinguishable from day-dreamers such as my 9 year old son, your refutiation is meaningless.
Not really. They've studied the brains of Zen practitioners in meditation and have determined that Zen meditation actually increases brainwave significantly -- more so than even normal daydreaming.
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Neutral is what doesn't dissolve you.:) It is not neccessarily aqueous pH7 for everything.
The most likely alternate chemistry for life though, is carbon based, but using ammonia instead of water. At above about 70 psi, and somewhere below zero celsius it has a liquid range and chemistry similar to water. Given a larger, colder planet than earth with a thick atmosphere, life in liquid ammonia is the most probable option.
I'm guessing that wasn't on their radar screen...
There is an excellent book by Alexander Graham Cairns-Smith called "Seven Clues to the Origin of Life" that talks about such self-replicating clay
The main feature of his argument is that the clay surfaces could serve as templates for catalysis of polynucleotides (RNA, probably). These, then would form the first RNA world.
He uses the metaphor of a rope, where no strand goes from one end to the other - the rope is time, and strands within it are clayworld, rna world, dna world...
I didn't find it on Google, but about 30 years ago I read an account of a creature like a giant sand dollar that was dislodged from the deep ocean by an undersea earthquake. I can't verify it until I find a reference, but I recall that the scientist examining it found that it was largely silicon, hydrogen, and sulphur (and decayed rapidly giving off H2S). His theory was that it was silicon based life - and that its chemistry required deep ocean temperature and pressure to remain stable. (Note that there are carbon based ocean creatures able to process silicon to create SiO2 structures.)
If your nine year old will, of his own volition, sit still for an hour at a time, you've either heavily medicated him, or have done an extraordinary job of parenting.
Anyway, the mental state of zazen is quite distinct from daydreaming, so Zen practitioners are distinguishable from daydreamers by the descriptions they give of their experiences.
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You cannot wash away blood with blood
Actually, a rock does grow, given the right conditions. Specifically, a rock exposed to supercooled rock vapour will have said vapour condense and freeze on its surface, resulting in a bigger rock.
Forget magic. Any technology distinguishable from divine power is insufficiently advanced.
Have you read some of the recent stuff about the Universe being a hologram? The Universe would not be God, but merely a thought of God, or the interaction of two separate beings. One becomes two. Two become many.
Aide-toi, le Ciel t'aidera - Jeanne D'Arc.
I think you are absolutely right. It seems that many people cannot understand how special the carbon atom is. They assume that our life being based on carbon wouldn't exclude life based on other atoms somewhere else.
Not true. There's a special, unique property in the carbon atom orbital structure that allows very complex structures. No other atom has that quality, unless some basic constants of the universe were changed. It's like comparing a set of Lego blocks with a box of marbles.
The same goes for temperature, to get life one needs a liquid solution that lets molecules interact. With a solid there's no interaction, with a gas the molecules don't stick together, so one needs a liquid for transporting the elements of life. If a planet is too cold or too hot life will not appear. These are some basic limits on the physics and chemistry that will allow for complex chemistry to gradually evolve.
And the funny thing is that we have both theory and experiment telling us that life isn't very common in the universe. We haven't found any sign of life in either Mars or Venus, which a hundred years ago many people thought would certainly have life. If planets like Venus and Mars, that are very close to the Earth in their characteristics, didn't create life, then one should assume that our position is very special.
My favorite thing about that story is thinking about what sort of world these creatures came from. The fact that they know what meat is means that they have seen it (or something close to what we call meat), and obviously anything that is similar enough to be recognizable as meat, would be living tissue of sort. But the fact that they are repulsed by the fact that a sentient life form is made of this stuff, would make me think that they have never seen it in any sort of animate life whatsoever
So on their world muscle tissue must be some sort of inanimate life form like plants, or coral. This is somewhat weird as the whole purpose of muscle tissue is to move. Most of the inanimate life forms that we know on earth are designed to (more or less) passively absorb what they need to survive from the environment through photosynthesis and mineral absorption, whereas meat-based animals can rarely passively absorb what they need and rely on hunting to survive. Furthermore, meat required more nutrients and energy to support than the tissues needed for passive energy collection. But apparently the meat they have seen in the past has been "dumb" or passive enough that they were surprised when they saw it in something that they recognized as life.
So what would this alien meat be moving? Maybe it is more like heart or lung muscle than limb muscle and was pumping surrounding liquid into itself so it could absorb all the nutrients and then spit it back out - might be more efficient than passively collecting whatever liquid happened to flow near it. What would be controlling the meat - most of the muscle-bound creatures I can think of have a central nervous system to control them, but these must be more like a simple pacemaker or very simple chemical sensor/response mechanism.
And more importantly where can I get this amorphous meat to put into my garden/aquarium/floating gas clouds :)
You can find a brief description here.
The article suggests that the hydrogen was produced only when rocks crack, meaning that the microbes' food supply was meager and sporadic. Now Freund has discovered a chemical process in Earth's crust that may produce enough hydrogen to feed a mass of underground life larger than the mass of all living things at the surface. "[T]he rocks around them will replenish the hydrogen supplyÃÂ--indefinitely, over eons of time," said Freund.
Talk about a shadow life form.
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You can't swap silicon for carbon in DNA. Silicon doesn't have the same talent for directionally bonding to itself.
I'm not a chemist and I'm not really sure where to look, but does carbon only have this unique talent for directionally bonding to itself at ANY temperature and pressure? Is it conceivable for another element to develop this property at radically different environments?