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Study Puts Hole In Comet Theory Of Life's Origin
Astervitude writes "A new study by US and Japanese scientists has put a serious dent into one version of the popular panspermia theory that credits comets for bringing the seeds of life to Earth. Surveys conducted by the University of Arizona, the National Astronomical Observatory of Japan and others now show that objects from the main asteroid belt between Jupiter and Mars were largely responsible for the period of Late Heavy Bombardment that ended 3.9 billion years ago. UA Professor Emeritus Robert Strom believes that no more than 10 percent of the Earth's water comes from comets and any oceans then extant would have been 'vaporized by the asteroid impacts during the cataclysm.'" Interesting, because this directly contradicts the Nova mini-series Origins that just finished running on PBS. Science never stops moving.
New study by scientists disagrees with programme made by television professionals to give the illusion of education to the masses?
;)
Shocking!
I don't read your sig, why do you read mine?
We all know that the Flying Spaghetti Monster created life, you fools!
Sure, this is an interesting paper with important ramifications - but I don't see how it has any bearing on the theory of panspermia.
Surely it only takes one tiny droplet of life-carrying comet water to make it into earth's early oceans without being boiled into sterility. If conditions were right, that initial small pocket of bacteria or virii could multiply to cover the planet in a matter of years.
You can't tell me that over millions of years and millions of impacts, not one would come down at a sufficiently low speed or favorable grazing angle to gently melt comet ice into an existing ocean.
Given what we've observed of Mars meteorites ending up on Earth, it's perfectly possible for life from one part of the universe to spread from planet to planet - and even solar system to solar system.
If you buy into the idea that there was life elsewhere in the universe long before life has been found to have existed on Earth - then panspermia is very possible.
My problem with that theory is that it doesn't answer any questions about how life formed in the first place. There still has to be an origin world - and explaining how life appeared there is just as hard as explaining how it might have formed here in the absence of panspermia.
www.sjbaker.org
> Why would it be easier to believe that life began elsewhere
> than to assume that life started here on Earth?
Two reasons:
1) We have some idea of the early conditions on Earth - but maybe
we have a hard time believing that those were conducive to
forming life from scratch. If life started elsewhere then there
is almost no limit to the range of concievable temperatures, pressures,
gravity, radiation and chemical environments in which it might
ultimately have formed.
2) Time: Is the Earth old enough for that very early phase of going
from completely non-biological materials to DNA, cell walls, etc?
If not - then panspermia explains that by saying that life was
around in some other place LONG before the Earth was formed.
So panspermia allows for a scientific explanation of life's formation
that is perhaps more plausible than formation on early Earth.
www.sjbaker.org
> 80 percent of all studies are wrong...
Which means that there is only a 20% chance that the study that shows that "80% of studies are wrong" is right.
Which means that we have no idea what the probability of error is without doing a lot more studies on the subject.
My head hurts.
www.sjbaker.org
Personally I always hate panspermia. It seemed to fail Occams Razor pretty soundly. Yes, life on this planet came from an asteroid or comet from another planet. Well, if life can exist there to bring it here why can't it just develop here. Seemed like a big waste of time to me. I see no reason we cannot have a homegrown abiogensis on good old Earth. It's not like we hit some major hitch and need an alternate explanation that explains nothing.
It is no longer uncommon to be uncommon.
Comment removed based on user account deletion
Although the panspermia theory is intriguing, it does NOT answer the question of the origin of life -- was it from another planet that was inoculated by an even earlier comet..... It's like the theory that the Earth rides on the back of a giant turtle/ But what does that turtle ride on? Or is it turtles all the way down.
If we are to assess the probability that life is exogenous or endogenous to Earth, we must ask about the relative probability of: a) life forming on a planetary body versus b) life forming on a planetary body which then survives being blasted into space, travelling interstellar distances, happening to collide with another forming planet of just the right composition (without ever venturing too close to some hot star), and surviving that collision.
Even if the probability of life arising on a planet very very low, the relative probability of endogenous versus exogenous origin is very skewed toward endogenous origin. Because exogenous origin requires both endogenous origin (somewhere else) and then a low probability trip between planets, exogenous origin would seem to be very unlikely unless there are large numbers of planets with endogenous life that spew lots of interstellar-traversing chunks. But if there are large numbers of planets with with their own endogenous life, then the probability of life forming on Earth endogenously must also be high and trump the low likelihood of life just happening to make it from somewhere else.
Two wrongs don't make a right, but three lefts do.
That's an interesting comment that glosses over many of the statements of science that are commonly excepted so much as "fact" that anyone that points out inconsistancies in them is labeled as anti-science or ignorant. Of course we are always learning more and yesterday's accepted theories have to adapt to new knowledge, but the virulence some people have for defending pet theories borders on intolerance. /. you get modded into oblivion. Please note I didn't relate it to Creationism or Intelligent Design, it's just that the theory of evolution itself has about as many holes as IE. Sure, right now it's the best idea going, but that doesn't mean it's the end of the conversation. Yet questioning it all usually does end the conversation.
A good case in point is evolution, where if you don't mention it in a glowing light on
If thou see a fair woman pay court to her, for thus thou wilt obtain love
Say there was an ocean on earth, and something big slammed into it, vaporizing all the water. Wouldn't that water just eventually precipitate back down?
I mean, vaporizing something like a person would pretty much destroy them, but it doesn't do much to eliminate individual atoms, it just moves them around. So the ocean itself might be turned into water vapor, but then where does that all go?
I'm sure a big enough impact could blow matter up into space, where it'll float away never to bother the busy earth again, but I would think that most matter gets propelled outwards from an impact, not up. So wouldn't a meteor hitting an ocean just spread the water around?
One time I threw a brick at a duck.
' at line 1.
People have to understand what "we know" means. Adults have to take everything we hear with some number of grains of salt. Scientific statements of "we know" are more reliable than metaphysical statements of "we know", and adults should understand that for ourselves.
Which is why it's important for people to learn about science before tehy accept its knowledge. Just like it's important for us to learn about religion. Not just to learn the science, like reading it in _Discover_ magazine, or to learn the religion, like reading it in a bible. But we need to learn how the "knowledge system" works: its history, its failures, its successes, its alternatives and their histories. Just like we don't need to learn enough science to be scientists in order to appreciate science (and our world that it explains), we don't need to become experts in the discipline, to become scientists or clerics. We need to understand what the strengths and limitations are, and what it means when a scientist or a cleric says "we know", "I believe" or "this is". Otherwise, we're just faking it, and we will make all kind of mistakes, without ways to recover. And that's very dangerous, considering how powerful are these ways of knowing, whether they're right or (especially when) they're wrong.
--
make install -not war
Many of the plaintiffs in lawsuits against idiotic creationist "equal time" laws have been religious figures. Do not make the assumption that all religious people buy into the creationist agenda.
Well, I will point out that the various theories of Creation in the last few hundred years has been far more stable than any scientific theory put forward.
That is because ignorance is stable.
Perhaps it would be better if science types started using rhetoric like "We Think" or "We Believe" instead of "We now know..."
We 'science types' usually do. The problem is that if we start saying 'we believe' too much in public, our ideas get attacked as 'just another form of religion'.
I mean, the version of Darwinism that was taught in my school has pretty much been shot to heck, but my Biology teacher sure enough said, "This is how it happened."
That is because the science taught at school has to be simplified hugely. The version of almost any scientific idea taught at school is largely wrong. The idea is to open minds to the principles of science.