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More Evidence For An Extinction Comet
Andy_Howell writes: "There is more evidence that a comet or an asteroid is believed to be the cause of another mass extinction. This one happened 250 million years ago, long before the one that killed the dinosaurs, it and wiped out most of the life on earth, including the trilobites. The evidence comes from buckyballs with unusual isotopes trapped inside -- isotopes that were apparently created in carbon stars."
Radiocarbon dating also isn't the only dating scheme. It works quite a ways back, but you can also cross-reference it with "dendrochronology". It requires trees in certain conditions, but when you can do it, you can get dates down to the year. For really old stuff, you can use potassium-argon dating, which watches the decay of an isotope of potassium into argon. Scientists who do this junk don't usually settle for one line of evidence to give them a date. They apply as many methods as possible to increase their certainty in the value.
ironic, since comets are also thought to be the source of the complex organic molecules that eventually assembled into life in the first place. See amara.com for a layman's introduction to the cosmic dust that comprise comets, and space.com for a discussion of the possible link to life.
For those of you without CS backgrounds, hill climbing is a general strategy for finding a solution to a problem. You basically characterize the problem in terms of a set of variables that define a multi-dimensional "surface", then define some function that maps these variables to a "goodness" value. Then you tell the computer to "climb the hill" until it finds the maximum (i.e. best) solution.
Of course, the problem is that you reach local maxima--locations that are peaks, but not the highest peak. So what do you do? You can do a random restart, where you start in a new location and start climbing again, then compare the new peak to the old. Another thing you can do is perturb the existing path a little and start climbing in a new direction.
Now, what if life on earth is a big hill-climbing experiment run by mice? The mice were unhappy with the simple ocean-dominated life of the Permian period, so they arranged to have a "random restart" in the form of a meteorite. Then they weren't happy with the dinosaurs in the Cretaceous period, so another meteorite.
Now, we've been giving mice AIDS and cancer for years. And we've been squishing them in mousetraps as part of a concerted effort to eradicate them. How long before they decide it's time for another restart?
[Apologies to Douglas Adams...]- ----------------
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Danny.
I have written over 900 book reviews
There is genetic variety evidence that some species
appear to be descended from a very small population.
Chetahs are one example, with all current individuals
nearly clones of each other.
Humans are another example, with evidence of an
Adam/Eve population about 200,000 years ago of
less than 10,000.
These bottlenecks, such as caused by meteors,
may drive rapid periods of evolution.
This discovery concerns the Permian extinction
300 mya. Only fishies then. Lot fewer afterwards,
The dinosaur extinction is 65 million years ago.
The Snowball earth is 600 mya.
There could be dozens of these catstropic events
in Earth'd four billion years.
Nader voters will be unaffected however.
> coincidence != causation
Maybe mass extinctions cause comet impacts.
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Sheesh, evil *and* a jerk. -- Jade
I have to ask - is the atmosphere actually boilng off?
If we perform a mass balance around the exosphere, yes, meteors do rain down an contribute mass. But, does the earth "shed" a sufficient amount of gaseous matter to even things out a bit?
If not, maybe we should just catapult old Buicks out of the exosphere?
.
As Darwin himself often pointed out, his theory of natural selection implied a general trend for later generations of creatures to be better suited to the environment of their ancestors (and thus to their own, assuming things hadn't changed much).
"Better" is a value judgement that has no place in discussions of evolution.
There is no "normal process of evolution". Some things die, some live, some reproduce, some don't; mutations occur, and either spread or disappear. Lifeforms today are different from lifeforms that were around a million years ago, due to these chance occurances. That's all there is to evolution.
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To blow a huge gaping hole in every atheist's personal beliefs and theories:
What if God and the Universe were literally the same thing?
Think about it for a second.
Rebuttal in advance: "So if God created the universe.. you're saying the universe created itself?" Maybe I am, maybe I'm not. Anybody who's ever studied the `big bang' realizes that the universe never actually was created, never actually started; time simply goes as far back as a certain point, and that's all there is. It's not like before that there was empty space; there *isn't* any "before that." It didn't exist!
God could be lots of things. God could be number theory. God could be the laws of physics. Who is anybody to say that God has to be some majestic humanoid? "And God created man in His image." Image... who's to say image means physical image? Maybe it's why we're conscious and no other species appear to be.
If God was the universe... then anything that anyone does, anything that anyone discovers by the scientific method, anything that happens to promote evolution and the big bang... would still be God.
Try picturing all of time and space as a single instant in a higher dimension.
If you're inside a vacuum, how do you know it's a vacuum? Because every environment pushes in on the walls, implying higher outer pressure? What if you went somewhere where the walls were pulled outwards?
You can't know anything from inside the bubble, nor from outside the bubble, so don't pretend to.
And a question to throw out there: So many scientific theories rely on general acceptance by the majority of the scientific community to be considered truth. These are often based on other widely-accepted postulates.
Suppose that these theories and postulates are partially correct; correct for the majority of applications.
What's 2/3 of 2/3 of 2/3 of 2/3? A majority of a majority of a majority of a majority, right? But that isn't a majority anymore... 16/81 is actually a pretty small fraction.
--TheOrangeSquid Is it any wonder things seem so awry? We swim in a sea of confusion and don't have to think to survive
"Comet hits Glasgow ned creating isotope of Buckfast Tonic"
I wonder if any research has been done as to whether the evolutionary changes brought about by this impact had similar effects as the impact that killed the dinasours. Some researchers claim that without this impact, mammals would never have become the dominant life form on the planet. It would be interesting to see how this older impact may have affected lower level life. It's rather amazing that these impacts, at just the right time could be responsible for the develpment of life as we know it.
The oort cloud.
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Soma: because a gramme is better than a damn.
We are the only species to ever inhabit Earth that has a chance to protect itself against an event as catastrophic as a comet/meteor/asteroid slamming into the planet and ending life as we know it.
However...
Our species also uses its spare time to do things like this, this, and even this so I wouldn't exactly get my hopes up if a comet was screaming our way...
Why do users with IDs under 100,000 or over 700,000 usually have the most worthwhile comments?
All of your bases belong to us!!
This has been going on for quite some time, and I hope that all you trolls and crap-flooders heed my words and correct your grammar in the future.
Remember, just because you like to defecate all over slashdot, you can still sound intelligent while you do it.
Keeping
No, I'm not wrong. Yeah, the earth is really really big, but only a small change in the distance of the earth to the sun, comparatively, would mean radical changes in climate. All this crap I've read and seen about dinosaurs has supported the idea that areas they roamed were tropical. Now, account for the estimated spread of Pangea, the timeframe of dinosaur existance and where they had lived (consider the range of fossil finds) and assume there was some migration winter-summer, they had to be living (condsidering dietary needs and conditions for plants herbivores dined on) in a relatively tropical or moderate climate year around. Present assumptions are these creatures were not covered in fur with big deposits of fat to insulate them, depends upon this, too. Probably most relevant of all is the size of these damn beasts. Nothing approaches their size today. Did they take too long to grow to that size and bacterial/viral threats evolved too fast for them to evolutionarily counter? Or might the gravity have been just enough less?
The point I'm driving at is Earth is _not_ the same size and orbit it was 250 million years ago. My posit of 1 KG of galactic jetsam washing up in the the atmosphere is, by any account, extremely conservative. How much does the earth gain each year, just in dust to tiny to see? In the change, just of the Earth's mass mass and adjusting its orbit I find problems not addressed. Just some big damn rock did it all. C'mon, think about it.
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A feeling of having made the same mistake before: Deja Foobar
It's unfortunate that NASA amongst others are so eager to publicize this as a finding of the cause of the permian extinction. This wouldn't be the first time they've been prone to Time Magazine-like exaggeration.
The scientists who've done this work have certainly done a good job in showing that there were interstellar asteroid collisions with the earth at that time which is interesting. However, there are also many other factors that could have played into the permian collapse (where an estimated 90% of species were eliminated), namely a tromendous amount of volcanic activity which I've heard would have been enough to bury the entire planet in 30ft of lava if it were spread evenly. As it is, the ash clouds could have blotted out the sky and killed plants, leaving animal species to wither. then again, there also could have been a fatal cross-species virus that wouldn't be detected in geological surveys. Who knows, really?
As the scientists who've done this work themselves would be happy to point out, it's relatively easy to prove that asteroid collisions and the permian extinction were coincident when compared to the daunting task of proving it was a major cause, if a cause at all. As of now we have knowledge of a number of catastrophic occurences at the end of the permian era along with an extinction, but what's needed is evidence other than perjorative that links the two and describes to what extent each catastrophe was playing a role, if any.
Just because the sun rises when I get up in the morning doesn't mean I make the sun rise by getting up in the morning.
The only tool you've got against psychosis is experience.
The important thing to remember is that, like all disasters, extinction level events are the will of god. Ditto for that bit earlier today about evolution. Sure, it doesnt make sense, but I've been assured that everything is gods will. Really! I swear!
the best part here is some people are going to take me seriously!
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The way to see by faith is to shut the eye of reason. --Ben Franklin
Hopefully the new Bush administration will increase the priority of this. Its a non-political issue really because it doesn't matter if you're Republican or Democrat when that big-assed asteroid hits you will be toast!
This theory was refuted in 1982 (from what I can rememeber) at about the same time that satellite images of the Yucatan Peninsula strengthened the hypothesis that a meteorite caused that (less severe) global extinction. I am incertain how good the online archives are on Scientific American but maybe somone else can chime in?
1) comets come from the oort cloud located just outside the solar system. The oort cloud is full of fresh new Ice chuncks just waiting to be knocked toward the sun so they may become a comet.
2)The moon is moving away from the earth at an infintesimal rate, and Yes if it was a constant rate then it would have been long gone; however there is a thing called physics(I know you Fundimentalists don't think that is true either).
when the moon was closer to the earths gravity was much more powerful and while the centripital force of the moon pulled it away from the earth, the net force was actualy vary small, infact it was nearly non-existant. Over time the moon, with this small net force, began to move away from the earth, however, because of the small magnitude of the force, the moon moved at a much slower rate than it does today. therefore it could not have gotten any further from earth than it already is.
btw, the moon is not the same age as the earth and the earth is not the same age as the universe. please don't try placing all three on the same time table like the bible does.
-The American people have overpaid; I am here to ask for a refund.
Assuming that by "The world", you mean planet Earth, a mass extinction means absolutely nothing. Short of the eventual expansion of the Sun int a red giant (in about 4 billion years) The Earth is still going to be here, no matter what. Life, in some form, will survive, no matter what.
Now, as a human being, I have a vested interest in human beings not going extinct. But I don't equate my personal interests with those of the planet.
-jon
Remember Amalek.
was a frood who really knew where his towel was. Here's the Fuller FAQ, as well as a coupla other (+1; Informative) links to Bucky/Buckyball info...
props to all dead homiez
A likely scenario has been suggested by Hermann Burchard (at okstate.edu):
To summarize the above--a comet crashed into Earth, which triggered massive volcanism, which in turn led to extinctions.Nice article explaining what a Buckyball is.
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A feeling of having made the same mistake before: Deja Foobar
I bet it'll happen again sometime. Maybe not in our lifetime, but it'll happen, and someone will be there to sell t-shirts.
Douglas Adams
1952-2001 :(
In answer to the question, you have to ask where are you going to get a lot of He/Ar (old stars) where carbon is abundant at a high enough density to create the Buckyballs, at a low enough temperature that it isn't destroyed in the stellar atmosphere, and mass outflow from the star to cause it to end up in comets -- q.e.d. Carbon stars.
This written in a book 1000's of years old which means the people of the time couldn't have had the scientific facilities to know this themselves... Coincidence? I would think most with an OPEN mind & willing to find out for themselves wouldn't believe so.
....
No, it's not a coincidence. And I think that you don't need ANY scientific "facilities" to discover that the 8th day is the first good one, it just takes a little experiment:
- circumcize on the 1st day: lots of blood and a death child.
- circumcize on the 2nd day: same thing happens.
- 3rd day, etc.
- 8th day: oh well, it works.
I don't understand why people keep seeing God in everything.
An even more interesting catastrophe is the collision with our then closest neighbor, which created the Moon. This planet, called Oberon IIRC, was supposedly located between the orbits of old Earth and Mars, and intersected the orbit of Earth.
At one point, old Earth and Oberon grazed each other, liquefying most of both planets and spinning a lump of rock off into orbit. The lump became the moon. The Discovery Channel devoted most of their "What if we had no Moon" program to this theory.
It is also speculated that the asteroid belt between Mars and Jupiter is the remnant of another such collision, where the planets involved did much more than graze each other.
The REAL jabber has the /. user id: 13196
The REAL jabber has the user id: 13196
What you do today will cost you a day of your life
According to this Space.com article, there would have been a bigger mass exinction that happened 600 to 700 million years ago, or 350 to 450 million years before the collision described in the article above, which would have killed about 95% of all life forms on the planet. Here's a short version of the Space.com article:
In the 1960's, geologists were unable to explain the evidence of glacial deposits found in the rock strata of every continent, including those at sea level aroung the equator. Was it evidence that ice had covered the entire planet at one time (i.e. a "super ice age")? Continental drift could have been responsible as well. Plus, how could the Earth get so cold as to have ice sheets covering it entirely?
A recent theory suggested that for every drop in global temperature there is an increase in surface snow and ice. As more snow and ice builds, more heat is reflected away, and it gets colder and colder. If ice glaciers had progressed as far as 30 degrees to the equator, a runaway ice age would have frozen the Earth completely. The massive cold snap would easily triggered an extinction like no other. The theory only had one problem, though: how did the Earth eventually thaw?
According to modern-day geologists, the levels of CO2 in the air are directly related to volcanic activity (which puts it there) and global temperature. As volcanoes erupt, they give off CO2 which is washed back to the Earth via rain. In turn, this CO2 is deposited back into the oceans where it settles on the sea floor as carbonate sediment. It is reheated to liquid, then gas, and the process starts anew when it is ejected again by volcanic activity.
If a frozen Earth was still geologically active (tectonic and volcanic action), all the CO2 thrown off my erupting volcanoes would have nowhere to go. As the amount of CO2 in the atmosphere rises, the global temperature rises as well. A few million years later, ice begins to melt, the water vaporates into rain where some of the CO2 is redeposited back onto the ice where the process is repeated. Complete thaw would be quick, happening in less than a couple of hundred years due to the excessive amounts of CO2.
As with the Permian-Triassic Boundary event (the meteor/comet incident 250 million years ago) that triggered the evolutionary process of the rise of the dinosaurs, the great freeze of 600 million years ago also triggered its own evolutionary growth: the Cambrian explosion. The massive dip in population followed by millions of years of harsh environments would have favored the birth of many new forms of life.
UNIX: Find it, fsck it, forget it.