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New Theory Explains Periodic Mass Extinctions
i_like_spam writes "The theory that the dinosaurs were wiped out by an asteroid impact, the K-T extinction, is well known and supported by fossil and geological evidence. Asteroid impact theory does not apply to the other fluctuations in biodiversity, however, which follow an approximate 62 million-year cycle. As reported in Science, a new theory seems to explain periodic mass extinctions. The new theory found that oscillations in the Sun relative to the plane of the Milky Way correlate with changes in biodiversity on Earth. The researchers suggest that an increase in the exposure of Earth to extragalactic cosmic rays causes mass extinctions. The original paper describing the findings is available online."
The article suggests that this does not explain the K-T event, which is already adequately explained by the asteroid impact theory. This theory explains the cyclical decreases in biodiversity that seem to happen about once every 62 million years. The K-T event is not part of this cyclical pattern.
It's not even a new slashdot article.
i took a bitchslapping for natalie portman
But NOVA Science Now told me it was global warming :(
I believe it was 28-30 million light years, and then its axis for gamma rays would have to be pointing directly at where the earth would cross the relatively brief beam. IOW, you're more likely to get directly hit by a killer asteroid.
The cesspool just got a check and balance.
Because what matters is the galactic plane, not the solar ecliptic. It's going to take a while (read: about as long as it'll take the Solar System) for the probe to get a decent reading.
...following the principles of Heisenburger's Uncertain Cat...
OK, I've only read the summary (I have a lecture to give half an hour from now to prepare for) but I can see some objections:
* My boss (David Penny, Massey University) argues that the mammals and birds were already outcompeting the dinosaurs at the end of the cretaceous, so the asteroid was at best a coup-de-grace for them.
* The "periodic extinctions" idea has been around for decades, including the possible link to oscillations through the galactic plane.
* Mass extinctions are sudden. The increase in extragalactic cosmic rays exposure would be slow, over millions of years.
* The extragalactic cosmic ray exposure changes should be highly regular. The extinctions are irregular.
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The Pioneer and Voyager probes weren't designed to specifically leave the solar system though, their primary mission was to probe the planets. If we made a probe dedicated to getting really far out of the solar system really fast (with no stops in between Earth and deep space, or indeed at all) then it would get there much faster.
The KT event, for example, had a much larger impact on biodiversity but happened off-cycle, and is pretty clearly the result of a specific meteor strike that we already know about.
Other events may have been volcanic or meteoric or the result of something we didn't know about.
All extinction events being triggered by only one type of external condition was never very likely.
You are correct in that in order to get 62my ago, you have to fudge quite a bit. Also, there is increasing evidence that the Permian Extinction (250my ago) was caused by simultaneous (almost) volcanic events from "megavolcanos". Try reading Peter Wards "Rivers in Time" for a paleontologist's investigation into the mass extinctions. http://www.amazon.com/Rivers-Time-Peter-D-Ward/dp/ 0231118635
Sounds like someone needed to "publish or perish" for this article.
I get it now. If you disagree with the majority on
Ben Hocking
Need a professional organizer?
Out of Thin Air by Peter Ward, READ IT.
The title of the summary is totally wrong. This has nothing to do with mass extinctions. Its looking at fossil Species and Family counts vs time correlated with Solar motion. The 62 MY cycle barely touches the Mass extinction events.
Better summary title - "Life's Diversity changes with Solar Galactic Orbit". Or something like that.
not only that but mass extinctions happened a lot earlier than that and with a far less predictable pattern. which leaves us to wonder why this cycle is this recent? why isn't there a cycle like this stretching back over a billion years?
As far as the fossil record is concerned, the only things that existed beyond 550 million years ago are basically algae, bacteria, simple worms, etc. It wasn't until after that time that biodiversity really took off. It's entirely possible that this pattern goes back through the entire earth's history. However, there didn't exist complex enough life for us to gauge it's impact via the fossil record.
This guy's the limit!
That's odd. The post-9/11 research into the effects of jet contrails suggested that they have two faint effects: mild warming and mild day/night temperature moderation. But the above quote seems to contradict that.
I am now even more suspicious of the conclusions of the contrail research, coming (as it did) in the middle of the global warming craze. Right now you can't even publish the simple observation that plants will grow usefully faster on a warmer Earth; no, you have to spin it as "OMG poison ivy will get worse!".
I'm ready to go nuclear/solar/wind, and drive an electric car, because I've always hated the power that petronomics gives to the backwards nations... but come on guys, can we at least give both sides a fair hearing?
FATMOUSE + YOU = FATMOUSE
You forgot to mention Christopher Columbus's theory that the earth is round... [...]when the rest of the so called "Intelligent" people of the world said it was flat.
LOL! You still believe that nursery school myth?
NO intelligent person in Columbus's time thought the world was flat -- as it clearly is not to anyone sufficiently observant. Columbus's problem is that he wanted to go to Asia via a western route, and everyone intelligent knew that with a circumference of about 25,000 miles, Eratosthenes having calculated it about 240 BC (as others had since). Hence they "knew" that with the sailing technology of the day, there was no way Columbus could make the voyage.
They were right, too. Had the Americas not been in his way, his expedition would have perished before he got as far as the longitude of Hawaii.
There is some evidence that Columbus may in fact have known that there was some land mass to the west considerably before Asia (the Vikings certainly did, and it is quite possible that fishermen who went as far as the Grand Banks were also aware). Whether from that he decided that Eratosthenes was wrong and the circumference was smaller (possibly influenced by Ptolemy's maps (from Geographica) which underestimated the circumference at about 18,000 miles), or whether he was just arguing that way to get backing for an expedition (with the secret purpose of discovering and exploiting just whatever land mass was there), we have no way of knowing.
That mistake alone discredits the rest of your post as to make it not even worth reading.
-- Alastair
Cycle:Min Diversity:Max Diversity
1:59 My:74 My
2:115 My:121 My
3:177 My:184 My
4:250 My:273 My
5:298 My:308 My
6:372 My:400 My
7:441 My:454 My
8:497 My:501 My
My calculations:
MinAgeDiff:MaxAgeDiff
56 My:47 My
62 My:63 My
73 My:89 My
48 My:35 Mr
74 My:92 My
69 My:54 My
56 My:47 My
Personally, I'm not impressed by the 62 My period conclusion based on the data they provide. Just how approximate are we talking here?
Ben Hocking
Need a professional organizer?
BTW, even though Columbus "discovered" the Americas, it was Juan Sebastian Elcano who proved the world was round by sailing westward (modulo a few detours) until he returned to Spain. Yeah, everyone says it was Magellan, but Magellan died on the expedition in the Philippines, it was Elcano who assumed command at that point and finished the circumnavigation (along with a dozen or so shipmates).
-- Alastair
I'm sure I've seen this before, possibly found out about it on /.
/ 03/10/MNGFIBN6PO1.DTL
Here's an article from March 2005
http://sfgate.com/cgi-bin/article.cgi?f=/c/a/2005
It's only one of many theories. The wikipedia page that points to the article above discusses them all
http://en.wikipedia.org/wiki/Mass_extinction
These posts express my own personal views, not those of my employer
Technically, it is correct that a probe launched to exit the solar system as fast as possible could do it faster, using certain definations of 'the solar system'. Not because it would go faster, it would go slower, but because to exit the solar system it is much faster to go north or south instead of following the plane of the planets. (But this doesn't help any if you want to exit the heliosphere, which is distorted like a comet tail. The fastest way out is in the direction of the movement of the sun.)
However, this would be utterly pointless, because we don't want to get outside the solar system to measure...we'd have nothing to compare it to. We'd want to send the probe close to the top (or bottom?) of the galaxy. Getting to the 'top' of the galaxy would require, what, a thousand years of travel at light speed? So we need all the speed we can.
I forget how the solar system plane lines up with the galactic plane, but we could trivially use Jupiter for a speed boost and, at the same time, sling the probe in whatever direction we need. My first assumption is that this would be straight in the direction the sun is going, but actually that's not correct...the sun is mainly orbiting in a circle with tiny up and down movements, thus it's taking 61 million years complete a cycle, whereas it's only three thousand lightyears. And, no, we're not just going really really slow.
Going straight out, with current technology, could easily let us beat the solar system out of the galaxy there and see what's going on. Even with 10% of light speed we could get there in a few thousand years. (Well, pretending we actually had probes that would operate for that long.)
People tend not to realize how flat the galaxy is, at least out here. Remember the Monty Python song. 'It bulges in the middle, sixteen thousand lightyears thick, but out by us it's just three thousand lightyears wide.' And we're apparently nearing the edge once again.
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