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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."
Only 7 million years from now, for all you long range planners. Better stock up on beans, bottled water and relocate your house 1 kilometer underground.
It's a perfectly reasonable hypothesis, though it'll be a while before we can test it. It's always a little weird though, to think of extra-solar events as relevant on a "local" scale. I mean, in the same way that Earth is endangered by rogue meteorites and asteroids, the whole solar system is vulnerable to a rogue star or brown dwarf. Anyone ever read Jack McDevitt? He's obsessed with that sort of disaster (pun intended).
Hard to get your mind around it...The odds are so long...
ad logicam Claiming a proposition is false because it was presented as the conclusion of a fallacious argument.
Will my tinfoil hat protect me ?
Shakespeare poems - infinite monkeys with infinite time.Computer tech support - a few trained ones working from 9 to 5.
How about 'new hypothesis may explain...'
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Im sure the Chinese do.
Everyone knows the extinctions were perfectly explained using the Theory of Intelligent Smiting.
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
Check out Figure 4 at the end of the linked paper. It shows that the periods of highest diversity coincide with the periods where the cosmic ray flux is lowest. Really amazing correlation if you ask me.
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
The researchers suggest that an increase in the exposure of Earth to extragalactic cosmic rays causes mass extinctions.
Or maybe, the increased radiation merely causes some periods of increased mutations... extinctions follow as species are outcompeted for resources.
But NOVA Science Now told me it was global warming :(
Can we please oh please oh please call them death rays?
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.
It's a perfectly reasonable hypothesis if one accepts the premise that mass extinctions have an approximately 62 million year period. From Wikipedia, the last 6 extinction events happened 65 million years ago, 200 million years ago, 251 million years ago, 360 million years ago, 444 million years ago, and 488 million years ago. The time between extinctions being 135 million years, 51 million years, 109 million years, 84 million years, and 44 million years. I'm having a hard time wrapping even an approximate 62 million year period into those.
Ben Hocking
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Humanity's chances of avoiding self-destruction or regression to a simian mean within the next 7 million years approximate zero, or worse (Cantor sets).
technical writing / development
I for one welcome our new cosmic ray-based overlords! (I just felt like I hadn't seen that lately. :'( Mod me as you wish. But, be gentle.)
you say: "A truth is a fact,"
Indiana Jones says, "Archaeology is the search for fact... not truth. If it's truth you're looking for, Dr. Tyree's philosophy class is right down the hall."
"If still these truths be held to be
Self evident."
-Edna St. Vincent Millay
Almost all of the diversity minima precede the cosmic ray maxima, and all of the declines (from diversity maxima) precede the cosmic ray maxima. I think you're on to something there... ;)
Ben Hocking
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Radiation doesn't kill things off that well. Look at Chernobyl or the Savannah river plant...Both shut down, both radioactive, both experiencing a resurgence of pretty healthy wildlife across the board.
Lot of the things we assumed about radiation back in the day (e.g. mutants and Godzilla) have turned out to not really happen so much. DNA isn't as fragile as we assumed, and while the extra rads may kill you quicker (only live to 60 instead of 80), it's not quick enough to keep you from reproducing.
We're not talking some kind of galactic nuke here...It's just a significant upswing in radiation. Hell, the fact that we've had these historically is maybe why the ecosystem tolerates increases in radiation so well.
ad logicam Claiming a proposition is false because it was presented as the conclusion of a fallacious argument.
The extinction events are too abrupt to be explained this way, and the "approximate 62 million-year cycle" only looks like a cycle if you squint really hard.
I recall reading one guys work on galactic dynamics where he suggested that our solar system "orbits" or oscillates (planar) through one of the arms (dense areas - we're not a pinwheel) of the galaxy. He suggested that as we pass through the middle, we're more likely to be hit by other objects. This was his explanation for the extinctions. Now we see that someone has concluded such an oscillation is really happening, however they suggest the a different phase relationship. The guy I was talking about would have the extinctions happen at the time of lowest cosmic ray flux. I guess he got the oscillation part right and the cause of the extinctions wrong. Too bad I can remember where I read that...
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.
Ben Hocking
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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.
Yeh i'd agree with Bombula. Henrik Svensmark is the guy who is at the forefront of cosmic ray effects on our climate - but the whole theory gets flamed by the mainstream greenhouse gas theory as it threatens it's 100% claim on the explanation of climate change. The correlation between cosmic rays and past climate is almost perfect (see fig. 5)... http://www.sciencebits.com/ice-ages
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
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
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I, for one, would like to commemorate a few periodic mass extinctions:
Dear AU, what has become of you? You may not be extinct, but I can never find you.
Humble Promethium. Your existence was "predicted" long after your demise.
Oh 271 Seaborgium, how did you decay? Let me count the ways. Alpha decay. Spontaneous fission.
272 Roentgenium, we hardly knew you. Half extinct at the tender age of 1.5ms. You're the one we'll truly miss.
https://www.eff.org/https-everywhere
Given the benefit of current technology, including technology developed for the US space program, catching up with the US government is more a question of funding than time. With insufficient funding, it could take much longer than 50 years to catch up; if somehow enough money became available, it could be done much more quickly.
In any case, commercial applications for interstellar probes seem unlikely, so you might never get that wakeup call.
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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