Slashdot Mirror
Galactic Origin For 62M-Year Extinction Cycle?
Hugh Pickens writes "Cosmologist Adrian Mellott has an article in Seed Magazine discussing his search for the mechanism behind the mass extinctions in earth's history that seem to occur with a period of about 62 million years. Scientists have identified nearly 20 mass extinctions throughout the fossil record, including the end-Permian event about 250 million years ago that killed off about 95 percent of life on Earth. Mellott notes that as our solar system orbits the Milky Way's center, it oscillates through the galactic plane with a period of around 65 million years. 'The space between galaxies is not empty. It's actually full of rarefied hot gas,' says Mellott. 'As our galaxy falls into the Local Supercluster, it should disturb this gas and create a shock wave, like the bow shock of a jet plane,' generating cascades of high-energy subatomic particles and radiation called 'cosmic rays.' These effects could cause enhanced cloud formation and depletion of the ozone layer, killing off many small organisms at the base of the food chain and potentially leading to a population crash. So where is the earth now in the 62-million year extinction cycle? '[W]e are on the downside of biodiversity, a few million years from hitting bottom,' writes Mellott."
yesterday there was the same story, except it was 150 million years.
The real question is; and so what if we're gone?
Not as if there'll be an alien civilization to take over or give a frickin' damn.
I read about it in books which must have been published 30 years ago, though I think the theory than was than the gravitational field of passing stars was changing the orbit of comets in the Oort cloud and causing comet impacts.
http://michaelsmith.id.au
BBC documentary series Horizon, c.late 1980s
My web domain.
Mabye cosmic rays effect the ozone layer, I don't really know. However claiming that CR's increase cloud cover is stretching the science well beyond what is known.
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
Imagine the earth floating on a sine wave. The sine wave passes though the zero point. The zero point is a plane which contains the hot gasses. Are going to be other civilisations outside this cycle? Are there other civilisations who thrive inside the plane? Do some humans need to grow a brain?
Does it go on forever?
There's really no need to pan@:P:{}n o c a r r i e r
Confucius say, "Find worm in apple - bad. Find half a worm - worse."
from TFA: It turns out that the biodiversity minima of the 62-million- year cycle happens when the Sun is âoebobbed upâ on only one side of the galaxy, when the solar system is on the diskâ(TM)s upper, âoenorthâ side...These [cosmic rays] should be showering the north side of the galaxyâ(TM)s disk. We are protected by the galactic magnetic field, much as the Earthâ(TM)s magnetic field protects our planet. When we rise to the north side, we are less protected.
I made that observation for myself a long time ago. Large meteor impacts tends to have 32M years interval.
Its also possible that my opening of a coke can will unsettle the quantum state of the water molecules vaporized in the air consequentially causing a pony to spontaneously appear. But as much as i wish it to be true, it aint going to happen (at least not for a really long time).
The whole point of the 65 million year cycle was not only the extinctions, but also the discover of elements in the ground only found as a result of asteroid impacts. Tha'ts why researches spend to much time trying to find a large mass that could disturb the Kuiper belt.
Those gas clouds are probably circulating at the same speed as us. Net speed zero. NTICBBRTFA (not that I can be bothered reading the f**king article). I mean, for Christ sakes. Couldn't it be that they had found 62 million years is the average time it takes a super duper virus to mutate. No, we have to be flying into some fucking cloud that just happens to be traveling at a speed in opposition to the rest of the galaxy.....in a few million years........I may have had a few glasses of wine tonight but there is no way I am going to fall for that.
What an f**king twit!
I reserve the write to mangle english.
The interval between extinctions is 62 million years only if you accept ~30 millions of year of error margin.
The current downfall of biodiversity is really fast compared to the time scale mentioned here. Its most likely reason has two legs, two arms, a big brain and a various set of forest-destroying machines as well as a bad habit of dumping various materials into the ocean.
The Wise adapts himself to the world. The Fool adapts the world to himself. Therefore, all progress depends on the Fool.
As others have noticed, this is hardly new. I'm starting to think we just have too much knowledge these days. I've lost count of the number of 'discoveries' that are already known, both in IT and the wider areas of science and beyond. It's effectively impossible for people to fully grasp the entire sum of knowledge in their field with the result we're starting to spend time 'reinventing the wheel' to a depressing level.
I want a list of atrocities done in your name - Recoil
Its actually the Infinite Improbability Drive in action. Research my ass. Before you ask any more questions, 42.
Real men read Slashdot articles at -1, bottom up.
theory about 20 years ago. However that one suggested the reason for the mass extinctions was because the stars in the galactic plane are much closer together so the likely hood of being in close proximity to a supernova and all the incumbent radiation that entails is much higher. This also explains why occasionally mass extinction skips a beat. Of course the 2 scientists who postulated this theory were promptly laughed at and ridiculed by the scientific community in that very grown up way that scientists do.
Cold fusion anyone?
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.
All this has happened before and will happen again.
Take a look at wikipedia's graph of extinctions from the article about the history of life. I haven't done any actual signal analysis on this data.
I would buy that there is a bit more energy in the per 62 million years signal, but I wouldn't call it clockwork-like regularity. If they came up with a p-value of 0.01, I'd say that there must be something happening, but I would expect a little more consistency out of a big cosmic event like the one they're describing.
[W]e are on the downside of biodiversity, a few million years from hitting bottom,' writes Mellott
I totally agree with that assumption, though I personally think Adrian Mellott should have left out "the few million" part.
Well we're all gonna die on December, 21 2012 anyway, so why bother???
had a story that's strangely similar: "The Poison Belt". Except that instead of radiation, it's poisonous aether.
Tor the "skeptics" are desparate for anything, anything at all which can be called "science" that can somehow justify continuing to mine and burn coal and avoid investing in environmentally responsible energy policy
Shut down the mass relays!
M94 is about the age of the universe: 13-18Bn years old.
It is out of the plane of the milky way.
Yet it still remains a cluster, not shocked apart by its life in the danger zone.
can't wait to see it in action the next michael bay movie
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
Ha! With good ol' human ingenuity, I'm sure we can hit bottom a lot faster than that!
http://alternatives.rzero.com/
Chime in here with any information on this.
I was lead to believe at one point that the Mayan Calendar's "Beginning of time/End of time", December 21 2012, corresponded to when our Solar System transverses the plane of the Milkway.
Where these people a few million years off? (Amongst other things)
Not to be anal, but his name is spelled Adrian Melott , with one L. This spelling will help if you google his name.
I attend the University of Kansas (where he teaches), and know this guy is associated with some pretty far out ideas.
Seriously, that would cause mass extinction [http://en.wikipedia.org/wiki/Gamma-ray_burst]. Though the odds aren't great of one happening. However, if one considers that galaxies move and collide all the time, then I suppose over the course of Earth's history it's possible that the Earth came really close to a Super Nova at the same time a Gamma Ray burst happened.
The odds aren't good.
FYI we get bombarded by Cosmic Rays all the time.
This guy needs to publish a paper and not "speculate" in a magazine. Pseudo Science, nothing to see here, move along.
So sue me.
It's still an old globular cluster.
Remember how many people on the planet think that just *believing* something is ok ("I believe in a god", "I blieve there is no global warming" etc etc) - it will take 5 million years to get everybody to accept this and start working on a solution!
If Google really cared they would fix Android Chrome to reflow text, instead of discriminating
Maybe it wasn't radiation that killed off all those critters. Maybe the stars were just right.
no time ;-(
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
This has all happened before, and it will all happen again...
Sure, but where's the silver surfer come to warn of Galactus? Maybe Jack Chick was right all along
FreeBSD for the impatient.
Nightfall (Isaac Asimov, 1941, and Isaac Asimov & Robert Silverberg, 1990)
Tsunami -- You can't bring a good wave down!
...to build the shield generators that will protect our ancestors from the rarified hot gases.
Guess that means no Duke Nukem Forever this time around. Hopefully they'll time-capsule the source, at least.
So when the stars are right, the living creatures of Earth all die. Sounds like it's nearly time for Cthulhu to rise again!
Interesting idea. But what about the Iridium anomaly then?
The very basics of "Cap'n Trade"
Rich people "Trade" us money for extended life. We pop a "Cap" in the poor people...
Same as our society has always run...
Cap'n Obvious
This hypothesis is old and was used as part of the story "Calculating God" written by Robert J. Sawyer in 2000. It's an excellent book which I can heartily recommend. You might also be familiar with his work through the "Hominids" alternate earth trilogy.
Know that this paper has come out we need to increase the chances for all life to survive. By increasing C02 levels, we will trap more radiant energy which will negate the increase cloud cover. The additional CO2 and smog will create a "shield" against the cosmic rays! Come on everyone buy any American SUV and start driving! We will stimulate our economy and save the Planet!
Usupported by actual data. If you look at the Phanerozoic biodiversity data, it doesnt validate the 62 million years extinction cycle theory. You cant just take a small subset, selectively ignore data points that don't fit into your theory and preach the end of the world. Admittedly that does seem to sell books.
I will not be pushed, filed, stamped, indexed, briefed, debriefed or numbered. My life is my own.
when we finally figure it all out, it will completely change...and some maintain it already has...
What?! I'm outraged!
Humans are responsible for all bad things! Humans are not part of nature! That's what the media tells me. How dare something else be responsible! How dare our actions not be as important as we think they are!
I find being offended by me offensive.
The Five Big Extinctions were at 65, 206, 251, 364 and 439 million years ago.
I don't see much of a 62-million year cycle in those extinctions.
Hrm, I'm only glancing over the article in question, but I was just last week at a conference (North American Paleontological Conference, held in Cincinnati) where this work was presented.
As others have pointed out, cycles of diversity in the fossil record have been pointed out before, as have cycles in extinction rates. Dave Raup and Jack Sepkoski did some very important work in this. However, paleontologists have gone back and forth on whether that cyclicity really exists or not.
Melott and Bambach (Richard Bambach... a very very important paleoecologist!) presented work at NAPC that they have found the 62 mya cycle in a number of very different datasets of fossil diversity. This is important... it means the signal is very likely to be real.
I can't speak as to the astronomical mechanism they postulate; in the talk at NAPC, they suggested it might have to do with continental erosion rates (which is related to an idea Bambach has pushed many times before, particularly in a paper entitled "Seafood through Time" in the journal Paleobiology).
It will be more interesting, as Mike Foote (UChicago) pointed out at NAPC, to see if this cyclicity exists in the seperate origination and extinction rates, the combination of which produce the changes in diversity. Melott and Bambach were not at NAPC however, and the person they asked to substitute for them to present their paper (Eugenie Scott, head of an important science education taskforce) could not speak on the details of their work.
Spiral Arms Did Not Cause Climate Change on Earth
A new map of the Milky Way galaxy proves that the sun's motion through the spiral arms could not have caused a well-known climate-change cycle.
http://www.technologyreview.com/blog/arxiv/23763/
And that was the one time Albert was wrong...
Well, I'm glad that if Mellott is actually correct, I'll be long dead before this actually occurs, kind of like my fervent hopes for the destruction of Earth at the hands of a gigantic meteor. Although, this poses a question. Would you LIKE to be around to see Armageddon, or not? I'm pretty sure you can classify this scenario as Armageddon if it essentially wipes out a huge amount of life on Earth.
..the Earth leaving the Sun's heliosphere? As described in this article a few days ago: http://www.newscientist.com/article/mg20227144.700-sun-leaves-earth-wide-open-to-cosmic-rays.html The (predicted) length of time for a cycle for this event, and the event described in the story is only a single order of magnitude off. Fairly common yet acceptable difference in in the field of Astronomy, I've been told.
... and a dollar short.
This is twice in a week that someone has made assertions about mass extinctions, and both times their (different) numbers don't match the commonly accepted numbers http://en.wikipedia.org/wiki/Milky_way . (No, the Big W is not necessarily authoritative, but the sources referenced are.)
The solar system orbits the galactic center in 220 Myr. It oscillates through the galactic plane 2.7 times per orbit. That's a period of 81.5 Myr, and each crossing at half-period being 40.75 Myr. I doubt anyone would consider that an acceptable error margin.
Furthermore, the matter density in the galactic plane oscillates with a period 1/2 that of the galactic rotation, expanding out from the center in waves (density wave 25 Myr; spiral structure 50 Myr). Passing through the plane would have little effect unless these two coincide.
"I may be synthetic, but I'm not stupid." -- Bishop 341-B
We already know why one extinction event happened. The current one is caused by us. These leads me to believe that there may be some variety in causes of mass extinctions, and that no single theory will cut it.
Play Command HQ online
Oil and coal formed as there were not enough species of bacteria to cause decay before they got fossilized Arguably this will not happen anymore as most organic (and even some non organic) have bacteria which will cause them to decay in very short period of time into CO2, methane etc etc...
Only one question matters: when is the next one due?
"It's the height of ridiculousness to say for those 9 lines you get hundreds of millions."
From universe today:
Past Climate Change Cannot Be Tied to Earth Passing Through Galactic Plane
http://www.universetoday.com/2009/06/26/past-climate-change-cannot-be-tied-to-earth-passing-through-galactic-plane/
will heed the galactic call to "Aboort! Aboort!"
Previously: "Linux... Toward the Sunrise..." Now: "Linux... Toward the-- No, now, part of Every Sunrise"
From TFA:
(Huh? Gravity pull is an acceleration, not a velocity.)
I don't follow this. If the supercluster is pulling us in, it's also pulling in the intergalactic gas. We should be flowing along with that gas, not blasting through it.
How will the "We Have To Get Off This Rock wackjobs react to this? a) they will realize they are utterly out to lunch and give up, or b) they will now stridently insist that not only must humanity magically leave earth, but leave the galaxy as well!
You know which one they'll choose...
"Melancholy Elephants". http://www.spiderrobinson.com/melancholyelephants.html
You are not a brain: http://books.google.com/books?id=2oV61CeDx-YC
And in particular, they will wave back.
OMG....! It's only Schrodinger's pony!
(and in one helluva damn big box!)
.
- aqk
F U
space ship snug and safe from the interstellar soup dust.
Ohai, do you have a PhD in Physics and decades of experience in research?
The inter-galactic gas of the Local Group will hit the inter-galactic gas of the supercluster (Virgo) resulting in shock waves which will be transmitted to gas within the component galaxies, with possibly significant effects within those galaxies.
Clearer now?
Birds are not dinosaur descendants;birds are dinosaurs, for all useful meanings of "birds", "are" and "dinosaurs"