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Fact or Fiction?: Dark Matter Killed the Dinosaurs

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Fact or Fiction?: Dark Matter Killed the Dinosaurs

Old 04-03-15, 12:20 AM
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Fact or Fiction?: Dark Matter Killed the Dinosaurs

The theory states that as our galaxy rotates, every 26 million years our solar system passes near a large collection of dark matter, whose gravity causes comets to smash into earth.

Scientific observations suggest that this theory has a lot of merit. I think it makes a lot of sense.


http://www.scientificamerican.com/ar...the-dinosaurs/

Fact or Fiction?: Dark Matter Killed the Dinosaurs

March 25, 2015

A new out-of-this-world theory links mass extinctions with exotic astrophysics and galactic architecture

Every once in a great while, something almost unspeakable happens to Earth. Some terrible force reaches out and tears the tree of life limb from limb. In a geological instant, countless creatures perish and entire lineages simply cease to exist.

The most famous of these mass extinctions happened about 66 million years ago, when the dinosaurs died out in the planet-wide environmental disruption that followed a mountain-sized space rock walloping Earth. We can still see the scar from the impact today as a nearly 200-kilometer-wide crater in the Yucatan Peninsula.

But this is only one of the “Big Five” cataclysmic mass extinctions recognized by paleontologists, and not even the worst. Some 252 million years ago, the Permian-Triassic mass extinction wiped out an estimated nine of every ten species on the planet—scientists call this one “the Great Dying.” In addition to the Big Five, evidence exists for dozens of other mass extinction events that were smaller and less severe. Not all of these are conclusively related to giant impacts; some are linked instead to enormous upticks in volcanic activity worldwide that caused dramatic, disruptive climate change and habitat loss. Researchers suspect that many—perhaps most—mass extinctions come about through the stresses caused by overlapping events, such as a giant impact paired with an erupting supervolcano. Maybe the worst mass extinctions are simply matters of poor timing, cases of planetary bad luck.

Or maybe mass extinctions are not matters of chaotic chance at all. Perhaps they are in fact predictable and certain, like clockwork. Some researchers have speculated as much because of curious patterns they perceive in giant impacts, volcanic activity and biodiversity declines.

In the early 1980s, the University of Chicago paleontologists David Raup and Jack Sepkoski found evidence for a 26-million-year pattern of mass extinction in the fossil record since the Great Dying of the Permian-Triassic. This 26-million-year periodicity overlaps and closely aligns with the Big Five extinctions, as well as several others.In subsequent work over the years, several other researchers examining Earth’s geological record have replicated Raup and Sepkoski’s original conclusions, finding a mass-extinction periodicity of roughly 30 million years that extends back half a billion years. Some of those same researchers have also claimed to detect similar, aligned periodicities in impact cratering and in volcanic activity. Every 30 million years, give or take a few million, it seems the stars align to make all life on Earth suffer. Yet for want of a clear mechanism linking all these different phenomena together, the idea has languished for years at the scientific fringe.

It may not be a fringe idea much longer. According to Michael Rampino, a geoscientist at New York University, dark matter may be the missing link—the mechanism behind Earth’s mysterious multi-million-year cycles of giant impacts, massive volcanism and planetary death.

Dark matter is an invisible substance that scarcely interacts with the rest of the universe through any force other than gravity. Whatever dark matter is, astronomers have inferred there is quite a lot of it by watching how large-scale structures respond to its gravitational pull. Dark matter seems to constitute almost 85 percent of all the mass in the universe, and it is thought to be the cosmic scaffolding upon which galaxies coalesce. Many theories, in fact, call for dark matter concentrating in the central planes of spiral galaxies such as the Milky Way. Our solar system, slowly orbiting the galactic core, periodically moves up and down through this plane like a cork bobbing in water. The period of our bobbing solar system is thought to be roughly 30 million years. Sound familiar?

In 2014, the Harvard University physicists Lisa Randall and Matthew Reece published a study showing how the gravitational pull from a thin disk of dark matter in the galactic plane could perturb the orbits of comets as our solar system passed through, periodically peppering Earth with giant impacts. To reliably knock the far-out comets down into Earth-crossing orbits, the dark-matter disk would need to be thin, about one-tenth the thickness of the Milky Way’s visible disk of stars, and with a density of at least one solar mass per square light-year.

Randall and Reece’s theory is broadly consistent with dark matter’s plausible properties, but the researchers only used it to explain the periodicity of impacts. In his new study, published in the Monthly Notices of the Royal Astronomical Society, Rampino suggests dark matter can explain the presumed periodicity of volcanism, too. The idea dates back to at least the 1990s in peer-reviewed literature.

If dark matter forms dense clumps rather than being uniformly spread throughout the disk, Rampino says, then Earth could sweep up and capture large numbers of dark-matter particles in its gravitational field as it passes through the disk. The particles would fall to Earth’s core, where they could reach sufficient densities to annihilate each other, heating the core by hundreds of degrees during the solar system’s crossing of the galactic plane. For millions of years, the overheated core would belch gigantic plumes of magma up toward the surface, birthing gigantic volcanic eruptions that rip apart continents, alter sea levels and change the climate. All the while, comets perturbed by the solar system’s passage through the dark-matter disk would still be pounding the planet. Death would come from above and below in a potent one-two punch that would set off waves of mass extinction.

If true, Rampino’s hypothesis would have profound implications not only for the past and future of life on Earth, but for planetary science as a whole. Scientists would be forced to consider the histories of Earth and the solar system’s other rocky worlds in a galactic context, where the Milky Way’s invisible dark-matter architecture is the true cause of key events in a planet’s life. “Most geologists will not like this, as it might mean that astrophysics trumps geology as the underlying driver for geological changes,” Rampino says. “But geology, or let us say planetary science, is really a subfield of astrophysics, isn't it?”

The key question, of course, is whether some of the Milky Way’s dark matter actually exists in a thin, clumpy disk. Fortunately, within a decade researchers should have a wealth of data in hand that could disprove or validate Rampino’s controversial idea. Launched in 2013 to map the motions of a billion stars in the Milky Way, the European Space Agency’s Gaia spacecraft will help pin down the dimensions of any dark-matter disk and how often our solar system oscillates through it. The discovery and study of additional ancient craters could also confirm or refute the postulated periodicity of giant impacts and help determine how many were caused by comets rather than asteroids. If Gaia’s results reveal no signs of a thin, dense dark-matter disk, or if studies show that more craters are caused by rocky asteroids from the inner solar system than by icy comets, Rampino and other researchers will probably have to go back to the drawing board.

Alternatively, evidence for or against dark-matter-driven mass extinctions could come from extragalactic astronomy and even from particle physics itself. Recent observations of small satellite galaxies orbiting Andromeda, the Milky Way’s nearest neighboring spiral galaxy, tentatively support the existence of a dark-matter disk there, suggesting that our galaxy probably has one, too.

Even so, the University of Michigan astrophysicist Katherine Freese, one of the first researchers to rigorously examine how dark-matter annihilation could occur inside Earth, notes that Rampino’s scenario would demand “very special dark matter.” Specifically, the dark matter would have to weakly interact with itself to dissipate enough energy to cool and settle into a placid, very thin disk. According to Lisa Randall, who co-authored the 2014 paper suggesting dark matter might drive extinctions through giant impacts, several plausible theoretical models predict such a disk, but very few allow the dense intra-disk clumps required by Rampino’s hypothesis.

“In most models of dark matter, these clumps don’t exist,” Randall says. “Even if they do exist and are distributed in a disk, we don’t see that they will pass through the Earth sufficiently often. After all, clumps are not space-filling—there is room in between for the solar system to pass through.” Further, Randall notes that if dense clumps do exist in a thin disk of dark matter, the dark matter should occasionally annihilate in the clumps to produce gamma rays. “It’s not clear why we wouldn’t have already observed that gamma-ray signal,” she says.

There is also the possibility that theories of thin, self-interacting dark-matter disks could be swept away entirely if and when one of the many dark-matter detection experiments now underway finally spots its quarry and pins down the particulate identity of this elusive cosmic substance.

Or, perhaps most likely, the purported periodicities of mass extinctions, impacts and flood basalts are not as clear-cut and precisely aligned as might be hoped. Coryn Bailer-Jones, an astrophysicist at the Max Planck Institute for Astronomy in Heidelberg, Germany who has performed statistical analyses of impact-cratering rates as well as of mass extinctions, is skeptical that either of these exhibit periodic phenomena at all.

The problem is that the available data are not very good and carry immense uncertainties. Impact-crater statistics for Earth are notoriously variable and suspect. Their supposed periodicity fluctuates greatly depending on the minimum sizes of evaluated craters, and craters can be erased, obscured or even mimicked by a variety of geological processes. According to Bailer-Jones, biodiversity statistics from the fossil record are still more problematic, due to an even greater number of complex mechanisms dictating how, when and where fossils of different varieties of organisms are formed and preserved. Furthermore, Bailer-Jones notes, the solar system’s up-and-down oscillation through the Milky Way still has multi-million-year uncertainties.

While claims of overlapping, aligning periodicities within all this data could be significant and valid, Bailer-Jones says, in all likelihood they are instead the product of an all-too-human tendency to project order and logic onto little more than chaotic noise. Periodicity proponents have strenuously disagreed, and the heated, back-and-forth battle is still ongoing in the scientific literature.

“I think it’s interesting and worthwhile to ask these questions,” Bailer-Jones says. “But we must be careful not to give the impression that we actually have a problem that needs dark matter as a mechanism for mass extinction. It’s fine to talk about the mechanism, but the supposed periodicities—or rather, lack thereof—don’t provide any evidence for it.”

Rampino and others who see periodicities in fossils and craters freely acknowledge that their conclusions are speculative and that some of their statistics are presently underwhelming. Yet the telltale hints of order they glimpse in shattered rocks and scattered fossils still fuel their search for some final puzzle piece, some crucial evidence that will at last make everything cohere and confirm what could be the greatest cycle of life and death ever discovered.

One way or another, time will eventually tell. On geological timescales, our oscillating, bobbing solar system has recently crossed the mid-plane of the Milky Way, passing through the very region where a dark-matter disk would exist. Perhaps the faraway comets feel that gentle tug even now, and Earth’s core is already sizzling with dark-matter annihilation. Confirmation may be as close as the next spate of extinction-level cometary impacts or supervolcanic eruptions. Keep watching the skies—and the ground right beneath your feet.
Old 04-03-15, 12:52 AM
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Re: Fact or Fiction?: Dark Matter Killed the Dinosaurs

"In 2014, the Harvard University physicists Lisa Randall and Matthew Reece published a study showing how the gravitational pull from a thin disk of dark matter in the galactic plane could perturb the orbits of comets as our solar system passed through, periodically peppering Earth with giant impacts."

This is hawt.

Also, either we will never know if the theory is true or we will be killed when it is proven.
Old 04-03-15, 01:13 AM
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Re: Fact or Fiction?: Dark Matter Killed the Dinosaurs

I still have some time, right?
Old 04-03-15, 08:31 AM
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Re: Fact or Fiction?: Dark Matter Killed the Dinosaurs

Originally Posted by Why So Blu? View Post
I still have some time, right?
Yeah you're good, our time and even future generations years and years from now are fine as well...we are not even a speck on the ball sack of time.
Old 04-03-15, 08:38 AM
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Re: Fact or Fiction?: Dark Matter Killed the Dinosaurs

We are probably much more likely to be killed off by invading extraterrestrials than we are to be killed off by a giant asteroid or comet.

If there is a giant asteroid/comet coming our way, then we can always send up some oil drillers to drill a hole and nuke it.

I guess we may be able to upload a virus to the alien mothership too, so who knows, maybe aliens with advanced weaponry won't be much of a threat either.
Old 04-03-15, 09:59 AM
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Re: Fact or Fiction?: Dark Matter Killed the Dinosaurs

Originally Posted by Why So Blu? View Post
I still have some time, right?
It better be enough time to watch all those DVDs and Blu-rays that I have sitting on the shelf!
Old 04-03-15, 10:16 AM
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Re: Fact or Fiction?: Dark Matter Killed the Dinosaurs

TLDR; Is the end nigh? I've got my suicide pill ready.
Old 04-03-15, 10:58 AM
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Re: Fact or Fiction?: Dark Matter Killed the Dinosaurs

Uhhh... what is distinctly missing from this article is when the last extinction event happened.

Maybe it was 26-30 million years ago and we're due for a new one.
Old 04-03-15, 11:01 AM
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Re: Fact or Fiction?: Dark Matter Killed the Dinosaurs

Old 04-03-15, 11:24 AM
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Re: Fact or Fiction?: Dark Matter Killed the Dinosaurs

Dark matter is just what was left over by what really killed the dinosaurs...

Spoiler:
Old 04-03-15, 11:31 AM
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Re: Fact or Fiction?: Dark Matter Killed the Dinosaurs

Hypothesis.
Old 04-03-15, 11:55 AM
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Re: Fact or Fiction?: Dark Matter Killed the Dinosaurs

Sugar in easter eggs killed the dinosaurs!
Old 04-03-15, 11:55 AM
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Re: Fact or Fiction?: Dark Matter Killed the Dinosaurs

That's exactly how The Sopranos ended.
Old 04-03-15, 12:03 PM
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Re: Fact or Fiction?: Dark Matter Killed the Dinosaurs

If I ejaculate dark matter that is bad right?
Old 04-03-15, 12:07 PM
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Re: Fact or Fiction?: Dark Matter Killed the Dinosaurs

Originally Posted by Kurtie Dee View Post
Sugar in easter eggs killed the dinosaurs!
That and a gallon of iced tea per day. Screw you diabetic dinosaurs!
Old 04-03-15, 02:22 PM
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Re: Fact or Fiction?: Dark Matter Killed the Dinosaurs

Fact lol
Old 04-03-15, 04:32 PM
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Re: Fact or Fiction?: Dark Matter Killed the Dinosaurs

Dark matter, shmark matter. Sure, scientists love to go to the "something ran into the earth" theory to explain everything away, but wasn't it proven back around 1997 or so that rocks on Mars just spontaneously jump off their planet to slam into ours?

I blame Mars. And their subsidiary, the Wrigley Company.

And of course, by extension, the Chicago Cubs.
Old 04-03-15, 04:48 PM
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Re: Fact or Fiction?: Dark Matter Killed the Dinosaurs

Originally Posted by Talkin2Phil View Post
I believe this rather than 26 million year theory. It's always nice to make up shit you'll never ever have the chance to be proven wrong on.
Old 04-03-15, 06:37 PM
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Re: Fact or Fiction?: Dark Matter Killed the Dinosaurs

Originally Posted by DVD Polizei View Post
I believe this rather than 26 million year theory. It's always nice to make up shit you'll never ever have the chance to be proven wrong on.
Good point.

There was no 26 million years ago. Jewish people buried those bones.
Old 04-03-15, 06:51 PM
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Re: Fact or Fiction?: Dark Matter Killed the Dinosaurs

Dinosaurs went extinct because there were no master dinosaurs on Noah's ark. They all died in the flood.
Old 04-04-15, 03:17 PM
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Re: Fact or Fiction?: Dark Matter Killed the Dinosaurs

I blame Obama.
Old 04-04-15, 03:20 PM
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Re: Fact or Fiction?: Dark Matter Killed the Dinosaurs

To the laypeople, Josh-da-man is referring to Obamasaurus Iblamethemostus, which in my upcoming book, was responsible for killing all dinosaur life, and has resurfaced this century.

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