Kawasaki Concours Forum
Mish mash => Open Forum => Topic started by: Conrad on February 18, 2018, 06:52:29 AM
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A VERY interesting article.
http://www.foxnews.com/science/2018/02/14/earths-inner-core-shouldnt-technically-exist.html (http://www.foxnews.com/science/2018/02/14/earths-inner-core-shouldnt-technically-exist.html) (see that G? CNN isn't my only news source)
One day, about a billion years ago, Earth's inner core had a growth spurt. The molten ball of liquid metal at the center of our planet rapidly crystallized due to lowering temperatures, growing steadily outward until it reached the roughly 760-mile (1,220 kilometers) diameter to which it's thought to extend today.
That's the conventional story of the inner core's creation, anyway. But according to a new paper published online this week in the journal Earth and Planetary Science Letters, that story is impossible.
In the paper, the researchers argued that the standard model of how the Earth's core formed is missing a crucial detail about how metals crystallize: a mandatory, massive drop in temperature that would be extremely difficult to achieve at core pressures. [6 Visions of Earth's Core]
Weirder still, the researchers said, once you account for this missing detail, the science seems to suggest that Earth's inner core shouldn't exist at all.
The paradox at the center of our planet
"Everyone, ourselves included, seemed to be missing this big problem," study author Steven Hauck, a professor of Earth, Environmental and Planetary Sciences at Case Western Reserve University in Ohio, said in a statement. Namely, they were missing "that metals don't start crystallizing instantly unless something is there that lowers the energy barrier a lot."
In chemistry, this extra energy is known as the nucleation barrier: the point at which a compound visibly changes its thermodynamic phase. Liquid water, for example, freezes into a solid at the familiar 32 degrees Fahrenheit (0 degrees Celsius). If you've ever made ice cubes at home though, you know that even water stored at its freezing point can take several hours to fully crystallize. To speed up the process, you need to either expose the water to significantly colder temperatures (this is called "supercooling") or expose it to an already-solid piece of ice to lower the nucleation barrier, reducing the amount of cooling required.
Supercooling is easily achieved for a single ice cube, but for Earth's gigantic inner core, things get a little trickier, the researchers said.
"At the pressures of the core, it would have to cool 1,000 degrees Kelvin[726 degrees C or 1,340 degrees F] or more below the melting temperature in order to crystallize spontaneously from pure liquid," Hauck told Live Science. "And that's a lot of cooling, especially since at the moment, the scientific community thinks the Earth cools maybe about 100 degrees K per billion years."
According to this model, "the inner core shouldn't exist at all, because it could not have been supercooled to that extent," study author Jim Van Orman, also a professor of Earth, Environmental and Planetary Sciences at Case Western, told Live Science. The molten inner core's nucleation barrier, he said, must have lowered some other way — but how?
The core of the problem
In their paper, the researchers proposed one possibility: Perhaps a massive nugget of solid metal alloy dropped from the mantle and plunged into the liquid core. Like an ice cube dropped into a glass of slowly freezing water, this solid chunk of metal could have lowered the core's nucleation barrier enough to kick-start a rapid crystallization.
There's a big caveat, though: It would have to be a truly massive chunk of metal to work.
"In order to be released into the core and then make it all the way down to the center of the Earth without dissolving … this droplet would have to be on the order of about 10 km [6.2 miles] in radius," Van Orman said. That means a diameter about the length of the island of Manhattan.
The Case Western researchers said that while they favor this new explanation over the conventional model, they're eager for members of the scientific community to weigh in with theories of their own.
"We've talked about what ideas are implausible, and we've suggested an idea that's potentially plausible," Hauck said. "If it happened that way, it's possible that some signature of that event might be detectable through seismic studies. Studying the centermost part of the planet is about the hardest to access with these waves, so it'll take time."
Hopefully, we can look forward to an answer within the next billion years.
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Maybe the massive hunk of iron was the meteor that caused one of the extinction events, instead of vaporizing when it hit the surface, it plunged straight on through to the center of the Earth.
Or perhaps I have been right all along, and this planet is hollow, and there is a super-massive alien spaceship that lies down there, made of a neutronium/vibranium alloy that shields them from detection, while they keep watch on us.
The truth is in there.......
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#2
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How can the earth have a core?
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How can the earth have a core?
How can it not?
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Maybe the massive hunk of iron was the meteor that caused one of the extinction events, instead of vaporizing when it hit the surface, it plunged straight on through to the center of the Earth.
Or perhaps I have been right all along, and this planet is hollow, and there is a super-massive alien spaceship that lies down there, made of a neutronium/vibranium alloy that shields them from detection, while they keep watch on us.
The truth is in there.......
fify
(http://orig10.deviantart.net/fa20/f/2011/196/b/f/the_truth_is_out_there_by_phrakked-d3t52b4.jpg)
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How can it not?
Does a pancake have a core?
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Does a pancake have a core?
Does French toast?
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Does French toast?
If you run a steam-roller over the globe from your kid's bookshelf, both the core-faithful and the flat-earthers should be happy.
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Does a pancake have a core?
Maybe your parents can get a refund of their school taxes.
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Maybe your parents can get a refund of their school taxes.
skool?
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Jules had it right over 100 years ago. It's hollow!
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Its a solid core and chemistry and physics both predict it...sorry...
The earth's core is under tremendous pressure and temperature. Most things melt as the temp goes up and the electrons fly around faster, however, get super pressure and super temp and the electrons eventually have no space to fly around in any more and "they align again" as they do in a solid.
(Yep that's the simplified explanation)
Pretty sure iron returns to a solid state at earth's core temps and pressures.
I'd let anyone contradict me on this, as nobody's ever been there yet to tap on it and see if'n its solid ;)
From Wikipedia:
The temperature of the inner core can be estimated by considering both the theoretical and the experimentally demonstrated constraints on the melting temperature of impure iron at the pressure which iron is under at the boundary of the inner core (about 330 GPa).
These considerations suggest that its temperature is about 5,700 K (5,400 °C; 9,800 °F).
The pressure in the Earth's inner core ranges from about 330 to 360 gigapascals (3,300,000 to 3,600,000 atm). Iron can be solid at such high temperatures only because its melting temperature increases dramatically at pressures of that magnitude (see the Clausius–Clapeyron relation).
A report published in the journal Science concludes that the melting temperature of iron at the inner core boundary is 6230 ± 500 K.
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If you run a steam-roller over the globe from your kid's bookshelf, both the core-faithful and the flat-earthers should be happy.
But what about the kid? He's not going to be too happy that his fav globe just got smooshed. (fyi, both of my sons are grown and have left the nest years ago)
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Know any kid (male, of any age) who doesn't enjoy getting stuff crushed by a steamroller, especially educational stuff? :)
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fify
(http://orig10.deviantart.net/fa20/f/2011/196/b/f/the_truth_is_out_there_by_phrakked-d3t52b4.jpg)
Only Arne Saknussem really knows.
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Arne's no joke - he's the real deal.
That said, all this pressure is getting to me. Probably time to retire.
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Arne's no joke - he's the real deal.
That said, all this pressure is getting to me. Probably time to retire.
From?
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As an aside to this thread, it has always amazed me at how far down we [have not] gone in this planet we live on. Humans have not drilled down very deep into the crust at all, and that is with a drill, never mind tunnel down with a hole big enough for a human to fit into (yep, there are several jokes in that). We have done some miraculous things with our feeble skills and efforts but excavating down into the Earth is not really one of the impressive ones, at least to me.
It is going to be a while before we get core samples me thinks.
Brian
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I saw where the last core sample test was a fail....
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From?
Work, of course. Except in my case, to retire from my 2nd career.
It can't happen soon enough.