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New Research Suggests Earth's Mantle Might Be Hotter Than Anyone Expected (sciencealert.com)
schwit1 quotes a report from ScienceAlert: New data suggests that the upper parts of Earth's mantle are around 60C (108F) hotter than previously expected. The mantle is the layer between our planet's super-hot core and outer crust, and it plays an incredibly important role in things like earthquakes, volcanic eruptions, and tectonic shifts. But despite the impact the mantle has on our planet, scientists have always struggled to pinpoint its temperature, and new research suggests our previous estimates were off the mark. If the new estimates made by scientists at the Carnegie Institution of Science in Washington DC are verified, it would mean the mantle is melting shallower than previously expected, and it could change the way we predict earthquakes and volcanic eruptions. The new estimates are based on the fact that the Earth's upper mantle is more affected by the presence of water in its minerals than we've assumed in the past. One of the most common ways to measure the temperature of the upper mantle is to analyze lava emerging from mid-ocean ridges - an underwater mountain range where two plates meet and hot mantle is drawn up and partially melts. So to more accurately measure the temperature at which this would melt, the researchers, led by Emily Sarafian, have used a new technique to add a quantifiable amount of water into mantle samples through tiny particles of the mineral olivine. This allowed them to more accurately measure the melting point of peridotite under mantle-like pressures in the presence of known amounts of water. "Small amounts of water have a big effect on melting temperature, and this is the first time experiments have ever been conducted to determine precisely how the mantle's melting temperature depends on such small amounts of water," said one of the researchers, Erik Hauri. They found that the potential temperature of the mantle beneath the oceanic crust is on average around 60C higher than previous estimates - with some parts much hotter than that. "Our experimental results indicate that mantle potential temperatures along all ocean spreading centers are hotter than existing estimates," the team writes in Science.
As an American Slashdot reader, for all science articles I suggest that you stop providing both metric and imperial units. Metric is fine with us. Really.
If we need the conversion, we can do it in our heads. Most importantly, it will improve the signal-to-noise ratio in the comments by eliminating the ever-present unit-conversion threads.
It is absolutely ideal to to use negative numbers.
At zero water freezes, below zero it is frozen: very important for drivers, planes/airports etc. or house owners who have to organize clearing of snow, Skiing/winter sports areas etc. or estimations how long it takes that lakes freeze over.
Nothing can be simpler than having 0 at the freezing point of water.
You are just not used to it.
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
This is why I am always amused at the metric FTW crowd. I's just another system base upon something, something.
Then you have not grasped it. The only thing that you can replace in the SI system, that is the official name, not metric, and all the laws of physics can still be used the same way: is actually temperature. Because it is slightly disconnected, or lets say orthogonal to the rest of the system.
Or in other words: shooting a rocket to Mars is super simple to calculate in SI units with a pencil on paper. And close to impossible to do correctly by hand on paper in imperial units.
That is why SI was invented: you want to have mass, force, acceleration, time, distance in _convenient_ units that work together. Not in fragmented separated units for every single aspect of life.
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
Now just between me and the people who actually do know "fuck-all" about physics, it is pretty damn humorous that the metric system, which I often hear fans bragging about how you don't use fractions, is measured to the highest available accuracy.......
By a fraction. Howbow dah?
Well, that's a little funny. But us in SI-land at least have a definition. What I find more funny is that you in imperial land don't even have a definition. What I find funnier is that imperial units are defined in terms of the relevant SI unit. E.g. " The international avoirdupois pound is equal to exactly 453.59237 grams." Now, that's funny.
And it doesn't matter if 0C is distilled or salt water or whatever. It's much more convenient to know that if I'm close to 0C when driving I better watch out for ice, than "thirty something". The approximate freezing point of water makes practical sense in a lot of contexts, worthy of a "special" number. (Most everyday thermometers aren't accurate to more than +/- 1C anyway (half that if you're lucky), so the exact definition in the physics lab isn't that important for most cases anyway.)
Stefan Axelsson