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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.
Next; 10 hours in a day, 10 minutes in an hour and 10 seconds in a minutes? Minutes, seconds and hours are still around aren't they?
You can evenly divide 12 sheep between 2,3,4 or 6 people. You can divide 60 sheep between 2,3,4,5,6,10,12,15,20,30 people. Not bad if you consider trying it with 10 or 100.
These numbers were viewed as convenient back then. That's why we still buy eggs by the dozen; 360 degrees, 24 hours, etc.
212F-32F is 180 which is 3*60 etc. etc.
You should get used to old units, they constitute a good mental exercise. It is a little like the queen of England speaking pretty good French. For them it a must, a sign of noblesse, despite the fact that French can be pretty awkward sometimes.
Good luck!
Everything I write is lies, read between the lines.
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.
It isn't like Celsius isn't just as arbitrary or obsolete
And in one fell swoop... you've revealed that you know fuck-all about basic physics and chemistry. Well done. ;)
To be certain, I use the metric system almost exclusively - I'm just under no illusion that it isn't arbitrary. So here we go.........
Tell me the boiling point of water at 10,000 meters in altitude. Is it 100 degrees Celsius? If not, why is 100 degrees celsius considered the boiling point of water, which the Celsius temperature is based upon?
Time for some telling.
Water, which someone decided was the universal and unambiguous basis of temperature, somehow knows that there are exactly 100 degrees between it's freezing point and it's boiling point. No it doesn't. Now some more questions. Is water that is cooled below 0 Celsius frozen? Not always - hence the term supercooled Liquid. What's the composition of that water anyhow? You might say distilled? More on that later.
Absolute zero in the Celsius scale is -273.15 degrees Celsius. You know you have an inexact system when your standard has significant digits tacked onto it. And the Boiling point of water at Sea level has been abandoned for the triple point of special water named "Vienna Standard Mean Ocean Water". This replaces "average Ocean Water and melted snow as references.
If that isn't ambiguous, I don't know what is. So what would be do?
What we are left with is Absolute zero and Absolute hot. These are probably the closest we can approach to unambiguous temperatures. Absolute 0 is assigned the value of 0 degrees Kelvin, and Absolute hot is at the moment considered to be 1.416785(71)×1032 degrees K. There is some argument over this - even this is eligible to change. I'm not going to give that the unambiguous label.
Other examples of the ambiguity and lack of precision in some accepted units are the Metre, which was originally described as 1 ten-millionth of the distance from the equator to the north pole. At a line running through a loaction in France. Important because the earth isn't spherical - it's na oblate spheroid. Then it became the length of a X shaped cross section Platinum-Iridium Meter bar, then it became referenced by Krypton-86, and stand by for this little bit of exactness. One Metre equals 1,650,763.73 wavelengths of the radiation corresponding to the transition between the levels 2p10 and 5d5 of the krypton 86 atom. in a Krypton 86 Discharge lamp in a vacuum. Good grief! I forgot to add, the lamp was running at the triple point of Nitrogen.
Today, we've at least simplified things a bit by using lasers and the distance traveled by light. First by a methane stabilized laser, and now by a Helium-Neon laser stabilized by iodine, and have come up with a new official definition of a Metre.
It is the length of this laser light travels in 1/299,792,458 th of a second.
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?
The shepherds did so well protecting the flock that the sheep no longer believed that wolves existed.
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