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  • I've just read the paper, which answers the question.

  • Why is mercury?

  • A liquid motor is special because it's the only metal that's unarguably liquid gallium.

  • You can melt when you warm it in your hands, but mercury is the only metal that's liquid at room temperature.

  • It's even liquid if you stick it in snow, so it's really no arguments.

  • There's something special about it.

  • Yes, chemists and physicists have known for a long time.

  • It's a liquid because the forces between the atoms are weaker than they are, say, with gold or other elements.

  • But nobody has been able to do calculations to show way the melting point of Mercury's minus 39 degrees centigrade.

  • But they have now, and it turns out that the key to all of this is relativity.

  • In fact, the article I've read has a special picture on the front of the journal cover, which shows a picture of Einstein when he had heard that looked like mine.

  • So it's really does connect relativity with motoring now.

  • The important aspect of relativity that's involved is the fact that relativity says that if you take an object and accelerated toe very high speed, close to the speed of light or a good fraction of it, it becomes heavier.

  • How does this apply to an atom?

  • Well, atom has a positively charged nucleus and the negatively charged electron going round and round.

  • So for light atoms like hydrogen, which has just a single positive charge, the electron goes round relatively slowly.

  • But as you get down the periodic table and get bigger and bigger atoms pretend this is mercury with a big nucleus, the inner electrons have to go around it.

  • Terrific speed or else they would tumble into the nucleus.

  • And in fact, that speed becomes a significant fraction of the speed of light so the electrons become heavier and sink towards the nucleus.

  • So heavy atoms are actually smaller than you might expect because of these relativistic effects, and you can do calculations to show that this has a genuine effect.

  • For example, the gold color of the metal gold is due to relativistic effects of the electrons in the case of Mercury, what this paper has shown, and it has quite a nice title, evidence for low temperature melting of mercury going to relativity, quite a simple title on a very bold statement.

  • What they have sown is that you can explain the weak interactions between mercury atoms in terms of this relativistic effect.

  • Now it's quite complicated.

  • In general, the forces between atoms are determined by their size and by their electron distribution, how the electrons are arranged on the small of the atom and the more tightly the electrons are held.

  • So the week of the forces.

  • Now what this paper says, which is very interesting, is that if you take too much re atoms isolated, imagining the gas phase, the forces between them don't change very much with if you include relativistic effects in the calculations or not.

  • But it is only when you think of a whole group of motoring atoms, as you would imagine in a small droplet or micro nano droplet that the relativistic effects become important.

  • And this work has taken a long time to do because you need a really big computer to be ableto handle the calculations when you have a large group of atoms and you're doing the calculation about all those atoms at the same time.

  • In these calculations, they have looked at the effect off putting a relativistic correction because you do the calculation with an atom without taking a relativity and account or with relativity in account.

  • And so they've done this for two atoms, and then they've done for lots and lots and lots, which simulates the liquid.

  • And in particular, they can calculate the melting point.

  • That is when a solid metal turns into liquid.

  • And they've shown that without relativistic effects, they calculate the melting point of 82 degrees centigrade, which is only a little bit less than the melting point of sodium on dhe, higher than the melting point of cesium.

  • But with the relativistic effects, the melting point drops to the close to the observed melting point of 39 degrees, so they can actually calculate a number which is very close to the melting point of victory.

  • What they're showing is that when you put in the relativistic effect and effectively contract the inner electrons of the mo tree atoms, this has enough effect on the outer electrons of the atoms to stop the forces that would make it into a solid, you can see.

  • Even without the relativistic events, mercury wouldn't have a very strong interaction between the atoms.

  • It would melt it 82 degrees centigrade rather than the thousands of degrees that you find on something.

  • Other elements.

  • But this is if you like the fine tuning the relativity that takes the melting point from a boring above room temperature to really exciting below room temp.

  • So the fact that mercury is a liquid is more proof that Einstein was right.

  • Yes, of course.

  • The next challenge is to do the same calculation with Copan itsy um, element 112 because it's in the same rumors Mercury on dhe as you know, that elements in the same group in the periodic table have similar properties.

  • So Copan it's, um, could have an even lower melting point.

  • So we look forward to the paper on the melting point of Copan.

  • It's him.

  • And so this actually led people to suggest that there might actually be another planet that was perturbing the orbit of mercury that was even closer to the sun.

I've just read the paper, which answers the question.


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汞和相對論 - 視頻週期表 (Mercury and Relativity - Periodic Table of Videos)

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    林宜悉 發佈於 2021 年 01 月 14 日