
Advance in high-pressure physics - nrkfeller
http://news.harvard.edu/gazette/story/2017/01/a-breakthrough-in-high-pressure-physics/
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gene-h
It hasn't been confirmed yet[0]. Their evidence so far is that they saw
something shiny in the diamond anvil. The shiny thing may not necessarily be
metallic hydrogen, and could just be the coating.

There are also questions that they reached as high of a pressure as they said
they did.

Metallic hydrogen has been created in the lab before. Of course, in these
previous cases the metallic hydrogen didn't last long(neither did the test
apparatus) as the necessary pressures were reached using explosions.

The first confirmed production of metallic hydrogen used a giant gun to shoot
a large bullet at a small container of liquid hydrogen at ~7 kilometers per
second.[1] One unconfirmed attempt even used a specially designed bomb to
compress liquid hydrogen[2].

[0][http://www.nature.com/news/physicists-doubt-bold-report-
of-m...](http://www.nature.com/news/physicists-doubt-bold-report-of-metallic-
hydrogen-1.21379) [1][https://en.wikipedia.org/wiki/Metallic_hydrogen#Shock-
wave_c...](https://en.wikipedia.org/wiki/Metallic_hydrogen#Shock-
wave_compression.2C_1996)
[2][http://web.archive.org/web/20120321111752/http://lateralscie...](http://web.archive.org/web/20120321111752/http://lateralscience.co.uk/Hmetal/index.html)

~~~
sandworm101
Compressing hydrogen with explosions and bullets is actually very old and
well-understood science ... if you have the clearance. Explosively compressing
hydrogen is how you trigger hydrogen bombs (also via radiation pressure, which
probably doesn't create metallic hydrogen). H-bomb research is all about
slamming things into liquid H2. I wouldn't be surprised to hear that metallic
hydrogen had been briefly produced somewhere in the desert during a bomb-
related test.

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Scramblejams
A few questions I didn't see addressed in the article:

Did they confirm metastability? I guess confirmation of that isn't as easy as
simply removing the pressure and seeing if it continues to shine and conduct
electricity, or they'd have mentioned it.

As rocket fuel, how do you convert it back to molecular hydrogen to release
all that energy? As simple as lighting it on fire in the presence of an
oxidizer?

Is it liquid or solid? If liquid, how practical is it going to be in their
suggested use in long-distance power transmission? You'd need some kind of
flexible packaging that doesn't allow for voids to open up (because then
you've lost conductivity) that also won't leak.

And if it's easy to light it on fire as rocket fuel, how can we prevent our
long-distance electricity lines from turning into fiery conflagrations in
hostile conditions? Could lightning strikes detonate them? Maybe that risk
could be reduced with high conductivity coatings on their outer wrap, but that
doesn't cover every eventuality.

I met a guy once who was in the business of providing valves for liquid
hydrogen handling, he said it was very tricky to handle the stuff safely.
Stringing it all over the countryside in a form that packs more than a 3x
energy punch of its conventional liquid form could be interesting.

~~~
wbl
It's solid, altough soft. For rocket fuel you could spray a disintegration
catalyst along with the oxidizer.

~~~
zardo
For rocket fuel, you probably would not want to oxidize it. Low molecular
weight in the propellent means higher exhaust velocities. Nuclear rocket
engines used H2 propellent.

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cowholio4
There are some skeptics. "Their main concern is that Silvera and Dias really
only have one data point: a single measurement of the reflectivity of their
sample at high pressure. While that could indicate metallic hydrogen, it could
also be something else, like the alumina coating they used on the diamonds to
prevent hydrogen from leaking into the crystal and making it brittle."
[http://www.forbes.com/sites/samlemonick/2017/01/27/theres-
re...](http://www.forbes.com/sites/samlemonick/2017/01/27/theres-reason-to-be-
skeptical-about-metallic-hydrogen/#764646e1ae27)

------
cowholio4
This has been the week for high pressure experiments. Scientists were also
able to create a stable helium-sodium compound under high pressures.

[http://www.nature.com/nchem/journal/vaop/ncurrent/full/nchem...](http://www.nature.com/nchem/journal/vaop/ncurrent/full/nchem.2716.html)

[http://www.sciencealert.com/forget-what-you-learned-
scientis...](http://www.sciencealert.com/forget-what-you-learned-scientists-
might-have-just-created-a-stable-helium-compound)

------
lutusp
Quote: “One prediction that’s very important is metallic hydrogen is predicted
to be meta-stable,” Silvera said. “That means if you take the pressure off, it
will stay metallic, similar to the way diamonds form from graphite under
intense heat and pressure, but remain diamonds when that pressure and heat are
removed.”

But the article doesn't say whether the observed result persisted after the
pressure was removed.

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corndoge
Previously:

[https://news.ycombinator.com/item?id=12875868](https://news.ycombinator.com/item?id=12875868)

