Metallic hydrogen created in the lab

[Auto-Didact]

Mentor note: Two threads got merged, the first nine posts are a mixture of two original threads.

http://science.sciencemag.org/content/early/2017/01/25/science.aal1579

Producing metallic hydrogen has been a great challenge to condensed matter physics. Metallic hydrogen may be a room temperature superconductor and metastable when the pressure is released and could have an important impact on energy and rocketry. We have studied solid molecular hydrogen under pressure at low temperatures. At a pressure of 495 GPa hydrogen becomes metallic with reflectivity as high as 0.91. We fit the reflectance using a Drude free electron model to determine the plasma frequency of 32.5 ± 2.1 eV at T = 5.5 K, with a corresponding electron carrier density of 7.7 ± 1.1 × 10^23 particles/cm^3, consistent with theoretical estimates of the atomic density. The properties are those of an atomic metal. We have produced the Wigner-Huntington dissociative transition to atomic metallic hydrogen in the laboratory.

The rest is behind a pay wall.
From the abstract alone it is somewhat unclear whether or not this metallic hydrogen remains (meta)stable when the pressure is removed.

 

[dwn]

The "click bait" has become endless. Attention-grabbing headlines flourish across every platform and frankly, it's become ridiculous to even try fact-checking articles. For every article supporting a claim, there are just as many disproving it. Fake news, plentiful it is.

Across the headline today, Metallic Hydrogen, It's About To Change The World (!). For the lay-person such as myself, it was such an exciting article to read -- the potential opportunities that could originate from this technology. Of course, my excitement was quickly dashed once I realized the absolute absurdity this article was proclaiming. Only after reading some of the comments below the article did I plant my feet firmly back on the ground.

Anyways, to the point of this post...would someone be able to explain what appears to be an impossible hurdle that must be overcome for superconductors (created at -297° F) to be utilized under less extreme conditions? Is this technology 10, 50, or 100+ years away?

(*sorry about the rant, but needed to vent my frustrations)

 

[Borek]

Perhaps the thing you are missing is that they are superconductors only in low temperatures. Once you heat them up they become normal conductors.

It is not that the low temperature is needed to make the superconductor, we can prepare the substance at much higher temperatures (and we typically do). But we have to cool it down to make it superconducting.

We do use that technology, just in places where cooling is not cost prohibitive (or, in other words, where the price of cooling is acceptable).

Sorry if that's just a trivial info you know and you were looking for something else.

 

[mfb]

Superconductors rely on the formation of Cooper pairs: weakly bound pairs of electrons. Heat the material too much and you destroy the pairs based on thermal fluctuations.

Finding materials where those Cooper pairs are stronger has always been challenging. Metallic hydrogen might be such a material, but it is unclear if it can exist outside diamond anvil cells. And even if it can, it is not something you want in your household: If it transforms back to normal hydrogen it releases a huge amount of energy.

 

[Ryan_m_b]

Finding materials where those Cooper pairs are stronger has always been challenging. Metallic hydrogen might be such a material, but it is unclear if it can exist outside diamond anvil cells. And even if it can, it is not something you want in your household: If it transforms back to normal hydrogen it releases a huge amount of energy.

Do we have any models predicting how stable MS-metallic hydrogen would be or is it still a very open question? Is there a chance that it would take quite a lot of activation energy to convert it back to gaseous hydrogen?

 

[mfb]

The publication doesn't discuss the status of the metallic hydrogen after reducing the pressure, so I guess it transformed back to normal hydrogen - even at the cryogenic temperatures used in the experiment (5-83 K).

Edit: Turns out that they didn't depressurize it at all, so we don't know. It got depressurized in an uncontrolled way in February.

 

[ZapperZ]

http://science.sciencemag.org/content/early/2017/01/25/science.aal1579
The rest is behind a pay wall.
From the abstract alone it is somewhat unclear whether or not this metallic hydrogen remains (meta)stable when the pressure is removed.

It isn't very stable to start with because of the extreme low temperature. However, this "metastable" state appears to be there only under such pressure.

BTW, let's not celebrate too quickly on this one.

http://www.nature.com/news/physicists-doubt-bold-report-of-metallic-hydrogen-1.21379

The popular media, as usual, are going bonkers over this.

Zz.

 

[Astronuc]

The publication doesn't discuss the status of the metallic hydrogen after reducing the pressure, so I guess it transformed back to normal hydrogen - even at the cryogenic temperatures used in the experiment (5-83 K).

From the abstract - "At a pressure of 495 GPa hydrogen becomes metallic . . . " Not very practical for large applications. I don't believe it will revolutionize space travel.

 

[StatGuy2000]

Since I do not have a subscription of the publication on Science magazine, I had read the pre-print on Arxiv, and did a quick search on Wikipedia, which pointed me to an article on Nature with other physicists expressing scepticism of the results of the Harvard researchers.

http://www.nature.com/news/physicists-doubt-bold-report-of-metallic-hydrogen-1.21379

 

[mfb]

From the abstract - "At a pressure of 495 GPa hydrogen becomes metallic . . . " Not very practical for large applications. I don't believe it will revolutionize space travel.

There seems to be some hope that it might be stable even after the pressure is reduced. Questionable, but at least not ruled out yet.

 

[hilbert2]

In the ideal case, it could keep metastable at STP, and there would exist some catalyst that would immediately make it convert explosively to normal $H_2$ gas...

 

[Buffu]

Can anyone explain to me what metallic mean in this context. Does hydrogen became shiny silvery thing which conduct electricity ?

It is still hydrogen not some magic, I guess it will still produce same compounds like water, peroxide and so on. How this is going to revolutionise anything ?

 

[ZapperZ]

Can anyone explain to me what metallic mean in this context. Does hydrogen became shiny silvery thing which conduct electricity ?

It is still hydrogen not some magic, I guess it will still produce same compounds like water, peroxide and so on. How this is going to revolutionise anything ?

But here's a lesson that many people do not know. More Is Different.

When a gazillion atoms get together and become close and comfy, the resulting material, a solid, often has a set of characteristics that can be VERY different than the characteristics of a single atom or molecule. We know this because atoms and molecules do not form energy bands that can turn the solid into a conductor, a semiconductor, an insulator, etc. These are all emergent phenomena that are not present in individual atoms. Thus, More Is Different.

Forming a metallic hydrogen, if they actually did this, means that they have pushed the hydrogen solid so close together that the conglomerate of all the hydrogen atoms have formed these energy bands, and that the band structure has produced a solid that is a metal/conductor. This is significant because IF we understand band structure, this was predicted a long time ago for hydrogen. The first step in this, which is forming a solid hydrogen, has already been accomplished. But the location of these hydrogen atom in the solid lattice are still too far from each other to produce this metallic properties that was predicted. That is why this experiment was done, because if this theory is correct, then we will have a better knowledge of another part of band theory.

More Is Different.

Zz.

 

[Andrew Wright]

In the ideal case, it could keep metastable at STP, and there would exist some catalyst that would immediately make it convert explosively to normal $H_2$ gas...

Sounds like a very expensive missile fuel
:(

 

[bhobba]

The popular media, as usual, are going bonkers over this.

It's really annoying after awhile.

I am so glad I can come here and in those areas I do know about help, and read from experts in areas, like this, I don't.

I am into audio as well and it has the same problem. I listen a lot to gear and the strange thing is some things you think are hooey make a huge difference, and others you think should be fantastic do nothing or make it worse. Other times its no so clear cut and people argue about - is it worse or better. I was caught in one of those on the weekend but that is a whole new story and a demonstration of my lead ears compared to those that have been doing it on a daily basis for 30 or 40 years as part of their job (one designs and builds speakers professionally, the other installs high end Hi Fi and home theatre systems). Its humbling.

One recent thing I have been mucking around with that did live up to the hype is MQA (and for good technical reasons):
https://en.wikipedia.org/wiki/Master_Quality_Authenticated

I was listening on a very good reference system with an extremely good audiophile (the speaker guy above) to MQA on the Tidal streaming system. He and I were gob-smacked. Then the reality check. He went home, set it up on his home system, and was equally gob-smacked except it dropped out every few minutes. Bummer. Just goes to show you make a genuine breakthrough then it gets ruined by other factors. It will of course get sorted out - eventually.

Thanks
Bill

 

[Auto-Didact]

But here's a lesson that many people do not know. More Is Different.

When a gazillion atoms get together and become close and comfy, the resulting material, a solid, often has a set of characteristics that can be VERY different than the characteristics of a single atom or molecule. We know this because atoms and molecules do not form energy bands that can turn the solid into a conductor, a semiconductor, an insulator, etc. These are all emergent phenomena that are not present in individual atoms. Thus, More Is Different.

Forming a metallic hydrogen, if they actually did this, means that they have pushed the hydrogen solid so close together that the conglomerate of all the hydrogen atoms have formed these energy bands, and that the band structure has produced a solid that is a metal/conductor. This is significant because IF we understand band structure, this was predicted a long time ago for hydrogen. The first step in this, which is forming a solid hydrogen, has already been accomplished. But the location of these hydrogen atom in the solid lattice are still too far from each other to produce this metallic properties that was predicted. That is why this experiment was done, because if this theory is correct, then we will have a better knowledge of another part of band theory.

More Is Different.

Zz.

On somewhat of a tangent but regarding Phil Anderson's statements toward the end of the paper, it is interesting and actually quite telling that he references Marx ("quantitative changes become qualitative ones"), famous of course for Marxism, i.e. dialectical materialism. I digress.

In any case, Anderson essentially seems to be arguing for a change in not merely the philosophy of physics, but more generally in the philosophy of science, rebuking not only the naive reductionism of the particle physicist but especially that of the (molecular) biologist as well. This reprehension is in my opinion fully warranted and it is somewhat a mystery that the reductionist point of view still isn't weeded out more actively during scientific training.

Reductionist scientific reasoning clearly is a relic of the (recent) past cancerously persisting into the present, where all phenomenon and even the laws themselves are in many circles still regarded as linear systems, i.e. the idea that the whole is nothing more than the sum of its parts and that effects are in direct proportion to causes. This provisional stance comes of course first didactically and is perhaps even pedagogically useful; ultimately however it can be at best nothing more than a first order approximation.

Whenever one looks more closely at matters, be it in quantum field theory, condensed matter physics or any much higher level phenomena, it is practically always quite clear that the naive stance of reductionism is never the entire story. The fact of the matter is that most if not all phenomena in nature are inherently nonlinear, up to and including the very laws themselves. Ignoring nonlinearity on grounds of mathematical simplicity i.e. linearity, whether it be through perturbation, linearization or approximation is exactly the greatest source of kneejerk bias in all of science.

 

[hilbert2]

Sounds like a very expensive missile fuel
:(

If the enthalpy of formation of the metallic phase has a large positive (endothermic) value, it could be used as a high-energy fuel for any kind of rockets, not only military ballistic missiles.

 

[mfb]

Metastable metallic hydrogen would allow rockets that work a bit like helicopters: Lauch upwards through the atmosphere, accelerate to orbital speeds, deliver the payload, slow down and land slowly and vertically. No heat shield necessary because the rocket never travels through the atmosphere at high speeds. All with a single stage that can be used thousands of times as it is never subject to high stress. Only the reaction chamber and nozzle would be problematic as they would get very hot.

 

[bhobba]

Reductionist scientific reasoning clearly is a relic of the (recent) past cancerously persisting into the present, where all phenomenon and even the laws themselves are in many circles still regarded as linear systems, i.e. the idea that the whole is nothing more than the sum of its parts and that effects are in direct proportion to causes. This provisional stance comes of course first didactically and is perhaps even pedagogically useful; ultimately however it can be at best nothing more than a first order approximation.

Interesting view, thanks for posting it.

Its just when I read such sophisticated thinking I am taken back to my days as a computer programmer. On a day to day basis issues like that were not on anyone's mind - still it may be happening subconsciously.

Certainly in my scientific study that is not what's happening for me. It's the search for beauty which I have found in symmetry - as one book on physics put it - there is fire in the equations and that fire is what drives me. Just my view.

Thanks
Bill

 

[Auto-Didact]

Interesting view, thanks for posting it.

Its just when I read such sophisticated thinking I am taken back to my days as a computer programmer. On a day to day basis issues like that were not on anyone's mind - still it may be happening subconsciously.

Certainly in my scientific study that is not what's happening for me. It's the search for beauty which I have found in symmetry - as one book on physics put it - there is fire in the equations and that fire is what drives me. Just my view.

Thanks
Bill

Of course, beauty drives me as well. The question is what is deemed beautiful and why, i.e. what determines ones aesthetic sense? This touches very close to what drives pure mathematics. For example, simplicity of form is just one aspect of beauty. Complicated and/or 'unnatural' looking equations tend to be discarded a priori based on these feelings alone. But how is one to judge mathematical beauty of which one is unaware of, eg. non-circular orbits before Newton's explanation, gravitation as curved spacetime before Riemannian geometry or fractal orbits in phase space before Mandelbrot, Lorenz et al?

It seems to be pretty clear that most of our primary intuitions of the mathematically aesthetic are pretty similar; this should be no surprise given that most people tend to have largely the same mathematical basis. Beyond a certain point however personal choices are made, eg. a preference for geometric over algebraic considerations, in which when considering some mathematical structure, there might be some geometric beauty, which is absent - and therefore unappreciated - if viewed algebraically or viceversa, which again might lead one to abandon further inspection of said structure.

To get back to the discussion, the same arguments apply to considerations of physical phenomena based on their representation through physical laws. Knowing the phenomenon of conductivity from Maxwell's equation does little to help one on the way to understanding superconductivity. Moreover, extending BCS theory, through all attempted mathematical extensions so far - no matter how beautiful - does nothing to describe high temperature superconductivity, making it again nothing more than a first order approximation. This is analogous to Newtonian mechanics versus special relativity; there is no doubt however that the correct equation of superconductivity and related mathematical theory will be (deemed) beautiful when viewed from the correct perspective, just as in the case of relativity.

 

[nsaspook]

 

[Dr Wu]

All this sounds to me like cold fusion. That said, if all the claims made for metallic hydrogen turn out to be true, I still don't quite see how it would benefit spaceflight. I accept that having a metallic fuel/propellant would be a big plus, but reducing the volume doesn't reduce the mass. . . or am I missing out on something here?

 

[mfb]

Metallic hydrogen, if it could be used as rocket fuel for some weird reason, would have an extremely high energy density (released when it converts back to normal hydrogen). It can leave the rocket at very high speeds. You get more thrust with the same amount of mass. The delta_v capability increases. All those statements are basically equivalent, corresponding to different views of the rocket equation and momentum conservation.

 

[Dr Wu]

Yes, I do understand now. Although metallic hydrogen is touted as being (potentially) meta-stable, by allowing it to expand back into its gaseous state releases a lot of energy. This obviously has applications for energy storage then, down here on Earth, that is - aside from offworld exotica, like enhanced rocket fuels. Another somewhat futuristic notion: the same principle, I assume, could be applied to antihydrogen? Just a thought.

 

[mfb]

Antihydrogen (or antimatter in general) has an energy density orders of magnitude higher than metallic hydrogen. Producing and storing it in relevant amounts is more than challenging.

 

[sshai45]

I am wondering why everyone is jumping on trying to figure out or debunk the "hype" -- to me, I am chiefly after here as to whether or not the metallic hydrogen has been created at all as some suggest it hasn't, e.g.:

http://www.forbes.com/sites/samlemo...eptical-about-metallic-hydrogen/#4d8555291ae2

To me, the mere fact of creation of metallic hydrogen, whether there is a "metastable" form under "ordinary" conditions or not, would be super cool because this stuff is the stuff that is supposedly found in the deep interiors of the gas giant planets and being able to understand this -- heck, being able to _produce_ it in a lab and then experiment on it -- would seem to be a major step toward gaining insight into the processes going on with such planets. Basic research is itself interesting, no, even if there isn't necessarily any immediate or direct application -- something else that comes off of it could have application. And all the better when this experiment is still relatively-"tabletop" in nature.

(I also wonder about applications too. Even if it is only stable at high static pressure, could not one potentially produce, someday, say, microscopic superconducting devices that are pre-pressurized to extreme pressure, perhaps in some kind of diamond seal, and that might have some utility even if you aren't going to be making big cables and wires out of the stuff? And I also wonder about the possibility of using it for making electrical devices that could operate in the deep interior of a gas giant, e.g. to make "dumb probes" that could probe down in there -- lots and lots of wild and crazy stuff comes to mind.)

 

[DrClaude]

I would like to remind everyone that PF is not the place for discussing philosophy.

 

[Greg Bernhardt]

The World's Only Metallic Hydrogen Sample Has Disappeared
http://www.sciencealert.com/the-world-s-only-metallic-hydrogen-sample-has-disappeared

 

[mfb]

Wait... they kept it in the diamond anvil cell the whole time? That is interesting.
It explains why they didn't comment on the depressurization process.

The idea of a tiny bit of metastable metallic hydrogen somewhere in the lab, just too small to be found, is quite funny. Get your magnifying glasses and keep the cleaning staff out!

Relevant xkcd

 

[PAllen]

This appears not posted yet. The original researchers respond to various criticisms:

https://arxiv.org/abs/1703.03064