# FeaturedI Metallic hydrogen created in the lab

1. Jan 26, 2017

### 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 [Broken]

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.

Last edited by a moderator: May 8, 2017
2. Jan 27, 2017

### 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)

3. Jan 27, 2017

### Staff: Mentor

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.

4. Jan 27, 2017

### Staff: Mentor

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.

5. Jan 27, 2017

### Staff: Mentor

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?

6. Jan 27, 2017

### Staff: Mentor

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.

Last edited: Feb 24, 2017
7. Jan 27, 2017

### ZapperZ

Staff Emeritus
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.

8. Jan 27, 2017

### Astronuc

Staff Emeritus
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.

9. Jan 27, 2017

### StatGuy2000

10. Jan 27, 2017

### Staff: Mentor

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.

11. Jan 27, 2017

### 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...

12. Jan 31, 2017

### 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 ?

13. Jan 31, 2017

### ZapperZ

Staff Emeritus
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.

14. Jan 31, 2017

### Andrew Wright

Sounds like a very expensive missile fuel
:(

15. Jan 31, 2017

### bhobba

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

16. Feb 1, 2017

### Auto-Didact

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.

17. Feb 1, 2017

### hilbert2

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.

18. Feb 1, 2017

### Staff: Mentor

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.

19. Feb 1, 2017

### bhobba

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 whats 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

20. Feb 2, 2017

### Auto-Didact

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.