Discussion of metallic hydrogen propulsion split from another thread.

[kerbiloid]

When somebody is sleeping and dreaming, usually the dream characters can't give answers beyond the sleeper's own knowledge, and the in-dream conversation looks like a monologue or a self-trolling.

Probably, we can now present at an unique situation, when two persons are sleeping and trying to talk in their common dream, but their cues don't form a queue.

P.S.
Never thought that METALLIC  HYDROGEN  (sic!) topic could be so flamy...

And they yet didn't start to discuss its electron clouds....

Edited July 28, 2020 by kerbiloid

[coyotesfrontier]

Skubtallic Hydrogen

[Vanamonde]

Many personal remarks have been removed. Please discuss the subject without making derogatory remarks about each other. 

[Guest]

7 hours ago, Hannu2 said:

I disagree. In my opinion it does not make idea realistic if some concepts are taken from real science, like fusion or antimatter, but every practical aspect is assumed to be technomagic. It also breaks the story. Why in the heck supercivilization able to build fusion powered machines and product and handle industrial quantities of antimatter has not investigated their whole solar system thousands of years before. It is as credible as astronauts in first manned rocket sent to investigate celestial crystal sphere of Moon would notice that "hey, you do not believe this, our planet is not flat disk but ball".

First of all, it doesn't take a "supercivilization" to make a fusion engine, most proposals for fusion spacecraft could have been built when they were proposed, assuming an astronomical budget. Second, you're not getting these engines at the start of the game, you have to develop them, so Kerbals were very much not capable of these things before you came along. In fact, you're in charge of doing the exact thing you mention. That is, exploring the entire Kerbol system, and the nearby stars, at the cusp of an era of fusion and antimatter power. In fact, by the time you get to these, you'll probably have gotten at least a probe to most of the planets using less efficient propulsion methods (at least, if the balance doesn't suck), and are making fusion ships to support permanent colonies on these planets.

8 hours ago, Hannu2 said:

Do you mean speculated real world hydrogen or dev's choice in the game? Latter can be of course whatever. I do not care much such details in this kind of situations. I think there is no need in thrusters more effective that NTR or fission powered ion engines in space exploration game, which models the civilization which makes first probes and manned excursions to bodies in their solar system. It takes probably hundreds or thousands of years development from that point to get those futuristic technomagic engines which makes it possible to colonize the whole system and make regular fast tourist and business traffic between planets.

Elon Musk is proposing to colonize Mars in this century, so it's hardly "hundreds and thousands of years". It might be a bit longer before the colonies start making money, but it's something that's within out reach right now, technologically speaking. The main barriers are economic. If humanity was to pour all its combined resources into it, we could likely manage to make an interstellar ship in a few decades, and that's what Kerbals are doing. They have no wars, no politics, or even cities, so they have leftover money to throw at the problem.  

Again, there's no "technomagic". Only the most advanced engines would require a serious breakthrough, things like inertial confinement or flow-stabilized Z-pinch have already been tested in a lab. An ICF engine is basically spaceborne NIF. It's far too expensive to build, but there's nothing wrong with the concept itself. There are unsolved engineering problems and, for the most advanced engines (mostly antimatter and non-pulsed fusion) some scientific ones, but again, people proposing various space missions using these engines are entirely serious about them. Even basic antimatter drives would be doable before the end of the century, if the whole humanity took an Apollo-style approach to it.

[DStaal]

21 hours ago, KerikBalm said:

[snip]

The point is that it seems like they just slung some buzzwords together, and I have yet to see any explanation as to how "cesium doping" is supposed to allow for magnetic confinement of ~6000k hydrogen.

It seems to me to make as much sense as saying they use a flux capacitor that modifies the phase variance to contain the exhaust.

If someone can explain how cesium doping is supposed to work, or provide the science behind it, I will withdraw my complaint.

Right now it seems to be prima facie techno-babble

My guess would be that it's really entrainment more than anything else - the cesium can be forced to move in the direction required, and the smaller, lighter hydrogen atoms will tend to follow the same paths.  (As they bump off of the cesium atoms or other hydrogen atoms that have bumped off of the cesium atoms.)  There would be some losses, but you design to balance the losses vs. reduction in ISP, and find a balance.

[KerikBalm]

13 hours ago, DStaal said:

the cesium can be forced to move in the direction required, and the smaller, lighter hydrogen atoms will tend to follow the same paths.  (As they bump off of the cesium atoms or other hydrogen atoms that have bumped off of the cesium atoms.)  There would be some losses, but you design to balance the losses vs. reduction in ISP, and find a balance.

I had considered this, but it clearly won't work. First, I think its worth noting that the devs have specifically mentioned the atomic rockets website. So I think hte stats given there are probably a good guess for how they intend the engine to work. They probably noted the theoretical 1700s figure... that would melt the engine and had no known design solution... and wanted that 1700s figure. 

http://www.projectrho.com/public_html/rocket/enginelist.php#id--Chemical--Metastable--Metallic_Hydrogen

Its competitor is simply dilution with liquid H₂ and an Isp of 1120s. Now, you need to consider that Cs is 133x heavier than H. If you had 133 H atoms per Cs atom, you've doubled the average MW. You've also roughly halved the energy storage per unit mass. The result is you've halved your Isp... 850s... LV-N territory, worse than if you just diluted with hydrogen, and did no magnetic confinement.

So, the break even with liquid H₂ dilution is about 160-165 H atoms per Cs atom. Now the Cs will ionize, and become a low density plasma, presumably pushed inward, but not even close to forming some sort of nozzle or confining wall. 

So you'll have a mass of cesium moving sqrt(1/133) as fast as the hydrogen atoms, or 8.67% as fast. This mass of Cs plasma would be going out the back, one could say that it would act as a very very very porous material from which the hydrogen gas would be diffusing out of in all directions. Now the diffusion out of it would be relative to the Cs plasma velocity (which would be very slow), and the dnesity at the end facing the ship would be higher than the end facing away from the ship, so you might get some more diffusion in one direction than another, but the lateral diffusion would be extreme, because the low density Cs would not be forming anything like the walls of a nozzle.

Now, I wondered if it would be possible to use the Cs gas to form something resembling a "plasma window"

However, such a technology would require a very high energy input, heating the plasma to temperatures higher than mH phase change could release, and seems to only work to generate a "flat plane" (really a cylinder of narrow diameter), not a bell shaped nozzle.

https://www.researchgate.net/figure/Schematic-of-the-plasma-window-reproduced-from-3_fig1_267413096

In the above diagrams, the plasma window is in the small space between the cylindrical copper plates.

That's the sort of thing you need to make plasma actually contain a gas, and you just make a cylinder of gas in the center separating the atmosphere from the vacuum.

 

 

[Hannu2]

15 hours ago, Dragon01 said:

First of all, it doesn't take a "supercivilization" to make a fusion engine, most proposals for fusion spacecraft could have been built when they were proposed, assuming an astronomical budget. Second, you're not getting these engines at the start of the game, you have to develop them, so Kerbals were very much not capable of these things before you came along. In fact, you're in charge of doing the exact thing you mention. That is, exploring the entire Kerbol system, and the nearby stars, at the cusp of an era of fusion and antimatter power. In fact, by the time you get to these, you'll probably have gotten at least a probe to most of the planets using less efficient propulsion methods (at least, if the balance doesn't suck), and are making fusion ships to support permanent colonies on these planets.

It is very different to make a game which stay interesting when focus moves from exploration to colonization. At colonization phase automation should take big role. Player plans service routes and take care that there are enough suitable ships to handle transportations. It is interesting to make exploration flight with lery limited resources but very boring to flight easy routine cargo flight with overpowered craft.

 

 

15 hours ago, Dragon01 said:

Elon Musk is proposing to colonize Mars in this century, so it's hardly "hundreds and thousands of years". It might be a bit longer before the colonies start making money, but it's something that's within out reach right now, technologically speaking. The main barriers are economic. If humanity was to pour all its combined resources into it, we could likely manage to make an interstellar ship in a few decades, and that's what Kerbals are doing. They have no wars, no politics, or even cities, so they have leftover money to throw at the problem.  

Musk's talks are 99 % repurposed bovine waste. And it is totally unrealistic assumption that civilization use all resources to space technology. At such level it is better to keep game without background story and just fly from empty planet.

 

15 hours ago, Dragon01 said:

Again, there's no "technomagic".

I think the most significant disagreement between us is meaning of words. You have researcher's optimistic attitude. Every phenomena which have been shown in lab experiment or observed in nature are almost ready and very realistic tech after "small" developing. I have engineer's pessimistic attitude, in which things are real when they are built and tested. For me technomagic is all necessary devices around reaction which keeps conditions possible for fusion and utilize produced energy to something useful, like thrust or electricity. As an engineer I am the guy who have to plan those practical devices before things happen and I am also the guy who is asked in boss's office when something does not work as intended. I can not see every exotic lab experiment as potentially usable technology in practice. They have to be developed much further before I can handle them as realistic possibilities to build something working and very large majority of ideas die in that process.

If I think fusion propulsion, fusion reactions are certainly real and their properties are well known physics. Some of them can be produced also in laboratory, but any such equipment can not do it long periods in real space conditions. Such spaceship is therefore not realistic currently. I can not put a deadline and trust that is is kept even I had superpower's military level funding. If such technology is decided to be developed, there may be dozens of drawbacks before any real application and no one can predict how many decades it take to solve all of them. For example fusion in terrestrial energy production has been 50 years away during my whole lifetime (little bit less that 50 years). Many expensive and some crazy expensive tests have been made, but always when some problem has been solved another has arisen and delayed success. Fusion may or may not be practical energy source on Earth or in space at some day distant future but not now. If it is used in entertainment, authors or devs must invent many things and it will be completely science fiction.

 

[Space Nerd]

I don't know if it's in an older post, but what kind of thrust would mMH engines have if MH is metastable?

[Guest]

On 7/29/2020 at 11:50 AM, Hannu2 said:

I think the most significant disagreement between us is meaning of words. You have researcher's optimistic attitude. Every phenomena which have been shown in lab experiment or observed in nature are almost ready and very realistic tech after "small" developing. I have engineer's pessimistic attitude, in which things are real when they are built and tested. For me technomagic is all necessary devices around reaction which keeps conditions possible for fusion and utilize produced energy to something useful, like thrust or electricity. As an engineer I am the guy who have to plan those practical devices before things happen and I am also the guy who is asked in boss's office when something does not work as intended. I can not see every exotic lab experiment as potentially usable technology in practice. They have to be developed much further before I can handle them as realistic possibilities to build something working and very large majority of ideas die in that process.

Of course, not every concept becomes reality. However, the reason many ideas die in the process is that something better comes up (usually something that's already in common use). For instance, IRL we are unlikely to ever develop gas core fission rockets, because fusion rocket research is actually quite advanced, and it would take a long time to go from early Soviet experiments to a working engine, all for something that's more limited than a fusion engine... of course, unless fusion engines develop even more unexpected problems. Then, it might be fusion that ends up in "more trouble than it's worth" bin, and gas core or electric propulsion might happen in its place. Even solid core NTRs, despite being quite a real and ground-tested technology, have not been flown for economic and political reasons, as there's no mission planned (save for very speculative Mars plans) that would make the most of such an engine. Indeed, nuclear reactor technology in general is a veritable graveyard of "works great, awesome numbers, fancy operating principle, too expensive to use" techs. 

I think you're confusing possibility with feasibility here. Maybe not a deadline, but I think a fusion engine of some sort (not necessarily steady state, a lot of concepts are pulsed) could be developed if you had superpower-level funding and this as your only goal (that is, nobody would be asking "just what is that thing good for?"). There are several concepts that would be good candidates. However, the big question is: is it worth spending all of that money on? Most of the time the answer is: it isn't. That's what we are ignoring in KSP. Developing even one of these engines would, IRL, be an ITER-scale project, lasting years (and there's no guarantee the end result will be worth it). We're doing the ITER instead, and notice how non-tokamak fusion power concepts have basically been shelved. Some suggest it was the wrong move, and I wouldn't be surprised if the first two working fusion reactors were tokamaks, then the rest polywells or something else that just plain works better. Alternatively, if no better way of sustaining fusion is found, the eventual fusion engine could be based on a tokamak, even if it's not optimal. In KSP, the player will be deciding on feasibility, and barriers to such technology will be greatly lowered compared to what they are IRL.

I'm fine with unfeasible, but possible concepts being in KSP. For instance, there were rocket engine concepts that ran on fluorine, mercury, ClF3, gelled propellants and pentaborane. None of them ever got anywhere, though most were tested in a lab. I'd be fine with either of them being included, as long as the reasons why they were not all that good ideas (that is, extreme propellant costs, in addition to handling difficulties) would be simulated. Metallic hydrogen engines are in a different category, things that are not possible even theoretically. There is no magic involved in making a ClF3 rocket, or a fusion or gas core nuclear rocket for that matter. It's just that problems involved are hard to solve, and they may not be worth solving. Kerbals, OTOH, don't care very much about whether something is worth doing.  That's why they are exploring space instead of, you know, building cities.  

Edited August 1, 2020 by Guest

[Hannu2]

On 8/2/2020 at 1:21 AM, Dragon01 said:

I think you're confusing possibility with feasibility here. Maybe not a deadline, but I think a fusion engine of some sort (not necessarily steady state, a lot of concepts are pulsed) could be developed if you had superpower-level funding and this as your only goal (that is, nobody would be asking "just what is that thing good for?"). There are several concepts that would be good candidates. However, the big question is: is it worth spending all of that money on? Most of the time the answer is: it isn't. That's what we are ignoring in KSP. Developing even one of these engines would, IRL, be an ITER-scale project, lasting years (and there's no guarantee the end result will be worth it). We're doing the ITER instead, and notice how non-tokamak fusion power concepts have basically been shelved. Some suggest it was the wrong move, and I wouldn't be surprised if the first two working fusion reactors were tokamaks, then the rest polywells or something else that just plain works better. Alternatively, if no better way of sustaining fusion is found, the eventual fusion engine could be based on a tokamak, even if it's not optimal. In KSP, the player will be deciding on feasibility, and barriers to such technology will be greatly lowered compared to what they are IRL.

I agree. I have tendency to think from very practical point of view and keep difference of unfeasible and impossible as philosophical pedantry. It is in those time scales and decisions which are reasonable in my life.

 

Quote

Kerbals, OTOH, don't care very much about whether something is worth doing.  That's why they are exploring space instead of, you know, building cities.  

In my opinion that is lazy base on story. Possibility of such species and civilization to survive and develop to astronomical state is just as possible as hydrogen atoms to bond metallic lattice. And as I said, there is also no gaming need for scifi propulsion. KSP propulsion set is very much enough for this kind of game. New things are practically same things with fancy names or ridiculously overpowered and break the idea of realistic space flight simulator.

Edited August 4, 2020 by Hannu2
Grammatical error

[Guest]

36 minutes ago, Hannu2 said:

In my opinion that is lazy base on story.

Certainly, but realistic storytelling has never been noted to be a strong point of KSP.  In fact, it's a classic case of "excuse plot" to give the player a bunch of fancy toys and explain away why there's no infrastructure modeled beside the spaceports (the real reason being, of course, devs not wanting to do it). Kerbals, the way they are depicted in marketing (in actual game they're pretty reasonable), wouldn't have a snowball's chance in hell of surviving in real world. However, keep in mind that we've seen some seriously weird civilizations here on Earth. With the society, nothing is really impossible, as long as you can come up with a way of getting there, however convoluted, that doesn't violate laws of physics.  

43 minutes ago, Hannu2 said:

I agree. I have tendency to think from very practical point of view and keep difference of unfeasible and impossible as philosophical pedantry. It is in those time scales and decisions which are reasonable in my life.

There is a critical difference, though: the former is not, ultimately, decided by humans, while the latter is. In fact, Apollo project, had it not been proposed by a particularly charismatic POTUS, would have been considered unfeasible under most ways of looking at it. This is best shown by how it petered out after several launches, and we haven't been back since. The US, in the late 50s, did not have the technology to economically and efficiently get to the Moon. This didn't stop them from rushing the development of several necessary techs, making a highly tuned ship with very thin margins, and launching it on top of a gigantic rocket. It was pretty "overteched" for its time, like attempting to build a machbuster in wood and canvas era of aviation would be, and that's why it didn't last, and also why Space Shuttle ended up what it was. Only now we are getting to the point when we can seriously think of setting up more regular flights to the Moon, and even then, it's because Musk is doing pretty much the same thing Kennedy did, only with Mars (and his own money, which is nice, I guess). 

The point of SF is to explore things that might happen beyond our lifetimes, and KSP2 in particular seeks to inspire those who will have a part in building that future. Besides, KSP1 is restricted to modern technology, and it's fun enough, but the sequel has to look further, because otherwise it'd end up not adding enough to be worth the money. Do note that these drives won't be completely overpowered (at least, I hope), because even fusion drives have weaknesses. Size is one thing, if you've see the trailers, the new engines are absolutely gargantuan. Also, at least if the career is done right, they'll likely have costs in billions of funds, requiring the player's budget to surpass most countries on Earth in order to build them (of course, achieving that is part of the game ).

[fragtzack]

Where is all the published documents from the real world wide scientific community  where the scientists of the world are agreeing that metastable is impossible in theory?

My searches for this topic from the true experts show a preponderance of theory work showing that metastable metallic hydrogen is possible.  I am not a scientist, so I need to see evidence from real scientist documents published works in theory and/or actual testing that shows metastable is impossible.  I don't give a rat's tail about your scientific opinion and more importantly...

 I hope the heck that KSP2 developers totally ignore this talk about "realistic" near future technologies because KSP2 is a game, not a hard core physics simulator. Hell, in KSP2  I want to see worm-holes, close to speed of light travel and even getting close to a black hole event horizon in KSP2 and intelligent alien life.  Arguing about the possibility of a real world technology in a computer video game reminds me of my dog who chases his own tail and even bites his tail at times.

 

[fragtzack]

 Far as I can tell, the Earth scientific community from the about 1700's has moved towards scientists proving and dis-proving each other theories in the scientific community. Scientists publish their opinions on agreement and disagreement.  Einstein's theories did not automatically get accepted because "he said so", he had to prove his theories AND the world wide scientific community agreed and some disagreed. These folks published their work on proving and disproving the theories, they did not just "Say so". This proving and disproving of theories through published works of opinions is the accepted way of scientific progress globally for hundreds of years now.

From what I can tell in the scientific community, scientists  love to prove and/or disprove each other. 

Searching the internets, there does not appear to be wide spread  scientific published opinions claiming  that metastable metallic hydrogen is impossible or even unlikely. There is plenty of published and by a large margin published scientific documents about the theory of metastable metallic hydrogen being possible.  The amount of work and published theories disproving metastable metallic hydrogen theories  is zero far as I can tell. 

Liquid hydrogen in use by humans today is NOT metastable at ambient Earth atmosphere temperature and pressure, yet humans have engineered tools and materials to make liquid hydrogen metastable and usable at earth pressures and temperatures. I.E. --> cryogenics.        Please correct if this assumption about liquid hydrogen being not metastable on earth ambient conditions is incorrect.

 Real world scientific published works matters. The opinion of a few here and a minority from what I can tell is not backed up by published work of scientists published and searchable on the internets. "Trust me, I know more than anyone" is the overwhelming attitude I am seeing from the few in this thread. Few = 2 posters.

 

 Think what I learned the most from this forum thread of fantasy physics drivel is to have high hopes the KSP2 dev's ignoring or rejecting this whole line of thinking in this thread about what is possible in a parallel universe of little green creatures where the laws of physics of Earth do not apply.

Published scientific works of opinions on the theory of metastable metallic hydrogen being possible:

hhttps://www.researchgate.net/publication/316955213_On_the_possibility_of_metastable_metallic_hydrogen

https://arxiv.org/pdf/1705.04900.pdf

http://www.jetp.ac.ru/cgi-bin/dn/e_034_06_1300.pdf

 

Published scientific works of theory disproving these works?

 

On 10/2/2019 at 2:41 PM, Dragon01 said:

Metallic hydrogen again... this is how scientific misconceptions are born. No, it doesn't work as a propellant,  I already assume that. 

 

Corrected for you.

On 2/22/2020 at 9:47 AM, KerikBalm said:

I reject your assertions. #1- No evidence has been given. #2 The most current mathematics do not predict metastability. Mathematics absolutely do not say it is possible. Math alone says nothing. Mathematical descriptions of the physical world are another thing.. ie physics equations. If a physics equation is bad, then the prediction is bad. If experimental results do not conform with the equations, then the equations are no good.

Newtons equations would predict that you can go faster than the speed of light. You can't. Just because the math works out using newtons equations doesn't mean you should accept the results given that #1) We have observations that contradict it (no, its not just that experiments haven't worked out) (#2) we have newer and better equations that conform much better to the observations.

The equations since the 1970s, that conform to the observations much better, do not predict metastability for anything other than picoseconds.

That means it is unreasonable to accept the claim of usefully metastable metallic hydrogen.

Where are these documents "since the 1970's" ?   You have links? Book titles maybe we can read from a library if not available on the internets?

[KerikBalm]

19 minutes ago, fragtzack said:

Liquid hydrogen in use by humans today is NOT metastable at ambient Earth atmosphere temperature and pressure, yet humans have engineered tools and materials to make liquid hydrogen metastable and usable at earth pressures and temperatures. I.E. --> cryogenics.        Please correct if this assumption about liquid hydrogen being not metastable on earth ambient conditions is incorrect.

You are incorrect. There is no metastable liquid hydrogen, and it does not exist at ambient temperature and pressure. That is why liquid hydrogen tanks have so much insulation, and why ice chunks fall of during launches

19 minutes ago, fragtzack said:

Where are these documents "since the 1970's" ?   You have links? 

Yes, I do, and have cited multiple times, but heck, one more time:

https://arxiv.org/abs/1709.05300

[Guest]

52 minutes ago, fragtzack said:

Published scientific works of theory disproving these works?

Works of theory do not disprove anything. They explain existing experiments and make testable predictions. A theory is nothing without an experiment that confirms predictions that it made, and it is by experiment that theories are disproven. 

As of works of experiment disproving the old theory, here you go:
https://www.nature.com/articles/s41586-019-1927-3
Annoyingly enough, a quick Google Scholar search does not turn it up, but it's been cited time and again in this thread (in fact, signature time!).  

52 minutes ago, fragtzack said:

Broke for you.

FTFY. The experiments disprove the old theory. The only thing I assume is that people running them know what they're doing.

52 minutes ago, fragtzack said:

 Searching the internets, there does not appear to be wide spread  scientific published opinions claiming  that metastable metallic hydrogen is impossible or even unlikely. There is plenty of published and by a large margin published scientific documents about the theory of metastable metallic hydrogen being possible.

The reason for this is quite simple: it's been disproven in 2019, and the actual paper appeared in Nature in early 2020. This is a very recent work, as opposed to theories that had been kicking around since 1970s, so naturally the body of work in favor is considerably larger, but again, those are theoretical papers. Which are now worthless, since the experiments proven them wrong. Go find me a single theory from 2020 that predicts metastability in some area and explains the recent results.

Quote

Liquid hydrogen in use by humans today is NOT metastable at ambient Earth atmosphere temperature and pressure, yet humans have engineered tools and materials to make liquid hydrogen metastable and usable at earth pressures and temperatures. I.E. --> cryogenics.        Please correct if this assumption about liquid hydrogen being not metastable on earth ambient conditions is incorrect.

I don't think you know what metastability means. A metastable material is one that is not in its lowest energy state, but does not have a readily available decomposition path leading to it, so it remains in the high-energy state. The thing with metallic hydrogen was that it was theorized to be possible for it to be reverted from that state in a controlled manner, releasing the (very considerable) stored energy. LH2 is just plain stable, and it does not store any energy. In fact, it is produced by removing a whole lot of energy from it as we can before stuffing it into a rocket. We do not get thrust out of LH2 changing phase (well, aside from those little vents for propellant settling), we get it from burning it with oxygen. 

Metastability is best illustrated by an experiment with microwaving distilled water (you can watch it, but don't do this at home). It will remain liquid even as the oven heats it well above 100 degrees celsius. Heat it too much, touch it or drop something in it, and it explodes, or more specifically, boils instantly across its entire volume, with spectacular (and highly dangerous) results. That is an example of metastability, and it is a rare phenomenon peculiar only to a few weird substances such as water.  

Edited August 4, 2020 by Guest

[fragtzack]

2 hours ago, KerikBalm said:

You are incorrect. There is no metastable liquid hydrogen, and it does not exist at ambient temperature and pressure. That is why liquid hydrogen tanks have so much insulation, and why ice chunks fall of during launches

Yes, I do, and have cited multiple times, but heck, one more time:

https://arxiv.org/abs/1709.05300

Thanks for the link, that document does appear to state metastable metallic hydrogen would have a life span at ambient conditions to be  so short as to not be usable. The document does not claim metastable state of metallic hydrogen impossible. 

That link and document does not prove that the scientific community agrees that metallic hydrogen is a waste of time. Quite the opposite in fact, much work has been done since 1974 to continue pursuing the theory of a usable stage of metal hydrogen. 

2017 article of work, concluding that metastable metallic hydrogen is possible but only under 200-300gPA. https://arxiv.org/pdf/1705.04900.pdf

2017 article of work, concluding that metastable metallic hydrogen is possible but also not under ambient conditions. https://www.researchgate.net/publication/316955213_On_the_possibility_of_metastable_metallic_hydrogen

Think I said "cryogenics" makes liquid hydrogen metastable inaccurately, but that is only inaccurate when considering earth ambient temperatures and pressures. Liquid hydrogen would be unnaturally occurring for most of our solar system, except the farthest outer edges. At the farthest edges, where extreme cold exists ,  liquid hydrogen would be considered metastable at the local ambient temperature. In interstellar space, liquid hydrogen would be considered metastable. 

 However, we need to discuss more practical terms of earth ambient and 99.9% of our solar system metastable. 

Liquid hydrogen is engineered  usable on earth with limitations because of engineering solutions(cryogenics) that provide for the temperature requirements for liquid to stay the required cold level for a limited time span. 

So if liquid hydrogen is NOT metastable and humans engineered a method to use liquid hydrogen, humans could also engineer a method to use non-metastable metallic hydrogen. Probably thousands of years from now when new stronger materials are discovered, but seems to me to make metallic hydrogen usable means engineering a material and method to handle insanely huge pressures OR mixing metallic hydrogen with another substance to make the pressure requirements not so extreme.   Exactly as with done with many wonderful engineered solutions that humans use, such as dynamite. Centuries and centuries went by humans thought nitroglycerin was too unstable (but powerful) to be used ... until Alfred Nobel mixed another substance in to stabilize the substance. 

 So this thread is no longer about:

1. If metallic hydrogen is possible   (Not seeing much disagreement here, seems to be agreed by all in theory)
2. If metallic hydrogen is metastable  (Disagreement here, but seems pointless in light of liquid hydrogen also being metastable at ambient conditions)

Hopefully, we are all  aware that new substances and elements are discovered by humans over time. The periodic table of elements has not remained static in my life time. 

Hopefully, we are also aware that humans do discover and develop stronger materials over time by mixing elements together. . Materials that one day might even be stronger than diamonds.  Materials so strong that maybe the material could withstand the pressures of Jupiter. Maybe not even a new material by itself, but a new material along with strong electo-magenetic force to meet the requirements of the physics at hand.

 

This thread went on and on about how metallic hydrogen is un-metastable which by itself proves metallic hydrogen can't be used. But that argument about metallic hydrogen being not metastable at ambient conditions is moot point  because humans have engineered solutions for many substances that are not metastable at ambient conditions. See liquid hydrogen for example.

Need to dig a little bit harder to tell humans why humans can't develop a solution to a chemical, atomic or elemental problem. Human history is full of examples of overcoming these types of challenges. Hanging a whole argument on "not-metastable" is quite thin and doesn't hold up to human history.  

 

Lastly, glad this got moved out of KSP2 game forum and to non-game discussions. Didn't catch that this thread moved read this response. I only went back to this thread today cause of a link from another post in the game forums.   Will not be participating anymore in this garbage unless this drivel comes back to the KSP game forums. Please stop making more threads about these  false science methods in the game forums, leave this drivel here outside the main game forums.    If humans went through the ages with this type of thinking of only trying  what we already know, humans  would still be living in caves. Thankfully, great humans in  history did not think like what I am seeing from the negativity flood by a very few in this thread. Thankfully, KSP is about Kerbals and a parallel universe.

 

 

 

 

 

 

 

 

 

Edited August 4, 2020 by fragtzack
missing word

[fragtzack]

 The most recent published article by a team of scientists on metallic hydrogen I can find is March 2020:

 

https://aip.scitation.org/doi/full/10.1063/5.0002104

 

 Seems very clear from reading those conclusions that scientists and scientific body looking into metallic hydrogen  is not in agreement here and the questions are very much open to the scientific community..

 

Not in agreement and open questions = Tis possible AND tis non-possible.  Means there is more work to be done.  No more, no less.

 

Your arguments implying "never" , implying "We all agree", and "disproven" are are blatantly false and emotionally charged. Have no  idea what would cause a few people to get emotional about such a theorized subject.  The evidence is very clear though, the scientific community disagrees with your implications of "not possible" , "we all agree" and "disproven". 

 

 

[Guest]

33 minutes ago, fragtzack said:

Think I said "cryogenics" makes liquid hydrogen metastable inaccurately, but that is only inaccurate when considering earth ambient temperatures and pressures. Liquid hydrogen would be unnaturally occurring for most of our solar system, except the farthest outer edges. At the farthest edges, where extreme cold exists ,  liquid hydrogen would be considered metastable at the local ambient temperature. In interstellar space, liquid hydrogen would be considered metastable. 

 However, we need to discuss more practical terms of earth ambient and 99.9% of our solar system metastable. 

No, it would not. It would be considered stable. These are different things. Liquid hydrogen has nothing to do with metastability. It's just plain stable, with no lower energy state to revert to. Do you even understand what you're talking about?

Metallic hydrogen metastability is not an engineering problem, it's a physics problem. Humans have not found a way to exceed the speed of light, make cold fusion or any other such thing. Metallic hydrogen can only exist in conditions that are not feasible to replicate in a rocket. Sure, you could do it, in theory, and you would end with a glorified cold gas thruster running off a tank that has horrible mass fraction. 

9 minutes ago, fragtzack said:

 The most recent published article by a team of scientists on metallic hydrogen I can find is March 2020:

The word "metastable" does not occur in this article. Try again. This is an interesting paper, and we're not saying metallic hydrogen is useless, or uninteresting. Just that it's not a rocket fuel. It's worthy of attention for many other reasons.

Your arguments implying that it's not disproven are blatantly false. Metastability was predicted by one specific theory. That theory has been disproven, because experimental results do not agree with it. End of the story. Other theories do not predict metastability, or they predict it in such a way that it's useless for rockets. 

[DStaal]

52 minutes ago, fragtzack said:

This thread went on and on about how metallic hydrogen is un-metastable which by itself proves metallic hydrogen can't be used. But that argument about metallic hydrogen being not metastable at ambient conditions is moot point  because humans have engineered solutions for many substances that are not metastable at ambient conditions. See liquid hydrogen for example.

Except that the only reason to consider using metallic hydrogen would be if it were metastable.  If it's not metastable, there's no advantage to metallic hydrogen over liquid hydrogen in energy density - you can react it either chemically or atomically and get the same amount of energy out of it regardless of what form it's stored in.

If it were metastable, that calculation would change: disturbing that 'stable' situation would release a large amount of energy as it reverted to more conventional forms of hydrogen.  You could in theory *then* react it like any other hydrogen, but the best-case on the theory was that you wouldn't bother as that breakdown of the metastable state would release more energy than any chemical reaction, and be on par with an atomic reaction.   (Without all the pesky radioactive side effects.)

Think of metastable MH as perching a bolder on top of a cliff, right on the edge.  As you raise the cliff up (return the surroundings to more normal temperatures/pressures) there will be more and more energy released when someone knocks the bolder off - but only if the boulder can sit there.  And it will only sit on that edge as long as it's metastable - if it's not, then it falls off, like everything else.

 

Without being metastable, metallic hydrogen is an interesting scientific experiment and little else.  We can prove it exists and it'll tell us a bit more about how well our theories of the universe work - but it's not useful for anything on it's own.

[KerikBalm]

And we go in circles again.

Before posting again, please read through the thread and see if your points have already been raised and addressed, because this is ridiculoud

9 hours ago, fragtzack said:

Thanks for the link, that document does appear to state metastable metallic hydrogen would have a life span at ambient conditions to be  so short as to not be usable. The document does not claim metastable state of metallic hydrogen impossible. 

As already mentioned, a metastability of picoseconds (as mentioned) is not worth discussing in the context of using mH as a rocket fuel

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That link and document does not prove that the scientific community agrees that metallic hydrogen is a waste of time. 

Nobody said that. Understanding hte interiors of gas giants has value. Refining models for high pressure physics has value. Its superconducting potential has value even if its not metastable.

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Think I said "cryogenics" makes liquid hydrogen metastable inaccurately, but that is only inaccurate when considering earth ambient temperatures and pressures. ...

No, its entirely inaccurate under every context that you go on to mention, and every foreseable context so far.

Such statememnts make me wonder if there is a polite way to say that you clearly do not understand the subject, and you should educate yourself much much more on the topic before returning.

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2017 article of work, concluding that metastable metallic hydrogen is possible but only under 200-300gPA. https://arxiv.org/pdf/1705.04900.pdf

2017 article of work, concluding that metastable metallic hydrogen is possible but also not under ambient conditions. https://www.researchgate.net/publication/316955213_On_the_possibility_of_metastable_metallic_hydrogen

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So if liquid hydrogen is NOT metastable and humans engineered a method to use liquid hydrogen, humans could also engineer a method to use non-metastable metallic hydrogen. Probably thousands of years from now when new stronger materials are discovered, but seems to me to make metallic hydrogen usable means engineering a material and method to handle insanely huge pressures

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1. If metallic hydrogen is metastable  (Disagreement here, but seems pointless in light of liquid hydrogen also being metastable at ambient conditions)

An often omitted phrase, for brevity, is substantially metastable to the point that it would be an attractive alternative to simple chemical rockets. i can even point to a 2016 paper that predicts some metastablity in the 10-20 GPa range ( https://arxiv.org/abs/1611.02593 ). The thing is that this does not agree with the 2019 and 2017 observations (if it doesn't agree with experimental evidence, its irrelevant), and that's predicting metastability at pressure that were though to be required to form mH in the 1970s, which were already known to be too high to be practical (thus metastability would be needed to allow storage at much lower pressures than that)

The thing is, if stronger materials are discovered, it doesn't apply to just mH tanks, it applies to everything, and its still not competitive:

Note that modern tanks have propellent:dry mass ratios of about 30:1. The Space shuttle main tank was pressurized to 250 kPa. That is 40,000x lower than 10 GPa.

Using the (disproven in light of 2019's experimental evidence) 2016 prediction would require a tank 40,000x stronger, and since these things have a certain strength to mass ratio, and they try to make them as light as possible, it follows that it would require a tank 40,000x more massive. The ratio becomes 30:40,000, or a full:empty mass ratio of 40,030:40,000, or 1.00075, while a standard tank has a mass ratio of 31:1. 

Now you should be familiar with the Tsiolkovsky rocket equation. Given an Isp of 1700s (dubious, as thats for what I cal the PSM^2 engine, which has even more problems), the maximum dV of a hydrolox rocket at 455s and a 31 mass ratio is: 9.81*455*ln(31)=15,327 m/s.

For a metallic hydrogen rocket with a tank with a mass ratio of 1.00075, and exhaust that will melt the engine, the dv is: 9.81* 1700 *ln(1.00075) = 12.5 m/s

Now, lets assume we make a tank with a strength to weight ratio 1,000x stronger than what we have now, the mass ratio is then (30+40)/40 = 1.75, and maximum dV is 9,332 m/s... not even 2/3 of what the hydrolox rocket gets, meanwhile the hydrolox rocket with such a tank can get a 30*1000:1 mass ratio... 30,000, giving it a dV of 46,014 m/s. Ok, so now the hydrolox is only outperforming the mmH by about 5:1, instead of 1,000:1

Lets say our tanks are 10,000x stronger, and mmH is stable down to 2.5 GPa, now we get a mmh tank mass ratio of 34:4, or 8.5...resulting dV is now: 35,690 m/s... now we're talking... except... wait,

thats still less than the hydrolox can get with a tank made of materials 1,000x weaker... what would the hydrolox get with this new material? the mass rato is now 300,000... and the dV is: 56,292 m/s

So even if we could make tanks that are have a strength/mass ratio 10,000x higher than what we have now, and if mmH was metastable down to 2.5 GPa, the hydrolox rocket would still get more dV...

This is why I consider metastability that would bring the pressure down from 415 GPa to 2.5 GPa to be "insufficient"

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 So this thread is no longer about:

1. If metallic hydrogen is possible   (Not seeing much disagreement here, seems to be agreed by all in theory)

It never was, please actually read the thread before posting in it.

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Lastly, glad this got moved out of KSP2 game forum and to non-game discussions. Didn't catch that this thread moved read this response.

That was ages ago.... you may be referring to the "what tech belongs in KSP 2" thread, which is still there.

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Please stop making more threads about these  false science methods in the game forums, leave this drivel here outside 

Please stop making more posts that just show your haven't read the thread or what you are replying to, leave this drivel here outside.

Edited August 5, 2020 by KerikBalm

[Hannu2]

11 hours ago, fragtzack said:

Liquid hydrogen would be unnaturally occurring for most of our solar system, except the farthest outer edges. At the farthest edges, where extreme cold exists ,  liquid hydrogen would be considered metastable at the local ambient temperature. In interstellar space, liquid hydrogen would be considered metastable. 

You should take some physics book and learn what metastability really is. You mean stability in your sentence but are still incorrect. Liquid hydrogen is not stable at outer space conditions but will evaporate rapidly at zero ambient pressure. Liquid phase is stable if ambient pressure is larger than vapor pressure at given temperature. There should be planet sized mass of liquid hydrogen free from any star which could keep evaporated gas as an atmosphere to reduce further evaporation.

Wikipedia have short article but it is intended to be reference and not school textbook and may not be very clear.

https://en.wikipedia.org/wiki/Metastability

 

11 hours ago, fragtzack said:

So if liquid hydrogen is NOT metastable and humans engineered a method to use liquid hydrogen, humans could also engineer a method to use non-metastable metallic hydrogen. Probably thousands of years from now when new stronger materials are discovered, but seems to me to make metallic hydrogen usable means engineering a material and method to handle insanely huge pressures OR mixing metallic hydrogen with another substance to make the pressure requirements not so extreme.  

It may be that there will be some applications for metallic hydrogen. However, it is not very credible that any of them have any relations to rocket propulsion. Metallic hydrogen need so extreme conditions to be manufactured and stored in significant quantities that civilization at such tech have no problem to use fusion or antimatter or whatever many orders of magnitude more energetic exotic phenomena to propel their spaceships. There will not be new materials able to handle it. If it will be useful it must be confined with crazy strong fields.

 

11 hours ago, fragtzack said:

Hopefully, we are all  aware that new substances and elements are discovered by humans over time. The periodic table of elements has not remained static in my life time. 

Hopefully, we are also aware that humans do discover and develop stronger materials over time by mixing elements together. . Materials that one day might even be stronger than diamonds.  Materials so strong that maybe the material could withstand the pressures of Jupiter. Maybe not even a new material by itself, but a new material along with strong electo-magenetic force to meet the requirements of the physics at hand.

All matters depend on same electromagnetic forces which affects in metallic hydrogen. Electron mediated bonds between atoms. Such bonds can not be infinitely strong. Crude estimates of bond strengths can be calculated even for non existing elements. I have never seen any estimates that there will be very strong bonds between heavy elements (or really stable heavy isotopes, "island of stability" means half life of whole seconds so that physical and chemical properties of predicted elements can be investigated instead of billions of years needed in practical use as structural material). Outer electrons of large atoms are relative loosely bounded and can not make strong bonds. Toughest compounds are those made from light elements, like diamond, boron nitride, aluminium oxide etc.

We should find completely new physics, interactions and particles able to form material, to be able to make material structures able to contain metallic hydrogen, fusion reactions etc. scifi stuff. Baryonic elements can not do it. I am not going to hold my breath during waiting.

11 hours ago, fragtzack said:

Lastly, glad this got moved out of KSP2 game forum and to non-game discussions.

I think you can feel safe to have all gorgeous and overpowered scifi stuff in KSP 2. It is clear that there is no economic market for more realistic nerdy game. Devs do not care our discussions. I hope that there will be tools to mod such scrap out of the game and put real things in. If not, KSP is very good game as long as future operating systems can run it.

[Hannu2]

11 hours ago, DStaal said:

Except that the only reason to consider using metallic hydrogen would be if it were metastable.  If it's not metastable, there's no advantage to metallic hydrogen over liquid hydrogen in energy density - you can react it either chemically or atomically and get the same amount of energy out of it regardless of what form it's stored in.

If it were metastable, that calculation would change: disturbing that 'stable' situation would release a large amount of energy as it reverted to more conventional forms of hydrogen.  You could in theory *then* react it like any other hydrogen, but the best-case on the theory was that you wouldn't bother as that breakdown of the metastable state would release more energy than any chemical reaction, and be on par with an atomic reaction.   (Without all the pesky radioactive side effects.)

Metastability is only practical thing. Metastable material would be stored in normal tanks and processed with normal tubes and pumps. But energy could be released also from non metastable metallic hydrogen.  Bond strength of metallic phase is much less than between atoms in H2 molecule. It takes something to overcome metastable barrier but combining released atoms to molecules give 216 MJ/kg. If you burn H2 with O2 you get only about 10 MJ/kg. Molecular mass of H2 is also much lighter so that it gets much higher velocity at same temperature. Transformation from metallic to molecular phase is chemical reaction which has nothing to do with nuclei.

Recombining pure metallic hydrogen to molecules would give ISP of 1700 s but 7000 K temperature would be impossible to handle. Practical solution would be to dilute metallic hydrogen with water (ISP about 500 s) or molecular hydrogen (ISP about 1000 s). Even that would give very significant buff to rocket's payload to intitial mass -ratio.

Numbers are based on this reference: https://dash.harvard.edu/bitstream/handle/1/9569212/Silvera_Metallic.pdf

[Guest]

1 hour ago, Hannu2 said:

I think you can feel safe to have all gorgeous and overpowered scifi stuff in KSP 2. It is clear that there is no economic market for more realistic nerdy game. Devs do not care our discussions.

I think they would care, if they only heard about it. Marketing and/or PR is probably keeping them in a bubble (just look at how consistently any direct refutation of metallic hydrogen is eradicated from the KSP2 board). It's been a while since they had a true, interactive session with the community. If anyone who cares managed to get into such a session (such as at E3), this could change, but they don't hold these in my country (or, since the pandemic started, at all). 

[Guest]

On 8/5/2020 at 4:44 AM, Dragon01 said:

I think they would care, if they only heard about it. Marketing and/or PR is probably keeping them in a bubble (just look at how consistently any direct refutation of metallic hydrogen is eradicated from the KSP2 board). It's been a while since they had a true, interactive session with the community. If anyone who cares managed to get into such a session (such as at E3), this could change, but they don't hold these in my country (or, since the pandemic started, at all). 

[snip]

No, I don't think they missed the argument, especially since half of the people writing in the KSP2 forum has something about metallic hydrogen in the signature.

Edited October 5, 2020 by Vanamonde

[Vanamonde]

A number of posts have been removed because the thread had wandered from the subject of metallic hydrogen propulsion and into personal characterizations of forum members and speculation about the internal communications of the company making the game. Please stick to the subject and refrain from attacking the people in the discussion.