Neutronium?

[Winston Blake]

That's exactly backwards. A collection of non-interacting fermions is by definition a Fermi gas, which is how the neutron stars are modeled. Interacting fermions form Fermi liquids. White dwarves, which are supported by electron degeneracy pressure, are Fermi liquids.

Amazing that your definitive of degenerative matter flies in the face of a known astronomers on the matter, such as Arthur S. Eddington who call Degenerative matter in white dwarves a gas. This is back by Horn's book's "Blackholes, wormholes and Time warps" where he goes in detail on the process of collasp of matter into hyperdense states, and has a wonderful chart on where Degenerative electron gas actually becomes a fluid in the Neutron star.

Basically due to fact the electrons in a white dwarf form a electron gas this is gone into in the following paper <snip>

For what it's worth, ultra-accurate almighty google tells me that both white dwarves and neutron stars are composed of Fermi gases and the behaviour of Fermi gases and liquids is supposed to be very similar.

While the neutrons in neutronium interact via Nuclear strong force and a neutron is basically a giant nucleus, in which the forms are said by nuclear physicist to behave as a giant drop of super dense liquid...

AFAIK the liquid drop model only applies to nuclei, not degenerate matter. Also, the term 'degenerate matter' doesn't only mean white dwarf matter but also stuff like neutronium and strange matter.

[omegaLancer]

[/quote]For what it's worth, ultra-accurate almighty google tells me that both white dwarves and neutron stars are composed of Fermi gases and the behaviour of Fermi gases and liquids is supposed to be very similar.
[/quote]
Wow Absolute astronomy.com said so, so it must be true :roll

Then all those research papers on the behavior of Fermi gas and Fermi liquid must be mistaken.

While Descripting the behavior of neutron in a neutron star as a drop is simple description of a very complex state of matter the different between the behavior of electron gas form of degenerative matter and Neutron Degenerative matter is vastly different.

First the Electrons in White drawf are not attracted by the nuclear strong force, while the neutrons in neutrons star are. The Pressure of the electron gas is alot weaker than that generated by neutrons.

Neutrons in a neutron star behave like a superfluid, just like supercool He4
a more indepth treatment of the matter can be found here
http://arxiv.org/PS_cache/astro-ph/pdf/0405/0405262.pdf

and at best Neutronium in a neutron star is not a Fermi Gas....

[Winston Blake]

For what it's worth, ultra-accurate almighty google tells me that both white dwarves and neutron stars are composed of Fermi gases and the behaviour of Fermi gases and liquids is supposed to be very similar.

Wow Absolute astronomy.com said so, so it must be true

Then all those research papers on the behavior of Fermi gas and Fermi liquid must be mistaken.

Well i said i wasn't sure it was completely accurate. What implies that all those papers must be mistaken?

While Descripting the behavior of neutron in a neutron star as a drop is simple description of a very complex state of matter the different between the behavior of electron gas form of degenerative matter and Neutron Degenerative matter is vastly different.

First the Electrons in White drawf are not attracted by the nuclear strong force, while the neutrons in neutrons star are. The Pressure of the electron gas is alot weaker than that generated by neutrons.

Yeah, so what? I was just pointing out your misuse of the term 'degenerate matter' to mean only that in white dwarfs:

Actually you thinking of degenerative matter, as in White dwarves. Degenerative matter is a gas, Neutronium ( or the stuff we find in neutron stars ) is consider a super liquid due to its higher density and properties.

I admit i don't fully understand why, but dineutrons, trineutrons and tetraneutrons are all supposed to be impossible under current mainstream models due to the crappiness of neutron-neutron forces, so why should a gazillianeutron bound system work?

Neutrons in a neutron star behave like a superfluid, just like supercool He4
a more indepth treatment of the matter can be found here
http://arxiv.org/PS_cache/astro-ph/pdf/0405/0405262.pdf

I don't know if a gas-like material can exhibit superfluidity, but the fact it's 'superfluid' and not 'superliquid' could mean it's not restricted to liquids.

------
I've just been googling for papers and this one came up, where it mentions:

The inner crust for 4×1011 g/cm3 < < 2×1014 g/cm3 consists of a lattice of neutron-rich nuclei together with a superfluid neutron gas and an electron gas.

(so it seems gases can be superfluid too)

but also says:

• The neutron liquid for 2 × 1014 g/cm3 < < 8 × 1014 g/cm3 contains mainly superfluid neutrons with a smaller concentration of superfluid protons and ‘normal’ electrons.
• The core region for > 8 × 1014 g/cm3 may or may not exist in some neutron stars, and will depend on whether or not kaon condensation or pion condensation occurs, or whether there is a transition to a neutron solid or quark matter or some other phase of hyperons physically distinct from a neutron liquid in the core.

(bolded mine- i didn't realise a neutron solid was possible)

It then goes on to model a neutron star as an ideal Fermi gas of noninteracting neutrons. So it looks like both sides are partially right.

[omegaLancer]

For what it's worth, ultra-accurate almighty google tells me that both white dwarves and neutron stars are composed of Fermi gases and the behaviour of Fermi gases and liquids is supposed to be very similar.

Wow Absolute astronomy.com said so, so it must be true

Then all those research papers on the behavior of Fermi gas and Fermi liquid must be mistaken.

Well i said i wasn't sure it was completely accurate. What implies that all those papers must be mistaken?

While Descripting the behavior of neutron in a neutron star as a drop is simple description of a very complex state of matter the different between the behavior of electron gas form of degenerative matter and Neutron Degenerative matter is vastly different.

First the Electrons in White drawf are not attracted by the nuclear strong force, while the neutrons in neutrons star are. The Pressure of the electron gas is alot weaker than that generated by neutrons.

Yeah, so what? I was just pointing out your misuse of the term 'degenerate matter' to mean only that in white dwarfs:

Actually you thinking of degenerative matter, as in White dwarves. Degenerative matter is a gas, Neutronium ( or the stuff we find in neutron stars ) is consider a super liquid due to its higher density and properties.

I admit i don't fully understand why, but dineutrons, trineutrons and tetraneutrons are all supposed to be impossible under current mainstream models due to the crappiness of neutron-neutron forces, so why should a gazillianeutron bound system work?

Neutrons in a neutron star behave like a superfluid, just like supercool He4
a more indepth treatment of the matter can be found here
http://arxiv.org/PS_cache/astro-ph/pdf/0405/0405262.pdf

I don't know if a gas-like material can exhibit superfluidity, but the fact it's 'superfluid' and not 'superliquid' could mean it's not restricted to liquids.

------
I've just been googling for papers and this one came up, where it mentions:

The inner crust for 4×1011 g/cm3 < < 2×1014 g/cm3 consists of a lattice of neutron-rich nuclei together with a superfluid neutron gas and an electron gas.

(so it seems gases can be superfluid too)

but also says:

• The neutron liquid for 2 × 1014 g/cm3 < < 8 × 1014 g/cm3 contains mainly superfluid neutrons with a smaller concentration of superfluid protons and ‘normal’ electrons.
• The core region for > 8 × 1014 g/cm3 may or may not exist in some neutron stars, and will depend on whether or not kaon condensation or pion condensation occurs, or whether there is a transition to a neutron solid or quark matter or some other phase of hyperons physically distinct from a neutron liquid in the core.

(bolded mine- i didn't realise a neutron solid was possible)

It then goes on to model a neutron star as an ideal Fermi gas of noninteracting neutrons. So it looks like both sides are partially right.

that the point is that our understanding of neutron rich dense matter is very lacking, it can be a gas,liquid and solid, and there are some physicist that believed polyneutrons collections may also be stable if the right number of neutrons are combine....

it really gives me a massive headache..

[SVPD]

Ok, so it's pretty safe to assume that the Trek device is not "solidly packed neutrons."

What do they mean then, when they call it neutronium?

[Darth Wong]

Ok, so it's pretty safe to assume that the Trek device is not "solidly packed neutrons."

What do they mean then, when they call it neutronium?

They just think it sounds cool. It's like calling something an "alloy" and then talking about mining it, as if there are naturally occurring alloys. Star Trek's abuse of terminology is legendary.

[Bounty]

What do they mean then, when they call it neutronium?

Because in the 60's, I doubt many kids watching a sci-fi show would know the exact properties of neutronium. And it sounds cool.

[Kuroneko]

Superfluidity is defined by the absense of viscosity in a fluid, so by itself the term means nothing as far as whether the substance is liquid or gaseous. I think the dispute can be fairly resolved through the answer is 'it depends', specifically on the density. Low-density neutronium would have very little interaction between the neutrons, meaning it will be a Fermi gas, fitting the definition almost exactly. For higher-density neutronium, there could be more significant interactivity due to the strong force, so it may be better described as liquid or even more complex structure. Based on Mr. Blake's post, 'low-density' means less than 2e14g/cm³, which is 2e17kg/m³, on the same order of magnitude that I used previously.

[omegaLancer]

Superfluidity is defined by the absense of viscosity in a fluid, so by itself the term means nothing as far as whether the substance is liquid or gaseous. I think the dispute can be fairly resolved through the answer is 'it depends', specifically on the density. Low-density neutronium would have very little interaction between the neutrons, meaning it will be a Fermi gas, fitting the definition almost exactly. For higher-density neutronium, there could be more significant interactivity due to the strong force, so it may be better described as liquid or even more complex structure. Based on Mr. Blake's post, 'low-density' means less than 2e14g/cm³, which is 2e17kg/m³, on the same order of magnitude that I used previously.

So for of the kiddie out there, you are saying that we are all right ...

[SVPD]

Ok, let me rephrase. What would be a good counter when he says "well they say it's solid packed neutrons, so it is!"?

[Kuroneko]

Ask if neutron-neutron interactions were strong enough to bind, then why have we not observed any two-neutron nuclei? There have been neutron-neutron collision experiments, and since they are both, well, neutral, there no electrostatic repulsion to overcome, so it ought to be easy if it is possible at all. In partcular, it should be much easier than fusing hydrogen into helium.

[wilfulton]

Ask if neutron-neutron interactions were strong enough to bind, then why have we not observed any two-neutron nuclei? There have been neutron-neutron collision experiments, and since they are both, well, neutral, there no electrostatic repulsion to overcome, so it ought to be easy if it is possible at all. In partcular, it should be much easier than fusing hydrogen into helium.

Actually, it has been observed. Check out the following link

http://rs2.ch.liv.ac.uk/~dlc/Administratium.html

[omegaLancer]

Ask if neutron-neutron interactions were strong enough to bind, then why have we not observed any two-neutron nuclei? There have been neutron-neutron collision experiments, and since they are both, well, neutral, there no electrostatic repulsion to overcome, so it ought to be easy if it is possible at all. In partcular, it should be much easier than fusing hydrogen into helium.

Actually dineutron are observed, but are not considered bound and is a stage of in the production of trition:

" dineutron is a particle consisting of two neutrons that is considered to have a transitory existence in nuclear reactions produced by tritons that result in the formation of a proton and a nucleus having the same atomic number as the target nucleus but a mass number two units greater."

and there is actually some search to find state where it is bound..There is also so research that believe have been position test results for multineutron states such as Tetraneutron which have been detected in the decay of unstable states of Be 10..

Then there is also Neutron halo found in heavy isotopes of He which actually form rings of neutrons on the outer edge of the nucleus.

[Kuroneko]

Actually dineutron are observed, but are not considered bound and is a stage of in the production of trition: ... .

Would those be the same multi-neutron observations used to explain cold fusion? Is there any credible evidence of dineutrons? Theoretical predictions quite bluntly say dineutrons are impossible.

and there is actually some search to find state where it is bound..There is also so research that believe have been position test results for multineutron states such as Tetraneutron which have been detected in the decay of unstable states of Be 10..

However, this seems to be one of the more contested observations by far--see, for example, nucl-th/0203003 and nucl-th/0301020, which cast serious doubt on whether the observations were actually tetraneutrons, and nucl-th/0302048, according to which the tetraneutron, if actually there, would destroy the successful predictions of current nuclear theory.

Then there is also Neutron halo found in heavy isotopes of He which actually form rings of neutrons on the outer edge of the nucleus.

That's interesting, but incompatible with the sci-fi neutronium at hand.

[omegaLancer]

Actually dineutron are observed, but are not considered bound and is a stage of in the production of trition: ... .

Would those be the same multi-neutron observations used to explain cold fusion? Is there any credible evidence of dineutrons? Theoretical predictions quite bluntly say dineutrons are impossible.

and there is actually some search to find state where it is bound..There is also so research that believe have been position test results for multineutron states such as Tetraneutron which have been detected in the decay of unstable states of Be 10..

However, this seems to be one of the more contested observations by far--see, for example, nucl-th/0203003 and nucl-th/0301020, which cast serious doubt on whether the observations were actually tetraneutrons, and nucl-th/0302048, according to which the tetraneutron, if actually there, would destroy the successful predictions of current nuclear theory.

Then there is also Neutron halo found in heavy isotopes of He which actually form rings of neutrons on the outer edge of the nucleus.

That's interesting, but incompatible with the sci-fi neutronium at hand.

Actually may supporters of cold fusion ( and yes there are many researchers in the field claiming positive results to various cold fusion experiments, so much so that the US department of energy is once again looking into the issue) claim that such multineutrons reactions are behind the cold fusion.


While tetraneutron would be a blow against current nuclear theories the fact is that no expert in the field can claim that present theories explain the full range of events that are being viewed.

There are bound mesons which are collection of six Quarks, that have longer life span than predicted by present theory, Pentaquarks also that go against the gain.

The Evident coming from the Tetraneutron experiments seem to stand up to examination of the data, Science is an evolutionary process. Data that goes agoes prediction of current theory means that after retesting if the data is correct then the present theory need to replace by one that better fits the data.

While the Nuetron Halo maynot match solid neutronium, Neutron skins many. There are a host of isotopes that contain an outer shield of neutrons, such as Sn132, Pb208, Ca70 and other would.

The skin of Neutron stars are basically a shell of neutron enrich Iron and there are several possible iron isotopes that would exist in there.

As it stand many researcher are actually using research in Neutron skins isotopes to better understand Neutron stars, and it these isotopes would be called a form of neutronium...

[omegaLancer]

omegaLancer wrote:
Actually dineutron are observed, but are not considered bound and is a stage of in the production of trition: ... .

Would those be the same multi-neutron observations used to explain cold fusion? Is there any credible evidence of dineutrons? Theoretical predictions quite bluntly say dineutrons are impossible.

Creditible evident? why of course:

"Evidence for dineutrons in extremely neutron-rich nuclei
Kamal K. Seth and Brett Parker

Northwestern University, Evanston, Illinois 60208"

"An Experimental Search for a Stable Dineutron
B. L. Cohen and T. H. Handley

Oak Ridge National Laboratory, Oak Ridge, Tennessee"

http://www.aip.org/png/html/dineutrons.html

"The Effect of Bound Dineutrons upon BBN," Physical Review D. 70. J. P. Kneller and G. C. McLaughlin,. (2004). p. 043512"

I can go on and on and then there is a host of papers by supporters of cold fusion...

[Kuroneko]

Aa. Well, I admit I was clearly not as specific as I should have been in my statement. The real issue is a reasonably stable configuration of neutrons, since this is obviously the only kind of pure-neutron collection that fits the bill for sci-fi neutronium. That's exactly what the polyneutron cold fusion debate about: whether or not polyneutron states could exist long enough to participate in nuclear reactions at all. I think we can agree that a material of that disintegrates on that kind of time scale is completely unacceptable for anything close to the role that sci-fi neutronium is meant to have. I've taken stability as a kind of obvious requirement, but in hindsight I should have specified it explicitly. The fault for that is entirely mine, but let's not use this oversight to take us into irrelevant territory.

[omegaLancer]

Aa. Well, I admit I was clearly not as specific as I should have been in my statement. The real issue is a reasonably stable configuration of neutrons, since this is obviously the only kind of pure-neutron collection that fits the bill for sci-fi neutronium. That's exactly what the polyneutron cold fusion debate about: whether or not polyneutron states could exist long enough to participate in nuclear reactions at all. I think we can agree that a material of that disintegrates on that kind of time scale is completely unacceptable for anything close to the role that sci-fi neutronium is meant to have. I've taken stability as a kind of obvious requirement, but in hindsight I should have specified it explicitly. The fault for that is entirely mine, but let's not use this oversight to take us into irrelevant territory.

Why would it not fit the bill, since the fact is that all these research in to polyneutron, neutron skins and tetraneutron are attempt to improve current model of neutron neutron reactions. As further research is conducted into Hyperdense and exotic nucleus it may show that Neutronium may be stable in large enought collection or in combination with other particles.

Strange particles have shorter life time that neutrons, yet it believed that collection of 1000's may be highly stable, actual search for strange nuggets involving searching for closely matching earthquake event have indicated that the earth may have been struck by such a Nugget that tunnel right thru the planet. And there are some indication that similar arrangement may be avaliable for polyneutrons...

[Kuroneko]

Why would it not fit the bill, since the fact is that all these research in to polyneutron, neutron skins and tetraneutron are attempt to improve current model of neutron neutron reactions. As further research is conducted into Hyperdense and exotic nucleus it may show that Neutronium may be stable in large enought collection or in combination with other particles.

There is no evidence for stability. As to limitations of standard nuclear theory, that is a good point, but in this case inapplicable: some of those alternative models indicate that the tetraneutron is less stable than the dineutron, while those invented to try to make 4n stable lead to unstable 6n, and vice versa. The attempted extensions are are a mess of mutually-contradictory predictions. Judgements of scientific facts should never depend on promissory notes.

Strange particles have shorter life time that neutrons, yet it believed that collection of 1000's may be highly stable ...

As an argument, this makes little sense. On one hand, we have strong neutron-neutron interactions, which limited to exchange of π0 and ρ0 mesons, only one of which is attractive. On the other, we have a mechanism specifically designed to resist strong decay. Even if large collections of strange particles prove to be stable, the two cases are simply not analogous unless better reasons are provided.

[Winston Blake]

Ok, let me rephrase. What would be a good counter when he says "well they say it's solid packed neutrons, so it is!"?

You could say that he's selecting properties of neutronium that are favourable to him (e.g. extreme density) while ignoring those that completely go against the idea (e.g. unobserved gravitational effects, instability outside a neutron star, beta decay). When he says "well they say the word 'neutronium' therefore it must be, even if it acts nothing like it" point out that neutronium is not a scientific term and is only used in scifi, so there's no universal definition of the word.

Although Kuroneko and omegaLancer are still sorting it out, i'd say that beta decay is a good point, since you can basically say "Well, neutrons have a half-life of about 615s, so if it was just neutrons then after 10 minutes half the hull would have decayed into hydrogen plasma/gas".

Also point out that going from 'extreme density' to 'completely indestructible' is a giant No-Limits Fallacy.

[omegaLancer]

Why would it not fit the bill, since the fact is that all these research in to polyneutron, neutron skins and tetraneutron are attempt to improve current model of neutron neutron reactions. As further research is conducted into Hyperdense and exotic nucleus it may show that Neutronium may be stable in large enought collection or in combination with other particles.

There is no evidence for stability. As to limitations of standard nuclear theory, that is a good point, but in this case inapplicable: some of those alternative models indicate that the tetraneutron is less stable than the dineutron, while those invented to try to make 4n stable lead to unstable 6n, and vice versa. The attempted extensions are are a mess of mutually-contradictory predictions. Judgements of scientific facts should never depend on promissory notes.

Strange particles have shorter life time that neutrons, yet it believed that collection of 1000's may be highly stable ...

As an argument, this makes little sense. On one hand, we have strong neutron-neutron interactions, which limited to exchange of π0 and ρ0 mesons, only one of which is attractive. On the other, we have a mechanism specifically designed to resist strong decay. Even if large collections of strange particles prove to be stable, the two cases are simply not analogous unless better reasons are provided.

you trend to use the term no evident alot, yet there is experimental proof of Dineutron which have a life span of 6 minutes, and recent experiment at Ganil have 6 Events of indication of Tetraneutron recently that back earlier experiments.

Further experiments with He8 and Li 6 have supported this research, see :
http://www.ganil.fr/research/events/con ... ltineutron'

As for Strange particle stabilities not making sense, Neutron and strange particle decay due to weak force ( not the strong as you stated) , and neutron are stabled in bound states ( in atomic nucleus) due to the fact that excess mass energy of Down quark is channel to strong force interaction. Resonance state of of N=> 30 and E => 2.5Mev have been observed.

With strange particles the larger the amount of particle involved in the strong force attraction the lower the energy that the strange quark has to create a virtual weak boson to promote decay, and it believed by some Physicist that this also can be true in large collection of bound neutrons... This is why research in Neutron halo and Skin are being pursued..

Now it should also be noted that Neutronium in Neutron stars are not a collection of purely neutrons, but a mixture of Nuetrons, protons and degenerated electrons and would meet you definition of a substance of Pure neutrons.

Even if such a collection of particles could be stable outside intense gravity fields it would be weakly bound and not a super strong substance that sci fi writers proclaim..

But the experimental evident for multineutron are enought that it doesnot meet your lack of proof, while it may fly against current theory you must remember that when experimental data show the theory is wrong and this experimental data is support by additional data ( We currently have Ganlil,CNRS, MSU and earlier soviet detection in the 90's that have experimental data showing that Tetraneutron exist) then the new theory must be found to fit the data, as so many papers on the subjects state.

[Guardsman Bass]

Assuming it were stable, and since it is resistant to being deformed, could you actually somehow put some of it in a starship hull? I think the mass by itself would be troublesome; neutron stars with the size of mountains contain the mass of upper class (O and A) stars. At least you wouldn't need to worry about artificial gravity.

[omegaLancer]

Assuming it were stable, and since it is resistant to being deformed, could you actually somehow put some of it in a starship hull? I think the mass by itself would be troublesome; neutron stars with the size of mountains contain the mass of upper class (O and A) stars. At least you wouldn't need to worry about artificial gravity.

Why not just use a layer a few particles thick over the main hull, I would think that that wouldn't be too masive, but how effect it would be as a means of defense is questionable..

[Kuroneko]

you trend to use the term no evident alot, yet there is experimental proof of Dineutron which have a life span of 6 minutes, and recent experiment at Ganil have 6 Events of indication of Tetraneutron recently that back earlier experiments.

Six minutes for the dineutron? Please elaborate. The sources you give have citations which never claim tetraneutron lifetime of more than a fraction of a microsecond, and unless I suddenly turned blind, do not mention dineutron lifetimes at all. (As to strong decay, I meant between nucleons, but that's very faulty counter-argument, so conceded.)

[omegaLancer]

you trend to use the term no evident alot, yet there is experimental proof of Dineutron which have a life span of 6 minutes, and recent experiment at Ganil have 6 Events of indication of Tetraneutron recently that back earlier experiments.

Six minutes for the dineutron? Please elaborate. The sources you give have citations which never claim tetraneutron lifetime of more than a fraction of a microsecond, and unless I suddenly turned blind, do not mention dineutron lifetimes at all. (As to strong decay, I meant between nucleons, but that's very faulty counter-argument, so conceded.)

First Dineutron and tertaneutron are seperate particles all together, estimate life time of dineutrons are 6 minutes since they are not boundthough the attraction between them is very nearly enough to make them so, and subject to the decay via weak force interaction. Di neutron have been detect and proven by numerous experiments..See for example:

http://www.ph.surrey.ac.uk/~php2ab/phys ... 'dineutron'

Teratneutrons would be bound systems if they exist, and their lifespan would be far greater than this due to the fact that they no longer are exposed to decay via the weak force, this is similar to neutronium that is found on neutron stars.. So this is a major different. the Ganlil and MSU experiments show that particle being detected is at least as massive as 4 neutrons and had to be stable enought to reach the detect, no present theory could account for this . A single event could be pure chance, 4 defies the odd and repeat experiment can safety rule this out.