Neutronium Armor: Could it Actually Protect?

[Danger]

Now, how quickly would a human, somehow 'instantly' transported to a spot some, say, 1 km above the surface of an NS:
a ) be ripped to atoms/molecules, by the tidal force or the magnetic field?
b ) 'fall' to the surface of the NS (how fast would they be going when they hit, assuming the NS has no 'atmosphere')?
c ) become smeared as a monolayer (atoms? neutrons??) over the surface of the NS?

Hi, Nereid;
Nice to see you again. I guess we're not hanging out in the same places much.
a) almost instantly by tidal forces; the magnetics wouldn't matter
b) from 1km altitude, somewhat short of light speed
c) within picoseconds of impact (and it would be in the form of neutrons)
**SPOILER ALERT** regarding Larry Niven's novel 'Protector'... One of the scenarios therein deals with a fellow in an unarmed spaceship being pursued by another ship bent upon his destruction. For reasons of no matter here, he has a high-power rifle on board (30-06 or similar). With the villian closing rapidly, he gets a brainstorm and steers for a nearby neutron star. He puts on his suit, climbs out on the hull with the rifle, and aims at his foe. At the appropriate time, he pulls the trigger and climbs back inside. The villian laughs his ass off at the futility of such a gesture and rapidly closes to weapons range... just in time to get fried into oblivion by the blast of gamma coming up as a consequence of a 180-grain chunk of lead impacting the neutron star at 95% of light speed.

 

[Art]

You don't need a repulsive force to cause an explosive-like expansion. As I suggested, think about how a gas works: pressure is generated simply because the individual molecules are moving. And in the case of neutronium, the HUP will guarantee that the particles are moving quite a lot, which gives rise to a pressure.

I am not disagreeing with you in regard to the neutronium changing from a liquid to a gaseous state. My question is in relation to your original contention which was that it would take the equivalent force of the gravitational field of a neutron star to contain the neutronium. Do you still contend this and if so why? Presumably as with other gasses the energy state (and so the pressure) of the neutrons would depend on the temperature. At 0 K what pressure would the neutronium gas exert?

 

[Hurkyl]

Do you still contend this and if so why?

Yes.

Neutronium's pauli pressure + Neutron star's gravitational pull = 0

And if we had

Neutronium's pauli pressure + some other containment method = 0

then we can solve and get

Neutron star's gravitational pull = some other containment method

At 0 K what pressure would the neutronium gas exert?

By the HUP, neutronium can't get anywhere near 0K, since a group of tightly packed neutrons necessarily exhibits a high variance in momenta.

 

[Art]

Yes.

Neutronium's pauli pressure + Neutron star's gravitational pull = 0

And if we had

Neutronium's pauli pressure + some other containment method = 0

then we can solve and get

Neutron star's gravitational pull = some other containment method

you are assuming they are in a state of delicate balance. To use an analogy: the Earths gravity keeps us rooted to the ground but if it were to diminish even quite substantially, we wouldn't just float off into space. We would still be held to the ground but with a lesser force. It seems probable that as neutron stars vary in size with a resulting variance in gravity that neutronium remains neutronium across a wide spectra. The question is, is there a way of actually calculating the point at which the containment force is no longer strong enough to prevent it's changing form?

 

[Hurkyl]

To use an analogy: the Earths gravity keeps us rooted to the ground but if it were to diminish even quite substantially, we wouldn't just float off into space. We would still be held to the ground but with a lesser force.

While we would remain rooted to the ground, the Earth would lose some of its atmosphere. Why do we lose one thing, but not the other?

Again, it comes back to the motion. Particles in the atmosphere are moving very fast. We are not moving very fast.

Of course, if Earth's gravity were to be sufficiently diminished, we would float off as well.

 

[Entropy]

within picoseconds of impact (and it would be in the form of neutrons)

Actually, the forces at the very surface of the neutron star are not strong enough to insue neutron degradation. The outer most surface of a neutron star is acutally composed of various atomic nuclei, mostly iron isotopes. Then as you barrow deeper neutrons will start to break free and form a neutron superfluid but still have protons and electrons mixed in with it. Then as you get even deeper it will eventually become entirely 100% neutrons. As for the core, it may just continue to be neutrons as well, but it might be that their is further degradation of neutrons into a type of quark matter.

 

[Astronuc]

The gravitational field of a neutron star 'freezes' the quarks that make up the neutrons... need some math to prove that? This is rapidly becoming a tiresome argument that is pointless.

If you mean the discussion of neutronium, yes, I agree. If neutronium could be 'made' into armor, which it can't for the various reasons mentioned, it would make great armor. I am fairly certain that the application of neutronium as armor falls into the realm of 'science fiction, not science and technology.

I would prefer to discuss the structure of neutron stars - which is pretty interesting because we cannot see into a neutron star, but rather we must make an 'educated' guess (or assessment) based upon our understanding of hadrons/baryons, quarks and the properties of matter as we know them.

Perhaps it is worthwhile to pursue further discussion of neutron stars in that thread.

I need to get up to speed on neutron stars - particularly the understanding of the internal structure.

 

[Danger]

Actually, the forces at the very surface of the neutron star are not strong enough to insue neutron degradation... ...it may just continue to be neutrons as well, but it might be that their is further degradation of neutrons into a type of quark matter.

Thanks for the correction, Entropy. It's been a very, very long time since I've had anything to do with the subject, and I'd forgotten about the internal structure variations. For some reason, I was remembering it as just a solid mass of neutrons, along with 'fluid' neutronium. (I think it's because the concept of free protons and electrons continuing to survive in that environment is so counter-intuitive to a non-scientist.) And now that you've mentioned it, the term 'quark soup' in reference to the core comes back to me, but I can't remember who coined it.
Sorry for the mis-lead, Nereid.

 

[Antiphon]

The outer most surface of a neutron star is acutally composed of various atomic nuclei, mostly iron isotopes. Then as you barrow deeper neutrons will start to break free and form a neutron superfluid but still have protons and electrons mixed in with it.

What a shame. I imagined the smooth black surface of solid neutrons
when in fact it's a dirty crusty junk-heap.

The job of a good armour is to absorb or deflect kinetic energy.
I'm not sure neutronium would be good at this even if stable and
thin enough to be wearable. But it would be water-clear in almost
any thickness! Now that would be cool to see.

 

[Chronos]

It takes immense force to pack neutrons as tightly as they are in a neutron star, as Hurkyl correctly noted. That is not in doubt. But indeed, the pure 'neutronium' layer lies beneath the mostly iron nuclei surface of a classical neutron star, as Entropy correctly noted. Not that we are likely to collect, but I would bet if you drug a scoopful of any of this stuff far away its gravity bucket, it would change to something else - and probably with some violence.

 

[LURCH]

I have been following this discuccion and found it more interesting than I expected. The main missunderstanding seems to be in relation to the strong nuclear force. The assumption was that the strong nuclear force would hold together any nucleons that manage to get so close to one another as to be within its very short effective range. Apparently, this is an incorrect assumption regarding neutrons. This leads to an obvious question, is there a causal link between charge and the strong nuclear force? I seem to recall hearing that (somewhat) recent developments in mathematics have revealed a connection between these two forces, with the weak nuclear force having already been unified to electromagnetic force.

I have also heard of the production of "positronium", and I thought I read somewhere that an "anti helium" atom had been produced, which would prove that the strong nuclear force works for negatively charged particles (anti protons), just as it does for protons.

Am I correct in assuming that the absence of strong nuclear force between neutral particles provides physical evidence of the unity between the strong nuclear force and the "electro-weak" force?

 

[Antiphon]

Not that we are likely to collect, but I would bet if you drug a scoopful of any of this stuff far away its gravity bucket, it would change to something else - and probably with some violence.

This must be true, otherwise there would be chunks of it floating around
from supernovas. The average meteorite is bad enough. A hunk of that
going 25k MPH could really ruin your day- and your planet.

 

[Astronuc]

It takes immense force to pack neutrons as tightly as they are in a neutron star, as Hurkyl correctly noted. That is not in doubt. But indeed, the pure 'neutronium' layer lies beneath the mostly iron nuclei surface of a classical neutron star, as Entropy correctly noted. Not that we are likely to collect, but I would bet if you drug a scoopful of any of this stuff far away its gravity bucket, it would change to something else - and probably with some violence.

Assuming one could get a collection device near the surface of a neutron star (remember temperatures are several millions of degrees K), it would become part of the neutron star. But then, consider the distances involved, and we don't have to worry about this hypothetical anytime soon.

I have also heard of the production of "positronium", and I thought I read somewhere that an "anti helium" atom had been produced, which would prove that the strong nuclear force works for negatively charged particles (anti protons), just as it does for protons.

As for positronium, it is a metastable state of a positron and electron, in which positron in free space quickly interacts (via Coulomb force) with an electron, and the pair will for a 'very short time' (10^-10 s) form a bound state. This state is similar to a hydrogen atom with the proton replaced by a positron. Upon annihilation, most commonly, two photons are produced. However, a positron and electron annihilation can sometimes produce three photons upon decay.

See -

Postronium

Positronium puzzle is solved

The Search for Positronium
I am not aware of any anti-He being produced, but I believe there has been some attempts (perhaps some successful) at forming anti-hydrogen. It's difficult given that one must bring a positron and anti-proton to essentially rest. It is one thing to store particles in a storage ring, it is quite another matter [unintentional pun] to bring anti-particles to rest in an environment consisting of normal matter.

The strong nuclear force should work for anti-nucleons, in the same way it works for 'normal' nucleons.

IIRC, the strong nuclear force does not hold two neutrons together, nor is it sufficient to overcome the Coulomb repulsion and keep two protons together - there is a requirement of at least one neutron for one of more protons (e.g. He³).

 

[LURCH]

Whoa, thanks for the correction, Astronuc! Somehow I got the term "positronium" mixed up with "antihydrogen". Don't know how I managed That .

I was trying to talk about the http://info.web.cern.ch/Press/PressReleases/Releases2002/PR09.02Eantihydrogen.html about the production of an anti-helium isotope.

So, the strong nuclear force will bind protons together, and antiprotons as well, but not neutrons. This would seem to imply a direct relationship between strong nuclear force and EM.

At any rate, the inability of strong nuclear force to bind neutrons together is the crucial bit of information needed in evaluating the feasibility of the type of armor alluded to in the original post. I'll also add that, if such armor did exist, I do not think it would collapse under its own weight. It would indeed be incredibly heavy, but it would also be incredibly strong; too strong to collapse. Instead, I think it would most likely sink straight through the crust and mantle of the Earth like a rock falling through air, until it reached the core, when it would sink more like a rock through water.

 

[Mk]

I think it would most likely sink straight through the crust and mantle of the Earth like a rock falling through air, until it reached the core, when it would sink more like a rock through water.

But then it would fly through the core to the center of the Earth, and out the other side from all the momentum it gained.

And up and down and up and down and up and down... That would mess up the environment considerably. The neutronium would cut through a person like a knife through hot butter! OUch! That'll hurt in the morning.

 

[LURCH]

Follow-on question: in theory, can there be variations in density of a neutron star at different depths (not counting the candy coating, I'm just talking about the chewey interior). Can neutronium come in different densities? My geuss would be "no", I would imagine the inside of a neutron star to be about the most homogenous thing in the universe, but it's very hard to grasp that it's no denser at the core than it is near the surface, or that a neutron star that is just above the Chandrasekhar limit is no more dense than one that's just a few metric tons short of collapsing into a BH.

 

[Chronos]

That depends on the equation of state you use to describe the interior of a neutron star... which is a very good question that does not have a very good answer to date.

 

[Astronuc]

That depends on the equation of state you use to describe the interior of a neutron star... which is a very good question that does not have a very good answer to date.

I was wondering about the constitutive model (or equations of state(s)) of a neutron star. I suspect it is beyond anything with which we are familiar. How would one work with a substance that is "millions of tons/cc"?


If one takes the diameter of a neutron as 10^-15 m and the diameter of a typical atom as 10^-10 m and assume a density on the order of 1 gm/cc, then a neutron star has a density on the order of (10^-10/10^-15)³ or 10¹⁵ g/cc or 1 billion metric tons/cc, i.e. it's very HEAVY!

 

[SkepticJ]

Everybody has covered why neutronium armor won't work. Perhaps now we can look at what might? This paper: http://nuri.pusan.ac.kr/~clee/ECT/Bowers.pdf

Has an interesting material called a Crystalline Colour Superconductor. It might be stable and very strong.

 

[NEOclassic]

When nature creates a normal neutron somewhere near the axis of rotation of the Milky Way it throws in what behaves like a singlet positronium that is the seed to the conversion of the neutron to a proton - a spinning electron is ejected with much energy leaving the charge only of the remnant positron still within the neutron shell. Occasionally nature fails to insert a singlet positronium and the result is a mule-neutron that is without the ability to decay so that it simply collects together with other mules and gets denser and denser. Dont forget that there are anti-mules with which the mules could annihilate although spins and magnetics might impede any mixing. Cheers, Jim PS. If this model seems unbelievable just call it sci-fi!

 

[SkepticJ]

When nature creates a normal neutron somewhere near the axis of rotation of the Milky Way it throws in what behaves like a singlet positronium that is the seed to the conversion of the neutron to a proton - a spinning electron is ejected with much energy leaving the charge only of the remnant positron still within the neutron shell. Occasionally nature fails to insert a singlet positronium and the result is a mule-neutron that is without the ability to decay so that it simply collects together with other mules and gets denser and denser. Dont forget that there are anti-mules with which the mules could annihilate although spins and magnetics might impede any mixing. Cheers, Jim PS. If this model seems unbelievable just call it sci-fi!

Can you give some proof of this? Sounds interesting, if true.

 

[NEOclassic]

Hi Skeptic, Not only is the conversion of a neutron to a proton, its daughter, accepted universally but the process is extremely spontaneous evidenced by the accompanying expulsion of a highly energetic electron with 0.783 MeV of energy (and an anti-neutrino that must be emitted in order to ballance off the spin-a-half that the electron carries off intrinsically) which can be accounted for as follows: There is internal to the neutron shell (whose mass and spin does not change with this convulsion) a singlet positronium unlike-charged (and galaxy created orbit of an electron and a positron) tiny neutral orbit. This orbit is the source of the electron energy as follows: 0.511 MeV due to the quantum leap of the positron mass from its
orbit to its zero mass at neutronic center, plus 0.256 MeV, the orbital kinetic energy of the expelled electron, plus 0.016 MeV, the energy required to strip the anti-spin from the bare positive charge of the proton. Like I said earlier, if this model is unbelievable, just treat it as Scifi. Cheers, Jim

 

[Anne.O.Neimau]

This is now a long-disused thread. However, maybe somebody will visit again, and respond.

The original question was, as the rest of this thread makes clear, obviously Science-Fiction in nature. Most of the responses addressed why Neutronium Armor couldn't be made/used/exist, (at least, with our current understanding of the Universe). They did not actually address the question itself, which starts with the presumption that such armor could somehow exist.

Since I can envision ways in which such armor could exist (although I can't tell you how craft it), I think most of you have completely dodged a legitimate question.

Examples of Neutronium Armor that could probably maintain existential stability include:

1. A neutron star - Interpose a neutron star between a target and an attack, and you ipso facto have neutronium armor. What would be the characteristics and utility of such armor in this case? For example, I would suspect it would not provide very effective armor against the gamma-ray blast of a quasar because of gravitational lensing. If you were close-enough to the neutron star that the lensing effect didn't "erase" the neutron-star's shadow, they you were probably "too close" to the neutron star in the various ways already presented in this thread. However, I haven't even attempted to run the math, so I might be way off on how much the gravitational lensing effect would bend the paths of the cosmic rays.
2. Thin, hollow neutronium shell - IIRC, the theoretical net gravitational "pull" inside a massive but thin hollow sphere (regardless of density) is zero, within the interior. Obviously, this mathematically assumes "thin" equals "zero thickness", which can't actually happen. However, what happens if "thin" equals "a minuscule percentage of the spherical radius"? Again, I haven't run the math (and it's been 3 decades since I used any calculus), but I suspect that there would be a fair-sized spherical interior region that exhibited tolerable levels of gravitational flux. Basically, we are most-worried about tidal effects across the largest chord of the object(s) we are attempting to shield with the armor. If this assumption is correct, then obviously there is some size of hollow sphere for which the net gravitational effect at the sphere's surface is sufficient to maintain the neutronium state. Granted, this may require more matter than exists in the known universe, but still it *could happen* ;-)
3. Gigantic Hollow Tube - Like the already-referenced Star-Trek doomsday machine. I'm not at all certain of the gravitational-flux physics of a hollow neutronium cylinder, spinning at a high-enough rate around its axis to maintain a cylindrical shape. It's mere existence would probably constitute a pretty good doomsday machine, even without some postulated star-annihilating weapon. However, postulating another sci-fi favorite - gravitic technology - might allow the maintenance of a "safe" region along the axis of the cylinder. At least, away from the ends, anyway. Again, what would the armor-characteristics of an enormous, rapidly-spinning cylinder of neutronium be?

Science Fiction, in it's "purest" sense, involves postulating some as-yet-impossible effect, and analyzing the implications on the rest of the otherwise-held-constant universe, both in terms of societal impact (the most popular expression of sci-fi), and in terms of pure physics. I feel that, in this latter expression, this question about neutronium armor is, in fact, a legitimate physics question. If some technique did exist for crafting neutronium armor, what are the resulting physical-science implications?

For example, the much-postulated sci-fi technology of "gravitics" - the ability to artificially manipulate the gravitational field in a given volume of space - would probably lend itself quite well to the collection, machining, and maintenance of neutronium. On the other hand, while anti-gravity, tractor-beams, and pressor-beams are obvious implied applications of gravitics, I think you could make some pretty dandy force-fields, too. A "black-hole level" repulsive gradient in a sphere around a "constant 1-gravity" spaceship interior would probably be a much better armor than "mere" neutronium. It might also incidentally provide a means of faster-than-light travel, since the ship-interior would be totally divorced from the rest of the universe - and thus, it's position might be an imaginary number only, which can be adjusted without pesky relativistic effects - until the force-field was deconstructed.

Similarly, some sort of "stasis" time-stop technology would allow the maintenance-of-state of neutronium (or anything else). Of course, a true stasis field would also probably be a better armor than "mere" neutronium, since there can be no energy-propagation in a time-stopped environment.

 

[Anne.O.Neimau]

In terms of my "gut" answer to the original question, I think it depends upon what you are attempting to armor against. Physical/Kinetic attacks might not be defended against as well as you might think. I suspect that the speed of sound through neutronium is pretty darned high, so kinetic attacks would rapidly be translated to the other side of the armor as a shockwave. Neutronium Armor plus internal buffer (like, kilometers of empty space between the protected target and the interior of the thin-sphere shell) might ameliorate this effect. But, if we're considering planet-sized thin-shell neutronium armor, we're probably also considering comet-massed relativistic kinetic projectiles. Might such an impact cause undesirable "spalling" off the interior of our shell, showering the target with high-speed neutrons?

"Classical" radiation-attacks are probably well defended against, with neutronium. I doubt X-rays and the like propagate through it at all. Extremely high-energy radiation (like being directly in the path of a relatively-nearby quasar radiation-stream) is another question entirely. Especially if neutronium is essentially a superfluid, it might be possible for intense-enough radiation to "blow it aside" to form a temporary hole.

The effects of gravitational attacks would also be of interest. Clearly, "low-grade" attacks aren't having much effect against something with a density in the billions-tonnes-per-cc range, if you've already solved the problem of how to maintain proximity to such a massive substance in the first place. However, I see two likely areas of concern against "higher-grade" attacks: tidal-effect warping of the armor-surface; and power-drain on your mechanism for maintaining a safe interior state.

Both of these are basically attacks on whatever mechanism is used to maintain the neutronium armor's configuration. If this is an "understood" physical process (the large thin sphere, or the spinning cylinder), then it should be possible to calculate the amount of gravitational flux required to cause dangerous tide-based thinning of the sphere, or disastrous structural imbalance of the spinning cylinder. If the state-maintenance mechanism is purely speculative (e.g. gravitics), then does the "attacker" have a force-multiplier advantage over the defender? In other words, is neutronium likely to be an innately-unstable state-of-matter (I think the thread consensus is "yes"), so that a local "overload" of the global state-maintenance effect might cause catastrophic failure?

 

[Vanadium 50]

IIRC, the theoretical net gravitational "pull" inside a massive but thin hollow sphere (regardless of density) is zero, within the interior. Obviously, this mathematically assumes "thin" equals "zero thickness", which can't actually happen. However, what happens if "thin" equals "a minuscule percentage of the spherical radius"? Again, I haven't run the math (and it's been 3 decades since I used any calculus), but I suspect that there would be a fair-sized spherical interior region that exhibited tolerable levels of gravitational flux.

Nope. A thick shell still has zero field inside it. (Think about it - the very outermost layer is a thin shell, so we can ignore it, and the then next layer is also a thin shell, and so on all the way down.

This is why one should bound one's speculation with calculation.

 

[fedaykin]

" When industrial diamonds are created using tremendous pressure they don't suddenly revert to their original form when the pressure is removed. "

At STP, diamonds are actually slightly less stable than graphite. Diamond won't become graphite very quickly, but if I recall correctly from the book "The New Alchemists" diamond in some earlier diamond synthesis machines was capable of bouncing back to graphite. I think one of the researchers stated that it was the world's best spring. I thought that was a little funny to mention that as an example of stability.

 

[granpa]

a large nucleus with all neutrons would be unstable (some of the neutrons would convert to protons by emitting electrons) so presumably armour made of neutron star material would be too.

why not use white dwarf material as armour instead? its my understanding that degenerate material can be produced here on earth.

 

[Vanadium 50]

why not use white dwarf material as armour instead? its my understanding that degenerate material can be produced here on earth.

If you mean white dwarf material has been produced on earth, that's wrong.

If you mean materials with a degenerate electron gas, that's correct. We call them "metals" and people have been building armor out of them for centuries.

 

[granpa]

I mean material that has been put under enough pressure to become degenerate.

http://www.wisegeek.com/what-is-a-diamond-anvil-cell.htm

The diamond anvil cell is a machine used by physicists to put samples under extremely high pressures (up to ~360 gigapascals) for the purpose of researching their properties, including phase transitions, atomic bonding, viscosity and diffraction levels, and crystallographic structure. Diamond anvil cells can simulate pressures of millions of atmospheres, recreating conditions similar to those at the center of the Earth or inside the gas giants. They are among the only laboratory apparatus capable of creating forms of degenerate matter like metallic hydrogen.

http://uplink.space.com/printthread.php?Cat=&Board=askastronomer&main=689723&type=thread

 

[Vanadium 50]

That is not white dwarf material.

Metallic hydrogen is, as the name suggests, metallic. Like I said above, a metal.