Researchers theorize that neutrons may be squished into cubes in neutron stars

Actually, the free electrons are behaving in the same way like the neutrons - just at much lower energy density. In three dimensions the sufficiently cooled electrons forming bulk-centered cubic lattice, which is known as Wigner crystal. A pretty well like the apples or oranges stacked in the pyramidal pile.

http://en.wikiped..._crystal

It means, when the neutrons are squeezed enough, their short distance repulsive lepton charge applies in similar way, like at the case of long distance electromagnetic charge of free electrons. It's not rocket science, despite it appears so at the first look.

the tipping point is believed to be such stars that are of twice the density as the sun

Mass, Bob, mass.

A much more interesting situation would emerge, when the repulsing particles are compressed even more. Due the asymptotic freedom of free quarks the neutrons would literally dissolve into superfluous quark-gluon condensate, the inner properties of which would appear quite similar to our vacuum. I presume, many intermediate semi crystalline states may appear during this, which would enable the formation of primitive molecules inside the core of neutron stars. The pieces of condensed neutrons would revolve mutually like planetary systems inside of molten quark gluon fluid and they should appear quite transparent for energy waves spreading through this fantastic system.

I presume, we could study such a geometry experimentally with electrons or tiny charged nanoparticles, attracted to surface of insulators with strong external electrostatic field.

So... gravity only works in 6 directions? Or we get a cube because gravity decides not to work normally?

Likening this to the 'orange pile' is no good. That pile only has one direction of gravitational force..

:-)
For some reason, this story reminded me of something here on Earth:

http://www.snopes...elon.asp

(square watermelons)

..or we get a cube because gravity decides not to work normally..

The gravitational force is strongest in just three dimensions. The surface/volume ratio is minimized just for 3D hyperspheres.

http://arxiv.org/abs/1106.4548
http://xxx.lanl.g.../0506053
http://mathworld....ing.html

the tipping point is believed to be such stars that are of twice the density as the sun

Mass, Bob, mass.

Gawad, I'm surprised you missed "Too small and they'd simply exist as run of the mill neutron stars."
Correction - too small and they would exist as run of the mill white dwarfs.

What happened to Oliver. This paper has relevant information on the sun's neutron core.

@shockr - the orange pile metaphor is perfectly fine. the neutrons pack in like a pyramid made of oranges. In fact, I think they over explained it. Let me lay it out simply for your reading comprehension skills. They are basically saying that the neutrons crystallize into a cubic type crystal.

There are tons of things that pack more efficiently than spheres. I remember seeing a paper with how M&Ms pack more efficiently than gumballs (both in random and ordered packing). Haven't read this paper, but I can't really see why they'd make the shift to cubes before slightly modifying their spherical shape.

Gawad, I'm surprised you missed "Too small and they'd simply exist as run of the mill neutron stars."

Good point, Guy. In my defence that "x2 the density" bit was just burning out my retina. :)

Also, I couldn't really make out if Bob was trying to situate these special case "squaring the neutrons" neutron stars between black holes and white dwarfs or between black holes (supposedly JUST above the mass limit for these special neutron stars) and "regular" neutron stars with round neutrons. It seems to me that Mr. Yirka usually manages to be a little more clear!

What happened to Oliver. This paper has relevant information on the sun's neutron core.

And geeze! Come on! The Spirit of Neutron Revulsion really doesn't need any encouragement!

Gawad, I'm surprised you missed "Too small and they'd simply exist as run of the mill neutron stars."

Good point, Guy. In my defence that "x2 the density" bit was just burning out my retina. :)

Also, I couldn't really make out if Bob was trying to situate these special case "squaring the neutrons" neutron stars between black holes and white dwarfs or between black holes (supposedly JUST above the mass limit for these special neutron stars) and "regular" neutron stars with round neutrons. It seems to me that Mr. Yirka usually manages to be a little more clear!

You're right, I didn't think about that. Maybe it was unclear instead of incorrect.

Maybe it was unclear instead of incorrect.

And a little frustratingly incomplete: what I would really like to know is whether neutrons would really deform under such pressures or dissolve into a quark-gluon strange matter plasma. He kind of hints at the alternate possibility when he writes "the blurring of lines between individual neutrons" but doesn't go any further.

Gawad, I'm surprised you missed "Too small and they'd simply exist as run of the mill neutron stars."

Good point, Guy. In my defence that "x2 the density" bit was just burning out my retina. :)

You're both wrong.

The author is saying that a NS of 1.4sols isn't massive, or dense, enough to pack its neutrons in the manner described.

Just sayin'

Gawad, I'm surprised you missed "Too small and they'd simply exist as run of the mill neutron stars."

Good point, Guy. In my defence that "x2 the density" bit was just burning out my retina. :)

You're both wrong.

The author is saying that a NS of 1.4sols isn't massive, or dense, enough to pack its neutrons in the manner described.

Just sayin'

Isn't that what Gawad is saying in the statement you quoted??

Maybe they turn into legos - That would be some kit!

addendum to my last comment - the part you omitted from your quote shootist.

Gawad, I'm surprised you missed "Too small and they'd simply exist as run of the mill neutron stars."

Good point, Guy. In my defence that "x2 the density" bit was just burning out my retina. :)

You're both wrong.

The author is saying that a NS of 1.4sols isn't massive, or dense, enough to pack its neutrons in the manner described.

Just sayin'

Isn't that what Gawad is saying in the statement you quoted??

It's OK, Guy, he's just being Shootist. Shootin' from the hip, BANG, BANG!

Some day he'll figure out either that twice the density of the Sun doesn't quiiiite match the density of any neutron star, or that doubling the Sun's *density* won't do Jack S*it as far as its mass. Or better yet, he'll pull those two ideas together and conclude that "twice the density as the sun" and "need to be twice the mass of the sun to be dense enough" aren't equivalent statements. And, yes, we all figured out what Bob was trying to say there anyway.

cubes does sounds a pretty unlikely packing arrangement. If this is happening then the normally fluid neutrons are basically crystallizing. They are likely to form the more close packed crystal latices. you can read about the packing arrangements in https://secure.wi...spheres. It looks to be much more likely that it would pack into dodecahedron 12 side shapes. This would reduce those low density regions on the vertices of cubes.

I imagine a bowtie to be a more likely configuration however in 3D so a cube surrounded by a "semi-soft" sphere.

I wonder if this model would yield a better picture of quadrupole magnetic reconnection events.

@shockr

So... gravity only works in 6 directions? Or we get a cube because gravity decides not to work normally?

Yes, such an object would have high gravity, but it's not actually about the gravity. It's about the pressure being generated by all the many particles being closely packed around each other in a VERY confined space and pushing against each other (density). This density being high enough to here generate this famous cube. The gravity field being generated will still be omnidirectional, but the shape of the field will follow the shape of the object as long as it is still separate. However, as all these objects and fields are in such close proximity, we get a collective field that is by extension, the field of gravity of the (collective) entity we call a neutron star.

honeycomb structure seems more likely

honeycomb structure seems more likely

At 2D, not 3D...

@DarkHorse66

I can appreciate that under pressure the neutrons may crystallise into such a lattice form. But surely there are still neutrons on the periphery that are not under such pressure and thus still mould around to form the sphere I'd expect from the gravity well. Is this still the case? I can't image anything having naturally flat sides. Surely some particles would adhere to the flat sides and make it non-uniform in that respect?

honeycomb structure seems more likely

I think he means 3D. Wouldn't that be a Octadecagon with 18 sides? I think that shape packs perfectly.

honeycomb structure seems more likely

I think he means 3D. Wouldn't that be a Octadecagon with 18 sides? I think that shape packs perfectly.

Aren't the apical angles wrong for that? Octadecagons are too like a sphere for close packing.

honeycomb structure seems more likely

Right, but the article is essentially defining a cubic honeycomb structure.

http://en.wikiped...oneycomb

The cubic honeycomb is the most space efficient because it's externally smooth (no outer layer graininess), when packed into a box.

But, I don't know if it's any more efficient than several other polyhedron shapes, when packed into a sphere.

http://en.wikiped...eometry)

But I suppose the outer layers might exhibit "smoothing" (to conform to the sphere's 2D boundary). Therefore, a variety of shapes seem just as likely.

Ubavontuba, even though Wikipedia uses the term "honeycomb" to desribe a cubic lattice, I think it is an unfortunate word, as it conjures up the hexagonal cells that bees make.

It looks to be much more likely that it would pack into dodecahedron 12 side shapes. This would reduce those low density regions on the vertices of cubes.

Exactly what I first thought. It seams logical that spheres would deform easier (read more likely) into something closer to spherical shape while utilizing the gaps.
If there is a reason for the neutrons to be aligned into cubical crystal lattice before they start to change their shape, yet the author has omitted to point this out.

@DavidMcC

...even though Wikipedia uses the term "honeycomb" to describe a cubic lattice, I think it is an unfortunate word, as it conjures up the hexagonal cells that bees make.

I generally agree, but the word simplifies the principle. I doubt the lay audience would easily understand the principle of "tessellation." I think the references I provided clear up any subsequent misunderstandings.

What I wonder is how much resistance to compression the neutrons may have. I definitely think it's likely harder to squeeze a sphere into a cube than a truncated octahedra, or some other semi-spherical polyhedron, as the corners of the cube are significantly extruded away from the center of mass/energy.

@Shockr:
You have deduced correctly, the outer particles would be under less pressure, therefore there would be correspondingly less 'deformity'. This is because the direction of the pressure is inwards, towards the centre and is greatest there. So, the further out from the centre the particle, the less it is being deformed. It is NOT a case of a couple of rounder ones sticking to a group of square ones. We are talking about a VERY large collection of VERY small (but uniform-sized) particles and that each deform gradually less and less, as we travel towards the outer parts. If you want a kind of a lineal analogy, maybe think of stacking a whole pile of loose fluffy cushions on top of each other. The top layer will still be loose and fluffy. As you go down the layers, each will be a little more flattened by the pressure being generated by the ones above. The direction of force is straight down, at a right angle to the floor. To take this to a 2D picture representative of a sphere..cont

...cont
cut down the middle, take your floor and roll it into a tight circle. The cushions are stuck together above and below, so that they don't fall off. The lines of force STILL point at right angles to the tangent of the corresponding point on the floor. And the operation of the force has not changed. The only difference is that the lines now meet at a central point. I tend to be somewhat pictorial (to be as clear as possible) when I try to explain things and I rather suspect that the picture I have painted is somewhat simplistic for you. I'm not trying to imply anything nasty, but I daresay that there are some on this site for whom this is what it takes. I prefer to hope that at least somebody has actually gained some genuine insight from this, however minor. As I would hope that others would do for me, when I don't get it right.

Cheers.

I think the most important issue in neutronium is "How is the degeneracy pressure that keeps a neutron star from collapsing to a black hole overcome?" The standard model posits that neutronium becomes "quark soup". However, this material would also have degeneracy pressure, because quarks aren't bosons. Particle physics eventually has to allow for the mass of a star to be converted to massive bosons, so that it loses its degeneracy pressure, and collapses to a black hole.