Physics of the Dyson Sphere

[The Silence and I]

Ok I was thinking about what we know about the Dyson sphere and I have two main questions:

1)
We know the sphere is constructed of something called Carbon Neutronium--as odd as this sounds. I was wondering if it were possible to encase degenerate matter within carbon moloecules, buckey balls for example, or maybe even buckey balls within nanotubes or some kind of freaky thing. We all know neutronium cannot chemically bond with carbon, but would this encasement work? Would this or something similar offer the pressure needed to maintain the degenerate form of neutronium? Even if not I am thinking it could contain the neutronium even if some other possibly active system is needed to maintain it.

2)
Gravity. We know it doesn't rotate to produce gravity, aside from being stupid with a sphere, IIRC we see the inside and the land scape is spread about the whole surface. So it can either be natural gravity from the insane mass of the wall (it has neutronium, it's gotta be heavy) or some active system--they have enough power for sure!

But I hit a problem, I was favoring the natural approach for reliability, but there would be no surface gravity inside the sphere! The vectors cancel out, this is true of any gravity generated evenly (and it must be even, else mess up the star) along the inner surface of the sphere; so how do they pull this off?

I am working on ideas, but wanted to see what you all had to say, thanks in advance

[Patrick Degan]

If you're looking for any remotely realistic explanation for TNG's Dyson Sphere, don't bother. For a start, that much mass as is entailed in the structure depicted would collapse inward; there'd be no way you could have normal gravity on the inner surface of the sphere simply because of the mass of the shell material. And "Carbon neutronium" is an even more ludicrous concept than dilithium.

The Fact Index page included this commentary on Dyson spheres:

There are several basic varieties of hypothetical design for a Dyson sphere. The most realistic of them, and the closest to Dyson's original conception, is the "Dyson swarm". It consists of a large number of independent solar collectors orbiting in a dense formation around the star. The solar collectors could range widely in individual size and design, and possibly include space habitats for biological creatures to live in, but as a group they would collectively intercept almost all of the star's total light output. A number of different orbital patterns for the collectors have been proposed, each with different benefits and drawbacks; whatever pattern is chosen, some solar collectors will spend part of their orbits in the shadows of other solar collectors, reducing the sphere's efficiency somewhat. Since the collectors operate largely independent of each other, a Dyson swarm can be constructed incrementally over a long period of time and provide useful output throughout.

A second type of Dyson sphere is a uniform solid shell around the star, sometimes called a "Dyson shell", often with a layer of atmosphere and soil on the inner surface to provide an astronomically large living space for organic life forms. This form of Dyson sphere is much more popular in science fiction, but is not physically feasible for a variety of reasons. One is the immense strength that would be required for such an enormous structure, and another is the fact that the net gravitational force exerted by a uniform hollow sphere on anything inside is zero; there would be nothing holding the atmosphere to the sphere's surface, and it would fall into the sun. The problem of gravity cannot be solved even using hypothetical gravity generators, since it is a characteristic of the fundamental inverse square falloff nature of gravitational force, but the sphere could be rotated to produce centrifugal pseudogravity around its equator. However, the structural strength requirements for the shell material becomes even larger in this case.

A third type of Dyson sphere called a "Dyson bubble" is occasionally considered, composed of statites that hover motionless relative to the englobed sun using light pressure; this form of Dyson sphere has such low mass requirements that it could potentially be built from the material contained in a single small moon or large asteroid. However, a Dyson bubble has few practical applications (harvesting energy would be difficult due to its low mass and dependence on high reflectivity) and so it is not often discussed.

Another possibility is the "Dyson net", a web of cables strung about the star which could have power or heat collection units strung between the cables. The Dyson net reduces to a special case of Dyson shell or bubble, however, depending on how the cables are supported against the sun's gravity.

This page gives some idea as to what a true Dyson sphere would be structured as.

[The Silence and I]

Well I realize our science cannot achieve this, I was wondering if any theories had been made explaining the very real existence of the sphere, complete with internal gravity. The strenght requirements are insane, yes, but so is Star Wars materials, or even Federation materials--this is possible/common in sci-fi.

Now for gravity, I was thinking any science capable of constructing an impossible structure may be able to match/exceed the force field technology already used by the Federation--fields of force which have end points/surfaces, and apply this to artificially generated gravity near the surface. A layer of gravity a little deeper than the atmosphere for example.

Or perhaps some application of anti gravity;
In the 2-D plane representing 3-D space which we use to visual gravity, think of the sphere as a ring placed flat on the plane. The ring sinks a bit, creating a slope toward it from outside, but inside the ring the plane is flat--that is normal. If gravity is a dip in the plane, anti-gravity would be a rise, using this simple visualization aid it makes sense to me they may be able to use antigravity to push a ring upward in the center of the plane, around the star i.e. a non-physical smaller sphere between the real sphere and the star but creating anti-gravity. This results in a symmetrical gravity field, keeping the star happy, and also creates a slope toward the inside of the ring.

Make sense? I was hoping for other ideas though, speak up

[Praxis]

Ok I was thinking about what we know about the Dyson sphere and I have two main questions:

1)
We know the sphere is constructed of something called Carbon Neutronium--as odd as this sounds. I was wondering if it were possible to encase degenerate matter within carbon moloecules, buckey balls for example, or maybe even buckey balls within nanotubes or some kind of freaky thing. We all know neutronium cannot chemically bond with carbon, but would this encasement work? Would this or something similar offer the pressure needed to maintain the degenerate form of neutronium? Even if not I am thinking it could contain the neutronium even if some other possibly active system is needed to maintain it.

Carbon Neutronium implies molecules of Carbon bonded with molecules of Carbon.

I don't know about the chemical composition of Neutronium. What is it? I assume it probably doesn't have any electrons (which would make it very, very difficult to bond with another chemical), since it's supposed to be in a black hole.

[Alyeska]

The Dyson sphere has to have artifical gravity. Being inside a spherical construct will netraulize all gravity and leave just the star as the local source. That has to be countered.

[The Silence and I]

No kidding Alyeska, but even artificial gravity will be canceled out too. That is why I asked for leading ideas/theories. There seem to be none, so I offered my own ideas above.

Praxis:
Neutronium is degenerate matter--i.e. atoms are crushed with insane pressure until the very electrons combine with their counterpart protons resulting in a "nucleus" of neutrons only--as the whole lot is under this same pressure all these "nuclei" are squeezed together until you are left with a mass of solidly packed neutrons.
Needless to say, this cannot chemically combine with any atom. Data said "carbon neutronium" as if it were a compound, but it may be interpreted to mean there is carbon, and neutronium present--the only way I know to possibly achieve this (and I can easily be wrong) is to encase the neutronium within a molecule.

A spherical buckeyball just happens to be very strong, hollow, and made of carbon. Which seems like a possible lucky break for those of us who try to make sense of this insanity.

Now, a buckeyball may not be strong enough to contain neutronium (merely maintaining it IIUC requires pressures that a mere molecule may not be able to provide) but artificial devices may allow the degenerate matter to be maintained. Carbon molecules may still be required to hold it in place though.

Has no one really thought about this before

[Praxis]

No kidding Alyeska, but even artificial gravity will be canceled out too. That is why I asked for leading ideas/theories. There seem to be none, so I offered my own ideas above.

Praxis:
Neutronium is degenerate matter--i.e. atoms are crushed with insane pressure until the very electrons combine with their counterpart protons resulting in a "nucleus" of neutrons only--as the whole lot is under this same pressure all these "nuclei" are squeezed together until you are left with a mass of solidly packed neutrons.
Needless to say, this cannot chemically combine with any atom. Data said "carbon neutronium" as if it were a compound, but it may be interpreted to mean there is carbon, and neutronium present--the only way I know to possibly achieve this (and I can easily be wrong) is to encase the neutronium within a molecule.

A spherical buckeyball just happens to be very strong, hollow, and made of carbon. Which seems like a possible lucky break for those of us who try to make sense of this insanity.

Now, a buckeyball may not be strong enough to contain neutronium (merely maintaining it IIUC requires pressures that a mere molecule may not be able to provide) but artificial devices may allow the degenerate matter to be maintained. Carbon molecules may still be required to hold it in place though.

Has no one really thought about this before

Interesting.

I assume Neutronium would be unable to maintain an electron orbit if you could find a (technobabble) way to forceibly add some valence electrons?

[The Silence and I]

Quite unable--there is no positive (or any) charge for the electrons to orbit.

I think there is no question that a chemical bond is impossible, I never even considered it really, I went immediately to molecular structures which may contain it.

[Howedar]

The fact that ST gravity can be varied deck by deck (done in Voyager) implies that they have some sort of magical gravity that does not falloff as an inverse square. Therefore gravity on the inside of a Dyson Sphere might well be possible (if stupid).

[Alyeska]

Artifical Gravity in Trek is not the same as normal gravity. They can apparently create bubbles of gravity where nothing outside of that is attracted to it. This means the Dyson Sphere can employ artifical gravity all throughout the system. I gotta wonder how many redudant systems they used in order to keep the whole thing safe from failure. Though artifical gravity in Trek appears to be on of the rock solid reliable systems that NEVER fails.

[The Silence and I]

Ah, not watching Voyager I was not aware of deck-by deck gravity, I assumed the gravity plating on each deck served to keep the overall field constant--of course First Contact's space walk should have clued me in there

But yeah, that calls for a lot of systems--if you lose gravity on a starship people get upset, on the inner surface of a dyson sphere...any competent engineer (and it takes those to build such a thing, I'd reckon) would ensure that never happens.

Can anyone comment on my molecular containment idea?

[brianeyci]

Though artifical gravity in Trek appears to be on of the rock solid reliable systems that NEVER fails.

If you can target a ship's gravitational array, you can take out the gravitational field al la ST:VI. Just hasn't been done a lot -- you'd wonder why in the TNG series, disrupting an enemy's ability to sit still and operate their consoles seems to be a good way to disable them apart from disabling their weapons array.

Maybe you need very specific information to do this... the Bird of Prey was firing on a D-7, so they obviously knew where to target exactly to knock out the gravitational field.

Brian

[The Silence and I]

Well first and formost hostile damage is a little different than a failure, per say.

Also, I think it may be that in TOS there was indeed a gravity field across the entire ship--but that was later replaced by deck-by deck generation without a centralized system to take out. For example, in ENT there is a "sweet spot" on the ship where the gravity field reverses itself--it is still a weird field, but it is throughout the ship. AFAIK no such sweet spot exists on TNG ships, and evidence such as phase cloaked individuals not passing through the deck suggests the actual deck plating contains the gravity generation systems.

[Kuroneko]

Now, a buckeyball may not be strong enough to contain neutronium (merely maintaining it IIUC requires pressures that a mere molecule may not be able to provide) but artificial devices may allow the degenerate matter to be maintained. Carbon molecules may still be required to hold it in place though.

They can do under very cold conditions. Neutronium is the simplest case of a Fermi-Dirac gas, so its pressure is directly proportional to its internal energy and inversely proportional to its confining volume. This is the same kind of this that occurs in the ideal gas, except that in this case the internal energy also includes the rest energy of the neutrons. If the neutronium has density ρ, then its minimal pressure (i.e., in the classical absolute zero limit) is P = (2/3)(ρ/c²). Even at the immense densities of typical neutron stars, ρ ~ 1e17kg/m³, the pressure is P ~ 1Pa. This is very miniscule, about one hundred-thousandths of the standard atmosphere. That may seem counter-intuitive, since neutron star pressures are much higher, but that is because their cores have temperatures on the order of 1e8K, whereas here it is the absolute-zero limit that is given.

If there are artifical devices keeping them near absolute zero, then it also solves another problem: neutrons are so tiny that they can typically go through other atoms as if they weren't there, making their containment virtually impossible. That is, unless they simply don't have much kinetic energy to appreciably move in the first place, as is in the absolute-zero case.

[Slartibartfast]

Isn't a bit of a brainfart that every time a Trek ship has a *total* power failure, the artificial gravity works just fine? Or maybe there haven't been any actual instances of total power failures... I could swear there's been two or three times.

There's definitely one in Enterprise, IIRC, with some telepathic dude. I didn't see anyone floating.

[brianeyci]

Brainfart or not, we should explain it in-universe. Perhaps all the Trek gravitational systems are powered independently of the main power grid -- unlikely, given that everything from the self destruct device to the transporters have failed when main power has failed. Trek engineers just don't build enough safeguards into their systems, so it would be unlikely that they would have one single isolated system that works redundantly and not apply the same methodology to other systems.

The next most possible explaination is that the gravitational field works without power. Perhaps the deck plating has properties that allows it to attract other bodies without relying on mass. If this sounds stupid, then we are back to the original explaination -- that Trek engineers designed a system independent of the main power grid, which doesn't follow the methodology of Trek designs.

Brian

[Praxis]

Quite unable--there is no positive (or any) charge for the electrons to orbit.

I think there is no question that a chemical bond is impossible, I never even considered it really, I went immediately to molecular structures which may contain it.

Thought so.

So there's no way it could be carbon bonded with Neutronium. Besides, if it was a compound it would be "neutronium carbonate" or something similar.

So, if I'm understanding this correctly, if Neutronium was in the periodic table, it would have an atomic number of 0 (having no protons), correct? Quite interesting.

However, I don't think encasing neutronium in a carbon molecule would do the trick. If I'm understanding this correctly, it would have all the protons of carbon (6 protons), all the neutrons of carbon (usually 6 but can be more or less), plus the ultra-dense neutronium (made of compacted neutrons). It would still have 6 protons, and therefore by the periodic table would just be carbon-something (where the something is the number of neutrons, such as Carbon-6).

Perhaps, though, they're using the name "neutronium" instead of a number? So it would be Carbon-Neutronium? I dunno. It's still very unrealistic, but it's the only semi-reasonable explanation i can think of.

[Praxis]

Though artifical gravity in Trek appears to be on of the rock solid reliable systems that NEVER fails.

If you can target a ship's gravitational array, you can take out the gravitational field al la ST:VI. Just hasn't been done a lot -- you'd wonder why in the TNG series, disrupting an enemy's ability to sit still and operate their consoles seems to be a good way to disable them apart from disabling their weapons array.

Maybe you need very specific information to do this... the Bird of Prey was firing on a D-7, so they obviously knew where to target exactly to knock out the gravitational field.

Brian

Good point, considering that in Star Trek they have no concept of a seat belt

[The Silence and I]

Snip

Thought so.

So there's no way it could be carbon bonded with Neutronium. Besides, if it was a compound it would be "neutronium carbonate" or something similar.

So, if I'm understanding this correctly, if Neutronium was in the periodic table, it would have an atomic number of 0 (having no protons), correct? Quite interesting.

However, I don't think encasing neutronium in a carbon molecule would do the trick. If I'm understanding this correctly, it would have all the protons of carbon (6 protons), all the neutrons of carbon (usually 6 but can be more or less), plus the ultra-dense neutronium (made of compacted neutrons). It would still have 6 protons, and therefore by the periodic table would just be carbon-something (where the something is the number of neutrons, such as Carbon-6).

Perhaps, though, they're using the name "neutronium" instead of a number? So it would be Carbon-Neutronium? I dunno. It's still very unrealistic, but it's the only semi-reasonable explanation i can think of.

Something I thought of a little after posting this was that neutrons, having no charge, cannot be electrically contained by a molecule But what Kuroneko has said is very helpful--as he is damn near every time I've ever seen him post anything

Also, they do have a concept of seat belts--sort of. In TOS movies the captain chair had some version of seat belts, leg locks more realistically, but hey it's something Ok, not much, but still, the idea has occured to someone.

[Praxis]

Now, a buckeyball may not be strong enough to contain neutronium (merely maintaining it IIUC requires pressures that a mere molecule may not be able to provide) but artificial devices may allow the degenerate matter to be maintained. Carbon molecules may still be required to hold it in place though.

They can do under very cold conditions. Neutronium is the simplest case of a Fermi-Dirac gas, so its pressure is directly proportional to its internal energy and inversely proportional to its confining volume. This is the same kind of this that occurs in the ideal gas, except that in this case the internal energy also includes the rest energy of the neutrons. If the neutronium has density ρ, then its minimal pressure (i.e., in the classical absolute zero limit) is P = (2/3)(ρ/c²). Even at the immense densities of typical neutron stars, ρ ~ 1e17kg/m³, the pressure is P ~ 1Pa. This is very miniscule, about one hundred-thousandths of the standard atmosphere. That may seem counter-intuitive, since neutron star pressures are much higher, but that is because their cores have temperatures on the order of 1e8K, whereas here it is the absolute-zero limit that is given.

If there are artifical devices keeping them near absolute zero, then it also solves another problem: neutrons are so tiny that they can typically go through other atoms as if they weren't there, making their containment virtually impossible. That is, unless they simply don't have much kinetic energy to appreciably move in the first place, as is in the absolute-zero case.

Meaning if someone found a way to heat a fair sized section of the dyson's sphere hull a bit (like Picard did in "Encounter at Farpoint"?), the Carbon Neutronium would collapse immediately and probably unravel the entire sphere. Yet, the impact and friction from the crash of Scotty's ship didn't seem to have even dented the Dyson's Sphere...

[Praxis]

Also, they do have a concept of seat belts--sort of. In TOS movies the captain chair had some version of seat belts, leg locks more realistically, but hey it's something Ok, not much, but still, the idea has occured to someone.

Another example of "lost technology" TOS had seatbelts, TNG didn't...

[Winston Blake]

So, if I'm understanding this correctly, if Neutronium was in the periodic table, it would have an atomic number of 0 (having no protons), correct? Quite interesting.

Firstly, sorry if i sound at all condescending, i'm no expert (just a kid and newbie).

The thing is, neutronium cannot be in the periodic table. It's not normal matter, its degenerate matter:
http://en.wikipedia.org/wiki/Neutronium
http://en.wikipedia.org/wiki/Degenerate_matter

There are no atoms and no actual nuclei, its just a sea of neutrons. The -ium suffix has nothing to do with being an element, neutronium is just an informal term.

However, I don't think encasing neutronium in a carbon molecule would do the trick. If I'm understanding this correctly, it would have all the protons of carbon (6 protons), all the neutrons of carbon (usually 6 but can be more or less), plus the ultra-dense neutronium (made of compacted neutrons). It would still have 6 protons, and therefore by the periodic table would just be carbon-something (where the something is the number of neutrons, such as Carbon-6).

Terms like "Carbon-14" refer to nuclides, particular kinds of atoms. A 'carbon encased neutronium pellet' would be a mixture, not a nuclide.

Nitpick: Carbon-6 would have a nucleus of 6 protons and nothing else (!) since the number refers to the number of nucleons (protons & neutrons).

I don't know about the chemical composition of Neutronium. What is it? I assume it probably doesn't have any electrons (which would make it very, very difficult to bond with another chemical), since it's supposed to be in a black hole.

Not a black hole, a neutron star. Black holes are weird and AFAIK don't contain matter at all, neutron stars are nice and friendly though.


Now, since neutronium is a fluid, it would not be that useful as a construction material. However it's extreme density is desirable.

It's instability outside of a neutron star is a major problem, but Kuroneko's brilliant idea of a 'supercold' neutronium allows a small pressure to keep it together.

That small pressure could be supplied with normal matter (for the Dyson Sphere, carbon). However since it's neutral it can't be acted on (contained) by that matter.

My solution is that it's not neutral, but has a handful of protons mixed in (IIRC neutron stars contain some protons in this way), kept inside against their repulsion by the strong force.

Electrons can then form a hazy cloud layer on the surface of a neutronium pellet/string/etc, allowing it to be repelled by the electrons of the normal atoms.

My guesses with this neutronium business would be:

1. A composite consisting of carbon nanotube fibres in a charged neutronium matrix (doesn't that sentence make you shiver in technobabble-joy?). The nanotubes would probably have to make up a high percentage of the material depending on how fluid neutronium is (i have no idea).

2. A carbon (diamond?) matrix with strings/pellets or a net of charged neutronium throughout it.

3. Based on Silence's idea: A whole bunch of buckyballs with single pellets of charged neutronium filling their interiors. The holes in the structure of a buckyball might let the neutronium out, probably depending on how fluid and charged it is. Buckyballs should be capable of it though: http://www.chem.wisc.edu/~newtrad/CurrR ... Bucky.html

Indeed, molecules of buckyball prepared in helium have probably always generated some of the material with helium gas trapped in the interior cavity of buckyball. Only one out of every 880,000 molecules of buckyball are believed to have helium trapped inside them, though, and these special complexes remained undetected until very sophisticated mass spectroscopy techniques were applied to the problem in 1993. The interior of C60 is large enough to accommodate an atom of any element in the periodic table, and many metals including lanthanide, uranium, cesium, and scandium have been trapped by fullerenes ranging in size from C28 to C82.

4. Based on Mike Wong's idea: "The use of neutronium micro-particles [atom sized rather than in above ideas] as interstitial alloying elements" in a metal matrix (i like the word matrix) would be a true 'neutronium alloy'. http://www.stardestroyer.net/Empire/Tec ... Beam2.html
However, unless there's a small percentage of metal in carbon-neutronium we'll have to settle for carbon and therefore a mixture.

In all cases, Carbon Neutronium would have to be a non-systematic common name, since they aren't alloys, like 'carbon steel' is (which no doubt inspired the writers).

[Praxis]

Very interesting stuff. Thank you. I know a bit about chemistry, but I never really learned what Neutronium was

[Winston Blake]

On a side note, buckyballs with atoms inside them are apparently called 'endohedral fullerenes'. When the atoms are metal, this is extended to 'endohedral metallofullerenes'.

Possibility #3 might then be called an 'endohedral neutronofullerene' (or maybe more generally 'degenerofullerene' for 'degenerate' matter).

[nasor]

I find it difficult to imagine how any sort of molecular carbon compound to contain neutronium. I would expect the neutronium to simply float around/between the carbon molecules as if they weren’t even there, even if the neutronium was at a very low temperature. Trying to cool neutrononium in order to keep it within a carbon structure would seem akin to surrounding the perimeter of large field with telephone poles placed 50 meters apart, then trying to use your telephone pole ‘fence’ to contain a herd of squirrels. Perhaps the squirrels would stay in place if you sedate them enough, but the telephone poles wouldn’t really matter one way or the other. I don’t think that the carbon cage could even really exert any pressure on the neutronium, since the neutrons would be about one hundred thousand times smaller than the holes between the carbon atoms.

I don't think that it would even be possible to trap neutronium in the interstitial spaces within a crystal - it would probably just float out.