Talk:Dyson sphere/Archive 1

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Dyson Sphere Chatter while prepping mathematical proofs for comparison

Ugh! Ok. I'm curious about actual detailed fact. I read numbers being thrown around on the web concerning size and volume of a Dyson Shell, even formulas, but not worked out proof and all in one spot. The Dyson FAQ comes most close on http://www.d.kth.se/~nv91-asa/dysonFAQ.html but I'm looking for both summary and proof in one shot about at least those three bits of data (volume, area, linear distance of arc). Other issues... CAN we get permission from the dysonFAQ page to republish it here? CAN we get the dysonFAQ to publish a link to this WIKI page? I don't believe the cross-pollination would be harmful.

Taker's, anyone? --Romaq

Bah! I learn a few things on Wikipedia, then other activites step in. Lesee...

1) Dyson FAQ didn't respond to an email asking to use material, so I will presume the answer is 'no' until further notice. I'm not sure if I should properly refer to the FAQ, I'll presume not to. (didn't/won't --Romaq)

2) Track down 'Earth' in reference to its size data and use THAT rather than the NASA reference, keeping data internalized. (done --Romaq)

3) While tracking down Wikipedia's 'earth' data, how are statistics already being treated? It MAY be prudent of me to move my 'statistics' info on Dyson Spheres to a sub article off the main. I don't know that anyone else would care to have all that just because I happen to be curious this moment. (Don't forget to pop this into scale comparison's page! --Romaq)

SO THEREFOR... I track down 'Earth' with relative statistics, hopefully internalize the reference and THEN decide how to progress with relative statistics on THIS article. Learn as you go, learn as you go, make mistakes, do it, then do it better. --Romaq

---

This section has been sitting in the article "pending more detail" for several months now with no sign that it's going to be finished. Furthermore, it appears to be all about the most unrealistic version of the Dyson sphere, a solid shell with Earthlike habitat somehow stuck to the inner surface. So in the interest of making the article appear more scholarly, I've moved it here instead. Bryan 19:27 15 Jun 2003 (UTC)

Further detail pending

1) Volume in both AU, km and miles, with proof, compared against Earth for a 1 AU Dyson shell
Volume V of a sphere with radius R:
V = 4/3 π R³

2) Surface area in both AU, km and miles, with proof, compared against Earth for a 1 AU Dyson shell
Area A of a sphere with radius R:
A = 4 π R²

3) The linear distance in one degree of arc longitude at 0 degrees latitude upon the surface, compared against Earth for a 1 AU Dyson shell
Linear distance of one degree of arc L with sphere of radius R:
L = (π R²)/360

Conjectural Statistics (Presumed 1 AU in radius):

	Kilometers	Miles	AU's
Diameter	299,200,000 km	185,920,000 miles	2 AU
Surface area			~12.57 AU2
Volume			~4.189 AU3
1/60 Arc minute			~0.00873 AU

Solid shell

Bryan Derksen: "...and there are no known materials that would be sufficient to construct a solid dyson shell."

There are ideas for using dynamic structures to support the shell. The Lofstrom Loop taken to the extreme. Rings of fast-moving stuff provide the outward pressure to support the shell.

—wwoods 08

07, 4 Sep 2004 (UTC)

Yeah, I thought about that after I'd made the edit. But the bit I was objecting to with that edit summary was "Structural requirements using known materials dictate that the shell would be thicker than the diameter of even the largest planet, and probably denser too," which doesn't sound much like the editor was thinking of a Lofstrom-loop-supported shell, so I think my removal is still justified. However, adding mention of a Lofstrom shell would be neat. Wouldn't the particles need to be rather fast, or massive, or both, given they'd be in such a large "orbit"? Bryan 15:34, 4 Sep 2004 (UTC)

Rather. A ring 1 AU from the Sun going 30 km/s could support its own mass. A ring going 300 km/s could support a shell nine times its mass. Etc.

—wwoods 16:39, 4 Sep 2004 (UTC)

I've added mention of this support method to the article. There are probably much better ways to spend money than on a Dyson shell supported this way, but it would be POV of me to make that suggestion to any Kardashev-II civilizations that may be reading this looking for ideas. :) Bryan 22:12, 13 Sep 2004 (UTC)

Has anyone here studied physics in depth? For a Dyson Sphere, the material requirements are irrelevant of the thickness. It's similar to the calculations for a centrifuge (I don't mean to be insulting, but it's clear that at least some people commenting here have never done this kind of thing), the tensile strength divided by density is the limiting factor, and it doesn't matter it's 1 mm or 1 million miles thick. That is for the solid shell idea, and yes, it will make little difference (in the limiting engineering parameters) rotating it... it's a sphere...

Rotating rings are yet a completely different story, and the discussion here seems to come to no valid conclusions. Why would you argue how much weight it could support at different rotational speeds? If you were going to have an orbiting loop, you would clearly have it at orbiting speed and not support any weight!

Someone mentioned at some point that you need a material 100 times the strength of steel for it to work. Please, someone show some equations and valid analysis of this thing. It seems most pictures uploaded are original work, but there's no work conveying anything about the real limits of this thing anywhere. The tensile strength over the density is the most valid problem from the perspective of a race that we have assumed to have sufficiently advanced technical abilities, because while material science can advance, the available elements will not and still have impose clear limits with bond strength and such.

Anyway, I see so much good work that this article needs. In my opinion it's still far too premature to talk about the featured article category.theanphibian 03:42, 21 September 2006 (UTC)

I'm not sure what article it is that you're reading. Let me point out a couple of things you seem to have blatantly misunderstood

1. Thickness is not mentioned with regards to compressive strength of the material. The massive compressive strength of the material needed is mentioned in one point. Thickness of the shell is mentioned in a totally different point. The possible thickness of the shell is brought up to illustrate estimates of the amount of potentially usable material in the solar system. Again - there is no conceptual link between thickness of shell, and required strength. Certainly no claims that the shell should be made thicker because of weak material as you seem to "correcting" people for.
2. There is no mention of constructing a Dyson sphere of rotating rings. Again, you misunderstand the point. Take a Dyson shell. Build a track along a great circle of the shell. Put a mass on it (or several masses, or a torus of super fluid, or whatever). What do you have? More stress because of the address mass pressing on the shell. Spin it up to orbital speed as you claim you would "clearly have", and the net result is zero. Spin the mass(es) up to 10 times the orbital speed and what do you have? You have a net nine times the gravitational force on the mass pressing outwards, counter-balancing the gravitational compressive force putting the immense strain of the shell - at least locally. Do you see the theory behind "dynamic stabilization" of the shell through such means yet? Is it practical? Probably not, any more than a Dyson shell is practical in the first place - but it is an interesting "thought experiment".
3. "someone mentioned..." - and they did this in the talk page not the article, so I'm not sure why you are criticizing the point as "potentially bad, or at least unsubstantiated science". There's also someone talking about constructing a Dyson sphere as a folding hoberman sphere, and someone mixing up the direction of gravity on the interior of the shell. You might want to level your criticisms at the article. You'll also note that the article stresses that the Dyson sphere is probably impossible, for the very reasons you point out, so I'm not sure what your complaints are in this regards.
4. I don't know how many people have studied physics in depth here, but the article is referencing the works of many people who have. If you think the coverage is incomplete, or incorrect, you are free to do your own research, and add points and sources yourself. Indeed, such would vastly improve the article.

Vedexent 14:13, 21 September 2006 (UTC)

Solid shell - construction

I have added a piece about a possible way to construct a solid dyson sphere through first building a Hoberman sphere of far greater radius and then collapsing in back on the star untill it's in the habitable zone. However, is anyone smart enough to figure out how big the initial Hoberman sphere would/should have to be in order to be significantly less effected by our sun's gravity? I have read figures (on c2.com) of a 1 lightyear radius, but with nothing to back that up. Sander Marechal 11:47, 24 Mar 2005 (UTC)

Apart from being an amazingly impractical idea with a myriad of shortcomings and improbababilties, this is orginal research - I dug out the comment on c2.com. The "reference" for this idea is a single comment made in a forum discussion. Peer reviewed journal this is not. I'm taking it out. 66.82.9.91 05:05, 23 December 2005 (UTC)

Hi, I have just overworked the construction paragraph. It is actually simple to avoid all these shortcomings and instead run the construction by means of established technology. I think we do not need to invent some extraordinary strong material or additional mystical technology. Still the enormous amount of material and fuel to do all this work seems to be unobtainable by current mankind. A shell 1 millimeter thick would consume 1/4 of earth's volume. Fault-finder 07:53, 23 December 2005 (UTC)

Hi again, I have done some calculations. What I have found is that the needed strength of the material is around 100 times the strength of steel. Thus, "no known or theorized material is strong enough" is correct for a non-spinning ring or sphere. A ring that is spinning with earths velocity and a radius of 1 AU is viable, even if uncompleted, because the sum of all forces is zero. Fault-finder 13:41, 2 January 2006 (UTC)

This doesn't work for a sphere, though, since the poles aren't supported by the sphere's rotation and so still need ultra-strong materials to stay up. A rotating ring is another matter but that's perhaps better dealt with in the ringworld article. Bryan 02:00, 3 January 2006 (UTC)

It works only for a ring, indeed. The ringworld article deals with that science fiction story, only. It is not an article about a science concept. I don't think it's a good idea to mix this. What I prefer is to clearly separate the science concept and science fiction. Actually, I think there is still too much science fiction in the Dyson sphere article. Fault-finder 12:35, 3 January 2006 (UTC)

How to construct the shell?

Here is some original research for you.

1. Create a static ring. Support against gravity is provided by superfluids circulating at high speeds in cooled pipes.
2. Construct multiple rings around initial ring.
3. Construct sphere from rings by moving them to positions at angles to each other.

The end result would be a solid sphere supported by pipes of superfluid criss-crossing around the sphere. There is no need for super-strength materials. As the supefluids consume no energy, no energy except for cooling of the pipes is needed to maintain stability of structure.

-- Petri Krohn 03:41, 9 February 2006 (UTC)

This is a more efficient (at least as far as frictional energy loss is concerned) variant of the "high-speed masses in tracks" idea mentioned in the article. It's an interesting idea, I admit.

I don't like the idea of a Dyson sphere that has to be maintained by having energy pumped into it, or it all implodes into the star and is vaporized. Seems... unreliable.

I'm wondering how much mass would have to be cooled, and how much energy this would require. The example of the "massses in tracks" had a 1:10 mass ratio of "masses in tracks" to the rest of the sphere.

I'm also wondering what sort of energy demands this would put on the sphere. Superfluids are cooled below the temperature of the Cosmic Background Radiation temperature (something that has impact for a space structure). Temperature "spikes" could be catastrophic. I have visions of fluids dropping below "critical temperature", attaining friction, and the sudden torsion ripping out vast swathes of shell, shell crumbling, imploding, vaporized as it falls into the star (sizzle, sizzle, sizzle...).

However, it's a really cool idea (if you'll pardon the pun), and I think it's a definate improvement on the "masses in tracks" idea. - Vedexent 13:44, 9 February 2006 (UTC)

Gravity generators

Patrick removed "The problem of gravity cannot be solved even using hypothetical gravity generators" and asked "if hypothetical, anything is possible, what is meant?" 'Hypothetical' doesn't actually mean 'anything is possible', however. The reason the net gravitation inside a hollow sphere is zero is because of the inverse square falloff of gravity over distance, and the inverse square falloff of strength is a fundamental feature of gravity itself. Gravity would still fall off with the inverse square of distance no matter how one generated it. If it didn't fall off in that manner, it wouldn't actually be gravity but rather some other completely made-up attractive force. Bryan 15:46, 14 Sep 2004 (UTC)

The remark in the article is rather odd unless gravity generator is a common concept in SF. If so, perhaps it should be explained somewhere in Wikipedia and linked to, or otherwise expanded upon in this article. It could be just another word for mass (perhaps with a large density), perhaps a special kind which is not an inertial mass, and/or one that can be switched off.

Heh. I have been familiar with the conventions of science fiction so long that it didn't occur to me that this might not be generally recognized outside the genre. Yes, "gravity generator" is a fairly common and specific type of science fictional device that magically creates gravity at the flick of a switch; it is common as a background element of TV and move SF to reduce the special effects cost by allowing weightlessness effects to be omitted from ship interiors. I've added a link and will work up a stub at some point soon. Bryan 01:10, 15 Sep 2004 (UTC)

Another thing is that only if the gravity generators are uniformly distributed they do not solve the problem, otherwise they solve it locally. --Patrick 21:02, 2004 Sep 14 (UTC)

The same applies for simply distributing the shell's mass non-uniformly. I'll try to work mention of that in too, if nobody beats me to it. Bryan 01:10, 15 Sep 2004 (UTC)

I think it's worth pointing out though that SF tends to use rather outlandish gravity generators that seem capable of generating a uniform field across a flat surface, rather than behaving like a point source. My instinct is that in practice the generators would have to be able to create an unusual shaped field that didn't really adhere properly to the inverse square law. Perhaps you could get around this with a large number of point sources, although I think that might create other problems. Anyway, the point is that some SF gravity generators probably could generate false gravity on the inside of a Dyson sphere. I doubt very much that would be true in the real universe though. Alastair 18:38, 16 Jun 2005 (UTC)

The science-fiction ability to create gravity from a point source might logically be associated with the ability to create anti-gravity from a point source. On the inside of a sphere this would work out rather nicely (except for the small problem of keeping the sun from expanding into a cloud of helium and hydrogen inside the sphere of course). One could even build the sphere around a magnestar, and the natural diamagnetic properties of water, carbon, and hemoglobin (bound iron is not magnetic) would push away from the star and onto the sphere. Now, a magnetic field too strong can be lethal, but they've diamagnetically levitated a frog without killing it, so this theory is somewhat viable. An easier alternative is to build a structural transparent sphere which the inhabitants stand on top of, with a pressurized roof (The gravity at 1au would be so dispersed that the atmosphere would be very thin and require too much air) of solar panels. Splarka 19:05, 16 Jun 2005 (UTC)

Are we talking about a construction that can possibly be built based on real physics or are we talking about science finction? The idea of a dyson spere in principle is viable (with still mad logistics effort), while gravity generators are pure fiction. I think this distinction should be taken care of. Fault-finder 07:38, 22 December 2005 (UTC)

Gravity generators are currently only mentioned in the section titled "Dyson spheres in fiction", hopefully that clears up the distinction adequately. Bryan 02:13, 3 January 2006 (UTC)

Yes, you are right. The current position is fine. Fault-finder 12:35, 3 January 2006 (UTC)

I really don't see why things would not be gravitationally attracted to the inside of the Dyson sphere? Things close to the surface should be attracted to the perpendicular (A line connecting the object to the Sphere). Taking the intregral around the Sphere, lateral forces would cancel out, but the perpendicular forces would be relative to the much closer this side of the shere, rather than the far side of the sphere, unless the mass of the sphere exactly equalled the mass of the sun. Sim 00:20, 13 November 2006 (UTC)

Think of it this way. Take a point inside the sphere, and draw a projecting cone through the center of the sphere, and directly away from the center of the sphere. Within the near cone there is a little bit of mass, but it is close. Within the far cone, there is a lot of mass, but it is far away. If you do the calculations you'll find that the attractions balance - lots of far away mass and a little nearby mass so that at any point within the sphere, the net attraction to the sphere due to gravity is zero. Or so many physics text books say - I've never tried to do the actual calculation myself. You can also find examples of this with spheres and electrostatic attraction/repulsion - it works for any force that works with the inverse square law. You can probably find explanations on the net with Google - I havn't looked for it personally - Vedexent (talk) - 04:15, 13 November 2006 (UTC)

No great amount of calculation is necessary, and the axis of the cone doesn't even have to run through the center of the sphere. In the limit as the angle of the cone goes to zero, the areas of the sphere inside the cones can be approximated by flat surfaces perpendicular to the cones' axis. The radiuses of the bases of a two opposing cones are proportional to the distances from the point to the bases. So the areas of the bases are proportional to the square of the distances. But the gravitational force is proportional to the inverse of the square of the distances. So, if the areal density of the bases are the same, then the gravitational force from one base is equal and opposite to that of the other, and there is no net force.

_ _ __.__
|   \r| /
|d   \|/
+ - - ·
|    /|\
|D  / | \
|  /  |  \
_ /___|___\ 
    R

$F_{1}={\frac {GM_{1}m}{d^{2}}}={\frac {G(\rho \centerdot \pi r^{2})m}{d^{2}}}={\frac {G(\rho \pi kd^{2})m}{d^{2}}}=G\rho \pi km$

$F_{2}=-{\frac {GM_{2}m}{D^{2}}}=-{\frac {G(\rho \centerdot \pi R^{2})m}{D^{2}}}=-{\frac {G(\rho \pi kD^{2})m}{D^{2}}}=-G\rho \pi km$

$F_{1}+F_{2}=0\,$

—wwoods 07:25, 13 November 2006 (UTC)

I am not a scientist

How efficient a reactor is the average star, or for the sake of argument our sun? If it was possible to create a more efficient fusion reactor by artificial means, would the whole concept of the Dyson sphere become obsolete? I'm not thinking of putting this in the article, I'm just curious; the impression I had from reading pop science books was that advanced civilisations would use Dyson spheres and could be recognised as such, but if something better comes along the concept would presumably be moot. -Ashley Pomeroy 13:33, 25 October 2005 (UTC)

They could still be handy in that stars are doing fusion for free anyway, so why not harvest the energy? It'd go to waste otherwise. If a more efficient mechanism of fusing hydrogen is possible (and specifically fusing protium, which is really hard to do) then an advanced civilization might want to invest in star lifting to collect fuel, which would leave as obvious a fingerprint as a Dyson sphere would. Even if a more efficient mechanism than stars isn't possible it might still be advantageous to do star lifting to build red dwarfs (the most efficient type of star). Bryan 08:20, 20 December 2005 (UTC)

IMHO, mankind could surely build more efficient fusion reactor, but definitely not bigger... I think, more interesting question is, how much material would it take to build Dzson sphere. Would there be enough mass (not to talk about specific materials) to build a whole Dyson sphere? —The preceding unsigned comment was added by 85.160.111.254 (talk • contribs) .

Depends on the details of the sphere you're building and whether you're able to dismantle large planets for it. The most realistic type, the swarm of bajillions of orbiting solar collectors, could probably be done quite easily; most of it would only be a few centimeters thick at most and you'd probably want to put it in pretty close to the star so it won't have as much surface area. Bryan 00:57, 14 January 2006 (UTC)

All stars are essentially 100% efficient. They convert all the energy generated by fusion into EM-radiation (light and heat). They do better than that, when the Hydrogen is used up, they start burning helium and heavier elements. But in the context of colleciton of that energy the whole dyson sphere system would not be 100% efficient - there is energy loss from black body radiation. I think the apeal is the scale of the thing. IMHO the whole concept is still very much fiction, I object to the statement in the first paragraph: 'some proposed design variants of the sphere do not require technology much in advance of our own.' Should this be re-worded?. - —The preceding unsigned comment was added by 162.61.65.5 (talk • contribs) .

It should not be reworded. It is completely accurate. I am unsure what your objections are based on. What is being asserted in the opening paragraph is that there are design variants whose technology is not that far beyond our reach, even though we lack the industrial capabilities to implement these technologies on the scale needed to create a Dyson sphere.

The two design variants that meet this criteria are the Dyson swarm and Dyson bubble.

The Dyson bubble is more technologically "out of reach" as it has not been shown that ultra-light nanomesh sail materials are practical, nor that the mass of the rigging estimated in the calculations can be kept that low. However, there are no major technological barriers between the creation and launching of solar-orbiting satellites; we've done it already. It is true that the creation of tens or hundreds of thousands of these, if not tens or hundreds of millions, is beyond our industrial capabilities, however, that point is also conceded in the opening paragraph.

It's true that at what point it can be said that such a "component based" approach to a Dyson sphere is arbitrary. Does it take 10 billion components? 1 million? 300? 1? It is also true that there would have to be technological improvements of such components, improving longevity, perhaps even introducing self-repair capabilities. However, the technology behind creating the components themselves is not fantastically out of reach.

The Dyson shell is well beyond anything we can even conceive of technologically. Such a variant requires large scale transformation of material, disassembly of the planetary system for building material, perhaps even star lifting for material. However, the opening paragraph only claims that some of the variants are not fantastically beyond our current technological understanding.

Despite your objections, unless you can show that the creation and launch of a solar sail, or a solar orbiting satellite, requires a fundamental breakthrough in theory that we have not experienced, I don't see the basis for any reasonable objection. - Vedexent 16:54, 8 February 2006 (UTC)

Dyson Bubble: Made of beans?

A dyson bubble is made of beans? Could this be clarified?

As you might guess, a Dyson Bubble is not composed of beans, but of statites - apararently some very old vandalizm that no one caught until you did. Good job - Beowulf314159 04:16, 17 December 2005 (UTC)

Dyson Bubble and Statites

It is claimed in the Dyson bubble part of the article that there are no practical uses for the idea of a "cloud" of statites around the sun - but is this accurate?

Photonic pressure, close to the sun, can pack a heck of wallop.

The only treatment I've seen of statites is in fiction - by Robert L. Forward who also invented and patented the statite concept - was in the novel Flight of the Dragonfly. Forward was a rigourous hard science fiction author and a professor of physics, so I'd guess his treatment of the statite was backed by figures. In the novel - an entire space habitat is suspended by a ring solar sail slipped over the shadow cone of mercury (with the habitat inside the shadow cone).

I find the idea of a statite based Dyson swarm very interesting - as it eliminates the orbital dynamic problems of "swarms" of worldlettes trying to avoid collision in the classical model. Statites can just "hover" at rest over the sun.

Beowulf314159 02:34, 18 December 2005 (UTC)

The Resources Available

For each one of those purposed methods of constructing a Dyson Sphere, where would we get the resources to make it? I'm not a scientist but reading through the article, it looks to me that you would need a lot of material to construct this sphere. Can anyone explain where we would get all the material to make a Dyson Sphere. —The preceding unsigned comment was added by 71.115.89.90 (talk • contribs) .

Dyson spheres usually require the "disassembly" of the rest of the planetary system - both to remove collision hazards, and - as you point out - getting material to build the structure. Construction scenerios sometimes differ on whether it's possible to "transmute" hydrogen (through fusion?) to more useful construction materials. If so, then there is a lot more material that in the system that can be used. In the later case, even the star might be "mined" for material. Beowulf314159 17:56, 3 January 2006 (UTC)

A defense of Staties.

I'm sure someone will question the Dyson bubble figures, so here's my calculations.

• The O'neill colony is decscribed as 3x10⁶ tons [1]
• This is ~2,721,554,220,000 grams.
• The areal density of the sail is 0.3g/m²
• The density of a statite around Sol has to be no more than 0.78g/m²
• Thus, the sail has an extra "carrying weight" of 0.4g/m² (pessimistic rounding)
• Dividing the mass of the colony by the excess carrying capacity = 2,721,554,220,000 grams / 0.4g/m² = 6.80388555 x 10¹² m².
• A circle of 6.80388555 x 10¹² m² has a diameter of 2,943,293 m = 2,943Km. Rounded up in 3000Km.
• a sail/paylog combination with a density of 0.8g/m² (pessimistic rounding) and a sail area of 6.80388555 x 10¹² m² masses 5,443,108,440kg, or about a 50/50 split between the mass of the sail and the colony.

Beowulf314159 02:57, 5 January 2006 (UTC)

I just noticed that this section here on talk: is provided as a reference for Dyson sphere#Dyson bubble. This is not a good thing, it looks like a violation of the Wikipedia:No original research policy (as well as the Wikipedia:Avoid self-references guideline). Can you provide an external reference for this stuff? Bryan 07:56, 3 March 2006 (UTC)

To me, it doesn't look like it's not provided as a reference, so much as shifting the "publishing details" (which are kind of clunky) off the main page. I think that the whole thing could be put in an "example side box" which is something you see in reference material all the time, albiet text-books. Perhaps some sort of inline example box, or a footnote, would be better?

As for "original research" - I don't know, is it? It's kind of blurry line. It's not so much deriving a point, as providing a numerical illustration of the point. You could take the calculations out and just say something along the lines of "but Dyson sphere's based on statites may be possible with advanced nanomesh sail material", without losing the point. The calculations are an illustrative example of the point, not the point itself, so I don't think the point is "original research".

All the figures for the calculations, and the basic physics itself does have external reference. The paragraph is stuffed with them.

It brings up a good point though as to whether or not illustrating a point concretely and mathematically has a place in an encyclopedic article. If I have external references for "a+b=c", and "a=2" and "b=3", am I then allowed to state in an article that "c=5"? The only difference here is the complexity of the calculation.

- Vedexent 13:28, 3 March 2006 (UTC)

Yeah, it is a bit of a blurry area. One factor that isn't blurry, though, is that all else aside we shouldn't be putting "publishing details" on a talk: page. When Wikipedia is mirrored the talk pages are usually left out, so in this case part of the article would be missing. Moving it into the article might work, though I tend to favor your other idea that we should just say "but Dyson sphere's based on statites may be possible with advanced nanomesh sail material" or something similar. Bryan 17:04, 3 March 2006 (UTC)

You could reference Dyson Bubbles at ToothyWiki which goes into further detail on Statites and the materials needed. --Douglas 13:16, 20 April 2007 (UTC)

I'm a bit confused by the figure 0.78g/m², which also appears in the article, or rather by the units. Is this intended to be "density per unit area of sail", or "mass per unit area of sail". If it's the former, shouldn't the units be g/m³/m² (or the obvious simplification)? If it's the latter, shouldn't the article read "have an overall mass"? 82.46.105.4 21:47, 29 May 2007 (UTC)

Dyson Drive

Wouldn't it be possible to put a series of satellites in orbit that somehow act similiarly to a solar sail to actually move a star? I don't know how the mechanics would work. Perhaps a magnetic field? Or the sattelites extend out the solar sails and somehow hook to the gravitational field of the sun, and turn off/ dissemble when it started to come loose. Or, you could maye set it up like a big rocket, with the solar wind being fired out the back. Or, if you could invent a material which could hook directly to the sun... but I don't think that's too likely anytime soon. Could someone please help me refine this idea? Scourgeofsmallishinsects 15:40, 9 January 2006 (UTC)

You've got a great huge fusion reactor harnessed! Use it as a rocket, or a photonic drive :) The idea is called a Shkadov thruster or a Stellar engine, depending on whether or not you want to used a Dyson shell as part of the thruster design or not - Beowulf314159 16:34, 9 January 2006 (UTC)

I'm also guessing you could alter the techniques for star lifting to make the sun a giant fusion rocket as well. - Beowulf314159 17:46, 9 January 2006 (UTC)

Thanks. For a bit there, I thought I had thought of something new. Dyson Drive is a good name, though. I hope I at least came up with that. :) Scourgeofsmallishinsects 20:56, 9 January 2006 (UTC)

Lol. that's interesting and highly possible (lock the star in a magnetic field (which is possible since it's a giant plasma ball) and suck out hydrogen and pump collected energy into it like a gigantic VASIMR) but doesn't it seem kinda pointless? I mean it's certainly not my place to argue why an advanced Type II civilization would want to move a star around, but it seems to me there's probably easier and faster ways of doing so. Plus, the biggest reason for harvesting solar power directly like that would be to power ships which could go quite unbelievably fast with that sort of energy. Seems to make more sense to move to another star rather than to take your star with you. AeoniosHaplo 06:28, 9 April 2007 (UTC)

Dyson sphere would be a result, not a process

It is important not to assume that a "Dyson sphere" would be a single artifact constructed by a single enterprise for a single purpose. After all, if one were constructed by humans, that would almost certainly not be the case. It is at least as likely that the Dyson sphere effect would be achieved as a result of energy-collection space stations being constructed for the purpose of fueling individual projects or settlements. Assuming a technology permitting such stations to be built and operated at a cost that produced an energy conversion in excess of the cost of building and operating the station, such stations may be built until there are no more places to put them. To the extent such a project were collectively undertaken, such as by a government, the regulatory process might resemble the U.S. Federal Communications Commission's allocation of radio frequency spectrum to private businesses more than the construction of ancient wonders such as Stonehenge or the Pyramids. But it is also possible that such a project would not be collectively undertaken. Presumably, earlier stations would be more sunward and less efficient while later stations would be farther out and more efficient, trapping energy missed by the more sunward stations. The stations may be constructed as close as practicable to industrial facilities or settlements where the energy is to be used, trading off closing to the destination against efficiency of collection. There would, thus, not be a need for a physical "sphere" and a "Dyson sphere" could result from a process of economic development without any conscious formulation of an intent to construct a "Dyson sphere" artifact. -- Bob (Bob99)

I'm afraid I don't follow. What changes are you suggesting need to be made to the article? If you're proposing splicing this mini-essay in somewhere, you should probably cite some of the sources of the assertions in it to avoid having it look like original research. Bryan 00:58, 24 January 2006 (UTC)

I think it is "original research" - although interesting research. Such a method of construction holds - would even be hard to avoid - for human constructions of a Dyson swarm or bubble form. How alien intelligence choose to build theirs - or their motives for such - is anyone's guess. Remember that Dyson proposed we look for evidence of such spheres as part of SETI. It's hard to see how a Dyson shell could be constructed piecemeal though (or at all, in my opinion). - Beowulf314159 14:05, 24 January 2006 (UTC)

Yes, though I don't think it rises to the level of "research" (as opposed to discussion or comment). The only contribution is to note that Dyson postulated a system of solar collection satellites and that such a system could otherwise be described as what would naturally happen if a solar system became so densely populated that effectively all light emitted by its sun were captured and used. My comment is that the effect of a Dyson sphere could foreseeably unfold through economic development of space, by the construction of increasingly dense solar power collectors, without anyone necessarily formulating an intent to construct a Dyson sphere, per se. Such would not be a Dyson "shell" and it is foreseeable that satellites might be placed in different orbits at varying distances outward from the relevant sun. Placement would depend on the technology for power collection (supply) and power delivery (demand). But the effect would be the same as any other Dyson-type construct, in that the sun's light would be captured and not emitted to observers on Earth. One difference is that the degree of totality with which a relevant sun's light is captured would be directly proportional to the technology used to capture it and economics driving the construction of the power collectors. (This assumes that supply-and-demand trade-offs for industrial investments are the same from species to species; it is hard to imagine an advanced species succeeding by making industrial investments that consume more resources to construct than they produce once constructed.) As far as use by SETI, it might also be useful to look for partial Dyson spheres of this type; that is, star systems where a significant number of accumulators had been constructed, but not enough to occlude the star completely. Here, one assumes that the solar collection technology of choice would be optimized to collect those frequencies of light that the relevant star emits in greatest abundance. If one finds that a star exhibits phenomena of regular diminishing of its most abundant frequencies of light, then such a star may be a candidate for a solar collection-type of Dyson sphere. The use of the plural form "phenomena" in the previous sentence is deliberate, because what is postulated is a system of multiple power collectors, each in its own orbit (though some might be in different locations along the same orbit). Analysis of data would become increasingly complicated as the number of collectors increased. Thus, it is possible that, in order to create effects observable from Earth, the most likely number of collectors would be so high that an intractable analysis of data would be required to show that the effect is more likely the result of a solar collection-based Dyson sphere than some other phenomenon. Nonetheless, it is possible that, as knowledge develops, a classification of solar systems by factors consistent with the development of intelligent life somehow similar to ours, an additional factor of interest might be observable light fluctuations in the frequencies that are most plentiful in that system -- even if it could not be shown that the fluctuations were necessarily the result of power collection.

Also, there is a level at which the construction of any type of Dyson sphere necessarily assumes a civilization that develops extremely advanced technology but does not develop cost-effective interstellar travel. That is because sufficiently cost-effective interstellar travel would make it less resource-intensive to expand to another solar system than to build a Dyson sphere. (While it is impossible to know what level of cost-effectiveness of interstellar travel would make a Dyson sphere economically inefficient, we can make analogies to the migrations to North and South American from Europe, Asia, and Africa during the last five centures. Only the Dutch sought to expand their territory into the sea, and even they expanded overseas.) Thus, the absence of Dyson sphere could be consistent both with the conclusion that there are no civilizations out there to build them and with the conclusion that it is easier to branch out into different star systems than to populate a system so densely that all emitted starlight is captured and used for power.

-- Bob (Bob99)

I would recommend you read the various wikipedia articles on SETI, Dyson Sphere, Stellar engines, and Fermi Paradox. This has all been covered in various locations.

Partial and incrementally constructuced Dyson swarms, and Dyson bubbles, are discussed in this article. Changes in stellar spectra re' Dyson spheres are discussed in several places - such as Fermi paradox. One doesn't have to look for 'diminishing' anything - just altered spectra - it's what Fermilabs current Dyson sphere survey is doing.

Terran population grows by tens of thousands daily. It does not seem feaible — without some "fantasic" means such as stable interstellar wormholes that, for some reason, didn't need vast amounts of energy/g of material not to collapse — to relieve population pressure through emmigration. - Beowulf314159 20:07, 24 January 2006 (UTC)

Thanks. I've seen a lot of that material. When you speak of "altered spectra," are you talking about periodically altering spectra? For example, if there were a massive power collection array near the Earth, it would orbit the Sun along with the Earth. Assuming it was in the right position relative to an observer, the spectrum would be altered only periodically. If there were many such arrays in different orbits (for example, at Venus, Mars, various places in the Asteroid Belt, Jupiter, Saturn, etc.), the result would be complicated and more difficult to analyze. Also, I would look for an alteration in the form of a reduction in the most abundant frequencies on the belief that it would be unreasonable to tune a power collection array to focus on something that was in scarce supply.

As for the comments on the practicality of cost-effective interstellar travel, I'm sure that none of us really knows. We have no way of knowing whether (a) interstellar travel is impossible or (b) a few generations of developments in physics will make it possible for interstellar travel to become relatively commonplace. After all, at the beginning of the nineteenth century, aluminum was considered a precious metal because there was no cost-effective way to refine it. Commercial air travel was not contemplated in an era when the steamship had not yet been invented. The telegraph had not yet been invented, and the telephone was not contemplated. The semiconductor is used to solve problems that had not even occurred to people at the beginning of the nineteenth century. If there are other human-habitable planets, and if it is possible to get to them, imagine the value -- in terms of real estate value alone.

-- Bob Bob99

The altered spectrum is due to black-body infrared light emitted by the warm solar collectors. All of the energy a star puts out is still radiated into space, but as heat instead of visible light - I've heard the term "infrared giant" used to describe how a fully Dyson sphered star would look to astronomers.

As for the interstellar travel issue, that's kind of moot either way. Even if it is cheap to ship excess population to the planets of neighboring stars, what happens when those planets are full too? Exponential growth means life always fills to the carrying capacity of the environment it's in, at which point you either curtail growth somehow (starvation is traditional but other means have also been used) or you modify the environment.

Which isn't really all that relevant, though, since talk pages are supposed to be about the associated article, not discussion of the topic in general. Are there any changes you think need to be made to the article Dyson sphere that you want to discuss? Bryan 00:27, 25 January 2006 (UTC)

This is why I steered you towards those articles. The answers are there. The answer is that radiating solid bodies exhibit blackbody radiation. In most cases of Dyson sphere, radiating with a peak in the infrared. Partial blocking means partial blackbody radiation mixed with emission lines of a stellar atmosphere.

I have just outlined the conditions under which interstellar emmigration as a means of population reduction becomes practical: when you can ship tens to hundreds of thousands of colonists daily. That is based on biological reproductive patterns happening now. It is totally independant of technological development. It is totally independant of the "economics" of the situation. If you can ship that many people off the planet every day, for the rest of the lifetime of your species — no matter how — then it's "feasible" to send people off planet to reduce populations pressures. If you can't ship that many people, it's not practical. Rate of emmigration must be greater than rate of population growth. - Beowulf314159 00:16, 25 January 2006 (UTC)