No dyson spheres in local galaxies

[magnemoe]

The Kardashev Scale has its limitations anyway. Energy use is only one aspect of a civilization, and one relating more to scale than technological advancement. With it Kardashev didn't seem to anticipate the rapid progress of miniaturisation - semiconductor devices with features 50-100 atoms across are now commonly owned.

This, combined with the limits on how much you can eat each day

Past some point it's just about status, cars has mostly been status a long time.

Yes its easy to use far more than an type 1 civilization, type 2 starts to get absurd.

[YNM]

Sphere rotate, hop, problem solved.

Not quite, especially when you add classical N-body or even GR into it. And with GR, even a ring - a slight dent (out of circular), maybe as eccentric as Earth orbit and there's the chance things are going off.

A saturn-like ring: non-detectable actually. We need a whole bunch of order of magnitude from actual telescopes, and even with, making the difference from "regular" rings will be extremely difficult if not at closes ranges.

When direct imaging of exoplanet is a thing I don't think it's that implausible. Just add a plate to block starlight.

Transparent Dyson sphere: If you don't take all spectrum, but just slightly adjust them (like a filter of wavelengths: it's what these transparent solar panels do), It will be indecernable from a bit more aged star for example.

Well, I said spectrograph, not a particular band like I, J, K and what else commonly used band there is for IR. Also, what would be their efficiency ? They need to make it as efficient as possible, no ?

[baggers]

Maybe a "flexible" Dyson sphere is more viable? Something like modular parts (maybe 10km*10km) with flex cables for energy/material/peoples transport from a module to another? I don't think you need a full rigid structure.

By the way, a full-dyson structure is probably overkill when 1/5 of a "saturn-dyson ring" around earth filled with 1% effiency solar panels give about 10.000.000 times the actual energy consuption of humanity.

(And if you don't like to see it, you can ever buid a transparent Dyson ring ^^ - theses transparents solar panels have 1% effiency, btw)

And this is a earth with on scale saturn rings. Pretty cool, isn't?

Still a dust of a dust compared to a full Dyson sphere...

- - - Updated - - -

Hey. I just noticed moon has a mass of 7,347*×10E22 kg when the rings of saturns are 3 x 10E19 kg.

Nobody care about theses nuclear heads lying around? I will try something...

Edited September 21, 2015 by baggers

[PB666]

Even more funny a Dyson Sphere made of fully transparent solar panels!!!

http://www.extremetech.com/extreme/188667-a-fully-transparent-solar-cell-that-could-make-every-window-and-screen-a-power-source

http://www.extremetech.com/wp-content/uploads/2014/08/transparent-luminescent-solar-concentrator-module-640x424.jpg

It's not really "transparent": it just absorb a specific non-visible wavelength of light.

If a civilization will make a "discrete" Dyson sphere, it could just absorb some wavelength of ligth so a regular Sun will for example look like a credible red dwarf from outside the Dyson Shere.

e = hv if you absorb at a v of 1 and emit at 0.1 or 0.01 unless you find a way to convert e into mass proper you will end up emitting 10 to 100 times the photons. This level of production would be equivilent to a supermassive red dwarf with no visible or uv production. It would stick out in the star feild like a sore thumb in IR/visible subtractions.

[magnemoe]

Maybe a "flexible" Dyson sphere is more viable? Something like modular parts (maybe 10km*10km) with flex cables for energy/material/peoples transport from a module to another? I don't think you need a full rigid structure.

By the way, a full-dyson structure is probably overkill when 1/5 of a "saturn-dyson ring" around earth filled with 1% effiency solar panels give about 10.000.000 times the actual energy consuption of humanity.

(And if you don't like to see it, you can ever buid a transparent Dyson ring ^^ - theses transparents solar panels have 1% effiency, btw)

And this is a earth with on scale saturn rings. Pretty cool, isn't?

http://i.imgur.com/eZrjHja.jpg

Still a dust of a dust compared to a full Dyson sphere...

- - - Updated - - -

Hey. I just noticed moon has a mass of 7,347*×10E22 kg when the rings of saturns are 3 x 10E19 kg.

Nobody care about theses nuclear heads lying around? I will try something...

Far more plausible, you start with some orbital solar farms and scale up.

However linking them together will generate some issues on large scale.

Making them transparent is inefficient, unless you think of having gaps 10x10 km array then 100 km to next who would have the same effect on distance.

For larger scale you want to putt the array closer to the sun.

This is the orginal dyson cloud idea, you have so many solar farms in solar orbit that you block out the sun.

dyson spheres are pretty stupid, you will need idiotic amount of idiotically strong materials to build it as an starter

[PB666]

Far more plausible, you start with some orbital solar farms and scale up.

However linking them together will generate some issues on large scale.

Making them transparent is inefficient, unless you think of having gaps 10x10 km array then 100 km to next who would have the same effect on distance.

For larger scale you want to putt the array closer to the sun.

This is the orginal dyson cloud idea, you have so many solar farms in solar orbit that you block out the sun.

dyson spheres are pretty stupid, you will need idiotic amount of idiotically strong materials to build it as an starter

A dyson ring is possible around a star, but you would have to sweep the system of roids and comets. The problem as i described in the other post is that horizontal strength does not afford verticle strength at the tiny dThete/distance. AS a rsult your ring must be in orbit and cannot exceed a certain distance in the normal. Otherwise the forces on the ring tear it apart.

[peadar1987]

You would also need active station keeping, as a rigid, or even a flexible, ring or sphere around a star is unstable. Very unstable. Imagine the mass of a Dyson Sphere. Now imagine the amount of propellant required to give it even the tiniest bit of delta-V.

[smjjames]

How would we know we are looking at a dyson sphere when we see one anyway? Other than maybe thermal signature.

[cantab]

Yeah, thermal signature. Compared to a bare star a Dyson sphere would be too dim in the visible and too bright in the infrared, and the spectral lines would be all wrong. If a significant portion of the stars in a whole galaxy had been Dyson sphered, we'd see it. But keep in mind even a million stars barely qualifies as a "significant portion", and partial Dyson spheres would proportionately reduce the effect.

And a reminder that a realistic Dyson sphere is just a load of big satellites all on their own orbits, enough that they soak up virtually all the star's light.

[PB666]

You would also need active station keeping, as a rigid, or even a flexible, ring or sphere around a star is unstable. Very unstable. Imagine the mass of a Dyson Sphere. Now imagine the amount of propellant required to give it even the tiniest bit of delta-V.

Not as much as you think, i a working on the translational calculations, but something made of diamond lattice has stretch flexibility, if made very thinly, it would actually stetch and compess to fit those forces. This is not the problem. even a single molecule thick and a meter wide is alot of carbon, and the solar forces would turn it inot graphite or worse. Every carbon needs to be sheilded by lead and some other metal, the layer cannot be thin, it needs to be at least a nanometer in thickness which offers some resistence to stretch firces, but increases shear forces on the outside edges. What are we going to place on the ring, solar panels, or solar film on the ring itself you need the

2nm x 1 meter x 125,000,000,000 x 6.28 = 3200000 kg of diamond to support itself, 32000000 kg to support a solar film, 100,000,000 kg to support the wiring and infrastructure. 1,000,000,000 kg of carbon to support hv AC conversion past 10 million volts for transmission. Then you can add structure for facilities conversion for lihgt emmision and transmission, for used of deep space illumination or transmission to planets or other celestials. All these things would be nodes every 100,000 km and require special bracing so we are talking about massive amounts of carbon somewger on the order of a trillion kilograms for the thinnest functional ring possible. The only product you could produce usefully is light or gas uv that would be useful elsewhere.

[NuclearNut]

And? What is the point of building a dyson sphere. It would seem to me that it would be much simpler to say use fusion reactors on the planets you are strip-mining rather than build a massive solar array orbiting the sun. If you are going to build a dyson whatever you are going to need a lot of material and energy, energy that even fission cannot supply, hence the assumption that the civilization has fusion. Thus I question how exactly a dyson sphere would be practical for any civilization that may or may not exist as they could just use nuclear fission and fusion directly controlled by them and once that runs out they should be done stripping the solar system clean of it's resources.

[baggers]

A star is just a "natural" fusion reactor. The amount of energy it leak in space is several order of magnitude higher than everything you can fusion on every planet of the star system (Sun mass is actually 99,86 % of the total Sun System mass). Just take them. Is what the Dyson sphere is made for.

[Kerbart]

Ok, no Dyson spheres. But what about Ringworlds?

[baggers]

It's an old book.

(actually loved them, remind me I only read the first of that series, will see if I can get the others...)

[netbumbler]

Yeah when 'Ringworld' was originally written Mr. Niven didn't consider the instability problem. So he went to a Science Fiction Convention after the first book was published and was greeted by some M.I.T. students (I think they were from M.I.T.....) that had a sign saying: "The Ringworld is unstable!" They explained to him how you would need constant adjustment of the orbit/spin to keep it from going off axis and crashing into the sun. In the sequel "Ringworld Engineers" Larry just puts rockets up on the wall of the Ringworld to constantly make small adjustments that keep everything stable. Unfortunately people looking to leave the Ringworld end up stealing these rockets to leave the system and hilarity ensues when the stability of the thing is compromised. Sorry if some of that is wrong; doing it all from memory and reading that stuff 20 years ago. I love me some Ringworld...

When thinking about the likelihood of Dyson Spheres, I just wonder: if you have all that time and ability to utilize vast resources then you are obviously wanting your civilization to last a very long time. I mean the star is going to die out and expand after a few billion years and unless you have a way of controlling the star itself (which may be plausible if you can make a freaking Dyson Sphere in the first place) then why not just make a bunch of slow-generation type ships with all that tech and material and plan out a longer-lived scenario of expansion and terraforming? Cause trust me, if you can make a Dyson Sphere, making a bunch of huge generation ships is way freaking easier than surrounding a star with a sphere that is thick enough to have a useful surface. And terraforming is pretty much a given if you can make a Dyson Sphere. That tech is way simpler than building a useful sphere at 1AU and scrubbing an entire solar system of comets, planets and asteroids. Also, what if another star comes barreling through your system (our own Sol system had a near miss about 70,000 years ago and in a couple million we are going to have the Ort Cloud disturbed once again by a star headed right for us)? Course again, if you can make a Dyson Sphere in the first place, you have probably figured all that out (and all this ignores possibly having FTL...).

I just think the much easier generation ship/terraforming game plan is way smarter than a Dyson sphere...decentralization is almost always better for long term survivability (this ignores that you might have a ruler/emperor/plutocracy/whatever that wants to keep control centralized in one system while lording over a host of sentients). And then there's the fact that eugenics might simply beg the question of why you would need all that living space? I mean unless the aliens are truly egalitarian (which I mean who the heck knows?) then you will probably have an elite ruling class that will eventually kill off or bleed dry the median populace and once robots come into common usage you just don't need that many humanoids (or whatever). Yeah now I could be totally wrong on that last bit (or wrong about all of it, of course...lol), but I just don't see lots of uncontrolled breeding in a civilization that has advanced that far. But again, who the heck knows?

Edited September 22, 2015 by netbumbler

[dansmithers]

The only reason to build a Dyson sphere would be to harness it for usable land area-stars are by no means the most efficient way of converting hydrogen into energy(even less so than fusion in a magnetically-confined reactor, due to the vast majority of gas being in the unused outer layers).

It would still be a good symbol of cultural and economic dominance though, just like the Great Wall of China

[cantab]

The star is already made for you though. What matters is whether it's more economical to build a big solar power satellite (complete with some method to send the power elsewhere) or a big nuclear fusion reactor (which might be close to where the power is needed).