0
$\begingroup$

It seems like Dyson Spheres are always brought up in the context of harvesting power. However, another use for a Dyson Sphere may be to cloak your solar system/inner planets. If the star's output doesn't escape from the sphere then it can't be observed except through gravitational effects which dramatically reduces the information you can get about the cloaked system. It seems like this would be useful for peaceful purposes like making it hard for aggressors to find you. It would also be useful for aggressive races to obscure their war production and/or mask initial acceleration so an object appears as a benign asteroid flying through space instead of an approaching warship.

I'd like to tie the concept of Dyson Spheres, or more correctly Matrioshka systems based on the linked answer, as cloaking mechanisms with the concept of dark matter too. I just don't know how plausible the idea of using Dyson Spheres are for hiding stars/inner planets, and if this would plausibly be interpreted as dark matter given our current to near future tech? The answer given by Serban Tanasa that I linked above to appears to support this as a possibility but it was given based on a question asking to alter the apparent size/class of a star, not cloak it out completely (baring gravitational affects).

Assuming this is possible, is there a scenario that would justify such an outrageously large engineering feat beyond "because we can." It seems to me that if you have the dedication and ability to pull this off then there is bound to be a cheaper solution to your problems...

$\endgroup$
  • 1
    $\begingroup$ you might get some justification for the effort from a [similar question]([worldbuilding.stackexchange.com/questions/35085/…) I asked a while back. In summary, such actions are justified by the existence of militant space empires in their galactic neighborhood. $\endgroup$ – Henry Taylor Oct 19 '16 at 21:12
6
$\begingroup$

It doesn't really hold water. Dyson spheres would block the visible light emissions of the star, but they'd glow just as brightly in infrared.

Pretty much any system that uses energy will generate waste heat. It's the good ol' second law of thermodynamics. If you use the energy of the star to do any kind of work, you will generate waste heat - heat that will need to be radiated from the outside of the sphere, or your civilization will cook. The only way around it would be to use 100% efficient direct conversion of energy into matter - but if you can do that, you honestly don't need the energy of an entire star. And if you're radiating heat into space, you're glowing like a Christmas tree in the infrared spectrum.

Edited to add:

If you've been following astronomy news this year, you've probably heard of KIC 8462852, AKA Tabby's Star, AKA "ZOMG-we've-totally-found-a-Dyson-Sphere-guys!!" star. One of the reasons astronomers are skeptical of the Dyson Sphere explanation for its puzzling dimming, apart from the normal skepticism of any good scientist about an amazing explanation, is the lack of this distinctive infrared signature coming from that star.

$\endgroup$
  • $\begingroup$ this doesn't answer the OP's question. He's asking "why was it done", not "why won't it work". $\endgroup$ – Henry Taylor Oct 19 '16 at 21:15
  • $\begingroup$ @HenryTaylor where does the OP ask that? He asks " I just don't know how plausible the idea of using Dyson Spheres are for hiding stars/inner planets, and if this would plausibly be interpreted as dark matter given our current to near future tech?" - it's not plausible, and wouldn't be plausibly interpreted as dark matter, as per my answer. "Assuming this is possible, is there a scenario that would justify such an outrageously large engineering feat " It isn't possible, so this question is irrelevant. How did I not answer the OPs questions? $\endgroup$ – Werrf Oct 20 '16 at 12:28
  • 2
    $\begingroup$ This answer was definitely in line with my first opinion. I am curious though, ignoring the "dark matter" stuff (which isn't really a known thing anyway), could you build it large enough that it dissipates the heat close enough to 3K to sneak past our sensors by hiding in the cosmic background radiation? $\endgroup$ – Cort Ammon Oct 20 '16 at 13:59
  • $\begingroup$ Sorry @Werrf. Reading it the way you did I can see how your answer applies. In my reading of it, I thought the OP was only asking for a reason why something so massive would be built. I read "Assuming this is possible" to mean that the OP didn't want to discuss if it was possible, but rather why it would be built in the first place. One of the other contributors answered a different question entirely in response to this OP post, so I guess I'm not alone in being confused about what is really being asked. $\endgroup$ – Henry Taylor Oct 20 '16 at 18:53
4
$\begingroup$

You seem to be asking: "Could Dyson spheres be the source of dark matter in the Universe?"

The answer is: No, dyson spheres put out blackbody radiation, the infra-red of which at least we should have detected by now.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.