Wacky idea about aliens & "dark matter".

[Daecon]

I was thinking about two different things:

 

1) From what we can see of our Galaxy, there isn't enough "visible" matter to account for the Galaxy having enough gravity to not tear itself apart.

 

2) If aliens are out there somewhere, why haven't we seen them?

 

Well... what about Dyson Spheres?

 

Suppose an advanced civilisation (or more than one) made itself a Dyson Sphere among some stars at the edge of the Galaxy, where the gravity isn't as intense as being near the core... so that the Sphere was more structurally stable.

 

That would account for both the undetected matter holding the Galaxy together and be an explanation for why we've not detected any evidence of aliens, because it's all nicely self-contained in a Dyson Sphere.

[Edtharan]

among some stars at the edge of the Galaxy, where the gravity isn't as intense as being near the core... so that the Sphere was more structurally stable.

The gravity of the star that a Dyson sphere would be around, would far exceed the gravity that the galaxy would put on it.

 

However, a p[roper Dyson sphere that completely blocked out the light from it's star would be orbitally unstable. Any small perturbation (from a nearby star passing close to it) could send it out of control and plunging into the star.

 

Also,over time a Dyson sphere would eventually radiate the energy of the start that it surrounds. Because the Dyson sphere traps all the light and heat from the star, that energy has to go somewhere.

 

As the energy can't be destroyed (it can be used, but then that energy still exists), then it will eventually make its way out of the dyson sphere. We would then be able to see this radiation (most likely as infra-red radiation). This means that Dyson sphere would not be Dark, but Hot and emitting infra-red radiation.

[Sayonara]

I seriously doubt that would be able to account for the missing mass, even if such structures were commonplace.

[SkepticLance]

As suggested, Dyson spheres would radiate in the infra red and be detectable. However, in another thread on a similar theme, it was suggested that Dyson swarms would be technically easier to construct. That is : instead of a continuous structure around a star, you have a trillion orbiting space habitats, with perhaps a million beings in each.

 

I have always felt that a species that is advanced enough for that kind of development would not be restricted to a star. They would have advanced nuclear fusion power. The deuterium required for this is enormously abundant, and each habitat could generate its own energy - all that it ever needed.

 

Thus, the galaxy might, for all we know, have octillions of space habitats, not only orbiting stars, but throughout interstellar space.

 

Of course, that does not answer the question of why none of them have ever come knocking on our door???