ManyThingsLittleTime t1_j68t9h4 wrote
You could certainly engineer it to make it work but keep in mind you'd need many many galaxies worth of material. Something like a Dyson sphere would need a few planets worth of material so they become less probable on those grounds alone.
RShArren t1_j6903sq wrote
Well, that depends on what kind of structure do you need and how you build it...
Let's say it's a ring made of nanites (which sort of solves all material tension problems, because we assume that nanites can automatically rebuild any damages). Let's assume that the radius of the ring is 50000 light years (an approximation for the Milky Way radius, which equals 5*10^19 m), its width is 1 km (10^3 m) and its thickness is 100 nm (a size of a nanite, 10^-7 m). Let's assume that the nanites are made of carbon and have its density, which equals 3*10^3 kg/m^3.
The mass of this structure is going to be:
M = ro * V = ro * S * L = ro * h * w * 2* pi * R = 3*10^3 * 10^3 * 10^-7 * 2 * 3 * 5 * 10^19 = 9 * 10^19 kg.
Milky Way mass is 10^12 solar masses, and the mass of the Sun is 10^30 kg. In fact, the mass of the Moon is 10^22 kg. So one Moon is more than enough to build such a ring around the Galaxy...
PopeBrendicus t1_j6bt0mp wrote
>Let's assume that the nanites are made of carbon
>the mass of the Moon is 10^22 kg. So one Moon is more than enough to build such a ring around the Galaxy...
Carbon is only available in trace amounts on the moon. Carbon makes up about 0.46% of the universe, but it's not like it's conveniently all in one place for mining.
[deleted] t1_j695q54 wrote
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FogeltheVogel t1_j69weaz wrote
A few planets is a tiny fraction of the mass of a start system. How exactly is that an example of a galaxy sized structure needing multiple galaxies worth of material?
ManyThingsLittleTime t1_j6afcrz wrote
It is an example to demonstrate how much mass is needed to accomplish even a small scale version of what their talking about. It's an analogy.
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