what sort of civilisation...

[NWO Sentryman]

... could construct a dyson sphere? and how long could it take?

 

[GodMark2]

If you were to take all the material in the planets and use it to make a spherical shell the same size of the earth's orbit, it would be about 10 meters thick. Honeycomb it and it might be enough for a bare-bones habitat. To move that mass would require changing the orbital energy of the system by about 10*10^35 Joules of, or about 80 years of the sun's entire output.

Any civ that could do that would be considered gods by any current civ.

Of course, I may have slipped a digit here or there.

 

[Ladewig]

... could construct a dyson sphere? and how long could it take?

Quick off topic question: why did you want to avoid using "Dyson sphere" in the title of a thread about Dyson spheres?

 

[theprestige]

... could construct a dyson sphere?

The sort of civilization that probably wouldn't need one.

On the other hand, maybe the sort of civilization that, due to the Fermi Paradox, has nothing better to do with it's time and energy.

 

[Horatius]

A really freakin' AWESOME one!


Duh.

 

[Brian-M]

... could construct a dyson sphere? and how long could it take?

The civilization would need to have a general population so small that they can be housed in independent habitats between the time their planets are dismantled and the time the sphere is habitable, and be both willing and capable of keeping their population growth to near-zero during this period to avoid over-crowding their living space.

The civilization would also need to have a population enormously huge and vast in order to be able to supply enough workers^* to create the sphere, and be either unwilling or incapable of keeping their population growth to near-zero, otherwise they would have insufficient incentive to create the sphere.

*Even if AI robots are doing the bulk of the work, there will still be a vast number of jobs for management, design, engineering, etc, when creating something that unimaginably huge.

 

[uk_dave]

FFS, it's only a vacuum cleaner!

 

[catsmate]

The sort of civilization that probably wouldn't need one.

Yep.

BTW the term "Dyson Sphere" is properly applied to Dyson's original concept; a dense spherical network of satellites orbiting a star for power capture. It was not meant to be inhabited. He proposed it was the logical solution to a Type II civilisation tapping all the energy output of their star. It's not an implausible solution, given that such a civilisation would already have surpassed Type I status (10¹⁷W).
The popular concept of a hollow, solid, sphere with a star at the centre is technically a Dyson Shell and is considered the least plausible concept for reasons of orbital drift, strength and quantity of materials required, lack of surface gravity and vulnerability to impact.

My personal opinion, for what it's worth, is that any civilisation that could create a Shell wouldn't need to and any that needed to, wouldn't be able to.

 

[Ririon]

So to conclude, the answers are:

Communists. Forever.