Is it possible to depend on a white dwarf as our power source, provided that we harness 99% of energy?

Can life be sustained?

How it will change the climate and the seasons of earth if it is our only star and source of solar energy?

(Expecting it to change since earths orbital mechanics will also change)

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  • $\begingroup$ Technically Earth's orbital mechanics don't change. On the inside of a dyson sphere, all the gravity of the sphere cancels out. It's called the shell theorem. Welcome to worldbuilding.SE. When you get a moment, please take our tour and visit our help center to learn more about us. $\endgroup$ – JBH Jun 9 '18 at 5:52
  • $\begingroup$ @JBH You just inspired me to ask a question.... $\endgroup$ – Joe Bloggs Jun 9 '18 at 12:51
  • $\begingroup$ Unclear what you're asking. If you have a Dyson sphere, you don't have a planet supporting life. How are the two connected? $\endgroup$ – SRM Jun 13 '18 at 15:35
  • $\begingroup$ Also, good questions but one to a post please. If you need followup questions as separate posts, great. However, with multiple questions, the answer to one question might invalidate another question, making it unanswerable. $\endgroup$ – ShadoCat Jun 13 '18 at 16:06

Not really, no. It would be possible to orbit a white dwarf; their mass is generally one Sol (ie the mass of our Sun). But they're only about the size of Earth, and way, way smaller. There is a narrow window of habitability (theorised) around white dwarfs of limited luminescence. Problem is, you'd have to be close. Really close. Close enough that your planet would most likely be ripped apart by tidal forces, or get very, very hot from the same. You'd end up with Venus, essentially. This is kind of moot anyway as white dwarfs are left when suns expand; any inner planets, anywhere close to this habitability area, will be very effectively sterilised. They'll probably just be the metal cores. Seasons will be moot and climate will be about none.

I'm going to go a solid 'no' on life, at least without heavy and truly impressive life support technology. Really, if you can build the Dyson Sphere, you might as well go all out and make a Ringworld, or just live on the sphere; it would almost certainly be easier than the planetary remains. You could even use them for material.

As for the Dyson Sphere, it should be good, I suppose. A hot white dwarf, with the numbers I found, radiates about $1\times 10^{23}W$ of energy. Sounds like a lot, and I suppose it is, but not compared to even our relatively small star. We're still talking about a billion times our current energy needs though (current energy consumption figures are around $1.7\times10^{13}W$ per year). 99% percent efficiency is amazing though, so even accounting for the vastly increased needs of such a civilisation, it should be okay. I do need to point out though that this is a diminishing returns situation. White dwarfs don't do anything. No fusion, no reactions. They're just really hot. That means that they're going to cool and you're going to get less energy as time goes on. Eventually, it's just going to be a cold mass floating in space with no energy output at all. Sure, this will take about a quadrillion years, give or take, but there'll be a point long before that where it's not economical to keep the Dyson sphere running, or where it won't capture enough energy.

The Dyson sphere would work great but if you're civilisation is advanced enough to make a 99% efficient sphere, then you're not going to need a planet. You'd just live in space.

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