# Dyson Sphere only ever possible theoretically

Assume technology more advanced than current levels, let us theorise for this question that we are capable of reaching and if needed extracting material from any planet or moon / body in our solar system.

Question simply is would there actually be enough material available allowing for the above ( and what we could extract from other planets via huge automated mining operations perhaps ) in our solar system to build such a creation.

Given the size it would have to likely be , there does not seem to be enough erm "stuff" around to make it any more than a theoretical dream ?

I was not 100% sure which S.E to put this in , sorry if I have chosen the wrong one! :) I do not know how to move if if it is wrong.

• It's not clear to me how you are computing the amount of material which needs to go into a Dyson sphere... Hint: Have you ever seen a really large mirror? Let's say a mirror 5 meters wide by 3 meters tall, 15 square meters (160 square feet) total area; how much silver do you think is in that mirror? How much silver would there be in a mirror with an area equal to the United States of America? Is that a lot of silver? – AlexP Jan 22 '20 at 17:19
• Hi AndyF. It's not clear to me what question you're actually asking. Can you maybe edit your post to clearly specify what your question is and what kind of answer you're looking for? – Morris The Cat Jan 22 '20 at 17:20
• I'm not sure how else I can ask it sorry :( The dead simple summary would be " I'm not sure there is enough material available in our solar system to build one even if we were capable " , Second paragraph . – AndyF Jan 22 '20 at 17:23
• Niven Rings and Dyson spheres have more problems than just the amount of mass/material available. They probably require ultra-exotic substances... low-grade (or even high-grade) steel just isn't going to cut it. The sphere builders will also probably need construction techniques sophisticated beyond anything you or I can imagine. I have to be honest, I struggle with getting the corner of the sheet on the mattress without the other side pulling off... imagine doing that with a partial sphere somewhere around the orbit of Jupiter. Ouch. – John O Jan 22 '20 at 18:26

Let's do some math to find out.

Let's say each "panel" of the sphere is 0.01 m thick, at a distance of 1 AU (149597871000 m) we would need to cover $$4\pi r^2=2.8 \cdot 10^{23} \ m^2$$, resulting in a volume of $$2.8 \cdot 10^{21} \ m^3$$.

Assuming a density equal to that of water, we get that we need $$2.8 \cdot 10^{24} \ kg$$ of matter to complete the Dyson sphere, which is the same order of magnitude of the mass of Earth ($$5.972 \cdot 10^{24} \ kg$$.)

So, being Earth not the biggest guy in the Solar system, we have plenty of mass to build a Dyson sphere.

• This proves only that there's enough matter in the Solar System to build a shell around the Sun. I'd be very surprised if it turns out that Dyson spheres only need to be 1 centimeter thick. – Halfthawed Jan 22 '20 at 20:48
• Agree with @Halfthawed; not only is 1cm a vanishingly thin layer, you're talking about needing about half Earth's mass worth of material suitable to build it. That means, in part, that you're looking for material strong enough in that thickness to support the weight of the polar regions of the sphere, whose gravitational pull toward the Sun is going to be significant and which isn't being counteracted by centripetal force of tangential orbital motion. – KeithS Jan 23 '20 at 0:41
• Dyson sphere was originally envisioned as gauze or a swarm of loosely associated satellites. So 1x1x1m satellites, 10 meters apart and viola. – pjp Jan 23 '20 at 11:25

You raise legitimate concerns. Even if there was simply enough mass, it may not be the right atoms (we don't build anything out of helium for instance).

Which is why some people already came up with the dyson swarm, as well as other variants.

A Dyson swarm is a swarm of smaller constructs which gather and send back the energy they collect. It is more "practical" because:

• it can be operational even with a few constructs
• once a part of the swarm is operational, the energy gathered can be used to complete the swarm

Once you have consequent operational dyson swarm, building a dyson sphere seems more feasible. Also, regarding the type of materials needed, let me remind you that with enough energy, we are already able to change atoms (by fusion or particle bombardment). So if you somehow run short of a rare element, you can just create more.

There are qualified people who already spent more time than you and me "planning" how to build a swarm. Maybe their plan will convince you.

• It's worse than just not having the right types of atoms... you might need something that's not even atomic in nature. Transmutation of elements is probably trivial by the time you have the technology to build one. – John O Jan 22 '20 at 18:28
• The swarm is quite an interesting idea , needing much less resources initially too. It was no a thought I had considered. – AndyF Jan 23 '20 at 10:35