Building a Dyson Sphere

Living on a planet has a lot of advantages, Like strong gravity to keep us from flying off into space, and the magnetic field and an atmosphere to protect us from damaging solar radiation. But, what if an advanced civilization ran out of room to grow on their home planet? What if they ran out of energy and resources to keep themselves going? Well, their best bet might be to build settlements in space, So they could capture more of their star’s energy Not another planet, though I mean, just sort of, floating around out there There’s a whole field of science that deals with how that might work. It’s called And it’s full of really cool, though still very hypothetical, ideas One of the most famous astroengineering concepts is known as a Dyson Sphere An object that captures more of the star’s light, and converts it into useful energy It’s named after Freeman Dyson, an astrophysicist who published a paper on this concept back in 1960 He pointed out that only a tiny amount of the sun’s light output hits Earth Since the rest is emitted in other directions And he proposed that other civilizations might have had to build some kind of structure to harness more energy from their local star And could now be using so much energy, that we’d be able to detect their waste heat, from here, on Earth But, he didn’t go into detail about how that might work Since then, astroengineers have been deveoping the concept And, one of the more well-known possibilities, first showed up in the 1930’s science fiction novel: Star Maker And has been featured in lots of stories since then What if they had a huge spherical shell, surrounding their sun, like some kind of cosmic egg? If their home-star was similar to ours and they built it with a radius of one astronomical unit, or AU, Which is the distance from the Earth to the Sun, Then, every point in that sphere would get the same amount of radiation as here on the Earth And, there’s a bonus! If they fixed up the surface of the shell with a nice atmosphere, and a comfortable habitat It would also provide a much larger area to spread out into But, of course there are lots of obvious limitations Though, another solar system might have more to work with But then the sphere, constantly being exposed to sunlight, would be too hot for life, electronics, and maybe even the structure itself They, could try building a bigger one, so that the shell, would be farther from the sun and wouldn’t get as hot, But, then they’d need even more stuff to build it Either way, they’d have some gravity problems Standing on the outside of the sphere, they would only feel the tiny pull of their home star And if they were on the inside of that shell, they’d feel the same pull and start floating toward their sun You could try to get the sphere spinning to simulate gravity, but it would take a lot of energy And you’d still only get an Earth-like gravitational pull near the equator On top of everything else, on the inside of the sphere, the gravitiational attraction cancels out So, it’d basically be free floating around their sun Any minor nudge, like from an asteroid hit, would set the thing drifting and eventually, it would crash into the star So, what if they built a swarm of smaller structures and spread them out around the sun, Instead of one huge, rigid, shell? That might be a little more doable It’s the same thing concept as the Dyson Sphere, Because they’re spreading out around the sun to gather more of its energy It’s just… not a sphere For example, they could try using solar collectors, devices that capture the sun’s energy Balanced on solar sails, thin mirrors designed to be pushed around by the pressure of the sun’s radiation Then, they could stick them right where the inward pull of their sun’s gravity would be just as strong as the outward push of its radiation They’d be like space power plants, transferring the extra energy they collected to smaller, more self-contained space habitats But, with all these hurdles, humans are no where near being able to build a Dyson Sphere or anything like it But, we are looking for signs that other civilizations might have That’s why astronomers are scanning other galaxies for infared spikes That seem like they shouldn’t be there So, these huge astroengineering projects might have to stay theoretical for now, But trying to figure out how they might work, gives us new ideas about how to look for other life That could be out there in the universe Thanks for watching this episode of SciShowSpace, and especially to our Patrons on Patreon Who help make this show possible If you wanna help support this content, just go to And don’t forget to go to and subscribe

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