#1254 How would a Dyson sphere work?

How would a Dyson sphere work? A Dyson sphere would work by capturing the energy output from the sun and transmitting it to Earth. It would probably be a series of satellites.

A Dyson sphere is obviously hypothetical because we don’t have the technology available to make it. However, that isn’t to say that we one day might be able to construct it. The idea was thought up by Freeman Dyson, who was a theoretical physicist and mathematician. He first mentioned the idea in a paper called “Search for Artificial Stellar Sources of Infra-Red Radiation”. He mentioned the idea of a Dyson sphere (although he didn’t call them that) as a way to find signs of intelligent life from Earth. As a civilization becomes more advanced, its energy requirements expand. This can be seen from our own civilization. Each year we have devices that need more power and more of them. Our energy needs increase year by year. He reasoned that at some point a civilization’s energy needs would outstrip the available energy on that planet and then they would have no choice but to look for energy elsewhere. He reasoned that an advanced civilization might be able to capture the energy from their nearest star. If they did this they would have to use some kind of device that would encircle the star, and that would change the light coming from the star into far-infrared radiation. If we search the cosmos for far-infrared radiation, that could be a way of looking for intelligent life.

There are different levels of civilization and they are listed on the Kardashev scale. They go from Type I to Type III. A Type I civilization can utilize all of the energy on its planet. We are not even a Type I civilization yet. A Type II civilization could use all of the energy coming from its star, and they would be the ones making a Dyson sphere. A Type III civilization can use all of the energy emitted by its galaxy, including black holes.

So, how would a Dyson sphere work? Whatever is built to cover the star has to be strong enough to survive the heat and the radiation. It has to be able to trap the heat and transfer the energy back to the home planet. And, presumably, it has to not block out the light from the star. That last one is a guess, but if a Type II civilization still needs daylight and still has plants, then it is going to need light from the star to reach the planet. That might be a few too many assumptions and they might not have any need of the sunlight at all. If they did need the sunlight, then a series of satellites would make more sense than a solid object. In fact, satellites are always going to make more sense because they are easier to build, control, and replace than a giant solid structure that is larger than a star. A satellite with a large solar panel on it would be a perfect way to trap the heat energy and with enough of them, they could trap most of the energy from the sun.

As far as being able to withstand the heat goes, that would depend on how close to the sun the satellites were. Mercury is about half of the Earth’s distance from the sun and the surface heats up to about 430 ℃. That is not a very high temperature for a Dyson ring. It would be fairly easy to create a solar panel based satellite system that can withstand that temperature. It would probably be easy enough to get even closer with even the materials we have today. It might even be possible to build the satellites on Mercury, using all of the iron and other metals that it is made of.

That means the biggest problem would be getting the power back to the Earth. You could have the satellites reflect the sunlight and focus it on a point on Earth, but that seems incredibly difficult. It is possible to send power along a laser or over microwaves, but these methods are not efficient. You would only be able to recover a fraction of the energy you put in, which would negate the value of the Dyson sphere. That is with modern technology, though. It may very well be possible to send power with a laser at 100% efficiency in the future. There may be another way of directing the energy that we haven’t thought of yet. It sounds like a pretty difficult challenge. I guess that is why we are not a Type I civilization yet. And this is what I learned today.

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Sources

https://science.howstuffworks.com/environmental/energy/dyson-sphere.htm