From what I can tell, pulsars emit light in beams from the poles of the pulsar. Would it be possible to construct something to get energy from a pulsar's beams of radiation? Or is this as idiotic of an idea as... erm, an idiotic idea. (I am not good at metaphors.) Would this be easier than building a Dyson sphere?
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$\begingroup$ Earth life has done OK capturing energy from our star. Plants have, anyway. And we do pretty well eating them. $\endgroup$– WillkApr 20, 2018 at 19:57
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1$\begingroup$ I am asking about pulsars specifically. $\endgroup$– SievertApr 20, 2018 at 19:59
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$\begingroup$ The question is why. What would your civilization do with that much energy, located quite a long distance from any liveable planet? (Since the supernova that created the pulsar would have sterilized everything within a radius of 25-50 light years.) $\endgroup$– jamesqfApr 21, 2018 at 5:07
1 Answer
If your civilization has reached the point where it can build Dyson spheres, harvesting a pulsar is actually a good idea. However, a special consideration must be taken.
Most stars produce energy through nuclear fusion at the core. Pulsars, on the other hand, are dead at the core. Their energy output comes from stored thermal energy, but mostly from a comparatively strong magnetic field. The field accelerates protons and electrons at the poles into relativistic speeds, thus generating the beams for which pulsars are famous.
So you could, in theory, build a dyson ring or sphere (since they do radiate in all directions, just not as strongly as through the poles) around the pulsar and it would work just fine. However, you could also tap the source of the pulsar directly, and that should be more efficient - if only because there is one less energy conversion in the way.
What you need is a toroidal coil of dysonic proportions. This is a toroidal coil:
Have one of these circling around the pulsar, preferably slightlgy misaligned with the pulsar's rotation plane. With this power source your amps' dials will be able to go way past eleven!
P.s.: All a regular dyson sphere does is passively collecting a stars' energy, without actually draining it. This dyson coil setup will however drain the pulsar and reduce its lifetime.
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$\begingroup$ That coil would have to be majorly superconductive or it would very quickly turn into something from Dali’s worst fever dreams. Very cool concept though. $\endgroup$ Apr 21, 2018 at 13:34
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$\begingroup$ Good idea! But I have a question if you don't mind: that harvest the magnetic field of the pulsar, right? Any start has magnetic fields... so could that be used on other stars? $\endgroup$ Dec 14, 2018 at 17:59
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3$\begingroup$ @EnderLook The simple answer is "yes." If you built a dysonic torroid and spun it in the opposite direction to the star's rotation, you'd geneate a whomping lot of power. I doubt the economics would make it worth it, but it could be done. What makes it potentially practical for a pulsar is the strength of the field and the fact that the field pole is off-axis to the rotation of the star. That really amps the generator, so to speak, but also means the torroid needs to be in exactly the right place to take advantage of it. $\endgroup$– JBHDec 14, 2018 at 19:24