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I still don't understand why you need to build a Dyson sphere and then transport the energy to where it's needed when you can build decentralized fusion reactor
by tomtomistaken 2y ago
I still don't understand why you need to build a Dyson sphere and then transport the energy to where it's needed when you can build decentralized fusion reactors. What am I missing?
- MadnessASAP 2y agoCan you build decentralized fusion reactors? This far the most efficient fusion reactor humanity has available to it exists approximately 1 AU away and is rather difficult to relocate.
- orbital-decay 2y agoFor comparison, how efficient is the biggest Dyson Sphere humanity built so far?
- vitiral 2y agoWell we have a very incomplete but about 10-15% efficient Dyson swarm on earth with solar and wind farms. Now we just need to scale up.
- aurareturn 2y agoPretty sure solar panels are 20% plus now with some much higher.
- vitiral 2y agoJust did a Google search. Most cells which are actually produced are 10-11%.
- aurareturn 2y agoMost residential deployments are near 20% or higher.
- vitiral 2y agoGood call, doing the search with those keywords yielded similar results
- TheLoafOfBread 2y agoThat will be average efficiency, because during night solar panels usually don't work, unless you live in Spain https://www.nationalreview.com/planet-gore/scandal-solar-power-spain-chris-horner/ https://www.nationalreview.com/planet-gore/scandal-solar-pow...
- Karellen 2y agoI thought the efficiency of a Dyson sphere/swarm was typically measured by how much of the star's total power was being used? We are not capturing 10-15% of the sun's total power output.
- vitiral 2y agoWell, by that metric we have 0.0000000001% of a Dyson sphere created.
- kiba 2y agoDon't forget the farms that feed humans and their farm animals.
- vitiral 2y agoWell, the entire ecosystem and weather is fed by solar. It would be interesting to think about what it's "efficiency" would be...
- belter 2y agoWhich Lazarus Cycle are you referring to?
- tomtomistaken 2y ago> Can you build decentralized fusion reactors? My guess is that if you can build Dyson spheres you can build fusion reactors. > This far the most efficient fusion reactor humanity has available to it exists approximately 1 AU away Efficient in terms of what? With what are you comparing it to?
- throwaway11460 2y agoDyson spheres can be very low tech. To reiterate, it's a swarm of objects orbiting the star, not a rigid sphere. If you have the time and raw resources, it was possible with 1960s technology.
- varjag 2y agoIt was not possible at all with 1960s technology, nor it is possible today.
- skirmish 2y agoAre you claiming that it is not possible to put a satellite into an orbit around the Sun? Please take a look at how many times this has been done already: [1]. Now just capture Sun's energy on one and do something useful with it: part of Dyson swarm. [1] https://en.wikipedia.org/wiki/List_of_artificial_objects_in_heliocentric_orbit https://en.wikipedia.org/wiki/List_of_artificial_objects_in_... .
- TheLoafOfBread 2y agoHow do you get energy from there? How do you deal with waste heat of satellite which is being heated up by sun from one side and heated up by your mode of energy transfer from the other side? Unless we have some magical solution which can convert waste heat into electricity and thus making such satellite working with 100% effectivity, then such satellite needs to transmit energy with very limited power otherwise it will fry itself up.
- helpfulContrib 2y agoYou're harnessing the entire energy output of a star. No need to transport anything - this is gathering, not hunting.
- tomtomistaken 2y ago> this is gathering, not hunting. This metaphor doesn’t make sense to me.
- quectophoton 2y agos/gathering/harvesting/, maybe? I'm guessing it's more like making a living space in the sphere itself or somewhere nearby and using the energy there (maybe exporting some percentage to Earth). Because if we're able to build the sphere itself, we probably would already know some way to cool it down in space so it doesn't burn itself, wasting all the money that went to its construction.
- helpfulContrib 2y ago[dead]
- e40 2y agoThe disconnect is the dyson searm is in space and we’re earth where we want to use the energy. How does it get to earth?
- z3phyr 2y ago> We are on earth No, if we have a dyson sphere, we are everywhere playa
- throwaway11460 2y agoIt doesn't, there's no need for planets at that time, people live on rotating artificial habitats that form the Dyson sphere itself.
- kibwen 2y agoFusion reactors will probably never be economical. It's the railgun problem: railguns let you trade complicated, unstable ammunition for cheap, stable slugs of metal. But the railgun imposes so much wear on its barrel, and the barrel itself is so much more expensive than in a traditional gun, that you've obliterated your cost savings. Likewise, it's irrelevant if fusion reactors can provide infinite energy from a single gram of hydrogen, because the reactor housing itself will be an impossibly complex machine with an extremely low lifespan from dealing with the energies involved. Is fusion possible? Probably. Will it ever be more economical than solar panels? Nope.
- vitiral 2y agoAlso: solar power is already a fusion generator
- earthling8118 2y agoSolar panels would be nowhere near as effective far away from a star. Building things as far out as Jupiter or to traverse interstellar areas can't rely on them.
- lven 2y agoI like the railgun analogy. I think you can stock up on other fusion cost arguments through my article, Engineering and Economic Challenges of Fusion: https://lvenneri.com/blog/ConFusion https://lvenneri.com/blog/ConFusion
- Detrytus 2y agoI know nothing about railguns, but if they are supposed to launch the projectiles with magnetic force then why do they need to impose any wear on its barrel at all? Couldn't you build a railgun where the projectile never even touches the barrel, being kept at the center by the same magnetic field that accelerates it? Or are we talking about the wear imposed by the magnetic field itself?
- andrewflnr 2y agoIf I recall correctly, a "railgun" per se is one that uses the projectile to conduct electricity between the "rails" that direct said projectile. So there's contact, between parts moving hypersonically relative to each other.
- jbotz 2y ago> What am I missing? The scale. The reason to build a Dyson Sphere (or Swarm) is that you want all (or at least a large fraction) of the energy output of a star. To "build decentralized fusion reactors" that can provide the same scale of energy is even less practical than building a shell around a star and would require far more materials! Also, fusion is really simple when the ignition energy is provided for free by the gravitational compression of something the size of a star, and not so simple when you're trying to get it started on a small scale using any other form of energy for ignition. The bottom line is we don't really know if small-scale, controlled, net-energy-positive fusion is possible at all, but if it is it has a lot of overhead costs... you then have to deal with ignition energy, containment, etc. You're trying to make a mini-star and keep it tame. The physics are not favorable to this, they are favorable to star-sized stars, where gravity and fusion energy pressure can balance each other for millions of years.
- ianburrell 2y agoThe concentrated energy of Dyson Sphere can be very useful. Feed some of it into lasers and then launch starships and then slow them down when they get to destination. Not tiny probes with fusion reactors but full size starships. Feed most of the energy of star to lasers and end up with weapon that will melt planets across the galaxy. Honestly, don't need to expand across the galaxy if have Dyson Sphere, which could be explanation of Fermi Paradox.
- mrtransient 2y agoDiffraction limit determines the fundamental beam divergence angle theta = lamda/pi/D, where D is the beam diameter, lamda is wavelegth of elwctromagnetic radiation (eg. light). To minimize theta, we need to either increase D or decrease lamda. Lets assume we would be able to make far infrared high power lasers, at say 10,000 nm = 1e-5 m wavelength. Lets assume we would be able to make D, the diameter of our laser beam, similar to the diameter of a typical planet, for Earth it is ~13,000 km = 13e6 m. Theta = 1e-5 / 3.14 / 13e6 ~= 1e-13 radians. Sun is ~ 25,000 light years from the center of our galaxy, ~= 25e3 y 3e8 m/s 31.5e6 s/year ~= 1e20 m. Laser beam diameter, there far away, would be: 1e-13 *1e20 = 1e7 m, similar to the diameter of Earth, not much further diverged, focused and delivering the wast amount of energy all over the planet thereby evaporating it to a gas. Indeed, what you say about the melting far away planets is possible, in theory.
- AwayMuchPitcher 2y ago> What am I missing? The small mindness. It's like an 1800s dude thinking aliens would do interstellar travel by having very huge horses, oh no wait...a billion of them (but still somewhat big) "This is what an advanced race would do...with our current understanding" is an oxymoron