Submitted by filosoful t3_123p87f in Futurology
Comments
ksigley t1_jdwhmmu wrote
This is the correct answer. If you do the math wrong, the math will be wrong.
OriVerda t1_jdwppnn wrote
What a deliciously poignant answer for someone who loves science but isn't smart enough to understand any of it. If you wrong, you wrong.
ItsAConspiracy t1_je1dhll wrote
And if you don't read the full article, you don't get the point of the article, which also said Dyson spheres are easily worthwhile if they're a meter thick with partial coverage. That's probably not a terrible approximation of a Dyson swarm.
i_should_be_coding t1_jdx2h8x wrote
See, now I'm wondering if there's actually enough material to build something like this.
The combined mass of the asteroid belt is about 2*(10^(21)) kg. Let's say R is the radius of the sphere, and it's 1000m thick. The radius is much larger than the thickness, so we can estimate the volume at 1000*4*pi*R^(2). As for the density, Aluminum is about 2700 kg/m^(3), and Iron/Steel is about 8000 kg/m^(3), so let's just say 5000 for the argument's sake.
So the we have R = sqrt(2*10^(21) / 5000*4000*pi) ~ 5.6*10^(6) m according to WolframAlpha. That's the radius of the sphere we would be able to build with all of the asteroid belt combined.
For scale, the orbit of Mercury is 43,000,000 km in its closest point to the sun, and our sphere's radius is about 60,000 km.
So unless I got the math really wrong, I'd say constructing any sort of Dyson sphere that's solid, has 100% coverage, and is large enough that the Earth still has sunlight, would probably mean we would have to disassemble planets, and even that might not be enough, as the mass we need would increase proportionately to R^(2), and a lot of the mass in the solar system isn't useful.
For now, let's focus on fixing some potholes or something.
starcraftre t1_jdx6l14 wrote
Assuming a 1 AU sphere for the original design spec, and assuming you want statites, then your target areal mass is around 1.6 g/m^2 .
Taking my 10% coverage estimate, the factored surface area of a 1 AU sphere is 2.81e22 m^2 or 4.5e19 kg of material. 2% of the Belt, assuming every rock is made of aluminum.
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i_should_be_coding t1_jdxb7c9 wrote
I liked the Kurzgesagt video on it. Was fairly interesting, and I love their "Let's just assume these magic technologies exist" attitude.
more_beans_mrtaggart t1_jdxc09w wrote
Might I suggest religious tolerance needs scooping up and shoving in to room 101.
ItsAConspiracy t1_je0k4ci wrote
Right, the article compares the energy cost of disassembling planets to the energy that could be collected by the Dyson sphere you could build from the materials.
ItsAConspiracy t1_je0js7a wrote
In fairness the article also talks about meter-thick solar panels, and concludes that it's easily worth it that way. And in most scenarios it's talking about partial coverage.
A meter seems like a reasonably fair estimate, if you include things like power transmission equipment, factories and spaceships for replacing panels, etc. Doesn't matter if you can go even thinner, since a meter thick already works great.
TakeshiKusanagi t1_jdvr4er wrote
Where do we get the materials to build it? Nevermind, the world would never unite to try.
Kahoots113 t1_jdvsfbr wrote
Asteroid mining would actually be a great source. No need to take from earth and its already in space. Build a processing plant on say the moon to refine and manufacture things. Its doable. Just need some stupidly rich person ro realize the gold mine and then do it and then live like a king while fucking all of us peasents over as they monopolize the fucking sun...
TakeshiKusanagi t1_jdvtg1v wrote
>Just need some stupidly rich person ro realize the gold mine and then do it and then live like a king while fucking all of us peasents over as they monopolize the fucking sun
More like an evil corporation would do it. Wayland-Yutani, maybe?
DadBodybuilder t1_jdw7eob wrote
Nah, Mom will build it.
Floebotomy t1_jdwgeyy wrote
nah mom would say we have a Dyson sphere at home
MrZwink t1_jdw8328 wrote
You'd need to dismantle a few planets to make a Dyson sphere.
Tyree_Callahan t1_jdwi9zt wrote
Or OP’s mom
Mercurionio t1_jdwr7vn wrote
Stellaris gonna wild these days
quettil t1_jdz9w2d wrote
Depends on how dense and wide it is. If you have it close enough to the sun you wouldn't need much material.
MrZwink t1_jdzawix wrote
Ye I've read papers with the math on this.
If just a few milimeters thick, you would still atleast need mercury and Venus. Remember the sun is hot, so you can't go to far in. You'd think getting a lower energy output star would help, but brown dwarves and red dwarves have unstable ejections and radiate making them unsuitable.
quettil t1_jdzcby8 wrote
A 1mm thick swarm at 0.1AU would need around 7% of the mass of Mercury. It's supposed to farm energy from the Sun so it has to tolerate heat. And just 1% of this is a trillion times Earth's current energy consumption.
MrZwink t1_jdzcnb1 wrote
You're assuming all the materials are useful. While infact you need metals. Luckily mercury has an iron core. And we were talking Dyson sphere not swarm. A swarm would be much easier, as it requires much less material, much less stabilisation. And you can construct it a segment at a time.
A Dyson swarm at 0.1 au would also be very toasty.
quettil t1_jdzcrro wrote
> And we were talking Dyson sphere not swarm.
A Dyson sphere is a swarm. Sphere is a misnomer. It was always a swarm.
MrZwink t1_jdzde4a wrote
Friedman Dyson proposed an actual sphere. But in practice the sphere would be very difficult to keep in orbit. A small imbalance and it would destabilize and fall into the sun.
Swarms are much more easily executable.
They are not the same thing.
Minibeave t1_jdzxpwc wrote
Just one, Venus.
MrZwink t1_je17kd4 wrote
tldr: venus is probably the worst choice.
venus is actually one of the most difficult to dismantle compared to mercury it has the following disadvantages:
- gravity:higher gravity on venus, means more energy is needed to launch mined material into space. on mercury a magnetic railgun powered by solar panels (that close to the sun) can more easily do it.
- atmosphere/climate:venus's atmosphere is thick, blocking most solar energy from reaching the surface. making solar a difficult power source. the rain on venus is so acidic almost noting survives on its surface for very long. where mercury has no atmosphere. meaning no friction, no hazardous weather etc. the fricture of venus' thick atmosphere would also be a huge detrimental force in lauching anything back up into space.
- surface temperature:venus has a much higher surface temperature than mercury, due to its runaway greenhouse effect. so high infact (up to 400*C) that most electronics will simply not operate. we would need to invent new cesium based electronics to operate anything on venus. Where mercury's day side is hot, its night side is actually very cold. ideal for operating electronics. and supercooling any magnets needed to operate a space launching railgun.
- available materials:mercury has large deposits of silicium on its surface, which can be used to locally product solar cells to operate machinery, factories and panels to power the dyson swarm. mercury also has a metalic core, which would be used to construct swarm segements, and electronics. where venus also has these materials (we think) its mostly its corrosive atmosphere with sulphuric acid rains that make production there almost impossible.
other more accesible targets:many asteroids in the asteroid belt between mars and jupiter would proably be mining targets sooner than venus is, simply because low gravity would make it easy to access, mine and launch towards the dyson swarm. some even have completely exposed metalic cores, could be moved into near earth orbit, or lunar orbit, and mined with more easy close to home.
this will be actually probably the first space mining industry's to develop, most people think blue origin and spacex final goal is space trips. but their final goal is probably space asteroid mining. capturing one of those metalic exposed asteroids and mining it, would make any company that achieves it an instant trillion dollar company. and it can probably me done with remotely controlled, or ai controlled space drones. within the next 50-100 years.
Scavenge101 t1_jdvsnaf wrote
A single stupidly rich person isn't stupidly rich enough to enable asteroid mining. One of the big 3 countries needs to do it for it to be possible. Takes a lot more than just spaceships and fuel.
Frenchtoad t1_jdwpjnk wrote
35 countries are joined for the ITER project for nuclear fusion. We'd need a complete union of all humanity to ever hope achieving a dyson sphere. It's certainly not for our current mindset, focused on easy, quick and dirty money, instead of survival.
ShadoWolf t1_jdwlorr wrote
to get a full dyson sphere as depicted by freeman dyson.. and not the pop sci-fi version of a solid sphere shell. Would still likely require as dismantling mercury for raw materials .. that or we get really ambitious and try for stellar mass lifting and mine Sol directory for materials
psilorder t1_jdwae8w wrote
>Also if assuming a radius of 1 AU, there may not be sufficient building material in the Solar System to construct a Dyson shell. Anders Sandberg estimates that there is 1.82×10^26 kg of easily usable building material in the Solar System, enough for a 1 AU shell with a mass of 600 kg/m2—about 8–20 cm thick on average, depending on the density of the material. This includes the hard-to-access cores of the gas giants; the inner planets alone provide only 11.79×10^24 kg, enough for a 1 AU shell with a mass of just 42 kg/m2.
>
> - https://en.wikipedia.org/wiki/Dyson_sphere
So they'd need to dismantle the planets to even get 8-20 cm thickness.
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hawkwings t1_jdwa050 wrote
One scientist said that we could rip Mercury apart even with near future technology.
FiftyfourForty1 t1_jdwz9eq wrote
mercury IS what the universe is made of....
Plaxsin t1_jdxaf98 wrote
ROCK AND STONE!
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alt4614 t1_jdwv1vs wrote
Stick rockets behind asteroids, shove em out to location
CriticalMemory t1_jdxpdb4 wrote
We can't get people to put masks on. Your point is definitely proven.
Brittainicus t1_jdxz122 wrote
Its a dyson sphere, the proposal starts with taking apart a planet or a moon.
Minibeave t1_jdzxiqd wrote
This video details pretty in depth the process of basically mining Venus for the resources we'd need to construct a Dyson swarm.
We could actually fairly feasibly build a swarm, or semi-swarm within our lifetimes.
>Where do we get the materials to build it? Nevermind, the world would never unite to try.
The first part I can answer. The second part? Lol, yeah we're pretty fucked.
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Kaz_55 t1_jdvozww wrote
>We ran the numbers
Did they though?
>In fact, humans have already begun this process; we have successfully lofted approximately 10,000–20,000 metric tons of material into orbit and beyond (and a good fraction of it has even stayed there). We just have 5,971,999,999,999,999,990,000 metric tons to go and we’re golden.
🧐
>An estimated 25 million meteoroids, micrometeoroids and other space debris enter Earth's atmosphere each day,[8] which results in an estimated 15,000 tonnes of that material entering the atmosphere each year.
https://en.wikipedia.org/wiki/Meteoroid
At the same time, earth loses about 5000 tons of Helium every year. Still, the earth has actually gained mass, not lost it.
Honestly, I don't see all that much evidence in the article of them "running the numbers" regarding Dyson spheres.
unknownpoltroon t1_jdvqhr9 wrote
>earth loses about 5000 tons of Helium every year. Still, the earth has actually gained mass, not lost it.
That's cause it's getting heavier without the floaty helium!!
carolathome t1_jdw8ics wrote
The sci-fi book with this premise implied it would take all the planet material from all the 8/9 planets and moons and asteroids to make a proper Dyson sphere.
Tobacco_Bhaji t1_jdw02nh wrote
Oh, Ars Technica ran the numbers. Well, that settles it.
Joe Rogan's opinion would be equally valuable.
filosoful OP t1_jdvkkdz wrote
The math behind making a star-encompassing megastructure
In 1960, visionary physicist Freeman Dyson proposed that an advanced alien civilization would someday quit fooling around with kindergarten-level stuff like wind turbines and nuclear reactors and finally go big, completely enclosing their home star to capture as much solar energy as they possibly could.
They would then go on to use that enormous amount of energy to mine bitcoin, make funny videos on social media, delve into the deepest mysteries of the Universe, and enjoy the bounties of their energy-rich civilization.
Kahoots113 t1_jdvs4lw wrote
The way this is written it seems like Dyson specifically mentioned bitcoin and social media, in the 1960s....
Plate_Of_Soup t1_jdxdh8n wrote
The sphere is just the first step, surely. After that, we have the energy of the heavenly bodies themselves to harness. The solar system is just a big gyroscope twiddling around forever and a day. Why not capture all of that
Eventually, we have to find some way to power all these stargates
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johnp299 t1_jdwiz9d wrote
If fusion is ever tamed, it would likely make Dyson spheres moot or shrink the dynamic. Stars are convenient energy sources because they already exist, but their power density is low. Fusion power would have much greater power density, opening the possibility for a self-sufficient Dyson-esque "town."
TheMightyPickaxe t1_jdxiet6 wrote
While the power density is low, after all the infrastructure is in place the energy is basically free. You wouldn't need to worry much about efficiency (other than heat dissipation) since you have a virtually unlimited source of energy.
DiceKnight t1_jdz1wky wrote
Plus if you scout out the correct stars or if your species becomes advanced enough to master stellar husbandry you'd just encourage many stars to become red dwarfs to ride out the heat death of the universe in style. The smaller red dwarfs have lifespans in the trillions of year range they fuse hydrogen so slowly that you are essentially guaranteeing an energy source for a long time.
quettil t1_jdz9y69 wrote
Only if you're near the Sun. Fusion is required to colonise the Oort Cloud.
Scavenge101 t1_jdvsvn6 wrote
The TLDR is currently no, but it's still an inevitability if the human race lives long enough. It takes several stages to build up to it and we're not even stage 1 right now.
TheCondor96 t1_jdx9oob wrote
Any answer other than yes is wrong because it means you aren't actually building a Dyson sphere.
mtj004 t1_jdvw0md wrote
Tl;DR: The amount of energy you would need to move all the mass of the structures you need is so high, that it would take over a million years, to make such an investment be profitable. The engineering part is a hold different aspect. In short the answer, if you're are bored and willing to use centuries upon centuries worth of energy to built it, then yes. But mostly no.
holmgangCore t1_jdxc5jr wrote
How does a Dyson Sphere deal with Solar Flares, huge Coronal Holes emitting massive solar winds, Carrington-class CMEs, or Miyake Events, which we have not even seen yet in the modern era?
gamerdude69 t1_jdy6k27 wrote
If made of individual drones rather than a solid shell, the drones could attempt to evade? Might not get out of the way successfully often, but maybe a little. I don't know the scale and speed of such events to know if evasion is possible. Maybe I'm talking about trying to dodge a bullet.
holmgangCore t1_jdylsf1 wrote
So a serious CME could hit Earth in 20 hours. 1 AU in 20 hours. That’s ~4.6 million mph and literally billions of tons of charged particles.
Anton Petrov had a recent episode on the CME of March 13th with some video from the SDO that might give you some sense of scale & speed.
How close would these drones be to the Sun? 1/2 AU? 1/4 AU?
FuturologyBot t1_jdvpsdz wrote
The following submission statement was provided by /u/filosoful:
The math behind making a star-encompassing megastructure
In 1960, visionary physicist Freeman Dyson proposed that an advanced alien civilization would someday quit fooling around with kindergarten-level stuff like wind turbines and nuclear reactors and finally go big, completely enclosing their home star to capture as much solar energy as they possibly could.
They would then go on to use that enormous amount of energy to mine bitcoin, make funny videos on social media, delve into the deepest mysteries of the Universe, and enjoy the bounties of their energy-rich civilization.
Please reply to OP's comment here: https://old.reddit.com/r/Futurology/comments/123p87f/would_building_a_dyson_sphere_be_worth_it_we_ran/jdvkkdz/
StraightOven4697 t1_jdw13fb wrote
There is absolutely zero point in thinking of this right now. Bare minimum we'd have to be a multi-planetary species to even consider it.
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Glittering_Cow945 t1_jdw47qs wrote
there is not enough mass in all of the planets put together to make a shell of any known material strong enough to stay intact, even given transmutation of elements.
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HaydosMang t1_jdwhmdp wrote
How else you gonna get that sweet sweet white science?
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AutoBudAlpha t1_jdxvcfj wrote
This is obviously not viable with our current technology. However, I have wondered about deploying a type of solar power collection in space.
With the cost of putting things in space significantly dropping (thanks space X), microwave energy might start making sense.
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420BigDawg_ t1_jdy1lov wrote
In the future if we have multiple different societies on multiple different moons and planets yeah
m0llusk t1_jdy7q4w wrote
Okay, but what about two Dyson spheres? Volume, volume, volume!
Slivizasmet t1_jdzlzpa wrote
Frankly if we ever progress so much that we have the technology for full scale space mining for the resources needed for a full Dyson sphere, we should also be able to make all sizes of fusion reactors, so what will be the need of a full scale dyson sphere if we would have already mastered fusion powerplants and could use them much easier to provide limitless power? Dyson spheres just sounds like a pointless fantasy unless we need to gather enough energy to blow up some other star or planet for some reason.
omguserius t1_je0qbdd wrote
Of course a dyson sphere is impractical.
The only true use for an actual dyson sphere I can think of would be to hide a star.
For any actual practical application, a dyson swarm of satellites is where its at.
GI_X_JACK t1_jdw4vc3 wrote
Short answer: no
long answer: Its not remotely feasible. Its a pipe dream at best.
ShadoWolf t1_jdwpi2f wrote
It quite feasible... you could literally do it with zero advancement in current manufacturing technologies it just be pretty slow. (way faster if you had space base industry first though.. or a lunar manufacturing colony)
A dyson sphere.. as outlined by Freeman Dyson propose a swam structure. For example the simplest and easiest dyson swam would a collection Mirror arrays that would let you directly control solar output for energy collection.
So think structures like countless medium size satellites with football field size Mylar reflectors in orbit around the sun. You need to get the orbital mechanics right to account for radiation pressure from Sol.. but super do able .. and Even well before you hit Dyson swarm like size.. something like this would be super useful for power collection is you had some optics to focus the energy
GI_X_JACK t1_jdwqbgs wrote
It is not, no. Perhaps the individual components are, but to Dyson scale, you'd need more literal material than the earth.
So you'd need to have a feasible way to mine, refine and manufacture in space, at scale. That does not exist. You'd also need advances in spaceship technology for all the mining and hauling materials and machines for processing.
In fact, I think even swarm, you'd need more material than all the rocky bodies in the solar system combined, so on top of being able to just strip all bodies including earth to nothing, which is not feasible with mining tech, you'd need interstellar travel to other worlds, and perhaps a way to harvest stuff off gas planets, etc...
So, the tech does not exist. Just ability to build small parts of it.
Next up, is building a dyson sphere even worth it, considering what other options open up once you have technology for that level of space travel, and resource harvesting needed for production at that scale?
Likely not.
ShadoWolf t1_jdwsggb wrote
ya you break down mercury for components. Or use stellar lifting to directly pull iron and other elements from solar plasma .. This is all a 100% do able.. it just a multi + generational project with current technologies. And it get a lot easier with functional fusion and AI systems
Its also a natural progression of something we are going to want to do anyway.
GI_X_JACK t1_jdwunhz wrote
>ya you break down mercury for component.
So you need to launch a space ship, that can land on mercury, then mine it, then launch that back into space. Then process that into building materials and construct that where?
None of the tech to do that exists.
> functional fusion
Fusion electricity is a pipe dream itself, but that is far far far closer to reality, and 50/50 that winds up working at some point.
sabboom t1_jdwb8lg wrote
Just imagine the number of star systems we would have to mine into extinction to make that thing. We would have to mine a galaxy to be fed by one finite star.
bynarySearch t1_jdwoqnx wrote
A very small fraction of the galaxy. Be it 50 or 500 or 10, 000 star systems, all very small fractions.
starcraftre t1_jdw12xv wrote
So, the article takes the pop culture version of a Dyson Sphere (big solid ball kilometers thick), rather than the actual original definition (lots of really low-mass satellites/statites), and concludes it isn't viable.
Meanwhile, the original definition only "loses" 1 order of magnitude of energy collected (~10% coverage), while requiring 16 orders of magnitude less energy to build and place.
Not to mention the maintenance costs of a kilometer-thick shell is astronomical compared to a bunch of millimeter-thick mirror sails (which you can just replace for pennies).