Is a space station using a Dyson sphere like structure to power itself invincible? [closed]

Question

Let's assume we have this super advanced civilization that actually goes around making Dyson spheres around stars.

The purpose of this is to capture all the energy of the star and be a hub of the system in shipbuilding, weapon building, administration, and military matters. Think the Citadel from Mass Effect.

All this free energy is being used to power shields and weapons.

If you had a civilization with such technology and such a station, with a near limitless power source, would the station be invincible?

We see in fiction how shields can be overpowered by constant bombardment. But if you have the sun as your power source, would it be possible to ever break the shields?

The station would also have incredibly powerful weapons, given its power source.

I understand that it's not a matter of pure power, but let's assume that the civilization has incredibly sophisticated shields and weapons, and all they need is the power to power them up.

Assume incredible overall technological ability to the point that their shields can be attacked for months without failing and their cannons,an constantly fire. Would that mean their stations would be invincible?

In the context of galactic empires fighting, Dyson Sphere stations seem like they are checkmate. They have a sun and unless you teleport to the system with your own sun you are not breaking through.

I'm no scientist and so the finer points of science would be very handy here. And I'm not looking to hand wave the whole thing by saying: their science is so advanced. At the same time I'm not interested in limiting this advanced universe to 2020 abilities and understanding.

One thing I've considered is that maybe it is simply impossible to translate the raw power of the sun to raw power for the station, or a time delay / technological obstacle preventing instantaneous transition of power to the shields and, to a lesser extent, weapons.

Is that the case? What are other potential problems with these invincible stations?

Answer 1

The Problem of Defense:

This is a similar problem to the one envisioned by the French after WW1. They imagined the Maginot line would make France invulnerable to attack, but the Germans simply side-stepped the defense, or, as in the case of the Belgian forts, they simply sabotaged them or used bigger explosives. There is always a struggle between defense and offense. While I agree that the Dyson sphere defense is probably invulnerable to lesser civilizations, any of their peers will simply apply engineering until they come up with a way to overcome it.

While a Dyson sphere is an amazing feat of engineering, it is still a gigantic passive power collector. So you use a Dyson sphere to power your station. Your "Invaders" threatening your "Spherians" arrive with a fleet to attack the thing.

The Invaders have planet-sized ships and antimatter-powered cannons. Your Dyson sphere is putting out a huge total amount of power, but it's still a giant collector for a known and fixed quantity of output - one star. When one ultra-powered race confronts another ultra-powered race, the conflict is using ultra weapons and ultra power sources. The Invaders can have hundreds of planet-sized attack ships and still not use up as much mass as the Spherians did building the sphere. the attackers can keep bringing more firepower to compensate until they exceed the defensive ability of the sphere. The sphere is fixed and cannot move away if the enemy has too many ships.

Further, because of the vast size of the sphere, it makes a HUGE target. The smallest sphere is as big as a star, assuming you're okay with the inside surface not being a habitable area. Shields protecting it need to be correspondingly vast. The Invader ships can be powered by devices that put out more power per unit of size - probably a lot more power, if they don't simply stream vast quantities of antimatter AT the sphere as an attack.

Your Dyson sphere is more a city or a factory and less a battleship. Cities can have walls, but no walled city is invulnerable. There's always a bigger cannon.

Answer 2

Invincible?

We honestly have no idea how closely a dysonsphere/swarm/blah could be built to a star. Future tech would suggest that it could be built as close as wanting... but that doesn't change a couple of issues.

That's a LOT of surface area to protect. As intoned by the great George S. Patton: "Fixed fortifications are monuments to man’s stupidity. If mountain ranges and oceans can be overcome, anything made by man can be overcome." You might have a near limitless amount of energy to work with compared to Ming the Merciless' Amassed Armada, but while you're filling the solar system with the future equivalent of hot lead hoping to hit those little itty-bitty ships, he's dropping a thunderous number of bombs on that massive shell.

To be fair, I'm having trouble finding a reference to the sun's total output and not just the amount of output experienced by the Earth. For example, this reference suggests 3.846×1026 watts... but goes on to ask something akin to "how can the Earth survive?" which leads me to wonder if that's all the energy released from the surface of the entire sphere, or just the portion we experience. But, to be honest, if that portion that reaches Earth is only equivalent of 696 TW over ground the size of Texas... maybe we can fudge it and assume that said number is the best you're going to get anywhere on your dysonsphere surface.

So that's the maximum you have to work with (estimatedly speaking). And the entire Texas-sized chunk of surface must be defended with it. And machinery run with it, etc.

Now, to be fair, unless Ming's fleet is gi-honking-normous, then an awful lot of energy batteries can be brought to bear. But that would be foolish. Energy weapons have effective ranges because there are limits to how well the optics (even if run with Clarkean magic-driven gravimetric fields) can focus and how far the energy can go before it begins to dissipate. So what would Ming do?

He drags mines, or the inexpensive equivalent. Nobody it going to attack a dysonsphere unless they think they have the technical capacity (or the foolish arrogance) to actually punch a hole in it. So Ming has the same gravity-based mass-collection system used by the Sphere builders to capture and haul mass to the construction site — only he's using it to drag asteroids. Bazillions of asteroids.

And he doesn't really have to punch a hole in your sphere. He just needs to shift it. And your defenses can't just break up the asteroids, they have to atomize them! Otherwise the mass will still hit your gravity-heavy sphere (which works in Ming's favor). Push it off center just a little bit, and you're hosed because you suddenly have to dump tons of that energy you were using on defense to push your sphere back on center. Stars are just a bit uncaring, dontchaknow!

So, frankly, I think that "invincible" really only applies where there's a serious technological difference between attacker and defender. If they're on par, it's just like any other siege — desperate.

Answer 3

Assuming I am a war-hungry civilisation, of equal or slightly greater tech your Dyson Sphere loving society, how would I destroy you in a frontal attack?

1. Find or create a small black hole.
2. Blackholes move towards mass, and behave as any other mass for orbital calculations, so have big, massive, ship nearby, both will be drawn towards each other. The black-hole will be very mobile, cause it's small. You want about 100 kg total mass. Too light and it'll come to you for hugs immediately upon creation. Too heavy and it'll be too hard to move.
3. Thrust the ship away from the blackhole, towards the enemy Dyson Sphere. The blackhole will follow (as it's attracted to mass)
4. When you start getting close to weapons range to the Dyson Sphere, accelerate something heavy back into the hole away from the Dyson Sphere, floor it and then GTFO.
5. Black hole consumes the mass you released, grows (making it much harder to change direction now), absorbs the momentum (so it doesn't overshoot the system), homes in on the Dyson Sphere mass, and collides with the Dyson Sphere.

Now this is borderline ridiculous, I think it'll work if you really want to do it, but there are ways to bring down a society without firing a shot, and a realistic military strategy wont attack an enemy at their strongest point.

Attack their transport / trade ships going between, set up barriers between spheres to stop them communicating, or hack their communications. Create rumors about the leadership. Spawn a religion that undermines their values. Give them a virus (computer or Covid).

Answer 4

Subterfuge

Let's assume you have the power of a star and can harness it with near perfection. In nearly all cases it's not possible to have a higher energy density within a solar system. The energy output is so high, that not even the whole astroid fields in our solar system have the energy to compare. Depending on how your cannons and shields work, they can vaporise or deflect anything short of a planet before it even became a threat. So you would basically need to hurl a planet, which isn't an insignificant feat, to even have enough energy to move the Dyson sphere a fraction. But any engineer would add something so it would be able to correct it self. So possibly the sphere would be invincible.

except that it's not*

The invincible object has been done often in fiction. Let's look at a famous example, the 2nd Death Star. I'm taking the second one, as I'm assuming not even small fighters can come close to a Dyson Sphere civilization. Computers would make calculating trajectories and blowing stuff up a piece of cake. What you need is subterfuge.

This can happen in many ways. Hacking the structure would be a great start. Although you can assume the computers are compartmentalised so you can't take over the whole structure easily, even taking over one part can be catastrophic. Redirecting the energy can lead to structural failure or possibly authorising a force to get onto the structure. You can have stealth to approach the structure and blow a hole in it. As soon as you can make a hole, the whole structure mightvalready collapse as sensitive areas might melt or fry, making a bigger hole etc.

But it might get even simpler. Possibly you can buy off lesser people in the civilization or place your own people. Like hacking, they might destroy, deactivate, authorise, remove authorisation or even give away control of large parts of the structure.

If all else fails, grab a gas giant or two. At a certain moment you will overwhelm the firepower and shields, or possibly cause the sphere to use so much energy in areas that the structure breaks on it's own. But throwing planets generally requires a Dyson sphere to pull off...

Answer 5

The practical Dyson sphere builder will construct not a solid shell, as the material cost would be absurd and the physical stresses positively insane, but an orbiting swarm of layers upon layers of satellites. Indeed, these could be fortified impressively against all-round attack, as the defender could amass trillions of weaponized stations good for defending against smallish things that stations could feasibly fight against. The weakness here, though, is the fact that energy can't be repeatedly bounced around and re-concentrated without power transmission losses; each station generally makes do with what its solar panels provide and radiates the rest into space (perhaps for the next layer out to absorb for their own processes; Matrioshka brain, anyone?) So you can't exactly concentrate the full star's worth of energy onto the shields or weapons systems of any particular station at once.

Such a swarm's key vulnerability would be to defeat in detail. As the swarm is spread out over quintillions of cubic kilometers of space, an attacker would only have to amass small, compact forces (admittedly, they may need a lot of them) capable of tanking the firepower of the few satellites they'll be in range of at any given time ("giant armored space battleships" suddenly don't seem like a bad idea here!), and then just sweep their ultra-fleets through the swarm, picking off everything around them and clearing out swathes as they go. Targeting the giant, fragile solar panels would be the obvious choice for an attacker to weaken the enemy's ability to fight back.

Answer 6

Surface area is the bottleneck.

Let's assume you have some voidshields protecting you. This has to be subdivided into sections with each section having a bunch of shield emitters. Let's assume for a moment that the shields can absorb energy on a 1:1 ratio.

Now imagine if the enemy starts bombarding A section of shield of say 1km. A miniscule area compared to the total surface area of the Dyson Sphere. They use an array of railguns 1 lightday away from the target. The railguns accelerate their projectiles to near the speed of light, making it easy for the railguns to relocate from any retaliation while the DysonSphere can't really move out of the way or detect the shots in time to shoot them down.

Now imagine that the attackers fire enough projectiles that will hit simultaneously to equal the power output of the sun for 1 second.

During the impact, the shield emitters on a 1km surface area have to run the entire sun's energy output through them. You can imagine that something will burn through with this much energy coursing through the entire structure. And let's not forget: The energy is distributed across the surface of the sphere. Energy farther than halfway up the sphere would require 7 minutes or more to reach the 1km surface area, with 14 minutes or more for energy located at the opposite end assuming it could travel in a straight line at lightspeed. So it is likely that a concentrated barrage timed to have each shot land at the same time, a trivial matter for this techlevel, would simply cause the shields to fail at the point of impact. You can then do interesting things with timing another barrage to arrive a fraction of a second later from a lot of angles, passing the shield and impacting on the surface kilometers away from the shield opening if the angle is steep enough.

And that is ignoring the question: What happens with the energy of the impact? Is it absorbed? Deflected? Does the energy basically "stop" in place? With the exception of deflection you could exploit it an force a local overload to breach the sphere.

Answer 7

A few random responses:

We don't know enough to build a Dyson Sphere with shields. By the time this is learned, anyone who may still properly be called your enemy may have techniques that circumvent a 3D sphere (things we might call today warp drive, wormholes, etc.)

If your enemy is part of your general culture (say, US vs. USSR) then tech might be on a relatively even footing. But if it's just some random race in space, one or the other will be millions or billions of years ahead. If you're ahead of them you wouldn't even notice them. If they're ahead of you... they would in turn sweep you aside without noticing you. For instance their attack could focus multiple suns' power at you.

Can the shields you mention be pointed towards any threat point, or are they simply fixed in all directions evenly? If the later, then an attack with many orders of magnitude less power, concentrated on one spot, could surely overwhelm those shields. Say we're standing outside your sphere, at 1AU (the earth's orbit). Even if your solar cell and shield generator were 100% efficient, the shield generated from 1m2 of solar cell couldn't be more powerful than the sun's rays on the 1m2, which isn't a lot of power. I think a few astronauts would be able to carry explosives or projectiles that have more power than that. Bigger "space battleships" would have greater cross section but more power. It seems like an astronaut, a ship, or a fleet could make a commensurately-sized hole in the sphere to get through.

Answer 8

Dyson spheres are colossal by galactic standards

English lacks words grandiose enough to convey just how large a Dyson Sphere is. The language peaks out somewhere between "astronomical" and "galactic". A Dyson Sphere is a megastructure larger than any naturally occuring astronomical object, including the stars they enclose. "Galactic" doesn't really fit, and a militarily-significant DS dwarfs "astronomical":

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 1.82×1026 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.

A shell about 8-20 centimeters thick will be slightly more resilient than tissue paper, at least to any weapon being used by any sort of starship. You are going to need more material. A lot more. Either large parts of your DS are undefended, and thus easy to rip to shreds - or the whole thing will need to be thick enough to not crumble under the force of guns firing off from defense batteries or ships taking off.

So let's be somewhat conservative. Use the high end of the cited guesstimate (20 cm thick for 1 solar system's worth of building material). And assume a uniform density of 1 meter will be enough to make the Sphere militarily defensible.

Even massaging the numbers by making two very optimistic assumptions, fifty star systems are still required to produce one sphere. In reality, significantly more will probably be required.

It doesn't scale

This simply can't be done en masse. A major power controlling hundreds of star systems would struggle to pull this off for even a small handful of Spheres protecting absolutely critically vital points. They'd more likely bankrupt themselves trying to transport dozens of star systems' worth of material to a single point.

Answer 9

The Worldbuilding

The main problem with the question is conflating things that are theoretically possible, and things that are absolutely not. From a story building perspective, if you decide to bend reality to your world to a certain degree, trying to apply realistic physics or theory creates such conundrums.

You mention "Void shields" and the energy they require, provided by a star. But truly the energy they need is inconsequential since there is no void shield physics to quote, void shields are not a thing. They could just as well need two AA batteries to run.

Thus, to make your world balanced, you may instead put a reasonable limit on void shields, such as their size, need to reset or something of the sort. No need to touch Dyson sphere physics at all.

The physics

Anyway so far I think that perhaps it is simply impossible, like with any tech, to translate the raw power of the sun to such raw power of the station.

You're onto something here. The thing is, energy isn't something you just consume. Energy really is made of things being on one spot and not the other. When you restrict a flow, like a dam on the river or Dyson sphere around a star, there still must be an outflow on the other side. Otherwise, your dam or Dyson sphere will burst eventually.

Thus, trying to consume all the raw energy from the star means you need to radiate it away on the outside of your sphere, otherwise it will get hotter and hotter inside. Even if you magically just consumed light, remember that machines powered by solar panels still heat up as they work.

Thus, a Dyson sphere can still only consume a fraction of stars energy. It cannot be a truly enclosed sphere, even with the best technology and a bit of magic, this is still absolutely unimaginable.

Truly, the strongest attack your Dyson sphere faces is from the inside.

Answer 10

Invincible - against what?

If a sunstation is the ultimate form of combat vessel, then the obvious choice when you want to take one down is to bring a larger one into the battle. Or an array of other ones.

Push come to shove, though, you can use strange matter. A single strangelet can destroy a whole star system, it's just a matter of time.

Answer 11

If you try to build a Dyson Sphere at Earth orbit, you will need too much material. Ton Day's answer has the math and the numbers are just too big.

So, you build it much smaller and closer to the star. You mention "force shields" which probably means the sphere doesn't have to be much bigger than the star itself. It will mostly be a powerful force shield and its generators.

And compared to defending against the star itself, defending against a battle fleet is easy. So the sun station itself is invincible.

BUT, the important part of the star system isn't the star, it is the planets. That is where people live. If a foreign invader manages to invade and conquer a planet, the sun station has a problem. Sure, they could fry the whole planet without problems, but most of the people there will still be their own countrymen.

On the other hand, the invaders also have a problem, the sun station will probably deny power to the planet making it costly to hold.

In short, it will be a hostage situation, which have all sorts of potential for good stories.

Answer 12

It may come down to a matter of power levels, that is if we ignore other types of possible solutions to successfully attacking one.

Let's assume a fraction of the Dyson Sphere's power is used for most needed internal things and that the most of it is successfully harvested and redirected to defenses/shields.

If the Dyson Sphere has a star similar to our Sun, it would output around 384 YW (Yotta watts - 1000^8 ) of energy. Different stars may have different output yields, but still limited.

In such a case all you have to do is build an energy weapon that exceeds that amount of power. And you can do that in multiple ways: a big ship powered a singularity core, multiple ships that merge energy outputs into one combined shot (like these Species 8472 ships destroying a planet) or using a stationary very long range direct on indirect weapon that could be power by anything starting with a bigger start, therefore having more energy output to work with. Those would be some the "fire with fire" cases.

An alternate way is just to find something to destabilize that energy or even turn it against it's own system. Here you can find also multiple ways to do so, even with very limited power and/or specialized weapons.

And finally, you have the option of sabotage. When something cannot be directly defeated or it is too inefficient/expensive to do so, sabotage is the good way to go. A power-off of the defense system and all that super sun-powered-shield becomes useless enough for an attack to happen.

So clearly, that amount of power would not make it even close to invincible. At that civilization level, harvesting singularity gravimetric power could be a much more efficient way to have higher than a sun power levels using easier means of harvesting.

Answer 13

Consider a Dyson sphere with a radius equal to the Earth's orbit. That's an area of 2.79E17 square km.

Currently there is something round-about some billions of processors on the Earth, more or less. So call it 10 billion, or 1E10. With even 1 processor per square km there would be 20 million times the total processing power of all of Earth. There would certainly be room for large numbers more, and there would be lots of energy to spare.

There are people who think the internet is getting close to waking up. Example, Example, Example, Example With 20 million times as many processors working together you would have a daunting potential AI. In other words, a trivial relative investment in computing power would probably produce something unimaginably smarter than humans. And almost certainly much smarter than anything that could be sustained on merely planet sized systems.

So it's pretty much impossible to predict what such an AI could or would do. It's smarter than any entity we have yet had experience of. Indeed, it would quite likely be able to do things we could not begin to comprehend. It would be like squirrels defeated by aluminum siding on a house.