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Old 11-17-2017, 11:00 AM   #101
Ulzgoroth
 
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Default Re: [Ultra-Tech] Conservative hard SF... but not implausibly conservative

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Originally Posted by AlexanderHowl View Post
Which means that you have lost a lot of energy. 1.8e32 J is a lot of energy by any measure. If you are going to spend that much energy to build 1% of a Dyson Swarm, you might as well just build a few million colony fleets and send them to colonize the galaxy through STL because it is cheaper.
It's less than two weeks of solar output.

So no, it's not a lot by any measure - it's a noticeable but fairly modest investment by K2 standards.
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Old 11-17-2017, 11:19 AM   #102
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Default Re: [Ultra-Tech] Conservative hard SF... but not implausibly conservative

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10,000 years is still just 1% of the time for a one million years old civilization though.
True. It's not what you get from naive extrapolations of exponential growth though. I think what you're looking at is:

Stage one, first space colonization revolution. A period of rapidly converting the asteroid belt into spin-gravity habitats. Might take a few centuries.

Stage is two a much slower stage of disassembling Mercury, various moons, and maybe Mars. This stage takes many thousands of years. I'm not clear on whether the railgun approach would work on Mars or not; I've seen people talk about putting it on Olympus Mons, and if that's necessary, it just kills your throughput. Also, if a serious Mars terraforming project gets going in those first few centuries, it could become a real barrier to disassembly.

About the same time as serious strip-mining of Mercury begins, serious resources probably also get devoted to interstellar colonization. Maybe Venus terraforming as well; I don't know if that's guaranteed-feasible or not.
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Old 11-17-2017, 12:00 PM   #103
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Default Re: [Ultra-Tech] Conservative hard SF... but not implausibly conservative

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It's less than two weeks of solar output.

So no, it's not a lot by any measure - it's a noticeable but fairly modest investment by K2 standards.
But you are not a K2 civilization when you start constructing a Dyson Swarm, and there are better uses for the energy required. You can send an SM+16 spacecraft at .01c for 9e23 J (when you include construction costs) which means that would could colonize 100 million star systems STL for less energy cost as constructing 1% of a Dyson Swarm. If an advanced society wants to expand, it just makes more sense to expand out than to build up.

Another thing to consider is that Dyson Swarms are also weapons of mass destruction. It would be easy for a Dyson Swarm to reflect and focus 1% of the sunlight it receives to a planetary target with 100 ly, so building a Dyson Swarm would probably be considered a prelude to annihilation of other civilizations. As soon as another advanced civilization detected the build up of a Dyson Swarm, they would probably send relativistic weapons to annihilate the builder civilization.
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Old 11-17-2017, 12:01 PM   #104
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Default Re: [Ultra-Tech] Conservative hard SF... but not implausibly conservative

Is anyone able to have an informed opinion on the guaranteed-to-be-feasible specific impulse for a fusion (or rocket)? That really matters for the speed of interstellar colonization.
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Old 11-17-2017, 12:05 PM   #105
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Default Re: [Ultra-Tech] Conservative hard SF... but not implausibly conservative

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But you are not a K2 civilization when you start constructing a Dyson Swarm, and there are better uses for the energy required. You can send an SM+16 spacecraft at .01c for 9e23 J (when you include construction costs) which means that would could colonize 100 million star systems STL for less energy cost as constructing 1% of a Dyson Swarm. If an advanced society wants to expand, it just makes more sense to expand out than to build up.
Expanding doesn't help me play Call of Duty MCLIII.
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Another thing to consider is that Dyson Swarms are also weapons of mass destruction. It would be easy for a Dyson Swarm to reflect and focus 1% of the sunlight it receives to a planetary target with 100 ly, so building a Dyson Swarm would probably be considered a prelude to annihilation of other civilizations. As soon as another advanced civilization detected the build up of a Dyson Swarm, they would probably send relativistic weapons to annihilate the builder civilization.
Building a fleet of invasion ships also looks like a threat.
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Old 11-17-2017, 12:06 PM   #106
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Default Re: [Ultra-Tech] Conservative hard SF... but not implausibly conservative

Atomic Rockets has an engine list (http://www.projectrho.com/public_htm...enginelist.php). You will want TW thrusters for STL interstellar ships.
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Old 11-17-2017, 01:20 PM   #107
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Default Re: [Ultra-Tech] Conservative hard SF... but not implausibly conservative

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But you are not a K2 civilization when you start constructing a Dyson Swarm, and there are better uses for the energy required. You can send an SM+16 spacecraft at .01c for 9e23 J (when you include construction costs) which means that would could colonize 100 million star systems STL for less energy cost as constructing 1% of a Dyson Swarm. If an advanced society wants to expand, it just makes more sense to expand out than to build up.
Why are you proposing throwing 3*10^23 tons of rock and heavy metals (that you've posited are useless for Dyson swarm construction) up the well from Mercury if you haven't already built a swarm?
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Is anyone able to have an informed opinion on the guaranteed-to-be-feasible specific impulse for a fusion (or rocket)? That really matters for the speed of interstellar colonization.
If you're using rockets, the answer is definitely going to be in the range of 'insanely expensive, and what's your motivation?'
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Old 11-17-2017, 01:44 PM   #108
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Default Re: [Ultra-Tech] Conservative hard SF... but not implausibly conservative

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Why are you proposing throwing 3*10^23 tons of rock and heavy metals (that you've posited are useless for Dyson swarm construction) up the well from Mercury if you haven't already built a swarm?
You need to dismantle Mercury to provide the required material for the Dyson Swarm (otherwise, you will not have enough material for 0.01% of a Dyson Swarm). If you do not move the remaining material, their weight will crush the mining robots as they delve into the interior of Mercury to find the materials that you want to use for the construction of the Dyson Swarm. I do agree though that it is a lot of effort for an excessive amount of energy production.
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Old 11-17-2017, 01:52 PM   #109
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Default Re: [Ultra-Tech] Conservative hard SF... but not implausibly conservative

There's no hard number for how much surface area constitutes a "true" Dyson ring, so I don't think that you can say what the mass of 1% or whatever is.

Besides he was asking about all the mass you need to build your colonization fleet.
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Old 11-17-2017, 02:20 PM   #110
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You need to dismantle Mercury to provide the required material for the Dyson Swarm (otherwise, you will not have enough material for 0.01% of a Dyson Swarm). If you do not move the remaining material, their weight will crush the mining robots as they delve into the interior of Mercury to find the materials that you want to use for the construction of the Dyson Swarm. I do agree though that it is a lot of effort for an excessive amount of energy production.
What elements that you need for light strong materials are you expecting to find in a planetary core? That's mostly heavier elements.

(Also, mercury is only two orders of magnitude more massive than the asteroid belt...)
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Besides he was asking about all the mass you need to build your colonization fleet.
If you mean me, I don't believe I was.
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