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Post by Kerr on Jun 10, 2017 14:30:18 GMT
What are you building then? fusion powerplant maybe How do you want to utilize the energy of the fusion/fission explosions? 100% of the energy is transformed into heat, which would be a bad thing of you have a engine, but considering your choice, it is pretty practical. Do you want to utilize neutrons and x-ray to heat the wall/heat exchangers? Using liquid sodium which then can heat water into steam which propels turbines which then use changing magnetic fields to produce electric currents? Basically a normal nuclear power plant which uses thermonuclear explosions instead of slow fission.
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Post by Rocket Witch on Jun 11, 2017 8:09:24 GMT
3. If you multiply the acceleration with 1 million. You'd still need 35k years to reach trappist-1. Even if humans will be living for hundred thousands of years, 35k for them is nearly as long as 35k for us. As far as I'm aware (I can't do math for myself) over the course of the Sun's natural lifetime we could move it anywhere in the galaxy or achieve escape velocity from it, towing a healthy amount of mass with us (though admittedly just the one solar system might not be a healthy amount on these timescales). One of those transhumanist ideas is to slow our subjective sense of time down so that 35k years could be made to feel like a 9 hour flight. Still, it's certainly not particularly apt as a means of travel in the traditional sense, but it might be a decent way of stationkeeping the contents of our galaxy when it collides with Andromeda. There are still many things you could do with the star in the meantime, like... Have you thinked about using solar sails instead? If you utilize 0.0001% of light energy of our sun in a Solar Gun™, you could accelerate a 500 million ton spacecraft with a constant acceleration of 1G. ... this. I did get a bit caught up on the megastructure idea. For most purposes using the stellar energy to form lasers for bitty little kilometre-long ships would be ideal.
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Post by Kerr on Jun 11, 2017 8:33:23 GMT
3. If you multiply the acceleration with 1 million. You'd still need 35k years to reach trappist-1. Even if humans will be living for hundred thousands of years, 35k for them is nearly as long as 35k for us. As far as I'm aware (I can't do math for myself) over the course of the Sun's natural lifetime we could move it anywhere in the galaxy or achieve escape velocity from it, towing a healthy amount of mass with us (though admittedly just the one solar system might not be a healthy amount on these timescales). One of those transhumanist ideas is to slow our subjective sense of time down so that 35k years could be made to feel like a 9 hour flight. Still, it's certainly not particularly apt as a means of travel in the traditional sense, but it might be a decent way of stationkeeping the contents of our galaxy when it collides with Andromeda. There are still many things you could do with the star in the meantime, like... Have you thinked about using solar sails instead? If you utilize 0.0001% of light energy of our sun in a Solar Gun™, you could accelerate a 500 million ton spacecraft with a constant acceleration of 1G. ... this. I did get a bit caught up on the megastructure idea. For most purposes using the stellar energy to form lasers for bitty little kilometre-long ships would be ideal. 1. So what? Either we can travel around the milky way in 5 billion years. But why? You had to decelerate to stop on a specific starsystem decreasing your effective cruise velocity, and if you can leave the milky way, then what? You are cruising at a fraction of c around the universe with no more fuel. 2. Example: A 5GT Ship, with a 500MT sail can reach 0.1G which the same laser setup, After 2 years the ship reached 21% of c. While having 4.5GT (4.5 billion tons) O'Neil cylinder, you could fit multiple millions on such a ship.
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Post by Rocket Witch on Jun 11, 2017 9:48:25 GMT
Assuming the current technological advance, fusion is less than 100 years away. That's probably even before someone set up a mine on Mercury. Remember what I said when I brought up mass as a fusion ignition: it may turn out to be the only useful means we ever get. This would put Dyson structures for solar power collection on our list of priorities, ergo we may as well move the star to a more convenient location if we can and if there is one. On the other end of extremes it may be that stellar fusion isn't even a thing and the only reasonable fusion sources are artificial. Comparing a literal star-ship and a fusion driven spacecraft is a bit apples and oranges in the sense that which one is better or even relevant depends on what extent artificial fusion becomes practically applicable. Under the standard model, gathering a load of mass to produce stellar fusion looks like the most reliable option. There are many kinds of star, but every observable long-lived fusion process essentially takes that form as far as I know. Building stellar powerplants won't be fast or pretty by any measure, but efficient if a star is tailored to consume all its hydrogen, and both personal life and the wider universe look to be geared toward rewarding long-term planning. This matter of planning raises some scepticism in me about the integrity of fusion research; as that 'always a decade away' technology it almost seems designed to obfuscate scientific knowledge and foresight, much like global warming. 1. So what? Either we can travel around the milky way in 5 billion years. But why? You had to decelerate to stop on a specific starsystem decreasing your effective cruise velocity, and if you can leave the milky way, then what? You are cruising at a fraction of c around the universe with no more fuel. 2. Example: A 5GT Ship, with a 500MT sail can reach 0.1G which the same laser setup, After 2 years the ship reached 21% of c. While having 4.5GT (4.5 billion tons) O'Neil cylinder, you could fit multiple millions on such a ship. Well, I don't know. We oughta eventually put a bubble around the Sun to stop wasting all that energy, in any case. The infrastructure would then already be in place if we wanted to move our green hydrogen ball. Raising our orbit so we're above most other objects orbiting the center of the Milky Way may have benefits like avoiding danger from the deaths of nearby stars. Once the Sun is at its destination it can be made smaller so it lives longer (larger stars are easier to move via Shkadov propulsion, if you're wondering why not make it smaller first). What's MT for the sail?
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Post by Kerr on Jun 11, 2017 10:30:20 GMT
Assuming the current technological advance, fusion is less than 100 years away. That's probably even before someone set up a mine on Mercury. Remember what I said when I brought up mass as a fusion ignition: it may turn out to be the only useful means we ever get. This would put Dyson structures for solar power collection on our list of priorities, ergo we may as well move the star to a more convenient location if we can and if there is one. On the other end of extremes it may be that stellar fusion isn't even a thing and the only reasonable fusion sources are artificial. Comparing a literal star-ship and a fusion driven spacecraft is a bit apples and oranges in the sense that which one is better or even relevant depends on what extent artificial fusion becomes practically applicable. Under the standard model, gathering a load of mass to produce stellar fusion looks like the most reliable option. There are many kinds of star, but every observable long-lived fusion process essentially takes that form as far as I know. Building stellar powerplants won't be fast or pretty by any measure, but efficient if a star is tailored to consume all its hydrogen, and both personal life and the wider universe look to be geared toward rewarding long-term planning. This matter of planning raises some scepticism in me about the integrity of fusion research; as that 'always a decade away' technology it almost seems designed to obfuscate scientific knowledge and foresight, much like global warming. 1. So what? Either we can travel around the milky way in 5 billion years. But why? You had to decelerate to stop on a specific starsystem decreasing your effective cruise velocity, and if you can leave the milky way, then what? You are cruising at a fraction of c around the universe with no more fuel. 2. Example: A 5GT Ship, with a 500MT sail can reach 0.1G which the same laser setup, After 2 years the ship reached 21% of c. While having 4.5GT (4.5 billion tons) O'Neil cylinder, you could fit multiple millions on such a ship. Well, I don't know. We oughta eventually put a bubble around the Sun to stop wasting all that energy, in any case. The infrastructure would then already be in place if we wanted to move our green hydrogen ball. Raising our orbit so we're above most other objects orbiting the center of the Milky Way may have benefits like avoiding danger from the deaths of nearby stars. Once the Sun is at its destination it can be made smaller so it lives longer (larger stars are easier to move via Shkadov propulsion, if you're wondering why not make it smaller first). What's MT for the sail? 1. Still, more of an mobile home than a way of traveling the milky way. 2. MT: megatons. Fusion: Yes, without any pressure fusion reactor seem very far away. But Fusion propulsion is a other thing, 1. We can already ignite fusion and get energy from it, but we can't make it live long enough to produce more than it takes. 2. For example Laser/Ion Beam ICF can compress it's fuel to 500x the density of lead plus over 100 million degrees. Same with Z-pinch.
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Post by Rocket Witch on Jun 11, 2017 11:43:48 GMT
Fusion: Yes, without any pressure fusion reactor seem very far away. But Fusion propulsion is a other thing, 1. We can already ignite fusion and get energy from it, but we can't make it live long enough to produce more than it takes. 2. For example Laser/Ion Beam ICF can compress it's fuel to 500x the density of lead plus over 100 million degrees. Same with Z-pinch. Would this necessarily be a sort of pulse propulsion?
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Post by Kerr on Jun 11, 2017 11:48:49 GMT
Fusion: Yes, without any pressure fusion reactor seem very far away. But Fusion propulsion is a other thing, 1. We can already ignite fusion and get energy from it, but we can't make it live long enough to produce more than it takes. 2. For example Laser/Ion Beam ICF can compress it's fuel to 500x the density of lead plus over 100 million degrees. Same with Z-pinch. Would this necessarily be a sort of pulse propulsion? Yes? for ICF, Z-pinch is continuous, but if you pulse fast enough, then there will be no difference between pulsed and continuous fusion propulsion.
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Post by Enderminion on Jun 11, 2017 15:47:42 GMT
Fusion: Yes, without any pressure fusion reactor seem very far away. But Fusion propulsion is a other thing, 1. We can already ignite fusion and get energy from it, but we can't make it live long enough to produce more than it takes. 2. For example Laser/Ion Beam ICF can compress it's fuel to 500x the density of lead plus over 100 million degrees. Same with Z-pinch. 1. also for the longest time we wanted fusion to take as short a time as possible. 2. fission explosives can do it to, list all your methods
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Post by Kerr on Jun 11, 2017 16:10:51 GMT
Fusion: Yes, without any pressure fusion reactor seem very far away. But Fusion propulsion is a other thing, 1. We can already ignite fusion and get energy from it, but we can't make it live long enough to produce more than it takes. 2. For example Laser/Ion Beam ICF can compress it's fuel to 500x the density of lead plus over 100 million degrees. Same with Z-pinch. 1. also for the longest time we wanted fusion to take as short a time as possible. 2. fission explosives can do it to, list all your methods 1. Are you referencing thermonuclear weapons there? 2. My methods? ICF: Laser or Particle beams strike the outer shell of a fusion pellet, flashing it to plasma which expands and compresses the inner ball. Another Beam strikes the inner ball, with high enough intensity to ignite fusion, 1 kj is enough if you can concentrate it enough. Z-Pinch: I send a bolt of electricity (over 5 mega ampere) through my chamber full of fusion fuel, the extremely strong magnetic field compresses and heats the ions to achieve the lawson criterion. Extremely effective. Antimatter: Just nuke the fusion fuel with science.
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