Timeline for Colonizing the galaxy by slow boating reality check
Current License: CC BY-SA 3.0
30 events
| when toggle format | what | by | license | comment | |
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| Feb 12, 2018 at 13:28 | comment | added | Murphy | @PhilH It's less the drag and more the energy you then need to dump and how few materials can stand up to the temperatures involved. Individual gas molecules are enough trouble, if you start hitting dust your shield has to be capable of coping with the equivalent of small nuclear weapons at point blank range. at .5 c a pebble is death. | |
| Feb 12, 2018 at 13:23 | comment | added | Phil H | Firstly, KE is relative, so if you use rockets you do not need to generate as much energy as you suggest. The dust heating is a fair argument, but requires only 3GW to overcome the drag; current fission reactors already produce >1GW, so 3GW seems doable. Any high fraction of c would require an ion drive or other highly mass-efficient propulsion, and captured interstellar dust is actually quite a useful source of mass. | |
| Feb 5, 2018 at 6:54 | comment | added | Epanoui | Stars aren't stationary relative to one another. I mention this because (maybe I'm wrong) there seems to be an accepted assumption that after speeding up for travel you'll have to "slow back down" to some shared frame where most things naturally rest. It is likely that if you're traveling toward something, you're not targeting something already moving away from you; but there a many ways in which you might accelerate toward a region of space anticipating a target body passing through, possibly with a velocity (speed & direction) similar to yours as it nears you. | |
| Feb 4, 2018 at 20:00 | comment | added | kubanczyk | Nitpick. "Watt hours per hour" is a unit of power, called by some a "watt". | |
| Feb 3, 2018 at 0:07 | comment | added | jpmc26 | For some context, even if 26 days is 2 orders of magnitude low, you still couldn't get to Alpha Centauri. At $.5 c$, it takes almost 8.5 years to reach Alpha Centauri, and $100*(26 \text{ days}) \approx 7.1 \text{ years}$. | |
| Feb 2, 2018 at 21:36 | comment | added | Polygnome | "At that speed it's not really a generation ship since you can get to many other stars within the original crews lifetime." at 25y/generation, thats about 30 stars (and you can only reach one of them with the same crew). Only a few of them have exoplanets in the habitable zone, but wether those are actually "habitable", even with terraforming is another question. earth is pretty special, it might be need to cover a lot of space to find a suitable candidate. | |
| Feb 2, 2018 at 17:51 | comment | added | leftaroundabout | Nice calculation about the energy gain by collisions with the interstellar medium, however this isn't actually such a problem, because unlike suggested, you can easily get rid of heat even in a vacuum: just make the shield of titanium or carbon-carbon. Wait until it's red-hot glowing, at that point it'll easily readiate away all that energy. Just make sure you put some insulating space and/or material between the shield and the ship. | |
| Feb 2, 2018 at 13:24 | comment | added | r41n | @Murphy, nice idea, BTW, your dad's name is Cooper, right? | |
| Feb 2, 2018 at 13:10 | comment | added | Murphy | @r41n I've been thinking for a while about making a quick reference sheet for different near-C speeds since this comes up quite often. With details like how many times hotter than the surface of the sun the front of the ship is at different speeds. It might save time in the long run. | |
| Feb 2, 2018 at 12:58 | comment | added | r41n | Wonderful answer, the extremes of space & speed are often underestimated. | |
| Feb 2, 2018 at 11:41 | history | edited | Murphy | CC BY-SA 3.0 |
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| Feb 2, 2018 at 11:37 | comment | added | Murphy | @Fels I was using the numbers for a cold, neutral, interstellar medium and for that magnets don't help you much. However if you were traveling through a region with ionized gas it could help and at the same time the ionized gas would tend to be less dense. (0.2–0.5 particles/cm3) | |
| Feb 2, 2018 at 11:33 | comment | added | Murphy | @Aaron I've added more details to the calculation, I made one mistake which threw off the calculations by 2x (calculating for a journey time of 10 years vs 20) but I've corrected that now. Let me know if you see anything off. | |
| Feb 2, 2018 at 11:32 | history | edited | Murphy | CC BY-SA 3.0 |
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| Feb 2, 2018 at 11:26 | history | edited | Murphy | CC BY-SA 3.0 |
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| Feb 2, 2018 at 10:03 | comment | added | Fels | Just out of interest: Would this interstellar particles be charged? So could you use a magnetic field to deflect them? | |
| Feb 2, 2018 at 6:09 | comment | added | RonJohn | @MontyHarder "The ship would be built on/in an asteroid" but the inhabitants would forget that their world is an asteroid, and the AI running the system would develop a religion to keep order in society (using little wireless pain mechanisms in one temple). All goes well for millennia until it drifts off course... :) | |
| Feb 2, 2018 at 0:03 | comment | added | Mazura | Surely some space junk and a little bit of waste heat isn't going to stop a civilization that can build engines capable of accelerating you to half the speed of light, and can create gravity. - I'm not sure which of those is more of a handwave, but I wouldn't be surprised if figuring out how to do one, tells you how to do the other. | |
| Feb 1, 2018 at 22:35 | vote | accept | Dan Clarke | ||
| Feb 1, 2018 at 21:45 | comment | added | Loduwijk | @Murphy Since the conversions you have done are non-trivial, would you please show your work? I am not suggesting you are wrong since I have note worked it out myself, but it makes it easy for others to verify if they don't have to redo everything you've done from scratch. | |
| Feb 1, 2018 at 18:35 | comment | added | Dan Clarke | @Murphy, well I guess they'll be going slower than that. Having the emergency supplies melt would not be good. | |
| Feb 1, 2018 at 16:44 | history | edited | Murphy | CC BY-SA 3.0 |
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| Feb 1, 2018 at 16:37 | history | edited | Murphy | CC BY-SA 3.0 |
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| Feb 1, 2018 at 16:27 | comment | added | Murphy | @DanClarke I've added an edit, unfortunately at 0.5c the asteroids they bring along would melt. | |
| Feb 1, 2018 at 16:27 | comment | added | Murphy | @MontyHarder I added the calculations to the answer. All I can say is I hope it's a very short journey. | |
| Feb 1, 2018 at 16:26 | history | edited | Murphy | CC BY-SA 3.0 |
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| Feb 1, 2018 at 15:09 | comment | added | Dan Clarke | @MontyHarder, and the meteors they bring alone to help with emergency supplies could be in front of the ships to take the hits, with some kind of cushioning to keep the ship from being damaged.. | |
| Feb 1, 2018 at 14:55 | comment | added | Monty Harder | The ship would be built on/in an asteroid with a hundred meters or more of solid rock on the side in which it's traveling. Then, the builders would probably want a few meters of ice on that side too. | |
| Feb 1, 2018 at 14:46 | comment | added | Dan Clarke | Good point. Taking four or five generations to get to a nearby star would be good, Thanks for doing the math. | |
| Feb 1, 2018 at 13:47 | history | answered | Murphy | CC BY-SA 3.0 |