• ExLisper@lemmy.curiana.net
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    1 day ago

    Found a calculator: https://www.calctool.org/relativity/space-travel

    Assuming we want to accelerate at a constant 1g for half of the travel and then brake at 1g for the second half of the travel we would need 151 years to get there but only 9.794 years would pass on the ship. Depending on the mass of the ship we would need coupe million/billion tons of fuel (anti-matter).

    • Thorry@feddit.org
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      1 day ago

      Oh only a billion tons of anti-matter. Good thing we’ve already made a few nanograms, so in a billion years or so we’ll have plenty.

      • Hotzilla@sopuli.xyz
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        19 hours ago

        Yeah, and antimatter converts to pure energy with e=mc^2 what means that 60 grams contains like Hiroshima worth of energy

        • Thorry@feddit.org
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          12 hours ago

          In theory yes, in practice we have absolutely no idea how to actually do that and use the energy in an efficient or practical way. Even just on paper without limitations of technology or costs, we have no idea. Physics simply isn’t as clean or neat like that in real life.

          • sga@piefed.social
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            6 hours ago

            adding to this comment, the best way that we currently know how to extract this energy is using spinning black holes, with theoretical efficiency of ~42% (answer to the universe)(src: a minute physics video precisely on this). the naive solution to just touch them gets like 0.01-0.1% of total energy, so in bad case, we need trillion years.

    • SubArcticTundra@lemmy.ml
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      1 day ago

      50% chance of being in the habitable zone

      Imagine sitting on a spaceship for 151 years just to discover your parents’ bet was wrong

    • Valmond@lemmy.dbzer0.com
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      1 day ago

      How can it take 151 years to go 150 light years when not close to lightspeed most of the time? I get the 9 year thing, but 151 years seems wrong.

      • ExLisper@lemmy.curiana.net
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        1 day ago

        Smarter people than me on the internet calculate that at constant 1g you only need 2.5 years to get very close to speed of light. So I guess you accelerate fast enough and reach ‘almost speed of light’ very early in your travel and total time is almost as if you traveled at speed of light the whole time.

        • Tiresia@slrpnk.net
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          20 hours ago

          The main advantage of keeping accelerating when you’re at >90% of the speed of light is that it means you arrive faster in subjective time. You could take 160 years to get there and use ten times less fuel (or thereabouts), but the subjective travel time would go up by decades.

          • ExLisper@lemmy.curiana.net
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            12 hours ago

            I think having constant gravity on the ship during the entire flight is also a big plus. Designing a ship where you can live in 0g for years and in 1g for years would be like designing two ships in one.

        • trolololol@lemmy.world
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          22 hours ago

          Not that smarter when they forget you’re running out of gas by the Oort cloud. Gotta spread christianism capitalism there and build a petrol station before we go further.

      • Grail@multiverse.soulism.net
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        1 day ago

        The closer you get to lightspeed, the slower you accelerate (from an outside perspective). It’s actually close to lightspeed for most of the time.

      • domdanial@reddthat.com
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        1 day ago

        I just used the calc, it’s closer to 152 years. Which I assume means acceleration at 1g for about a year to reach .999c, and deceleration for the same time.

        I just confirmed with dV= a*t, a year of 1g(9.8m/s/s) gets you just over the speed of light. I think it’s more complicated than that, If I remember right relativistic speeds require more and more energy to accelerate so you can’t ever “reach” light speed.

      • degenerate_neutron_matter@fedia.io
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        1 day ago

        Most of the journey is spent traveling very close to light speed. It’s not a linear ramping up and ramping down of speed, since it takes more energy to accelerate the closer you get to light speed. Rather you quickly accelerate to near light speed and spend most of the trip working on that last small bit of velocity.

      • skulblaka@sh.itjust.works
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        1 day ago

        Constant acceleration at 9.8m/s^2 in a given direction will bring you close to the speed of light eventually, but yeah, I’m also not super sure how this math checks out

    • m0darn@lemmy.ca
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      19 hours ago

      What about accelerating 1g for 16 hours of ‘day’, then 8 hours of 3g ‘night’. It would be one hell of a weighted blanket lol.

      • mexicancartel@lemmy.dbzer0.com
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        13 hours ago

        It’s not just blanket entire body experience that force including internal organs… So i guess sleeping with tgat would be more than just uncomfortable

      • MinnesotaGoddam@lemmy.world
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        14 hours ago

        I say have a spinny ship that does that with the shape of the ring. Some kind of parabolic bullshit I’m sure there’s a way to get it to math without having to have a 1g ring and a 3g ring but that works too

        • m0darn@lemmy.ca
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          13 hours ago

          The purpose of my idea is to average 2g without expecting people to function in 2g. Not just for the purpose of a weighted blanket

          • MinnesotaGoddam@lemmy.world
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            13 hours ago

            I mean, yeah. They’d probably have reasons to have stuff in the high grav areas besides sleep areas. I’m not a spaceshipologist I can’t think of anything but radon to keep there tho

    • AngryCommieKender@lemmy.world
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      23 hours ago

      So a bit quicker than terraforming Venus by chucking several oceans worth of ice at it, and some cyanobactera once it cools down in a few hundred thousand years.

    • Venat0r@lemmy.world
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      1 day ago

      And you’ll only need about 320 million GWh per ~80kg person… plus 4 million GWh per kg of supplies, equipment and ship weight…

      • bufalo1973@piefed.social
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        3 hours ago

        So 340 PWh per person. A couple of guys with a static bike and a dynamo and that’s it😜

        Note: the Earth receives 170 PWh of energy from the Sun in a year.

        • Venat0r@lemmy.world
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          22 minutes ago

          Sounds feasible for a fusion reactor to provide at some point in the very distant future.

          • bufalo1973@piefed.social
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            18 minutes ago

            Twice the full energy the Sun gives the Earth in a year for each person is not a future fusion reactor level. 😀

      • Venator@lemmy.nz
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        21 hours ago

        Oh and also thats just the pure energy for acceleration/deceleration, not life support, steering, thrust ineffeciencies, take off, landing etc… 😅

    • ColeSloth@discuss.tchncs.de
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      20 hours ago

      Your statement makes things sound a bit confusing.

      To clarify, if you are inside the ship, 152 years will pass.

      Edit: Nevermind. Time travel is stupid.

      • FUCKING_CUNO@lemmy.dbzer0.com
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        1 day ago

        No, the people in the ship will experience less time then 152 years. Relativity tells us the faster an observer is moving, the slower it moves through time.