• 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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        18 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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          10 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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        21 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