• MsPenguinette@lemmy.world
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    1 month ago

    If photon hitting a surface can impart momentum, does generating photons also impart momentum? Like, if you put a solar powered laser pointer in space, would it move?

    • nooneescapesthelaw@mander.xyz
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      1 month ago

      Yes, it’s called radiation pressure by emmision

      The formula for it is Irradiance^1 of the emission/speed of light.

      1: irradiance is basically how much power per unit area is emmited by the object, it’s units are watt/m^2

      As for the lasers thing, I’m not a 100% sure how effective that will be and TBH lasers are pretty complicated and I don’t really get them

    • ch00f@lemmy.world
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      1 month ago

      Sure, but it would be less efficient than a sail, and since the incoming radiation would impart inertia on the solar panels, you would still be limited on where you could steer.

      • SchmidtGenetics@lemmy.world
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        1 month ago

        Sail absorbs power while also acting as a sail, and you can use the lasers to steer?

        It would also be like steering a boat more or less no?

    • OrganicMustard@lemmy.world
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      1 month ago

      Yes, but that would be a lot less efficient. With a dielectric mirror you can get easily 99.9% of the maximum momentum gain from the light, while with a solar powered laser you would get for the emission the compounded efficiency of the solar panel + storage + laser, so way below 10%. So you would gain around 10 times more impulse from your solar panel absorbing light than from the actual laser.

      The final momentum gain is a bit different as the maximum you can gain from a photon is double its momentum (because you can reflect it back with opposite direction).