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Cake day: August 9th, 2023

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  • OrganicMustard@lemmy.worldtoScience Memes@mander.xyzFuck geometry
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    11 days ago

    It depends which metric definition are you using. The one I wrote is a pseudo-Riemannian metric that is not positive defined.

    Normally physicists use that generalized metric definition because spacetime in most cases has a metric signature of (-1, 1, 1, 1). Points with zero distance are not necessarily the same point, they just are in the same null geodesic.




  • 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).