• Droggelbecher@lemmy.world
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    1 month ago

    The only things that aren’t bound by gravity are massless. Massless things always have to be moving at the speed of light. So really the question is, what direction would the ghost shoot off to? Momentum would have to be preserved, so it’d be the opposite direction of where the corpse drops. Or maybe the corpse just move a teensy bit to the opposite direction of the ghost?

    Note: this assumes Newtonian or at least semi classical physics. In general relativity, there is no such thing as being unbound by gravity.

  • proton_lynx@lemmy.world
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    1 month ago

    We move (with the Sun) around the Milky Way at about 792.000 km/h. At that speed, you wouldn’t even see the earth getting away from you.

  • ytorf@lemmy.world
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    1 month ago

    I have a memory of seeing this exact idea in another comic on here but can’t find it! (Assuming it is a case of multiple discovery and not plagiarism)

      • FiniteBanjo@lemmy.today
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        1 month ago

        The cosmic microwave background has no center, any claims that it even has a direction is controversial.

        • NoSpotOfGround@lemmy.world
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          1 month ago

          Is it controversial? I thought it was pretty established. In Wikipedia it says:

          From the CMB data, it is seen that the Sun appears to be moving at 369.82±0.11 km/s relative to the reference frame of the CMB (also called the CMB rest frame, or the frame of reference in which there is no motion through the CMB). The Local Group — the galaxy group that includes our own Milky Way galaxy — appears to be moving at 620±15 km/s in the direction of galactic longitude ℓ = 271.9°±2°, b = 30°±3°.[88] The dipole is now used to calibrate mapping studies.

          • FiniteBanjo@lemmy.today
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            1 month ago

            Don’t cite Wikipedia. Look at the tiny numbers in blue, click the one next to the statement you want to verify, it will show you the source of the information at the bottom of the page next to the matching number.

            • NoSpotOfGround@lemmy.world
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              1 month ago

              Well, following the main reference in the Wikipedia page leads to this:

              The implied velocity for the Solar System barycenter is v = 369.82 ± 0.11 km s−1, assuming a value T0 = Tγ , towards (l, b) = (264.021◦ ± 0.011◦, 48.253◦ ± 0.005◦) [13]. Such a Solar System motion implies a velocity for the Galaxy and the Local Group of galaxies relative to the CMB. The derived value is vLG = 620 ± 15 km s−1 towards (l, b) = (271.9◦ ± 2.0◦, 29.6◦ ± 1.4◦) [13], where most of the error comes from uncertainty in the velocity of the Solar System relative to the Local Group. The dipole is a frame-dependent quantity, and one can thus determine the ‘CMB frame’ (in some sense this is a special frame) as that in which the CMB dipole would be zero. Any velocity of the receiver relative to the Earth and the Earth around the Sun is removed for the purposes of CMB anisotropy studies, while our velocity relative to the Local Group of galaxies and the Local Group’s motion relative to the CMB frame are normally removed for cosmological studies. The dipole is now routinely used as a primary calibrator for mapping experiments, either via the time- varying orbital motion of the Earth, or through the cosmological dipole measured by satellite experiments.

              Do any references suggest this dipole is under debate?

              • FiniteBanjo@lemmy.today
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                1 month ago

                Here is a paper from University College London LINK

                And researcher Saadeh’s following interview LINK

                Which supports the idea that, based on observed CMB data compared to mathematical models, the universe behaves the same in every direction, an anisotropic model with no preferred motion direction.

  • Flying Squid@lemmy.world
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    1 month ago

    I always thought that this would be a similar issue with time machines. Go back even 1 second and you’re floating in the void.

    • credit crazy@lemmy.world
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      1 month ago

      That’s actually kinda my head cannon as to why the doctor in doctor who is so hands on when piloting the TARDIS a time machine that only travels through time is useless because you can’t affect history while floating out in space and it’s also dangerous if you happen to pop into existence inside a block of dirt the more I think about it doctor who is a pretty realistic depiction of what time travel will be like even with the TARDIS moving air out the way before landing instead of creating a shockwave from TARDIS molecules materializeing inside of atmosphere molecules

      • Flying Squid@lemmy.world
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        1 month ago

        I guess it depends on the sort of time machine. I’m thinking the H.G. Wells variety- a machine you get in or on and it takes you back in time, but to the same location.

        That’s also how it works in Back to the Future.

        • Valmond@lemmy.world
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          1 month ago

          That’s not what the same location means.

          Also, now lets talk about relative speed differences!

            • Valmond@lemmy.world
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              1 month ago

              Well if you time trivel to “the same location” then that would be in space somewhere because the planet had moved on.

              In films you travel to another location, which is where the earth is now/then.

              Also, we rocketeer forwards on this spinning globe, so if you time travel 6 months, the planet will be going in the opposite direction (and also be on the other side of the sun ofc.) so iven if you move yourself there, you’d get smashed against the planet at high speed or ejected away from it at high speeds probably be killed by the atmosphere if by nothing else.

    • exocortex@discuss.tchncs.de
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      1 month ago

      Well, but general relativity teaches us that all coordinate systems (also constantly moving, but not accelerating ones) are equally relevant. This means that the one with earth as it’s origin is as correct as one where with the center of the galaxy (or the sun ) as is every other. So the one where earth moves somehow through space is just as random as any other.

  • danc4498@lemmy.world
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    1 month ago

    Maybe the gravity ghosts are subjected to is in relation to the location they died and not the mass of earth.

  • metallic_z3r0@infosec.pub
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    1 month ago

    Is the reference frame the CMB? You’d think you could just choose the reference frame at that point and move however you want, but arguing the physics of hypothetical metaphysical beings probably doesn’t make much sense.