knightly the Sneptaur

  • 34 Posts
  • 2.11K Comments
Joined 2 years ago
cake
Cake day: July 5th, 2023

help-circle




  • So you do have a minor misconception there in that first paragraph, time dilation is relative. The slowdown of something falling into a black hole is seen from the perspective of a distant observer, the thing falling in experiences time normally but sees the outside universe running in fast-forward during the fall toward the horizon. Neither is losing energy, the extreme curvature of spacetime stretches out the light moving outward and compresses it in the other direction.

    As to whether any particles can catch up to each other beneath the event horizon, our best theories suggest it is indeed possible. The steeply curved spacetime beneath the event horizon should still include valid paths where particles thrown in at an angle will intersect with each other as they spiral in. Velocity is relevant too, something that dives in at 99% the speed of light should be able to catch up to something that was dropped from a relative standstill just above the horizon if the time gap between them is small enough.

    Also, space isn’t just “the gaps between things”, it’s dynamic, squashing and stretching in response to gravity and expanding due to dark energy. We have to account for these effects in order to keep the atomic clocks in our GPS satellites synced and the system functional.








  • It helps a bit if you think of time inside a black hole like an onion. The outer skin is the event horizon where information about the moment the black hole was created is “stored”. Going deeper leaves that past behind you and surrounds you with more recent light, and each new layer is smaller than the last because there’s less past left to pass through between the moment the black hole was created and the moment you fell in. The singularity is the point at the center where there’s no more past left to see but future light can reach you from all directions, like a big bang in reverse.


  • That depends on one’s position on the path from the event horizon to the singularity. At the event horizon you’ll pass all the outward-pointing photons that were emitted the instant the event horizon formed, making all of “down” impossibly bright. Deeper, the only light that reaches you from “down” is light that entered the black hole at an angle and looped around the singularity before you caught up to it, creating a ring of light around a circle of absolute dark. That ring grows thinner and the black circle expands as you get closer to the singularity.

    Photons from “above” have the opposite appearance, with an expanding ring of blackness around a contracting circle of incoming light paths.



  • As far as we can figure it, basically, yeah. Wrapping your brain around the concept is less tricky than you’d think.

    So gravity gets stronger the closer you are to a black hole, but at the event horizon things get weird. The extreme curvature of spacetime forces space itself to flow toward the singularity at its center faster than the speed of light, so on the inside there’s no “other” direction to point to, even photons emitted straight “out” can’t reach the event horizon and end up moving in the same direction as everything else. So space becomes timelike, proceeding inexorably from point A to B.

    Time is more complicated, because it’s really hard to visualize. If you fall into a black hole, you’ll pass through all the outward-pointing light that’s been failing to escape since the event horizon formed, which makes all the past history of the black hole visible below you. Meanwhile, anything that falls into the black hole after you can be seen falling from above as the downward-pointing photons catch up. The timeline of the inside of the black hole is laid out with the past and future being directions you can point to, making time spacelike.


  • knightly the SneptaurtoScience Memes@mander.xyztrapped in the middle with u
    link
    fedilink
    English
    arrow-up
    6
    arrow-down
    1
    ·
    edit-2
    2 days ago

    Okay!

    Entanglement is what we call any sort of quantum interaction that causes some property of two particles to become linked, like photon gun that always spits out two photons of the same polarization, or bouncing a couple of molecules together so that they spin in opposite directions. So long as nothing comes along to disrupt that state, we could measure one particle and we’d know the state of the other particle no matter where it is without having to measure it. So a couple of intergalactic hydrogen atoms could exchange a photon across light years and become entangled for the rest of time, casually sharing some quantum of secrets as they coast to infinity.

    The “inexplicable connection” there is just information about a quantum pair, but it’s spooky because that information literally doesn’t exist until it is measured. Schrodinger’s cat isn’t “either dead or alive but we don’t know which until we check”, the entangled possibilities are both equally real and can interfere with themselves like the electrons in the double slit experiment.

    Bonus answer, I think time is real but isn’t like what we imagine it to be.