Comment on Black Holes

adry@piefed.social ⁨4⁩ ⁨days⁩ ago

• TheLeadenSea@sh.itjust.works ⁨4⁩ ⁨days⁩ ago

  I heard it more like, the fact that our universe is expanding faster than light, means there are parts of the universe we can never reach, even at light speed, which is mathematically identical to the event horizon of a black hole, which not even light can escape from. There’s not a singularity at the center on our observable universe, though.

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  • VoterFrog@lemmy.world ⁨4⁩ ⁨days⁩ ago

    I heard it more like, the fact that our universe is expanding faster than light, means there are parts of the universe we can never reach, even at light speed, which is mathematically identical to the event horizon of a black hole, which not even light can escape from. There’s not a singularity at the center of our observable universe, though.

    Just to add to this… It’s not like there’s an event horizon like with a black hole. It’s just that in the amount of time it would take the light to reach us, there will have been more space “created” than the distance the light was able to travel. For someone living near the edge of our observable universe, there’s nothing strange happening. In fact, we’d be at the edge of their observable universe.

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  • NaibofTabr@infosec.pub ⁨4⁩ ⁨days⁩ ago

    There’s not a singularity at the center of our observable universe, though.

    Well, er, how would you know?

    Perhaps the space inside the event horizon is so large, and the distance to the singularity so great, that the expansion we observe from our reference point appears uniform.

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    • TheLeadenSea@sh.itjust.works ⁨4⁩ ⁨days⁩ ago

      I know there is no singularity at the center of our observable universe as we are at the center of our observable universe and the Earth has not been destroyed by a singularity.

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      • bstix@feddit.dk ⁨4⁩ ⁨days⁩ ago

        That’s sounds exactly like what someone trapped inside a singularity would say.

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      • NaibofTabr@infosec.pub ⁨3⁩ ⁨days⁩ ago

        Hmm, but what if the Earth has not been destroyed by a singularity yet?

        We are at the center of what we can observe, obviously, but assuming that everything (including what we can not observe) is within the event horizon of a singularity then what we can observe may all be experiencing the same (relative) spacetime curvature and is apparently “expanding” because it is accelerating as it falls deeper into the singularity.

        I’m kind of thinking of the classic spacetime expansion demo of dots on the surface of a balloon, extended into 3(+?) dimensions… the singularity (the balloon) is expanding as we (and everything else) are drawn further into it, resulting in the objects we can see (the observable universe) appearing to accelerate away from us. The actual center of the singularity is so far away that we can’t observe it, and the acceleration appears (locally) uniform to us in the same way that the surface of an infinite-radius sphere would appear flat.

        There’s probably some obvious physics reason this doesn’t work in reality, but I don’t know what it is.

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    • VoterFrog@lemmy.world ⁨4⁩ ⁨days⁩ ago

      Well probably because we’re at the center of the observable universe.

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• woodenghost@hexbear.net ⁨4⁩ ⁨days⁩ ago

  That was just a metaphor. An event horizon is different from the Hubble radius in several ways.

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