Comment on Scientists confirm that the first black hole ever imaged is actually spinning

• AbouBenAdhem@lemmy.world ⁨1⁩ ⁨year⁩ ago

  The black hole and the stuff outside it constitute a single system, and within that system, angular momentum is conserved. So as objects cross the event horizon, their angular momentum is transferred to the black hole.

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  • hotdaniel@lemmy.zip ⁨1⁩ ⁨year⁩ ago

    Well… does it? If all the stuff falls in and only the volume remains, who could say that it’s spinning? How could you detect it?

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    • AbouBenAdhem@lemmy.world ⁨1⁩ ⁨year⁩ ago

      For one thing, the size and shape of the event horizon changes depending on the black hole’s spin.

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      • Smokeydabear94@lemmy.world ⁨1⁩ ⁨year⁩ ago

        What would happen if one were to stop spinning? Could one even stop spinning?

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      • hotdaniel@lemmy.zip ⁨1⁩ ⁨year⁩ ago

        I see. Thank you. So, you can use light to infer the mass, and then the volume information to infer the spin? Easy enough.

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    • Fungah@lemmy.world ⁨1⁩ ⁨year⁩ ago

      I thought nothing actually crossed the event horizon and was essentially frozen approaching a complete stop in time in a kind of 2f representation of 3d reality until it slowly leaked out trillions of years later as hawking radiation?

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      • hotdaniel@lemmy.zip ⁨1⁩ ⁨year⁩ ago

        From an outsider’s perspective, you would see an object approach and then freeze. It would red-shift dimmer until it disappeared. From an in-falling perspective, I don’t think you’d notice anything at all.

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• scarabic@lemmy.world ⁨1⁩ ⁨year⁩ ago

  Isn’t most everything spinning? Seems like having zero angular momentum would be rare and remarkable. I’m not even sure how exactly to define zero momentum in terms of reference frames.

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• tdawg@lemmy.world ⁨1⁩ ⁨year⁩ ago

  If you’re asking that then you first need to ask what the distinction between the two is. and further does it even make sense for one to spin and not the other

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  • NewNewAccount@lemmy.world ⁨1⁩ ⁨year⁩ ago

    Is there not a distinction? I assume the singularity at its center has different properties than the matter outside of that point.

    Note: I have a rudimentary understanding of what black holes and their components are.

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    • Telodzrum@lemmy.world ⁨1⁩ ⁨year⁩ ago

      Even if there is heterogeneity inside the system, that does not indicate severability or that the whole system is made up of smaller constituent systems.

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• KidsTryThisAtHome@lemm.ee ⁨1⁩ ⁨year⁩ ago

  It’s in space and everything is relative, how do we know *everything else" isn’t just spinning around the black hole? 🤔

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  • Devion@feddit.nl ⁨1⁩ ⁨year⁩ ago

    Because that would require a centripetal force on everything else, which obviously isn’t the case.

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• sleep_deprived@lemmy.world ⁨1⁩ ⁨year⁩ ago

  Yes.

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