I'm a bit puzzled by the dynamics of things falling into a black hole. If I start with a test mass at infinity, it will fall freely into the black hole and reach the speed of light at the event horizon.(adsbygoogle = window.adsbygoogle || []).push({});

What happens if I throw something towards the black hole? Will it already reach the speed of light before reaching the event horizon?

On the other hand - if I start with an object at a certain distance of the BH but that is kept still, it will also fall onto the BH, but be slower than the particle falling from infinity at every point.

Will the speeds of the three objects as seen from the reference frame of the particle falling from infinity be the same at the event horizon or will it be different? (I assume that one can use a Gullstrand-Painleve metric to calculate this, but my maths abilities are not sufficient to actually do this...)

And looking from far away - if all particles reach c at the event horizon, what about energy conservation? (After all, the particles started with different energies.)

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# Throwing something into a black hole

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