• Question: What is at the bottom of a black hole?

    Asked by HabztheG to Josh, Susan, Rob, Rebecca, Chris on 16 Jun 2015. This question was also asked by katie, Kate and Peckasso :), charliebam, estherisboss.
    • Photo: Josh Meyers

      Josh Meyers answered on 16 Jun 2015:

      I have no idea. I leave that to the physicists!

    • Photo: Susan Cartwright

      Susan Cartwright answered on 19 Jun 2015:

      According to General Relativity, something called a “singularity”, which is a point of well-defined mass but infinite density.

      This is certainly wrong. Below a distance called the Planck length, 1.6×10^-35 m (i.e. 0.000 000 000 000 000 000 000 000 000 000 000 016 m), we cannot ignore quantum mechanics when trying to do calculations with gravity, and we don’t yet have a quantum theory of gravity, so we are stuffed.

      However, this is all academic really. Black holes have an “event horizon”, which is located where the escape velocity from the black hole becomes equal to the speed of light. Nothing, not even light itself, can reach us from below the event horizon of a black hole – and, therefore, we can never actually obtain any information about what’s inside.

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