After a previous episode about the relationship between mathematics and reality, we received a flood of profound and difficult questions, so we dive back into the world of maths, physics and philosophy to try and answer them.

A panel of experts help us puzzle out whether some infinities are bigger than others - and why that matters, as well as what quantum mechanics can teach us about the workings of the brain. And we seek answers for one of our listeners who surprised himself by being able to figure out mathematics equations he previously found unfathomable.

With philosopher of physics Dr Eleanor Knox, mathematician Dr Katie Steckles, and Dr Aldo Faisal, an expert in neurotechnology.

Presented by Marnie Chesterton

Produced by Cathy Edwards for the BBC World Service

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