And finally… ‘Black hole’ 50p recognises Hawkings’ beautiful mind

A black hole is a region of spacetime that has such strong gravitational effects that nothing—not even particles and electromagnetic radiation such as light—can escape from inside it.

The coin features Hawking’s name, a drawing of concentric circles representing a black hole, and one of Hawking’s most famous creations: an equation giving the entropy of a black hole; a measure of its internal randomness or disorder.

That discovery that a black hole’s entropy depends on its area was one of Hawking’s most important scientific contributions. It means that when anything falls into a black hole, its area increases.

This realisation led to a breakthrough: if a black hole can gain entropy from outside it, it should also be able to radiate some away into the universe. The phenomenon of a black hole slowly losing its energy is called Hawking radiation.

The coin will be available to buy from the Royal Mint’s website later this month – a year after his death, aged 76.

Professor Hawking became one of the most renowned scientists in his field despite being diagnosed with motor neurone disease in 1963 when he was only 21.

The coin’s design features a black hole represented by concentric circles as well as his most famous equation, which suggested that black holes were not completely black but emitted radiation – now known as Hawking radiation.

The coin’s designer Edwina Ellis said she wanted to portray how Professor Hawking “made difficult subjects accessible, engaging and relatable”.

His daughter Lucy said: “It is a great privilege… I hope my father would be pleased to be alongside Sir Isaac Newton and Charles Darwin as scientists who have made it on to money.”