They are invisible, and yet they are a constant presence in daily life. The discovery of new ones is regularly reported, and it seems there is one at the centre of our galaxy. Described as mysterious, extreme objects, they have served to instil fear in many of us — it has been rumoured that tiny ones created in particle accelerators could consume the planet.

From the way they are presented it would seem that they are the stuff of speculation and dreams, existing only in the minds of astrophysicists. But that is not so. They are real enough.

This book explains precisely how to detect them — so we can set out to discover one of the most powerful, most spectacular energy sources in the Universe!

• Freed of mathematics and of lyrical digressions, this gem of scientific popularisation will enable readers to understand what is now known about these fascinating objects, which though invisible are essential for our planet.

Jean-Pierre Lasota is an emeritus research director at the Paris Institute of Astrophysics and a professor at the Jagellon University of Krakow, Poland. An astrophysicist, he is the author of many scientific works on black holes, compact astrophysical objects, double stars and accretion discs.