“It is plain that there is such a concept as nothing, and that in some sense nothing is something” – Bertrand Russell Imagine you are having dinner with a mathematician and that the other guests are a physicist and a philosopher. And so a conversation among friends turns into a book: three former schoolmates reunite and explore the mathematical concept of zero, the physical one of the void and the philosophical one of nothing, thus re-iterating an adventure that has accompanied the entire history of thought. What do these three concepts have in common? Surely an embarrassing paradox: a number representing “non-existence”, an indispensable but basically impenetrable notion; a vacuum that “fills” our daily lives and remains a cutting-edge idea in modern physics; an absence, a deficiency, a sparkling and thought-provoking negation that draws us to the brink of reality. That oval-shaped symbol may seem sterile, but it can be a source of endless amusement.

Claudio Bartocci teaches Mathematical Physics and History of Mathematics at the University of Genoa.

Piero Martin teaches Experimental Physics at the University of Padua.

Andrea Tagliapietra teaches History of Philosophy and History of Ideas and Philosophical Hermeneutics at the San Raffaele University in Milan.