It’s hard to imagine something as mind-bogglingly small as an atom.

But CrowdScience listener Alan has been attempting to do just that. All things in nature appear to be different and unique; like trees and snowflakes, could it be that no two atoms are ever the same?

Alan isn’t the first person to wonder this. Philosopher and scientist Gottfried Leibnitz had a similar idea in the 17th century; in this episode, philosopher of physics Eleanor Knox helps us unpick the very idea of uniqueness.

And with the help of physicist Andrew Pontzen, presenter Anand Jagatia zooms into the nucleus of an atom in search of answers. Listener Alan has a hunch that the constant movement of electrons means no atom is exactly the same at any given moment in time. Is that hunch right? We discover that the world of tiny subatomic particles is even stranger than it might seem once you get into quantum realms.

Can we pinpoint where uniqueness begins? And if the universe is infinite, is uniqueness even possible?

In the podcast edition of this show, we peer into that expansive universe, as we discover that the quantum world of hydrogen - the tiniest and most abundant of all atoms - allows us to observe galaxies far, far away. Featuring: Dr Eleanor Knox – King’s College London Prof Andrew Pontzen – University College London Dr Sarah Blyth – University of Cape Town Dr Lucia Marchetti – University of Cape Town

Presented by Anand Jagatia Produced by Florian Bohr Editor: Cathy Edwards Production Coordinators: Ishmael Soriano and Liz Tuohy Studio Manager: Emma Harth

(Photo: Twelve snow crystals photographed under a microscope, circa 1935. Credit: Herbert/Archive Photos/Getty Images)