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Hello, one of the greatest scientific breakthroughs of the 20th century and certainly the

most controversial was the development of nuclear physics. Harnessing the enigmatic qualities

of the atoms tiny core brought us nuclear power and gave us the

bomb, a breakthrough with such far-reaching consequences that it moved the physicist Albert Einstein

to say had I known I should have become a watchmaker.

How can such outlandish power be released from such infinitesimal amounts of matter?

And what does the science of the nucleus tell us about how our universe is built? Nuclear technology

provokes strong emotional and political reactions. But what are the plain facts behind its

development as a science? With me to discuss the development of nuclear physics is Jim Alcalili, senior lecture in physics at the University of Surrey, and author of

Nucleus, a trip into the heart of matter.

Christine Sutton, Part physicist and lecturer in

physics at St Catharines College Oxford, author of Space Ship Neutrino, and John

Gibbon, visiting fellow in astronomy at at the University of Sussex, an author of

Q is for Quantum and in search of Schrodinger's Cat.

John Grebin, can we begin with a brief outline of how an atom is arranged?

What do we know about its constituent parts?

We know that it's mostly empty space. I think that's the most staggering thing about it.

There's a very, very tiny nucleus that contains virtually all of its mass,

and that's surrounded by a cloud of electrons

which have very little mass indeed with a lot of space between them.

...