Vaccination is an emotive business. The furore around the MMR vaccine and autism has shown that vaccination health scares can cause considerable damage: stop vaccinating, and epidemics are sure to follow. But how do scientists decide whether a vaccine and a vaccination strategy are effective and safe? We talk to Paddy Farrington, Professor of statistics at the Open University. You can also read the accompanying article.

In our fourth online poll to find out what you would most like to know about our Universe, you told us that you would like to know how gravity works. We took the question to Bangalore Sathyaprakash from the University of Cardiff, and here is his answer. You can also read the accompanying article.

A Gomboc is a strange thing. It looks like an egg with sharp edges, and when you put it down it starts wriggling and rolling around as if it were alive. Until quite recently, no-one knew whether Gombocs even existed. Even now, Gabor Domokos, one of their discoverers, reckons that in some sense they barely exists at all. So what are Gombocs and what makes them special?

As part of our celebration of the International Year of Astronomy 2009 we brought you the article Are the constants of nature really constant?, in which John D. Barrow tells us how it all depends on which constants you choose. In the podcast of this interview you can hear how changes in the constants that define our Universe might have implications for extra dimensions, gravity, and climbing flies...

If you're worried that a mathematics degree might limit your career options, then there couldn't be a better person to talk to than Steve Hewson. Find out how his varied career has taken him from the lofty heights of theoretical physics, via the trading floor of a major investment bank, into the maths classroom, and has also seen him writing his very own maths book. This podcast accompanies the career interview from issue 50 of Plus.

In our online poll to find out what Plus readers would most like to know about the Universe, you told us that you'd like to find out what happened before the Big Bang. We took the question to the renowned cosmologist John D. Barrow and here is his answer. The Universe is an infinitely self-perpetuating foam of bubbles, it seems. This podcast accompanies the article What happened before the Big Bang?.

We talk to Professor Robin Wilson, author of the book

Lewis Carroll in numberland, about the mathematical work of the famous author of the Alice books, whose real name was Charles Dodgson.

Victoria Gould has always known she would be an actor, and went straight from studying arts at school to running her own theatre company. But she eventually had to come clean about her guilty secret - she loves maths - and has since managed to combine a career as a research mathematician and teacher with a successful acting career on television and in theatre. In this, the first of a two part podcast, Victoria tells Plus why she needs to use boths sides of her brain. This podcast accompanies the career interview from issue 49 of Plus.

Mathematics takes to the stage with A disappearing number, a work by Complicite, inspired by the mathematical collaboration of Hardy and

Ramanujan. Plus spoke to Victoria Gould and Marcus du Sautoy about the mathematical and creative process of developing this show. This podcast accompanies the career podcast with Victoria and the article A disappearing number from issue 49 of Plus.

What do the human brain, the Internet and climate change have in common? They're all hugely complex, and while they're very different, the tools used to grapple with this complexity are likely to be similar. We visited the Cambridge complex systems consortium, dedicated to building an over-arching science of complexity, and talked to neuroscientist Ed Bullmore, mathematician Frank Kelly and climate scientist Hans Graf about their take on complexity. This podcast accompanies the article Catching terrorists with maths.