Jim Al-Khalili

This is what's called inflation.

Now, inflation theory says the early universe dramatically expanded right after the Big Bang.

Let's see now, that's a million trillion trillion, right?

I mean, it's just incredible because, you know, here we are talking about the universe being 13.8 billion years.

Now we're talking about something that seems to have happened within such a tiny, tiny fraction of a second.

This was the first evidence-based standard model of cosmology, as we now call it, the origin evolution of the early universe.

And it's now pretty much accepted, I guess, but it's not a done deal.

You know, there are still those who argue that inflation isn't necessary.

Do you think that it's well understood enough now that it's confirmed?

Which is what makes it all so fascinating, right?

What was it like for you working on this?

Stephen Hawking called that, certainly the evidence for inflation that you and others had provided, the most exciting development in physics during his career.

Well, I'm certainly old enough to remember that cosmology, the field concerned with the origin and evolution of the universe, was very much the Wild West of physics.

Your work ushered in what has become known as precision cosmology.

We're no longer relying on speculation.

We're relying on hard data.

We should also, I guess, remember here that all of this work that you were doing was still part of your PhD research.

Well, where do you go from there?

You stayed working on this project before you then moved to the University of Chicago, but you were soon tempted back to Cambridge to analyse data coming from another space mission.

This was the European Space Agency's Planck Observatory, which was also mapping the cosmic microwave background.