For world-renowned physicist Neil Turok, his theory on how the universe began stemmed from a simple question that his former primary school teacher asked him: What banged?

The standard, long-held theory is that the universe was created after a "big bang." But when his former instructor contacted him and posed the simple question, it got him thinking.

"The conventional explanation ... doesn't address that question," Turok, this year's Massey Lecturer, said to Quirks and Quarks host Bob McDonald in an interview.

In turn, Turok — who is now director of the Perimeter Institute for Theoretical Physics in Waterloo, Ont.— developed an alternate theory.

Rather than a singular "bang," Turok hypothesizes that the universe is cyclical.

"The vacuum energy or dark energy which is dominating the universe today is not eternal. It won't last forever," said Turok.

"It's actually unstable, and when it decays, it will create the next big bang.… It's not a one-off universe, which started and will sort of last in empty eternity, dominated by dark energy. In fact, the universe cycles again and again through big bang after big bang after big bang."

Ahead of the airing later this month of this year's CBC Massey Lectures, Quirks and Quarks spoke with Turok about his childhood in South Africa in the late 1960s, during the fight against apartheid, and his theory of the origins of the universe.

The interview airs on Quirks and Quarks on Nov. 3. The full Massey Lectures will air on CBC Radio's Ideas from Nov. 12 to 16.