It's a question you can almost guarantee no self-respecting cosmologist has ever considered. That is, until it was put to theoretical physicist Stephen Hawking during his Sydney Opera House talk over the weekend.

Hawking may be one of the greatest living scientists but he's now the hero of millions of teenage girls after he revealed it may be possible that Zayn is still a member of the boy band – in another universe.

"My advice to any heartbroken young girl is to pay close attention to the study of theoretical physics because one day there may be proof of multiple universes," said Professor Hawking, his image beamed onto the stage from his home in Cambridge, UK via a live video stream.

"It would not then be beyond the realms of possibility that somewhere outside of our own universe lies another different universe and in that universe Zayn is still in One Direction," he said.

While it was the prospect of hearing the enigmatic professor talk about his extraordinary achievements that drew people to his two Opera House talks on Saturday and Sunday evening, it was his comments about ordinary life that were the most illuminating – and funny.

When asked his thoughts on the recently released biopic film The Theory of Everything, the famous scientist admitted he was initially apprehensive about it because it was based on a book by his ex-wife. And who could blame him.

But after seeing the film he felt "it was surprisingly honest about our marriage."

Although Professor Hawking's disability prevented him from flying to Sydney to speak, it was fitting that he appeared as a hologram – a first for Australian audiences.

After a brief introduction by his friend, physicist Paul Davies, and Hawking's daughter Lucy, the famous physicist spoke of his early life growing up in wartime Britain. As a young boy, he didn't learn to read until he was eight, and his handwriting was a constant disappointment to his teachers. A classmate even bet him that he wouldn't amount to anything.

As well as talking about boy bands and his childhood, Hawking gave the physics enthusiasts in the audience what they came for – a brief history of how our understanding of the universe has changed.

But when asked whether the universe was "as it is" because it was designed by a creator or God, Hawking, with his characteristic wit and economy of words, simply replied: "No."

After a brief pause he joked about what this "God" might have been doing before creating the universe.

"Was he building Hell for people who ask such questions?" he teased.