Aleks is looking at regret, that sinking, nagging feeling when we realise we have made the wrong choice or when things have not gone the way we hoped or envisaged. Ethan Zuckerman was one of the early architects of user generated content on the internet in the mid nineties. He created the code that lead to the pop up advert which he still regrets today but Aleks finds out not for the reasons you would think.

Denise Locke was on Flight 1549 which miraculously landed in the Hudson River in 2009. She had a choice to get on the flight that day because the weather delay meant she was texted by the airline to give her the option not to fly. She flew anyway and despite suffering post traumatic stress she does not regret the experience. It has changed her life, she now lives much more in the present.

Professor Amy Summerville runs a regret lab at Miami University, Ohio, she talks about the importance of regret and why it helps us to understand the world around us. Amy thinks that in our modern world we experience more regret, because of what she refers to as counterfactual thinking and the abundance of choice we now have because of technology.

Simon Yates one of the protagonists in the film and book Touching the Void, speaks about why he cut the rope his climbing partner was dangling on up a mountain in Peru and why he has no regrets about what he did.

Mel Slater and Doron Friedman both push the boundaries of what' s possible in virtual reality. They're exploring the use of clones in VR which are able to go back in time and re live past experiences. They believe this technology will have great impacts not only on our how we perceive the self and on identity but also how we experience and deal with regret in the future.

Produced by Kate Bissell.