Torchwood is a successful spin-off of Doctor Who
A special radio episode of sci-fi drama Torchwood is to be broadcast as part of BBC Radio 4's Big Bang day.
The station will broadcast from the European nuclear research facility in Geneva on 10 September where scientists are to recreate the Big Bang aftermath.
Presenter Andrew Marr will report on the day's events for Radio 4 which has exclusive access to the site.
The episode of Torchwood will be set inside the European Organisation for Nuclear Research (CERN).
The show's star John Barrowman will also appear in discussion with CERN physicist Brian Cox.
Cox, a former member of chart-topping band D:Ream, will also talk to Alan Alda, Eddie Izzard and comic actor Ben Miller - all of whom are particle physics enthusiasts.
The moment just after the Big Bang will be recreated by the fastest atom smasher in the world by scientists at CERN.
They are hoping it will give them an insight into the origins of the universe and its composition.
The experiment will be launched live on the Today programme.
In a statement, Andrew Marr said: "This will be one of the greatest scientific experiments, as well as the most expensive, ever conducted on Earth, which - fingers crossed - will reveal truths about existence guessed at but never demonstrated.
"The eyes of the thinking world will be watching CERN, which is why it will be such a privilege to report there for Radio 4's special day."