How long does light last?

When listener Rob from Devon, UK, heard of a newly detected planet light years away, he was struck by the sheer scale the light must travel to reach us here on Earth. It got him wondering: How long does light last? What is the oldest light we have ever observed? And does light ever die?

To find out, presenter Anand Jagatia calls on some of the brightest minds in astronomy and physics.

Astronomer Matthew Middleton from the University of Southampton explains how scientists still struggle to define exactly what light is. What we do know...