What if we could travel not just through space, but through time itself? If you could travel through time, would you change the past or the future? What if you found it couldn't be changed? What price does the time traveler - and the people they are closest to - pay? This is a journey from H. G. Wells' The Time Machine through ideas like The Grandfather Paradox and The Butterfly Effect to the professional time traveler that is the ever popular Doctor...

The protective gear worn by motorcyclists can be extremely hot and uncomfortable in sweltering Australian conditions. Does heat stress contribute to accidents, and how protective is safety gear anyway? Mark Horstman lays his mind and body on the line as scientists put motorcycle clothing to the test. Also, what did the beginning of time look like - that moment of creation? What are the biggest explosions in the universe like? We've never been able...