Question

Set the world alight = Set the world on fire

Accepted Answer

Achieve something sensational (informal)

A British variant of this expression is set the Thames on fire.
1976 Dick Francis - In the Frame - He was the same sort of man my father had been, middle-aged, middle-of-the-road, expert at his chosen job but unlikely to set the world on fire. Achieve something sensational (informal)

A British variant of this expression is set the Thames on fire.
1976 Dick Franc

Set World Fire Achieve Sensational Informal British Variant