Were Charles I of England and Isaac Newton alive at the same time?
Yes. Charles I of England and Isaac Newton were alive at the same time for 6 years, from 1642 to 1649.
Charles I of England was 42 when Isaac Newton was born.
Isaac Newton was 6 when Charles I of England died, aged 48.
Charles I of England
King of England, Scotland, and Ireland from 1625 to 1649
Born 19 November 1600 (Julian calendar) · died 30 January 1649 (Julian calendar), aged 48
Isaac Newton
English mathematician and physicist
Born 25 December 1642 (Julian calendar) · died 20 March 1727 (Julian calendar), aged 84