Arcadia, is currently enjoying a well-received revival at the Barrymore theater. Tom Riley, the 30-year-old British actor making his Broadway debut in the production as the 19th-century poet, tutor to a genius and lothario Septimus Hodge, talked with us about sound amplification on Broadway, Tom Stoppard's way with words, working with the actor who originated your role on Broadway, and why they really need you to turn off your cell phone before the show (hint: a remote-controlled tortoise is involved).