Question: Who played guitar on is there anybody out there?
Disambiguated questions and answers: question: Who played the bass guitar on "Is There Anybody Out There?"?
Who played the classical guitar on "Is There Anybody Out There?"?
Who played the guitar and wah-wah pedal on "Is There Anybody Out There?"?
answer: Roger Waters
Joe DiBlasi
David Gilmour
Natural Questions answer: Joe DiBlasi (from the Wikipedia article "Is There Anybody Out There?")