Who are "they" in Interstellar?

In Interstellar, NASA scientists keep saying "they" in most of their conversation with Cooper.

Does "they" refer to some alien or supernatural race?

Best Answer

The 'They' being referred to is (at this point in the movie) some unknown, supposedly extra-terrestrial higher knowledge that is manipulating gravity to send messages in Binary, and Morse code.

For some reason, they are directing NASA on Earth towards a solution to their planet's exhaustion; which is why when Coop shows up at the base after following the co-ordinates, the immediately assume his presence is some kind of providence and recruit him into the team...

However, we later learn that...

... 'they' are in fact the future remnants of the human race, that have achieved a technology so advanced they are able to manipulate the 4th dimension: namely, time. It is Coop's future invocation that is directing himself to NASA, and onto the program. With the help of CASE, Coop transmits the data required to complete Murph/Brand's formula, and achieve the necessary scientific knowledge to leave Earth with full colonies.The 'They' is a combination of the future human race which sent back the Space/time interface for Coop to manipulate, and Coop himself...