What is the name of the time-inversion machine in Tenet?

The time-inversion machine in Tenet is called the Turnstile. In the film, it is a device that reverses the entropy of people and objects, allowing them to move backward through time relative to the normal world.

The machine’s name comes from its visual and functional design: characters enter a chamber, pass through a rotating structure, and emerge inverted. The process does not send someone instantly to an earlier date. Instead, an inverted person experiences time in reverse and must travel physically through the intervening period. To return to normal, the character uses another turnstile and reverses the process.

Turnstiles appear at several important locations, including a freeport at Oslo Airport and a facility in Tallinn. Their operation creates the film’s distinctive scenes in which a character encounters another version of themselves moving in the opposite temporal direction. The machine therefore supports Tenet’s central idea of a temporal pincer movement, in which information or action approaches an event from both directions in time.

The other options describe concepts from the film but are not the machine’s name. The Algorithm is a dangerous device that can invert the entropy of the world, while “inverted” describes a state rather than the machine itself.