A Turing machine is a hypothetical device that manipulates symbols on a strip of tape according to a table of rules.

A tachyonic antitelephone is a hypothetical device in theoretical physics that could be used to send signals into one's own past.

A hypothetical device named after physicist John Bell which allows signals to be sent faster than the speed of light using quantum mechanics.

This suggests that it was a kind of "overbalanced wheel," a hypothetical gravity-powered device which is now recognized by physicists as impossible (see perpetual motion).

An acoustic cloak is a hypothetical device that would make objects impervious towards sound waves.

TWIRL is still a hypothetical device - no implementation has been publicly reported.

"You really think I'm this hypothetical human fail-safe device?"

These hypothetical devices would have to be set so that the propellant regained its inertia after leaving the craft otherwise the drive would be ineffective.

An ansible is a hypothetical device capable of instantaneous or superluminal communication used in all Ender's universe novels.

At the time of writing, Mark Weiser compared stereos, thermostats and light switches to a hypothetical device that could more directly transfer information.