The universe is held together by the force of gravity, thus absolute zero gravity is not possible.  Reduced gravity, or microgravity (1 x 10 ^-6 g), can be accomplished by going into free fall, which is state of weightlessness.  Astronauts train for microgravity by flying in air crafts that follow a parabolic path, nicknamed the "Vomit Comet" as shown in the photo to the right.⁹

Microgravity experiments can also be conducted in NASA's drop towers.  Free fall is achieved and lasts just over 5 seconds in this tower of almost 500 feet tall.⁹