Zero gravity, also known as weightlessness, is a state in which an object is not subject to any gravitational forces and thus experiences no sensation of weight. In practice, a state of zero gravity is nearly impossible to achieve, but it can be simulated in a variety of ways.
One way to simulate zero gravity is to use an aircraft that flies in a parabolic arc. As the aircraft climbs, it experiences a brief period of weightlessness as it reaches the top of its arc. Another way to simulate zero gravity is to use a drop tower. A drop tower is a tall structure from which an object is dropped. As the object falls, it experiences a brief period of weightlessness before it hits the ground.
