Hang time is the illusion that a basketball player is floating in air and defying gravity. Although it is cool to imagine that Michael Jordan can float in the air, it is a myth. This is because, neglecting air resistance, once the basketball player leaves the ground, the only force acting upon him is gravity. Since gravity acts upon an object with a constant force, it will take the same amount of time for an object to reach it's maximum height as it will for it to return to its original height.
The Image above is a famous picture of Michael Jordan dunking a basketball and appearing to float through the air. What adds to this illusion is that once Jordan reaches his maximum height, he then lifts his arm into the air and bring his legs down. His veloicty with respect the ground is also greater then a normal person dunking a ball. Because of this, he will travel further at his maximum height than if he were to go straight up and down, adding to the illusion that he is floating through the air.