It sounds strange, but the truth is you don't need to be far away from the Earth to experience something that, in effect, is the same as weightlessness. To begin with, you must understand that the only reason your body feels weight in the first place is because you are constantly being pressed against the Earth. When an object is falling, and therefore not in contact with the Earth, it is as good as weightless!
To illustrate this concept, lets conduct a little hypothetical experiment. For this experiment we will take person A, lets call him Norman, and place him in an ordinary room filled with various other objects. This room will be sealed inside a closed container and then dropped from an airplane a dozen or so kilometers above the ground. As soon as the container begins to fall, it will appear to Norman that everything in the room has become weightless! Objects will float in mid-air and Norman will be able jump off the floor and land on the ceiling. Because everything around him is accelerating at the same rate, it will seem to Norman that the force of gravity has suddenly been eliminated. Unfortunately this illusion will end quite abruptly as soon as his sealed-off room hits the ground, yet, as long as he is in free fall, Norman will be weightless and all the objects in the room will be weightless relative to each other.
Incidentally, a rather similar technique is used by NASA to simulate weightlessness. But instead of dropping potential astronauts out of an airplane as was Norman’s fate, they drop the entire airplane so to speak. Using their own special Boeing KC-135 which is affectionately referred to as the “Vomit Comet”, they fly up to a safe height and then cut the engines, allowing the aircraft to enter free fall. This produces the same type of effect as our friend Norman experienced but, because the pilots eventually turn the engines back on, it doesn’t end in a violent collision. It is also important to note that this weightlessness due to free fall is also the type of weightlessness that astronauts experience when they orbit the Earth. It is not because they are outside the Earth’s gravitational pull, but simply because orbits are a type of free fall. For more on orbits see Large Scale Effects Pages 4, 5 and 6.
There is one more method that might be able to produce weightlessness right here on Earth but, unlike the last two, it has nothing to do with free fall. You see, in 1992, a Polish scientist named Podkletnov was fooling around with some superconductors and claims to have discovered a way to shield objects from gravity! According to reports, he found that by exposing a rotating superconducting disk to high frequency magnetic fields, it seemed to show a reduction in weight of objects levitating above the rotating disk (basically, picture a spinning top (the superconducting disk) with an object floating above it).
But did this device really repel the force of gravity? Nobody knows for sure at the moment, but Podkletnov’s results were enough to convince NASA to spend a fair amount of money researching the idea! Just imagine the possibilities if shielding gravity were indeed possible! Why, you could launch rockets with a push of your finger! People confined to wheelchairs could instead hover above the ground! The possibilities just go on and on! Research into the very interesting phenomenon of repelling gravity is continuing all the time. You never know, an idea that was once something you read about in a science fiction novel may turn out to be fact!
