Ask A Scientist
Can there be zero gravity somewhere on earth so people can experience what zero gravity feels like?
Asked by: Lance Williams
School: Maine-Endwell Middle School
Teacher: Kevin Wagstaff
Hobbies/Interests: Minecraft and computer exploring
Career Interest: Marine biologist
Answer from Hiroki Sayama
Director, Collective Dynamics of Complex Systems Research Group & Associate Professor
Research area: Complex systems, artificial life, mathematical biology, computer & information sciences
PhD school: University of Tokyo
Interests/hobbies: Traveling, walking and swimming
Family: Wife, Mari; two sons (Takehiro - 14) and (Yukihiro - 10)
Web page address: http://bingweb.binghamton.edu/~sayama
Lance, I can answer your question in two different ways. One answer is negative -- “No, there isn’t a single place on Earth with zero gravity.” The other is positive and optimistic -- “Yes, it is rather easy to create zero gravity.” They are both correct in some sense. Let me explain.
Gravity is a relatively weak, but very penetrative, far-reaching force that acts between any two objects that have mass. Unlike an electro-magnetic force that can be easily blocked by wrapping things with conductive or magnetic materials, gravity cannot be blocked by any materials or methods. “Gravitational shielding” still remains a dream in science fiction. So, anywhere in the world, Earth’s gravity penetrates through anything and catches everything that has mass. Its gravity even reaches the International Space Station and Moon, so they are also trapped in Earth’s gravitational field. In this sense, there is absolutely no zero gravity possible on or near Earth.
But then, how come astronauts in the Space Station can enjoy zero gravity while they are still trapped in Earth’s gravity? This is the key part in understanding the trick of zero gravity: If you and your surrounding environment are both free-falling at the same gravitational acceleration, then you won’t feel any gravitational force. Both the Space Station and astronauts inside it are always pulled toward Earth by its gravity, so they are free-falling at the same acceleration. This is why it looks like there is no gravity at all inside the Space Station. Fortunately, the Space Station is flying so fast that it won’t actually hit the ground. Rather, it is free-falling indefinitely, circling around Earth.
Now you probably realize how easy it is to create zero gravity. Get into a large wooden box and have someone kick it off the top of a high vertical cliff, then you could feel zero gravity for a moment (if air resistance is ignored) --- but you will most certainly die, so don’t try it! Luckily, there are now companies offering zero gravity experiences simulated in an airplane. In such a “weightless flight”, a specially trained pilot will fly the aircraft in a parabolic trajectory that simulates a freefall, inside which you can feel no gravity at all. As of today, a ticket for such a flight costs about five thousand dollars. You may want to try it once you get rich :) Moreover, the possibility of space tourism is also within reach, so you may actually be able to experience the “real” outer space zero gravity in the future when you grow up!