Understanding Artificial Gravity

Stanford Torus
A so-called "Stanford Torus" artist's concept by Don Davis, created for a proof-of-concept study by NASA. Public domain (NASA).

The film series Star Trek makes use of many technologies to make the show interesting. Some of these are rooted in scientific theory, others are pure fantasy. However, the difference is sometimes difficult to identify.

One of these key technologies is the creation of artificially generated gravitational fields on board the star ships. Without them, the crew members would be floating around the ship in the same way that modern-day astronauts do when on board the International Space Station.

Would it someday be possible to create such gravitational fields? Or are the scenes depicted in Star Trek exclusive only to science fiction?

Counteracting Gravity

Humans evolved in a gravity-bound environment. Our current space travelers on board the International Space Station, for example, have to exercise several hours a day using special straps and bungee cords to keep them upright and apply a sort of "fake" gravitational force. This helps them keep their bones strong, among other things, since it's well-known that space travelers are physically affected (and not in a good way) by long-term habitation in space. So, coming up with artificial gravity would be a boon to space travelers.

There are technologies that allow one to levitate objects in a gravitational field. For instance, it is possible to use powerful magnets to float metal objects in air. The magnets are applying a force on the object that balances against the force of gravity. Since the two forces are equal and opposite, the object appears to float in air.

When it comes to spacecraft the most sensible way, using current technology, is to create a centrifuge. It would be a giant rotating ring, very much like the centrifuge in the movie 2001: A Space Odyssey. Astronauts would be able to enter the ring, and would feel the centripetal force created by its rotation.

Currently NASA is designing just such devices for future spacecraft that would undertake long-duration missions (like to Mars).However, these methods are not the same thing as creating gravity. They merely fight against it. Actually creating a generated gravitational field is quite tricky.

Nature's primary way of producing gravity is through the simple existence of mass. It appears that the more mass something has, the more gravity it produces. This is why the gravity is greater on Earth than it is on the Moon.

But suppose you wanted to actually create gravity. Is it possible?

Artificial Gravity

Einstein's theory of General Relativity predicts that mass currents (like rotating mass disks) could produce gravitational waves (or gravitons), which carry the force of gravity. However, the mass would have to rotate very quickly and the overall effect would be very small. Some small-scale experiments have been done, but applying these to a space ship would be a challenge.

Could We Ever Engineer an Anti-Gravity Device like those on Star Trek?

While it is theoretically possible to create a gravitational field, there is little evidence that we will be able to do so on a large-enough scale to create artificial gravity on a spaceship. Of course, with advances in technology and a better understanding of the nature of gravity, this may very well change in the future.

For now, however, it seems that using a centrifuge is the most readily available technology for simulating gravity. Though not ideal, it could pave the way for safer space travel in zero-gravtiy environments.