Written by TKS Boston Student Amelia Settembre. 

Artificial gravity has been one of the biggest question marks when considering actual, plausible space flight — and more specifically, improving it for the people. Of course, there are still a ton of issues with the current system, and our knowledge of artificial gravity is a far cry from futuristic shows like Star Trek and Battlestar Galactica. For a brief overview of artificial gravity, check out my other article on it here.

So now let’s take the next step deeper and look at some of the physics, both known and experimental, that physicists are analyzing this very moment to improve future space tech. In current gravity, the gravity of an object increases when the mass does. Unfortunately, when an astronaut is on a spaceship, there isn’t enough difference in mass for the craft to generate enough gravity to keep the astronaut on it.

Modern Artificial Gravity And Principles

Back in Einstein’s time, he proposed something called the equivalence principle, which basically stated that gravitational force is indistinguishable from a pseudo-force generated in an accelerated frame of reference. This meant that we didn’t need to have a massive, planet-sized spacecraft, we only need to have sufficient acceleration to simulate gravity.

As it turns out, there are three big types of acceleration:

  • Linear, which is like driving in a car.
  • Rotational, which is like spinning a bucket around with water in it.
  • Gravitational, which is like dropping a penny off the Empire State Building. Here, it accelerates due to gravity.

For humans, we can’t go above a certain amount of g-force. On Earth, the g-force we experience is around 1 g. That’s not very much. However, air force pilots often experience intense change in the g-force. The most g-force any human has managed to survive is 214g, which occurred during a car racing match.

On the Enterprise, travelling at warp one, a human would be subjected to around 4,000 g. Unless in the distant future they’re able to come up with some kind of reverse-accelerator to protect astronauts, it’s not going to bode very well — for anyone. Now that we’ve ruled that out, that doesn’t mean there aren’t any ideas for getting stable artificial gravity. One of the biggest questions regarding this is compensation.

In other forces, like electromagnetism, you could just put all the people into a conductive capsule and block out the extra electromagnetic waves. The remaining amount can be contained and pushed around within the capsule, making it safe for the crew.

This diagram represents the inner capacitor in which the electric field — kept with an opposite and equal charges — is arranged safely between two plates, making the capacitor safe and livable for all humans inside it.

Unfortunately, there’s no negative gravitational mass in the known universe, which does make it more difficult to determine how to reverse the effects of gravity. However, in theory, if there is indeed a particle such as the “graviton”, then it’s possible for there to be another exotic particle, perhaps dubbed the “anti-graviton”. Up until this point, there’s no proof that the known universe even contains any gravitons.

That’s the biggest issue experienced with gravity — unlike other forces (like electricity) which have positive and negative values — it only has one, and that’s the attractive quality it always has. All this means is scientists are either going to have to get incredibly theoretical, find new physics, or just use the acceleration methods we all know and love.

The most considered one of these acceleration methods concerning artificial gravity is rotation. By taking a spacecraft and rotating it quickly, artificial gravity can theoretically be generated, holding the contents of the spacecraft secure.

In this figure, the acceleration as relating to the center of the figure and the outside is mentioned, in which what changes is the acceleration in relation to the center of the circle [pictured on the left]. In the other image, when taking into account speed which increases, by using the acceleration in relation to the center of the figure and outside of the figure can help determine what the overall acceleration is.

As it turns out, physicists have designed formulas to calculate the exact acceleration of artificial gravity. In the formulas below, we’re assuming that there are two chambers in a spacecraft which are connected by a tunnel with a length of 2R. Here, let ‘v’ represent the frequency of the tunnel and ‘t’ can be the time period.

Remember that centripetal acceleration we talked about a little earlier with the circle figure? Well, it comes back into play here, as you’re trying to also solve for how it fits into the rotation of the artificial gravity chamber.