Artificial gravity in space

How is the “artificial gravity” on board Space Battleship Yamato created?

Kodai: “float, float”

Rikao Yanagita, Senior Researcher, Dream-Science Laboratory

Published on, February 27, 2023. See the original article here.

Illustrations by Yutaka Kondo

There are many unforgettable works by Mr. Leiji Matsumoto, and we certainly can’t ignore Space Battleship Yamato. It was not planned by Mr. Matsumoto, but it is well known. The image of the Earth devastated by Planet Bombs, the concept of going to a planet 148,000 light-years away, and mecha such as Yamato and the Wave-Motion Gun were also created by Mr. Matsumoto. In Wadachi, which he drew shortly before Yamato, we see the emigration of the majority of Japanese people to space, which may have also contributed to the concept of Yamato.

In any case, the elements and concepts in Yamato are exquisitely stimulating to the scientific mind. This is why Yamato was a groundbreaking work that excited the enthusiasm of junior high and high school students at the time. This author was a bit surprised at the line “Energy at 120%” and wondered, “Is it safe to put that much in?” When I saw row upon row of various meters, I was stunned. “It seems really hard to just check on something.” At the same time, however, I was also excited by the terms and descriptions.

I believe Yamato became warmer with the addition of Mr. Matsumoto’s unique excesses to the worldview colored by science.

How can gravity be created?

Naturally, I used Yamato in my first Dream-Science Reader in 1996. Looking back on it now, I think there were other subjects. (Journey to the Magellanic Galaxy, Warp, Wave-Motion gun, etc.) I chose “artificial gravity” as the subject matter.

This was not even mentioned in the anime. (In the side-story manga Eternal Story of Jura, it was said that artificial gravity was working inside the ship.) After some study, I came to the following conclusion: “Yamato must be flying while being chased by a spinning ring!”

The methods to artificially generate gravity are as follows:

(1) Placing an extremely heavy object nearby

(2) Continuously increasing speed (if a car starts suddenly, your back will be pressed against the seat)

(3) spinning to create centrifugal force.

In our present, there is no possibility of realizing an artificial gravity generator, but the centrifugal force method has been considered for a long time. If a circular space station or a cylindrical space colony is rotated, centrifugal force is generated toward the outside, which would create an environment similar to that of Earth. However, since Yamato is in the shape of a ship, it would be difficult to determine which direction to rotate it in.

(1) Vertical rotation: Yamato moves forward while repeating forward somersaults.

(2) Horizontal rotation: Yamato goes through space while rotating with its bridge tower as its axis.

(3) Spinning rotation: a line connecting the bow and stern is the axis of rotation, and the ship moves forward while rotating like a drill.

In each of these cases, gravity does not pull you toward the floor, so it would be hard for Kodai and Shima to sit still in their seats. In the case of (1) and (2), it would be difficult to hit a target with the Wave-Motion Gun.

A tougher opponent than Gamilas!

Then I came up with the idea of using Einstein’s special theory of relativity. “When an object moves at high speed, the same phenomenon occurs as if its mass increased.”

No matter how much energy we use, we cannot exceed the speed of light. As we approach the speed of light, instead of increasing speed, we increase our mass. By applying this phenomenon, Yamato can generate artificial gravity!

For example, if we spin a huge ring at a tremendous speed, it would become incredibly heavy, and thus gravity would be generated. Suppose we make a steel ring, 2 meters thick with a diameter of 200 meters.

To create 1G in a space 100m away from the ring, the ring should rotate at 99.999999999999994% of the speed of light. If we place this ring close to the bottom of Yamato, gravity would pull the ship downward so that the ship’s interior can be lived in exactly the same as on the ground.

However, gravity does not work only inside the ship. Yamato itself is also pulled by the gravity-generating device, just as it would be on the ground. Therefore, Yamato must counter the gravity by firing its engine downward. But Yamato‘s main engine is facing backward, so it might be better to use it to counter the strong gravity of the rotating ring.

Thus, this ring would be located aft of Yamato and would be chasing the ship from behind, spinning at high speed! In normal space navigation, once the ship reaches the target speed, the law of inertia allows the ship fly at a constant speed without any engine thrust. However, in this posture, there is no such merit. As long as the gravity generator is working, the main engine cannot be stopped.

If the thrust drops even a little, our Yamato will have its rear scraped by the oncoming rotating ring. Even the thought of firing the Wave-Motion gun is frightening. The biggest threat to Yamato would not be the Gamilas Army, but this artificial gravity generator!

While thinking about artificial gravity, I came to this conclusion…

Of course, it would be easier to say that artificial gravity has been created in some other way by science and technology in the year 2199. But the idea of “considering anime events with real science” is what The Dream-Science Reader is all about.

Needless to say, fans of Yamato were furious with me. Even so, every time I published articles about it, Mr. Matsumoto was not offended. When I asked him to use the images in my subsequent examinations of Galaxy Express 999 and Queen Emeraldas, he readily agreed. He was very kind to me in many ways. I cannot thank him enough.

Above all, I would like to express my deepest gratitude for the “world where roman, science, and warmth are fused together” that Mr. Matsumoto drew. That is the world I would like to continue to aim for in The Dream-Science Reader.

The following illustrations were published with this essay in The Dream Science Reader…

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