When it comes to training and getting stronger in the world of Dragon Ball, you really can't beat the Room of Spirit and Time!

It's the place that our heroes used to train up for the final showdowns with Cell and Majin Buu, after all. Among the benefits of the room is how a year of time in the room is equivalent to a day of real-world time, plus it boasts ten times the amount of Earth's gravity.

I bet that many Dragon Ball fans have wondered if they too would be able to power up like Goku and the others if they trained in the Room of Spirit and Time.

At first glance, it's easy to assume that the Room of Spirit and Time couldn't actually exist in the real world, but what insights might an actual physicist be able to offer on this matter?

To find out, I interviewed Professor Nobuyoshi Ohta, a physicist at Taiwan's National Central University. Professor Ohta's field of expertise involves research into particle physics, space, gravity, and more!

Profiles

Interviewee: Professor Nobuyoshi Ohta
Former associate professor at the University of Osaka's School of Science and professor at Kindai University's School of Science and Engineering. Currently serves as a visiting professor of physics at the National Central University (Taiwan) since April 2021. Conducts research specializing in elementary particles and gravity (including black holes and the beginning of the universe). Recent research interests include the theory of quantum gravity.

Interviewer: Maishiro
Entertainment analyst. Author of many articles based on serious research (including data analysis and interviews) into non-serious subjects. Articles often featured on Yahoo's freelance page and the Daily Portal Z website.
Has a particular fondness for music, films, and manga! Twitter：＠_maishilo

Contents

—The Room of Spirit and Time has many special features, but probably the most well-known aspect of this amazing room is that you can spend a year inside with only a day passing in the outside world.

Ohta: In terms of physics, the exact opposite of that is possible.

If it were "a year had passed in another place, but it has only been a day for me," that sort of phenomenon has been observed.

—What?! So you're saying that time flows differently depending on where you are?

Ohta: Well, you see, time flows slower where there is stronger gravity.

Let's compare a space station to Earth. We know that time flows more slowly on Earth where there is stronger gravity, right? So, similarly, if we were to compare a baby born where there is stronger gravity to a baby born where there is weaker gravity, they would grow at different speeds.

So, in other words, if you went to a place where there is stronger gravity, your own time would proceed much more slowly.

—You could put your enemy in a tough spot if they were in a place where only a day had passed, but you were able to train for a whole year.

Ohta: Yes, you could. It's different from the Room of Spirit and Time, but a fighter could really gain an advantage if, while they remain on Earth, they were able to somehow create a place nearby with stronger gravity and throw their enemies inside!

On the other hand, if you don't mind traveling far away from Earth, there is another method. You could throw your enemy inside an existing place with stronger gravity, and, while your enemy is there, keep training in a place without strong gravity.

—Could you explain a bit more what a "place with stronger gravity" would be like?

Ohta: Large astronomical bodies like Jupiter and our Sun are good examples of what they're like. But there is a place you could put your enemies where the gravity is not necessarily strong. That place is near the event horizon of a black hole.

Time flows extremely slowly at an event horizon. The larger a black hole is, the weaker the gravity is near the event horizon. Even though the gravity is weak, time would still flow very slowly there.

This is because the event horizon of a large black hole is farther from the center. However, it would be dangerous. If you go inside an event horizon, you can't leave. So, you'd have to get close as you could without actually going inside.

—How big of a black hole would you need to create a one year time gap like the Room of Spirit and Time?

Ohta: If you want to create a time difference of a year, then assuming we're talking about on Earth, you would need an enormous planetary body with the mass of one billion Earths.

But black holes don't need to be quite that massive. Time slows down as you get closer and closer to an event horizon. You don't want a black hole that's too small either, though. This is because for smaller black holes, even if you got close to the event horizon, the strength of the gravity would increase.

The largest black hole discovered in the universe thus far has the mass of about 10 billion suns. But humans creating a black hole of that size, while theoretically possible, seems like it'd be difficult to actually pull off.

—Wow, the largest black hole in the universe sounds mind-bogglingly massive! I guess that the Room of Spirit and Time would be considered quite an unusual place no matter where in the universe you went!

—Next, I'd like to ask you about some of the other aspects of the Room of Spirit and Time. Goku explained that the Room of Spirit and Time is as big as the Earth itself.

Ohta: Actually, it seems like they might just warp to another place the moment they open the door.

—Is a warp like that something that could be created in the real-world?

Ohta: If there is a world above the three dimensions we live in, then warping is theoretically possible.

Let's use an example of two dots on opposite ends of a sheet of paper. Normally, to get from one point to the other, you'd move along the paper at a high speed. Warping would be creating a path by bending the paper and putting the two points together.

However, you can't just bend the paper and put the points together yourself. To "fold" it, you'd need "extra dimensions" (a dimension above the dimensions we live in).

For us, since we live in three dimensions, a world above the three dimensions is equivalent to an extra dimension. In order for this to work, you'd need to be able to access the world above the third dimension.

—"Warps?" "A different dimension?" This all sounds like stuff from science fiction, but you're saying that it's all academically plausible, correct?

Ohta: That's right. The only difficulty here is that no research has found any proof of a world with more than three dimensions.

Research is currently proceeding based on the thinking that if there is a dimension above the third, it must have some kind of effect on experiments currently being done on Earth.

—So if this research continues to make progress, we might be able to utilize warping in the real world at some point, and maybe there will be a day where there could really be a Room of Spirit and Time! I also wanted to ask you about how the Room of Spirit and Time has ten times the strength of Earth's gravity.

Ohta: Ten times the strength of Earth's gravity would be a ton of gravity. The amount of gravity is actually determined by the mass and density of the planet.

Therefore, if planets have the same density, the one with more mass will have stronger gravity. But even large planets may not have such strong gravity if they have a low density.

In our solar system, Jupiter has about twice the strength of Earth's gravity and the Sun has about 28 times the strength of Earth's gravity. So it looks like that upon entering the Room of Spirit and Time, you might be warped to a planet with a size and density somewhere between those two.

— Your theory that you warp the moment you enter the Room of Spirit and Time seems more and more likely to me, but is there a way that you could increase the amount of gravity without warping?

Ohta: Well, if we were to exclude warping, another possibility is that the Room of Spirit and Time itself might be constantly accelerating at an extremely high speed.

Have you ever noticed that when a bullet train starts moving, you feel like you're being pulled from behind a bit? Just like that sensation, whenever a vehicle is accelerating, the gravity pulling on it also increases. So, maybe the room itself is flying somewhere while continuing to accelerate faster and faster.

—It's really fun to think about so many different possibilities. By the way, could a human survive if the strength of gravity were to increase to ten times that of Earth's?

Ohta: Human beings are quite adaptable, so I think humans would probably figure out a way to make it work even if the gravity increased tenfold.

But it would be an extremely difficult environment for humans to live in. You might be unable to walk and be forced to remain in a lying down pose.

It would be rough on a human's internal organs as well, so it could even cause things like scoliosis.

—Goku and the others are training in a place that's tougher than anything we could imagine!

—So Goku explains that the air in the Room of Spirit and Time has about a quarter of the density of Earth's.

Ohta: If we are thinking in terms of Earth, that would be about the same density as ten kilometers above the surface.

However, normally you'd expect that where there is stronger gravity, the air would be denser. So, since the Room of Spirit and Time has ten times the gravity, the air should be that much more dense. For this situation to be possible, it might be that someone is letting the air out on purpose to make it thinner.

—Oh, so there's the possibility it's being deliberately made into this harsh environment! Speaking of the air, Goku also explains that the temperature of the Room of Spirit and Time ranges from minus 40 degrees Celsius (-40F) to around 50 degrees Celsius (120F).

Ohta: I think that aspect is totally possible. When there isn't a lot of air, the sun has a much greater influence on the temperature, so it would be easier for it to fluctuate drastically.

There isn't a sun in the Room of Spirit and Time, but maybe there is something like a white ceiling. Let's suppose that white ceiling is made up of a thin layer of clouds that hide the sun. If that is true, it wouldn't be strange at all for the air to be so thin and the temperature to change so drastically.

—Moving on, what aspect of the Room of Spirit and Time do you think would be the most effective for training?

Ohta: I think that strong gravity would be especially effective for training. Just moving around in the room would make someone build up a lot of muscle, and that would definitely give you an advantage in battles where there isn't strong gravity!

Also training with thinner air is actually done by athletes like marathon runners. By training to be able to move where the air isn't dense, you can strengthen your heart and lungs, so that would surely increase the effectiveness of the training, too.

—Okay, let's switch it up a bit. What aspect of this room do you think would be the most difficult part for normal people to deal with?

Ohta: The thinness of the air would be the first thing you'd feel as you entered the room. That in and of itself could be immediately life threatening.

But, even if you aren't like Goku or the other Z-Warriors, you could probably adapt to the other aspects of the room just by spending time there.

Anyone who could manage to survive any length of time in that room would come back much stronger.

—At first, it seemed like the Room of Spirit and Time couldn't actually exist, but it was fascinating to hear from a real physicist that it's not something limited to the realm of science fiction. Thank you so much for your time today!