Disclaimer: This post has minor spoilers from the latter half of Jojo’s Bizarre Adventure Part 6: Stone Ocean.
Welcome back to FictionPhysics! In this post, I will be discussing C-Moon, a stand from Jojo’s Bizarre Adventure Part 6 which has gravity manipulation abilities. The stand’s main abilities are as follows:
1. Gravity Shift- this ability allows the user to repel any objects in a three-kilometre radius away from him in all directions. Eg. If you are above the head of the user, your body would start moving upwards. Furthermore, he can manipulate gravity such that it is directed towards the surface his feet are touching.
2. Surface Inversion- If any object comes into contact with the stand, it is turned inside out as its ‘gravity is inverted’. This ability when directed towards the circulatory system can reverse the direction of blood flow, causing brain death.
3. Time Acceleration- This is inflicted on objects in proximity of the user, causing the natural speed at which they act to increase. For non-living things, this could be objects falling more rapidly than they should or the hands of clocks moving more quickly. For living beings, this involves rapid ageing and growth, such as rapidly growing fingernails.
Gravity is a very important aspect of physics, which piqued my curiosity as to if these effects could theoretically be achieved in real life. The purpose of this investigation is to explain all these abilities through Physics.
Introduction to Gravity
A field is a fluid like substance which is spread throughout all of space. Fields can take different values at different points, facilitating the interaction between two objects without them necessarily touching each other.
The gravitational field is used to explain the regions which objects with mass exert an attractive force on each other. The greater the mass of an object is, the stronger its gravitational field as well as the force it exerts on objects around it. For this investigation, I will be using the Gravitational concepts established by Newton to explain the first two abilities as they don’t involve near light speed travel. However, for the final ability we must delve into general relativity.
Part 1: Gravity Shift
As mentioned earlier, the first ability involves repelling objects from the user in all directions. The multidirectional is in line with the field theory of gravity, as it is exerted in all directions. In Newtonian gravity, the force exerted between two masses due to gravity is given by the following equation:
Where Fg is the gravitational force (attractive), m1 and m2 are the masses of the objects and r is the distance between them.
In this case, we are trying to create a negative gravitational force. As r2 can’t be negative, we must resort to the theoretical concept of negative mass. From the ability, we can see that the force exerted is equivalent to earth’s gravitational field strength close to the surface, i.e. 9.81 N/kg. This field needs to be at least this strong at 3 kilometres from the user. The equation for gravitational field strength is as follows:
Where g is the gravitational field strength, G is the universal gravitational constant, M is the mass of the object and r is the distance from the object.
in this case, the following apply:
g is negative as repulsion is occurring in this case. Rearranging the above equation, we get
Therefore, for C moon to be able to create the ‘inverse gravitational field’ if it could bring this mass to one location. However, in theory, the mass would also repel the user as well if the stand were to be outside the user’s body. Therefore, this ability would only work if the user doesn’t reveal their stand. In addition, the stand has to have a mechanism to negate Earth’s gravitational pull, possibly by using another mass to cancel Earth’s gravitational field.
The second part of this ability involves attracting objects towards the surface on which the user is standing. This ability could work on a building on Earth (as this is where this ability is demonstrated) by changing the orientation of the building itself rather than manipulating gravity. I propose this because gravity acts in all directions, therefore placing an object of high mass on a floor would likely cause the walls to crumble as well as they also feel gravitational attraction. Therefore, C moon probably makes use of Earth’s gravitational pull as the force only appears to act downwards meaning that the field is coming from an object of similar dimensions to Earth.
Part 2: Surface Inversion
This ability is described as being able to ‘reverse the gravity of an object’, which if taken literally suggests that the gravitational field of the object affected is reversed, resulting in repulsion instead of attraction. For any object, we take its mass to be concentrated at the centre of mass- this is the point from which the gravitational field is emitted. By reversing the direction of the gravitational field, the centre of mass would start to repel the surfaces around it, which in a multilayered object could, if the field strength is high enough, cause the inner parts to spew out- this would have an affect on the position of the centre of mass however, which would change the position from which the repulsion occurs. Therefore, I propose that this ability works by placing a point mass which has negative mass, like the one discussed in Part 1. This negative mass repels the surfaces in immediate contact, which in a body would cause tissues and blood to spew out.
Another complication arises when we consider ‘inversion’, which suggests that the outside parts are pulled inwards as well, which is also demonstrated in the show. This would require two selective gravitational fields, one pulling the outer layers inwards while the other repels the inner layers. This even theoretically is a massive stretch and so I deem it to be not possible.
Moreover, this ability can reverse the circulation of the human body using gravity. Gravity does in fact affect blood circulation, but not in the way depicted in the show. Gravity plays an important role in providing blood circulation to the legs and abdomen in real life, and reversing gravity (which in tis case could also be achieved by hanging upside down) would limit blood circulation to the legs. Despite this, there would not be a significant impact on the brain as the brain would still receive oxygen. Therefore, I don’t think there is a way to achieve this theoretically only through gravity.
Part 3:Time Acceleration
The following equation relates time and gravity:
Where T is time, G is the gravitational constant, m is the mass, c is the speed of light, and R is the distance from the object.
In one scene, we can see that the stand affects the speed of a clock’s hands- In a period of 12 seconds in unaffected time, the clock’s minute hand shows that twelve minutes have passed, which is 720 seconds. As established earlier, C-moon seems to negate earth’s gravity, so time without gravity is 12 seconds and time with gravity is 12/720 seconds. Let’s assume that R is 1 cm as in the scene the user is virtually touching the watch. Hence, we get the mass required for this to be
Conclusion
In sum, looking at C-Moon's powers in Jojo’s Bizarre Adventure mixes fantasy with some physics ideas. Gravity Shift suggests pushing things away using negative mass, while Surface Inversion flips gravity around, which is a bit of a stretch. Time Acceleration kind of fits with how gravity can change time, but it's simplified for the story. While these powers are cool for storytelling, they're more about imagination than strict science. Still, exploring them helps us see how physics can inspire creative stories in Jojo’s Bizarre Adventure.
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