Maddox Krape

Coding the Universe

For this simulation, I used 3 main classes to achieve a functional and logically sound simulation.

Classes

• UniverseState

Since this simulation was technically built inside a game engine, we need a class to take care of the current state of the universe. These are things like the camera, windows, gui, time, gravitational constant, etc.

• UniverseManager

This class is used a to compute and update the state of the universe. It also stores the ArrayLists of celestial bodies and updates them.

• CelestialBody

The most essential class. This classes purpose is to be used as an object to store a body's mass, velocity, and geometry.

Simulating Gravity

Simulating a universe with gravity can be done using one formula: Newton's law of universal gravitation.

Converting this formula into code can also be quite simple. I've done this by iterating through the ArrayList of celestial bodies and calculating the total effect of gravitational pull from each body on eachother. As seen in code here:

for (CelestialBody other : allBodies) {
	if (other != this) {
		Vector3f direction = other.getGeometry().getLocalTranslation().subtract(this.getGeometry().getLocalTranslation());
		Vector3f force = direction.mult(UniverseState.G * other.getMass() / direction.lengthSquared()); // Newton's Law of Universal Gravitation 
		Vector3f acceleration = force.divide(this.getMass());
		this.currentVelocity = this.currentVelocity.add(acceleration.mult(timeStep));
	}
}

Deep Dive

Here is the first example instance of me getting gravity to work. There is initaly 3 bodies with similar mass but different starting postitions and velocity. Tweaking with some numbers, this was able to produce two bodies that dance together as a binary pair and the other body to orbit them. This is whats know as an "circumbinary system" and is pretty cool to watch. If you'd like to create your own, id highly recommend it as this teached me multiple valuable learning lessons in my software engineering journey. Next, you can try to experiment with different starting positions, velocities, and masses for the bodies in your simulation. This will allow you to see how different initial conditions affect the final outcome of the simulation. You can also try adjusting the gravitational constant to see how it affects the motion of the bodies. You can also try simulating more complex scenarios, such as a system of multiple planets orbiting a star or a galaxy with multiple stars. These types of simulations can be quite challenging to create, but they can also be very rewarding. As you continue to develop your gravity simulator, you can also research and read about the latest advances in the field of celestial mechanics. This will help you to better understand the physics behind your simulation and to improve its accuracy. Overall, developing a gravity simulator can be a fun and educational experience, and can also be a great way to learn about the complexities of the universe. Specifically, how difficult it is to get planets to orbit.

On the right is one of my final versions of my simulator. This includes various controls for things like time, gravity, camera, and options to create custom celestial bodies.

Key Takeaways

• How to use object orriented programming as a paradigm to store and manage data as objects.
• Fundimental physics that is applied in astrophysics
• How to work with 3 dimensional mathematics such as vectors and how to manipulate them

You can browse the project on my Github:

• Here