Good example of simulation of solar system formation - testing theories and models

Scientists use advanced computer simulations to test theories. For anyone who has done even basic programming, mathematical equations can be put into code and the computer does the calculations. For simulations, this takes the equations from some theory or mathematical model and runs them to see what happens in one tiny amount of time, called a time step. For something like a solar system, where everything is moving and things like the gravitational force, acceleration, speeds, energy, momentum, radius from other objects, and so on, are all changing constantly, by advancing an object through some small time then allows the computer to re-calculate all of those quantities through another small time interval, readjusts where everything is, and then re-computes the next advancement of all quantities, over and over and over again. This is why fast computers are needed for simulations with multiple objects moving around and interacting with each other, such as through gravity.

In the end, astronomers can use the relevant mathematics like Newton's laws of gravity and motion, and even corrections coming from Einstein's general theory of relativity, to create a simulation for the creation and evolution of our solar system over billions of years of simulated time. This is a computer experiment that produces results from a theory, that can then be compared directly to the present structure and behavior of the actual solar system. If there is agreement, of course we then have good confidence that the theory is valid and providing some understanding for how Nature works.