A computer processing unit (CPU) is a device able to perform mathematical operations with data stored as electrical voltage. It can only perform simple operations, but so many of them can be done in a second that it is possible to create a program (a defined combination of oper-ations) to perform complex tasks. However, the processing unit of a computer is limited to processing virtual information that is electrically coded inside the computer. This information can be connected to the real world through an interface (a keyboard, a screen, etc.) but the main processing unit is not subject to physical rules like human being is. It is obvious that gravity has no effect on the way a computer performs its task; this also means that the computer has no idea what gravity is.
If you want your computer to move a fader like you do, you have to teach it how to do so. You must also teach your computer how gravity, the fader, and your muscles interact with each other in order to change the position of the fader.
First, we will compare and analyze the way a human moves a single fader (such as a mixer fader) with the simplest way a computer moves a virtual fader. Then we will explore certain physical modeling tools as a solution to teach a computer the basics of physical notions and will give a short overview of the possibilities of such tools. This article is not a complete math-ematical or physical justification of particular physical modeling; rather it introduces basic ideas in order to allow anyone to use these tools.