Particles do not directly exert force to each other, instead they indirectly exert force through a Time-Space Function called "FIELD".
There are two or more kinds of force fields we heard frequently. Gravity Force & Gravity Field, Electric Force & Electric Field, Magnetic Force & Magnetic Field....etc! I think I don't need to explain to you what is force. Human being knew Force and defined Force since long long ago. But the idea of Field come out much later than Force. The reason why we need to "Invent" or more accurately saying "Discover" the idea of Field is initially for the convenience of calculation for the energy stored inside the place where it is full filled with Force action such as the Earth ground surface. We all know Newton's gravity force law. If I want to know the gravity force that the Earth exert on me first I have to know my mass, the earth mass and the distance between me and the earth. But not all the time that people have always known the mass especially when one of the object is extremely large such as the Earth. So we want to ask if there is another way to calculate the force between me and the earth but without knowing the mass of the earth? The answer is YES! Once you can measure the magnitude of the gravity force field you can calculate the gravity force that the earth exert on any object that known mass already. Furthermore the Physicist gradually figure out that the earth didn't exert its gravity force on objects such us directly, but through its gravity field first. Also, the gravity field is not constant but dynamically changing depends on the place and time. You will get different values when you measure the gravity field in the same place but in different time even though the difference is very small. This is realted to the movement of mass inside of the earth (lava). You also will get different values when you measure the gravity field in different place but in the same time. That is why we said the FIELD is a time-space function which meant it is changing depends on two factors, Time and Place. The idea of force field is very useful when we want to calculate the force interation between two marcomolecules such as Protein and your developed drug. We called it Molecular Modeling and Docking.
