Models in physics As I said in another question I am just a physics enthusiast so I am sorry for my very poor knowledge. What is meant by models in physics? what is their function and why physicists imply them? 
Are the actual phenomena the exact reproduction in the real world of a physical model?
 A: A model in physics usually means a mathematical description of a system which is used to make testable predictions about its behavior. When writing about physics, some people prefer the term "model" over "theory" because most non-physicists don't know the difference between "theory" in the scientific sense and in its everyday usage. 
All models are approximations to actual behavior, shown to be relevant and useful in prescribed sets of circumstances. "Adding more physics" to a model usually means accounting for more subtle physical effects by including them in the math, in the interests of improving the model's accuracy. 
Sometimes, making a model more accurate a representation of the real world requires it to be fundamentally rewritten, as for example in the case of our understanding of gravity. Newton's original formulation was the first mathematical treatment of gravity and is perfectly useful today in predicting the movements of planets and satellites, but fails when called on to account for the behavior of extremely massive or extremely fast-moving things. Einstein's formulation of gravity encompasses the Newtonian treatment and also gives useful results in these special cases. 
