However, another fundamental question is raised. Now that we know that the mathematical tools used in physics are always consistent, then how can a physical theory be disproved by observation?

The answer lies in the inaccurate assumptions which the structure of the theory is based upon them. Each scientific theory is based upon some generalizable observations that is consistent with the scientific method. But in any case, the observer is to decide whether his particular observations can be generalized to the nature or not. And what ultimately leads him to accept the correctness or discarding of his assumptions is consecutive observations and experiments. In the meantime, each scientific community has a dominant intellectual discipline or worldview which the theories are based upon it. Also, scientist of each field admits specific methods and tools for observation and experimentation and usually reject disparate or contradictory methods. Therefore, what encourages scientists to accept or reject a scientific method can lead to errors in the theory due to human or tool errors. That the development and improvement of observational and laboratory tools, or the evolution of an intellectual discipline or worldview governing a scientific field, can ultimately reveal the errors.

In the new era, experimenting and collecting data have an effect directly on the development of physical findings. More precisely, the predictions made by mathematical modeling of theories in theoretical physics should always be tested in experimental physics labs, and also the data derived from empirical physics experiments can be used to describe a Phenomena or understanding of the unresolved problems of theories. So that physics requires experiments to refer to and to collect data, and theoretical physics finds the validity of theories in line with experiments.

So far, we analyzed the aspects of nature studied in physics, and we found that observation and experimentation are of fundamental importance to physicists. We also mentioned mathematics as a tool of expressing physical findings. The findings that arise as theories or rules and are consecutively validated through experiment. In the following, considering the importance of the quantities in both theoretical and experimental physics, we will study the different types of quantities and properties of each one.