We need to use physics to understand the laws that exist deep in nature. This idea cannot be ignored when considering what physics is. The further development of physics has not only expanded its scope, but also developed from mechanics to light, heat, electromagnetism, atoms and molecules, and even chemistry has been included in the scope of physics. There is a tendency to reunify all phenomena and integrate all disciplines. We might as well call it unification theory as opposed to differentiation theory. The famous physicist Rutherford's famous saying: "All science is either physics or stamp collecting." can be regarded as the most concise definition of the general theory of physics.
Such a simple definition is convenient and specific for scientists who actually engage in scientific research. But for the public, it’s a bit confusing. This means that when scientists talk about science, when the general public talks about science, and even when researchers from different disciplines (such as natural sciences and humanities) talk about science, they may have different definitions in mind.
We believe that science generally includes: astronomy, physics, chemistry, biology, medicine, etc. Consistent with the definition of Science in English, it refers to natural science.
Why we don’t include mathematics in the field of science is because mathematics discusses purely formal problems and is not related to any specific phenomena. Of course, if we examine the historical process of the emergence of mathematics, we will think that experience still plays an irreplaceable role, but once mathematics forms a strict system, it has nothing to do with experience, and the various experiences that led to the emergence of mathematics can be seen as promoting the emergence of mathematics. The stairs are useful before going upstairs, but once you have gone upstairs, the stairs become redundant.
If science is defined as natural science, we will find that all natural sciences will form an organic whole based on physics. When we talk about the foundation of science, we will say that quantum mechanics and relativity are the foundation of all science.
Some physicists, such as Feynman, simply believe that only systematic theoretical and quantitative knowledge such as physics can be considered science. Rutherford also expressed a similar view, and his famous quote clearly expressed his view, which is why he was dissatisfied with awarding him the Nobel Prize in Chemistry rather than Physics.
The reason why Rutherford was able to say such extreme things was because at that time, except for physics, the level of quantitative research in other sciences was still very low. For example, biology is mainly at the stage of collecting materials and classifying and describing them. This is indeed similar to stamp collecting. However, after the discovery of the DNA double helix structure, biological and medical research became largely physical. On the one hand, a large number of outstanding physicists have directly devoted themselves to the field of life sciences. On the other hand, life science research has made extensive use of physical principles and techniques, which has suddenly brought biological research from macro narrative science to the molecular level.
Physics is indeed the most expansionary discipline. Today we often look forward to the bright future of life science research. In fact, it is precisely the manifestation of the vitality of the physics discipline. What is really declining in this process is actually It's traditional biology.
Systematization and quantification are trends in scientific research. In this sense, physics is a model for all scientific research, and the birth of science is generally marked by Newton's classical mechanics. After Newton, science was undoubtedly born. Before Newton, it can be seen as the birth and budding period of science.