# Physics

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**Physics**, in its broadest sense, refers to the study of matter, energy, and motion. There are many subdisciplines, often overlapping with other fields, such as physical chemistry. The main goal of many physicists is to discover how the universe was created. In general, the main goal of physics is just to find out how complicated stuff works by figuring out the basic laws that everything in the universe has to obey.
Physics is known as the *exact science* because of high precision and accuracy obtainable in the measurement of physical quantities.
Physics is also the most basic of all sciences due to its role in every field of science such as life science, medicine, technology and industry, and even chemical science.

There is yet another theoretical flaw in the GUT theory, which is called "hierarchy problem." The GUT theory has the curious property that it assumes there is a tremendous gap between two energy scales. The first scale is approximately 10 to the 16 billion electron volts, which is found only at the beginning of time. The other scale is the energy scale of ordinary particle physics, which is measured in mere billions of electron volts. The GUT theory requires a rigid separation between these two energy scales. (Between present-day energies and 10 to the 16 billion electron volts, there is a vast "desert" where no new interactions can be found.) However, this rigid separation, which is vital for the theory, begins to collapse once we start to calculate corrections to the theory given by Feynman diagrams. The only satisfactory way of keeping this hierarchy intact when we begin to add Feynman diagrams is to incorporate four-dimensional supersymmetry into GUT theory (called SUSY GUT theory). The SUSY GUT theory, although it solves the hierarchy problem, is quite clumsy-looking. It is hard to believe that anything so contrived can be fundamental. Furthermore, it says nothing about gravity. From the point of view of a superstring physicist, the problem lies in the that the SUSY GUT theory doesn't go far enough. If the SUSY GUT theory is extended so that it becomes the superstring theory, then once again it becomes elegant and simple. As a bonus, it also solves the problem of incorporating quantum gravity(be205)

Soviet experimental physics did not have a high reputation for accuracy(dft127)

Physics is much more than just mathematics. A physical theory introduces concepts and provides relationships between them. Usually these relationships are mathematical(fp104)

Mirror symmetry amounts to a literal reflection in a mirror of all coordinates of a physical system. Mathematically, it amounts to changing all z-coordinates to -z where z points toward the mirror(gp350)

Part of the reason for the success of the step-by-step approach is that many physical systems are approximately linear in nature. In physics, a linear system is, simply speaking, one in which the whole is equal to the sum of its parts (no more, no less), and in which the sum of a collection of causes produces a corresponding sum of effects(mm44)

There is nothing in the physics of Newton which would require the motion of an oscillating particle to be restricted to certain energies(sm7)

In classical theory, particles are indestructible. In special relativity, they can be converted into pure energy, and vice versa. Hence nuclear power and the atomic bomb. In classical mechanics, particles are primary and waves are secondary. Waves are undulations in some particular substance, like water. In quantum physics, light waves and particles are equally fundamental (W320)

In constructing physics we have emphasized the spatio-temporal aspect of our perceptions, which is the aspect that is most abstract and most nearly akin to logic and mathematics(hk19)

The laws of physics themselves are partly tautologies, but in their most important parts they are hypotheses that are found to explain great numbers of subordinate inductions(hk156)

Whether complete precision is or is not theoretically possible depends on whether the physical world is discrete or continuous(hk164)

The physical world, as it is independently of perception, can be known to have a certain structural similarity to the world of our percepts but cannot be known to have any qualitative similarity. Those facts which consist of space-time structure- are such as we can imagine(hk168)

The present century has somewhat modified the assumptions of physics. First, there is a four-dimensional manifold of events, instead of the two manifolds of space and time; second, causal laws do not suffice to determine individual events, but only statistical distributions; third, change is probably discontinous(hk216)

Modern physics is not reversible(mpd18)

Impact was ultimately, for Leibniz, the only form of dynamical interaction(pl89)

In order to develop the theory of an all-pervading fluid which continues to infinity, Leibniz needed, what in his day did not exist, either Hydrodynamics or the modern Dynamics of the ether(pl90)

I(Quine) do place the claims of physics somewhat above those of set theory, because I see the justification of mathematics only in what it contributes to our integral science of nature(pol86)