Section 3–7 How did it get that way?

(Physicist’s language / Changing laws of physics / A glass of wine)

This section provides a brilliant ending to the chapter by combining physics with biology, chemistry, geology, astronomy, and psychology. In this section, the three interesting ideas discussed are a physicist’s language, changing laws of physics, and a glass of wine.

1. Physicist’s language:

“… In order for physics to be useful to other sciences in a theoretical way, other than in the invention of instruments, the science in question must supply to the physicist a description of the object in a physicist’s language (Feynman et al., 1963, section 3.7 How did it get that way?).”

According to Feynman, physics are useful in a theoretical way, other than in the invention of instruments, if a description of the object can be expressed in a physicist’s language. For example, a physicist may not be able to answer the question “why does a frog jump?” unless the frog is well defined or the number of molecules is specified with additional information. In addition, a physical theory is useful when physicists have some knowledge of the locations of the atoms. Similarly, to understand chemistry, we must know exactly what atoms are present such that we can analyze them.

In general, physicists may idealize a frog or a dog as a point object. Thus, they can formulate the motion of the frog or dog by assigning mathematical quantities such as its mass, velocity, or position. Furthermore, during a Messenger Lecture, Feynman elaborates that “physicists delight themselves by using ordinary words for something else (p. 84).” That is, physicists redefine words, such as force, action, heat, energy, and symmetry, in order that they have technical or mathematical meanings.

2. Changing laws of physics:

“…We do not imagine, at the moment, that the laws of physics are somehow changing with time, that they were different in the past than they are at present (Feynman et al., 1963, section 3.7 How did it get that way?).”

Curiously, Feynman mentions that there is no historical question being studied in physics. He elaborates that we do not have a question such as “Here are the laws of physics, how did they get that way?” In other words, physicists do not imagine that the laws of physics are changing with time or how they were different in the past as compared to how they are at present. However, Feynman suggests that if we can understand how the laws of physics are changing with time, it will be wrapped up with the history of the universe, and then physicists will be talking about the same problems with astronomers, geologists, and biologists.

In a sense, Feynman contradicts himself when he later discusses whether Newton’s gravitational law is varying with time in chapter 7 of The Feynman Lectures on Physics. In his own words, “it has been proposed that the gravitational constant is related to the age of the universe. If that were the case, the gravitational constant would change with time, because as the universe got older the ratio of the age of the universe to the time which it takes for light to go across a proton would be gradually increasing. Is it possible that the gravitational constant is changing with time? Of course, the changes would be so small that it is quite difficult to be sure (Feynman et al., 1963, section 7.7 What is gravity?).” Simply put, the gravitational law would change with time if the gravitational constant is observed to be changing with time.

Note: For example, Dirac (1938) writes that “the ratio of the gravitational force to the electric force between electron and proton varying in inverse proportion to the epoch, and since, with our atomic units of time, distance, and mass, the electric force between electron and proton at a constant distance apart is constant, the gravitational force between them must be inversely proportional to the epoch. Thus the gravitational constant will be inversely proportional to the epoch (p. 206).” In other words, one may imagine how the gravitational constant is varying with time in relation to the age of the universe. This is also known as Dirac Large Number hypothesis.

3. A glass of wine:

“…A poet once said, “The whole universe is in a glass of wine.” … But it is true that if we look at a glass of wine closely enough we see the entire universe (Feynman et al., 1963, section 3.7 How did it get that way?).”

A glass of wine can be analyzed from the perspectives of physics, geology, astronomy, chemistry, biology, and psychology.

(1) Physics: the twisting liquid wine which evaporates is dependent on the wind and weather as well as the reflections in the glass.

(2) Geology and Astronomy: the glass is an extraction of the earth’s rocks, and its atomic composition is related to the age of the universe and the evolution of stars.

(3) Chemistry: the chemicals in the wine may be explained by the ferments, the enzymes, the substrates, the products, and chemical processes.

(4) Biology: all life is fermentation and Louis Pasteur published Études sur le Vin that is about the diseases of wine.

(5) Psychology: the consciousness that watches the wine.

Note: it should be easy for Feynman to give another brilliant explanation if the poet says “[t]he whole universe is in a cup of tea.”

Questions for discussion:

1. How does one describe an object using a physicist’s language?

2. Are the laws of physics changing with time?

3. How do we see the entire universe in a glass of wine or a cup of tea?

The moral of the lesson: we may find a glass of wine tastes better if we can divide this glass of wine, this universe, into parts—physics, biology, geology, astronomy, psychology, and so on.

References:

1. Dirac, P. A. (1938). A new basis for cosmology. Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences. 165(921), 199-208.

2. Feynman, R. P. (1965). The character of physical law. Cambridge: MIT Press.

3. Feynman, R. P., Leighton, R. B., & Sands, M. (1963). The Feynman Lectures on Physics, Vol I: Mainly mechanics, radiation, and heat. Reading, MA: Addison-Wesley.