Section 3–5 Geology

(The conditions of air / Mountain-forming processes / Earth’s interior)

Feynman opines that physicists have not worked out a satisfactory theory of meteorology and they have been unable to get a good theory as to how dense a substance should be at the pressures that would be expected at the center of the earth. In this section, the three interesting ideas discussed are the conditions of air, mountain-forming processes, and earth’s interior.

1. The conditions of air:

“… So if we know the condition of air today, why can’t we figure out the condition of the air tomorrow? (Feynman et al., 1963, section 3.5 Geology).”

According to Feynman, one problem of meteorology is that the motion of air is rather complex and the condition of air can be very sensitive as well as unstable. The meaning of unstable condition can be illustrated by two water molecules that are initially beside each other and how they may be widely separated after flowing for some time. In other words, two initial similar conditions may result in two significantly different final conditions even in a smooth flow of water. Furthermore, physicists are unable to predict the size of the lumps of water and exactly how they will continue to flow. Similarly, a smooth flow of air molecules going over a mountain may result in a turbulent flow, complex whirlpools, and eddies.

Some meteorologists might argue that Feynman was pessimistic because he only discusses the “chaos in order” and omits the “order in chaos.” Currently, they agree that a climatic system is deterministic and predictable in principle, but it is unpredictable in practice. That is, meteorologists have a better understanding of chaos theory and are able to develop better weather-prediction models with the help of powerful computers and satellite images. Interestingly, Albert Hibbs, under the supervision of Feynman, completed a Ph.D. thesis titled “The growth of water waves due to the action of the wind” in 1955. Perhaps Feynman would have a different opinion of “butterfly effect”: a tornado could be related to the butterfly diagram of the sun (that is farther away) instead of a butterfly in Brazil (that is nearer)?

Note: Ilya Prigogine is a Belgian scientist that opines that chaos can give rise to order. In his Nobel lecture, Prigogine (1977) explains that “in a town, in a living system, we have a quite different type of functional order. To obtain a thermodynamic theory for this type of structure we have to show that that non-equilibrium may be a source of order. Irreversible processes may lead to a new type of dynamic states of matter which I have called ‘dissipative structures’ (p. 263).” He received a Nobel Prize in Chemistry in 1977 for his research in non-equilibrium thermodynamics, particularly the theory of dissipative structures.

2. Mountain-forming processes:

“…You will find, if you study geology, that there are mountain-forming processes and volcanism, which nobody understands but which is half of geology (Feynman et al., 1963, section 3.5 Geology).”

Feynman suggests that most geological processes are in front of our eyes, for example, the erosion processes of the rivers, directions of winds, and mountain-forming processes. However, he believes that nobody understands mountain-forming processes and volcanism, which is half of geology. In addition, the cause of an earthquake is not well understood. Simply phrased, geologists understand that something is pushing something else, it snaps and will slide, but it is unclear what pushes, and why? Feynman explains circulating currents inside the earth, due to the temperature difference inside and outside, push the surface of the earth slightly. If there are two opposite circulations next to each other, some matter will be collected in the region where they meet and cause belts of mountains which are in stressed conditions, and it may further result in volcanoes and earthquakes.

Geologists may criticize this section of his lecture because Feynman did not specify the theory of continental drift and explain how earthquakes could be caused by movements of plate tectonics. (If you listen to the audio CD of this lecture, Feynman mentions “tectonics” and says that nobody understands tectonics.) Plate tectonics is the unifying theory of geology which provides explanations of geographical phenomena such as earthquakes and volcanoes. This ground-breaking theory (pun unintended) describes how the lithosphere of the Earth is broken into various plates. Roughly speaking, the plates are of the order of 100 kilometers thick and are constantly moving towards, away from, or past each other.”

3. Earth’s interior:

“… What about the inside of the earth? A great deal is known about the speed of earthquake waves through the earth and the density of distribution of the earth (Feynman et al., 1963, section 3.5 Geology).”

Feynman elaborates that geologists have some knowledge of earthquake waves through the earth, but physicists do not have a good theory of density of a substance with respect to the pressures at the center of the earth. Essentially, the mathematics involved is difficult, but someone may realize this is an important problem and it could be solved soon. Another problem is that even if we know the density of the substance in the earth’s interior, it is difficult to figure out the circulating currents (or circulating electric current within the iron core). Geologists generally agree that circulating currents in Earth’s iron core generate changing magnetic fields.

Geophysicists are studying anomalies in the gravitational field which are due to distributions of masses or minerals within the earth. In general, geodynamical processes such as mountain forming and convective motions in the earth have changed the mass distribution within the earth that result in changing gravitational attraction. Current understanding in geophysics is accelerated by inventions of sensitive gravity meters that can measure tiny changes in the earth’s gravitational field. Furthermore, sensitive magnetometers can measure tiny changes in the earth’s magnetic field that may be caused by flowing oil. Thus, it has important implications for oil industries and future economy.

Note: In his Nobel Lecture, Willard Frank Libby (1960) says that “[r]adiocarbon dating had its origin in a study of the possible effects that cosmic rays might have on the earth and in the earth’s atmosphere (p. 593).” Libby was awarded Nobel prize in Chemistry in 1960 for the development of radiocarbon dating method in using carbon-14 for age determination in archaeology, geology, geophysics, and other branches of science. For example, archaeologists can measure the amount of carbon-14 compared to the stable isotope carbon-12 and determine the age of an item. Nevertheless, Feynman could have discussed whether atoms in the earth’s atmosphere are exactly of the same kind as atoms at the center of the earth.

Questions for discussion:

1. Can meteorologists determine the exact conditions of air today such that they can predict the future conditions of air?

2. Do you agree with the theory in which there are currents inside the earth—circulating currents, due to the difference in temperature inside and outside—which, moving towards, away from, or past each other?

3. Do we know much less about earth’s interior than the conditions of matter in the stars?

The moral of the lesson: we cannot predict the future conditions (temperature, pressure, and velocity) of air because of the limitations of meteorological instruments as well as our limited knowledge of current conditions of air.

References:

1. 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.

2. Libby, W. F. (1960). Radiocarbon dating. In Nobel Lectures in Chemistry 1942 – 1962. Singapore: World Scientific.

3. Prigogine, I. (1977). Time, structure, and fluctuations. In Nobel Lectures in Chemistry 1971 – 1980. Singapore: World Scientific.

Section 3–4 Astronomy

(Stars / An astronomer / Nuclear energy)

Feynman states that astronomy got physics started by showing the beautiful simplicity of the motion of the stars and planets. In this section, the three interesting points mentioned are stars, an astronomer, and nuclear energy.

1. Stars:

“What goes on inside a star is better understood than one might guess from the difficulty of having to look at a little dot of light through a telescope… (Feynman et al., 1963, section 3.4 Astronomy).”

According to Feynman, we understand the distribution of matter in the interior of the sun far better than the interior of the earth by just analyzing a small little dot of light through a telescope. This is because atoms emit light which has definite frequencies of light waves, just like the timbre of a musical instrument which has definite frequencies of sound. By using a spectroscope, we can analyze the frequencies of light waves and deduce various atomic compositions that are in different stars. By using statistical mechanics, we can analyze the behavior of the stellar objects under conditions of high temperature and not very high density. Interestingly, the most remarkable discovery in astronomy is that the stars are made of atoms of the same kind as those on the earth.

It is potentially misleading when Feynman mentions that technetium and helium were discovered in stars before they were discovered on earth. Initially, the discovery of technetium was confirmed in a December 1936 experiment at the University of Palermo in Sicily by Carlo Perrier and Emilio Segrè. Next, Paul Merrill in California detected the spectral signature of technetium in 1952 in light waves from S-type red giants (stars). To be precise, Perrier and Segrè discovered artificially produced technetium. Furthermore (or theoretically speaking), there is no natural technetium that has been discovered on earth. (If you listen to the audio CD of this lecture, Feynman only said helium.)

Note: Feynman could have made fun of Auguste Comte, the father of “positive philosophy.” Historically, Comte predicted that we can never know the atomic composition of stars. In The Positive Philosophy, Comte (1896) writes that “[w]e may obtain positive knowledge of their geometrical and mechanical phenomena; but all physical, chemical, physiological, and social researches, for which our powers fit us on our own earth, are out of the question in regards to the planets. Whatever knowledge is obtainable by means of the sense of Sight, we may hope to attain with regard to the stars, whether we at present see the method or not; and whatever knowledge requires the aid of other senses, we must at once exclude from our expectations, in spite of any appearances to the contrary (p. 148).”

2. An astronomer:

“… One of the men who discovered this was out with his girlfriend the night after he realized that nuclear reactions must be going on in the stars in order to make them shine (Feynman et al., 1963, section 3.4 Astronomy).”

In a section titled Feynman the sexist pig in his autobiography, Feynman identifies the astronomer as Eddington. In Feynman’s (1988) words, “[t]he other story they objected to was told by the great astronomer Arthur Eddington, who had just figured out that the stars get their power from burning hydrogen in a nuclear reaction producing helium. He recounted how, on the night after his discovery, he was sitting on a bench with his girlfriend. She said, ‘Look how pretty the stars shine!’ To which he replied, ‘Yes, and right now, I’m the only man in the world who knows how they shine.’ He was describing a kind of wonderful loneliness you have when you make a discovery (p. 72).” However, Feynman was accused of being anti-woman for this part of the lecture. A feminist group claimed that Feynman was saying a woman is unable to understand nuclear reactions.

Feynman mentions that Eddington’s girlfriend was not impressed with the only man who knew why stars shine. Curiously, this might not be true because Eddington was a Quaker, that is, he was a religious person and he was never married. On the other hand, shortly after the 1957 Rochester Conference, Feynman (1997) expresses that “[i]t was the first time, and the only time, in my career that I knew a law of nature that nobody else knew (p. 250).” Note that Feynman was separated from Mary Louise Bell in 1956 (for working calculus problems continuously) and he was married to Gweneth Howarth in 1960. Thus, in a sense, Feynman could be referring to himself instead of Eddington when Feynman says “it is sad to be alone, but that is the way it is in this world.”

Note: In his 1920 presidential address to the British Association for the Advancement of Science, Eddington suggests that the solar energy is due to the conversion of hydrogen atoms to helium by citing Aston's measurement of the mass difference between hydrogen and helium. In an article titled The source of stellar energy, he elaborates that “[i]t has, for example, been objected that the temperature of the stars is not great enough for the transmutation of hydrogen into helium – so ruling out one possible source of energy. But helium exists, and it is not much use for the critic to urge that the stars are not hot enough for its formation unless he is prepared to show us a hotter place (Eddington, 1926, p. 30).”

3. Nuclear energy:

“… It is the nuclear ‘burning’ of hydrogen which supplies the energy of the sun; the hydrogen is converted into helium (Feynman et al., 1963, section 3. 4 Astronomy).”

It is the not simply nuclear “burning” of hydrogen which supplies the energy of the sun. Essentially, there is a continuously making of various chemical elements in the centers of the stars from hydrogen and other atoms. Thus, it is debatable whether Eddington exactly understood how the stars shine. More important, the making of atoms such as C¹², C¹³ or Technetium is a result of nuclear reactions instead of chemical reactions. Interestingly, Feynman elaborates that our elements were “made” in the stars and spit out in the explosions which we call novae and supernovae.

Hans Bethe provides an in-depth explanation of nuclear energy in stars. In 1967, Bethe was awarded Nobel prize in Physics for his contributions to the theory of nuclear reactions, especially his research on the energy production in stars. In short, he conceptualizes the carbon-nitrogen-oxygen (CNO) cycle by which stars convert hydrogen into helium and heavier elements. In general, the CNO cycle may have the following nuclear reactions: ¹²C + H → ¹³N + g ; ¹³N → ¹³C + e⁺ + n ; ¹³C + H → ¹⁴N + g ; ¹⁴N + H → ¹⁵O + g ; ¹⁵O → ¹⁵N + e⁺ + n ; ¹⁵N + H → ¹²C + ⁴He.

Note: In his Nobel Lecture, Bethe (1967) says that “Eddington, in the 1920’s, investigated very thoroughly the interior constitution of the sun and other stars, and was much concerned about the sources of stellar energy. His favorite hypothesis was the complete annihilation of matter, changing nuclei and electrons into radiation (p. 216).” (Feynman was assigned to Bethe’s Theoretical Division in Los Alamos during World War II.) However, according to Jeans (1926), “I find that some of the most fruitful ideas which I have introduced into astronomical physics – e.g., the annihilation of matter as a source of stellar energy, and highly dissociated atoms and free electrons as the substance of the stars – are by now fairly generally attributed to Prof. Eddington (p. 335).”

Questions for discussion:

1. Is it still true that we understand the distribution of matter in the interior of the sun far better than we understand the interior of the earth by looking at a little dot of light through a telescope?

2. Should Eddington be recognized as the first person that has a correct understanding of nuclear reactions that make stars shine?

3. How does the nuclear “burning” of hydrogen supply the energy of the sun?

The moral of the lesson: the stars are made of atoms of the same kind as those on the earth because our elements were initially “made” in the stars and spit out in the explosions which we call novae or supernovae.

References:

1. Bethe, H. A. (1968). Energy production in stars. In Nobel Lectures in Physics 1963-1970. Singapore: World Scientific.

2. Comte, A. (1896). Positive philosophy (Vol. 1). London: Bell.

3. Eddington, A. S. (1926). The source of stellar energy. Nature, 117(2948), 25-32.

4. Feynman, R. P. (1988). What Do You Care What Other People Think? New York: W W Norton.

5. Feynman, R. P. (1997). Surely, you’re Joking, Mr. Feynman. New York: Norton.

6. 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.

7. Jeans, J. H. (1926). Diffuse matter in interstellar space. The Observatory, 49, 333-335.

Section 3–3 Biology

(Nerves / Enzymes of Krebs cycle / DNA molecules)

Feynman mentions that there is an early relationship between physics and biology in which biology helped physics in the discovery of the law of conservation of energy. This section on biology is significantly much longer as compared to other sections such as chemistry and astronomy. It could be explained by Feynman’s participation in biological research during his sabbatical year (1959 – 1960) in California Institute of Technology. It is remarkable that first-year biological students of Caltech did not know who Feynman was, and ranked Feynman as “the best teaching assistant” (Mehra, 1994, p. 441) in explaining biology. In this section, the three main ideas discussed are nerves, enzymes of Krebs cycle, and DNA molecules.

1. Nerves:

“… nerves are very fine tubes with a complex wall which is very thin; through this wall, the cell pumps ions, so that there are positive ions on the outside and negative ions on the inside, like a capacitor (Feynman et al., 1963, section 3.3 Biology).”

According to Feynman, nerves are very fine tubes (like wires) with a very thin wall (or membrane); through this wall, the cell pumps ions (sodium and potassium) to and fro such that they function like a capacitor. Essentially, when the membrane or wall “discharges” in a location, a movement of ions results in a reduction of electric voltage there. Moreover, an electrical influence on the ions in a nerve affects the membrane in which it lets the ions move along the nerve. Next, it causes a wave of “penetrability” of the membrane which runs further down the nerve fiber. This wave is like a sequence of vertical dominoes: if one domino is pushed and falls, it pushes the next and eventually all others fall. Importantly, he clarifies that the dominoes need to be re-set in order to get the nerve ready for the next nerve impulse.

The potential difference between the interior and exterior of a cell changes by about 0.1 V in a nerve impulse. Physicists’ concepts of propagating electrical phenomena in nerves (or action potentials) originate from the model of Alan Hodgkin and Andrew Huxley. They were awarded Nobel Prize in Physiology or Medicine in 1963 for their research concerning the ionic mechanisms in the nerve cell membrane. They propose the change in electrical potential in nerve membranes is due to movements of sodium and potassium ions through individual proteins (or ion channels). In his Nobel Lecture, Huxley (1963) states that a small area of membrane behaves as if it obeyed Ohm’s law. He also explains that the analysis of currents through the membranes was challenging because nerve impulses only last a fraction of a millisecond and they needed to measure the changing electrical potential at different points along the nerve.

Note: Erwin Neher and Bert Sakmann were awarded Nobel Prize in Physiology or Medicine in 1991 for their research on the function of single ion channels in cells. Note that electrical measurements were difficult in membranes since the methods available for measuring electric currents in living cells have high background noise levels. It is worth mentioning that Neher and Sakmann were well trained in physics (or biophysics). Neher studied physics at the Technische Hochschule in Munich. In University of Wisconsin at Madison, he worked in a laboratory involved in low angle X-ray scattering and was conferred a degree in biophysics. On the other hand, Sakmann was trained in cellular biophysics in University College London. His only real interests in school were physics lessons and spent much of his time designing and building model motors and sailing ships as well as remote control planes.

2. Enzymes of Krebs cycle:

“… whole series of molecules which change from one to another in a sequence or cycle of rather small steps. It is called the Krebs cycle, the respiratory cycle (Feynman et al., 1963, section 3.1 Biology).”

The Krebs cycle is a respiratory cycle (or citric acid cycle) that provides the mechanism for energy production in all forms of life. In short, it involves a whole series of molecules that change from one to another in a cycle of small steps. Feynman gives an analogy for a small step of the cycle: one molecule does not just change into another because they are usually separated by an energy barrier or “hill.” To carry an object from one location to another at the same height but on the other side of a hill, it requires the need of additional energy (activation energy) to push it over the top. Alternatively, we can also imagine holding the molecules (enzymes) in our hands and creating a hole in it to let some new atoms to roll in; thus, this way of moving around the hill does not require extra energy and the reaction is still possible.

The most important feature of the Krebs cycle is the transformation from GDP to GTP (guanosine-di-phosphate to guanosine-tri-phosphate) such that energy is stored in GTP molecules. In essence, GTP (“energy currency” molecules) has more energy than GDP and if the cycle is going in one way such that it results in more molecules which have extra energy, it can drive another process which requires energy, e.g., the contraction of muscles. Interestingly, Feynman explains that an enzyme does not care in which direction the reaction (e.g., “GDP to GTP” or “GTP to GDP”) goes because if it did it would violate one of the laws of physics. It is possible that he is referring to the reversible laws of motion instead of the second law of thermodynamics that favor irreversible processes. However, in his lectures on computation, Feynman (1996) also says that “the laws of quantum physics are reversible in time… (p. 185).”

The Krebs cycle is applicable to living beings including animals and plants. Feynman mentions that there is a machinery for absorbing light and generating glucose, which is consumed in the dark to keep plants alive. During a British Broadcasting Corporation interview, Feynman (1994) elaborates that “[p]eople look at trees and they think they come out of the ground, but really trees come out of the air. The carbon dioxide in the air goes into the tree, and it changes it: it kicks out the oxygen, pushing the oxygen away from the carbon, and leaving the carbon substance with water (p. 129).” He also clarifies that sunlight is involved during the process and says that “[i]t’s sort of ‘stored sun’ that’s coming out when you burn the log (p. 130).” In other words, trees also come from the sun and provide ‘light and heat’ when placed in a fireplace.

3. DNA molecules:

“… The DNA molecule is a pair of chains, twisted upon each other. The backbone of each of these chains, which are analogous to the chains of proteins but chemically quite different, is a series of sugar and phosphate groups (Feynman et al., 1963, section 3.3 Biology).”

Feynman explains that the structure of the DNA was studied chemically to find the composition and then with x-rays to find the pattern in space. That is, physics is of great importance in biology because it has to do with experimental techniques. Historically speaking, Francis Crick, James Watson, and Maurice Wilkins were awarded Nobel Prize in Physiology or Medicine in 1962 for their research in the molecular structure of nucleic acids and its significance for information transfer in living material. Coincidentally, Crick and Wilkins also have a strong background in physics. Crick’s unfinished Ph.D. research was on measuring the viscosity of water at high temperatures and Wilkins’s Ph.D. thesis is titled, “Phosphorescence decay laws and electronic processes in solids.” More important, Wilkins was able to achieve a better resolution of x-ray diffraction patterns as compared to those available to Pauling and other researchers.

Feynman calls adenine (A), thymine (T), cytosine (C), and guanine (G), namely, A, B, C, and D instead of A, T, C, and G. In short, he explains that only certain pairs can sit opposite each other, for example, A with B and C with D. In biology, this is known as Chargaff's second parity rule that specifies DNA molecules from any cell of all organisms should have a 1:1 ratio such that the amount of guanine is equal to cytosine and the amount of adenine is equal to thymine. Recently, Mitchell and Bridge (2006) found that this parity rule holds for all types of double-stranded DNA genomes with the exception of the organellar DNA.

Note: During his sabbatical year (1959 – 1960), Feynman made friends with Crick, Watson, and other well-known biologists. In the section, A map of the cat of his autobiography, Feynman (1997) recalls that “Watson thought the stuff I had done with phages was of some interest, so he invited me to go to Harvard. I gave a talk to the biology department about the double mutations which occurred so close together. I told them my guess was that one mutation made a change in the protein, such as changing the pH of an amino acid, while the other mutation made the opposite change on a different amino acid in the same protein, so that it partially balanced the first imitation -- not perfectly, but enough to let the phage operate again. I thought they were two changes in the same protein, which chemically compensated each other. That turned out not to be the case… (p. 75).”

Questions for discussion:

1. How do the nerves function like a capacitor?

2. Is it really true that an enzyme does not care in which direction a reaction goes because if it did it would violate one of the laws of physics?

3. How did physicists help to understand the structure of DNA molecules?

Note: The diffraction pattern due to a series of points equally spaced along a helix can be approximately modeled in terms of the squares of Bessel functions (Wilkins, Stokes, & Wilson, 1953).

The moral of the lesson: the nature of life can be reduced to all things are made of atoms, and that everything that living things do can be understood in terms of the jigglings and wigglings of atoms; physicists have also helped to build the foundations of biology by using equipment such as x-ray machines.

References:

1. Feynman, R. P. (1994). No Ordinary Genius: The Illustrated Richard Feynman. New York: W. W. Norton & Company.

2. Feynman, R. P. (1996). Feynman lectures on computation. Reading, Massachusetts: Addison-Wesley.

3. Feynman, R. P. (1997). Surely, you’re Joking, Mr. Feynman. New York: Norton.

4. 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.

5. Huxley, A. F. (1963). Nobel lecture: The Quantitative Analysis of Excitation and Conduction in Nerve. In Lindsten J. (ed.) Nobel Lectures in Physiology or Medicine, 1963–1970. Singapore: World Scientific.

6. Mehra, J. (1994). The Beat of a Different Drum: The life and science of Richard Feynman. Oxford: Oxford University Press.

7. Mitchell, D., & Bridge, R. (2006). A test of Chargaff’s second rule. Biochemical and biophysical research communications, 340(1), 90-94.

8. Wilkins, M. H. F., Stokes, A. R., & Wilson, H. R. (1953). Molecular structure of nucleic acids: molecular structure of deoxypentose nucleic acids. Nature, 171(4356), 738-740.

Section 3–2 Chemistry

(Theoretical chemistry / Inorganic chemistry / Organic chemistry)

Feynman states that the science which is perhaps the most deeply affected by physics is chemistry. In this section, the three main ideas discussed are theoretical chemistry, inorganic chemistry, and organic chemistry.

1. Theoretical chemistry:

“… All these rules were ultimately explained in principle by quantum mechanics, so that theoretical chemistry is in fact physics (Feynman et al., 1963, section 3.2 Chemistry).”

According to Feynman, the deepest part of theoretical chemistry must end up in quantum mechanics and in short, theoretical chemistry is physics. Furthermore, statistical mechanics, the science of the phenomena of heat or thermodynamics, was developed by both sciences. This branch of physics and chemistry adopts statistical methods in microscopic situations that are also based on mechanical laws. In general, chemical reactions involve a large number of atoms that are all jiggling around in a random and complicated manner. Nevertheless, it is practically impossible to follow in detail the motions of all molecules, and it is beyond the capacity of computers and the human mind to predict the motions of all molecules. The method for dealing with such complicated situations is also known as statistical thermodynamics in chemistry.

In a sense, chemistry is closely related to physics to the extent that Marie Sklodowska Curie was known to be a chemist and physicist for her works in radioactivity. In 1903, she was awarded Nobel Prize in Physics for her research on the radiation phenomena discovered by Henri Becquerel. In 1911, Marie was awarded Nobel Prize in Chemistry for the discovery of the elements radium and polonium, by the isolation of radium and the study of the nature and compounds of radium. In her Nobel Lecture, Curie (1911) mentions that “only 15 years after Becquerel's discovery, we are face to face with a whole world of new phenomena belonging to a field which, despite its close connexion with the fields of physics and chemistry, is particularly well-defined (p. 202).” She also calls this field of science as the chemistry of the imponderable.

2. Inorganic chemistry:

“Inorganic chemistry is, as a science, now reduced essentially to what are called physical chemistry and quantum chemistry … (Feynman et al., 1963, section 3.2 Chemistry).”

Inorganic chemistry can be described as the chemistry of substances which are not associated with living things. For example, it can be related to elements and how they form various relatively simple compounds that are found in rocks and earth. In addition, Feynman explains that inorganic chemistry can be further classified as physical chemistry and quantum chemistry: (1) physical chemistry studies the rates of chemical reactions and their detailed processes; (2) quantum chemistry helps us to understand what happens in terms of the physical laws. To be more precise, quantum chemistry focuses on applying principles of quantum mechanics in physical models and experiments of chemical systems.

It is worth mentioning that Ernest Rutherford was awarded Nobel Prize in Chemistry in 1908 for his work in the disintegration of the elements, and the chemistry of radioactive substances. Interestingly, Rutherford was startled and joked that the sudden “metamorphosis into a chemist” was quite unexpected. However, the Nobel Committees for Physics and Chemistry view that Rutherford’s research is more relevant to chemistry than physics. On the other hand, Walter Kohn was awarded Nobel Prize in Chemistry in 1998 for his work in the development of the density-functional theory. It helps to calculate quantum mechanical electronic structure by equations involving the electronic density instead of the many-body wavefunction. Kohn was conferred a Ph.D. degree in physics by Harvard University in 1948, where was supervised by Schwinger on the three-body scattering problem.

Note: John Pople was awarded Nobel Prize in Chemistry in 1998 for his work in the development of computational methods in quantum chemistry. He was conferred a Ph.D. in mathematics in 1951 for his research on lone pair electrons and considered himself more of a mathematician instead of a chemist. Pople also accepted positions as a professor of chemical physics at Carnegie Institute of Technology and head of the new Basic Physics Division at the National Physical Laboratory.

3. Organic chemistry:

“…The other branch of chemistry is organic chemistry, the chemistry of the substances which are associated with living things (Feynman et al., 1963, section 3.2 Chemistry).”

Organic chemistry is a branch of chemistry that studies the structure, properties, and reactions of organic compounds. Historically, the substances associated with living things were so complicated that scientists believed they could not be made by human beings from inorganic materials. This is not true because organic materials are similar to substances made in inorganic chemistry, but they are usually more complicated arrangements of atoms. In daily lives, organic chemistry has a very close relationship to the biology and industry, and more importantly, physical chemistry and quantum mechanics can be applied to both organic and inorganic compounds. Currently, organic chemistry involves the analysis and synthesis of the substances which are formed in biological systems, and thus, it leads to further branches such as biochemistry and molecular biology.

Recently, William Moerner was awarded Nobel Prize in Chemistry in 2014 for his work in the development of super-resolved fluorescence microscopy. Moerner is sometimes known as a physical chemist or chemical physicist that contributes in imaging of organic molecules and probing biological processes. He was conferred a Ph.D. degree in physics in 1982 for his research on vibrational relaxation dynamics of an IR-laser-excited molecular impurity mode in alkali halide lattices.

Questions for discussion:

1. Do you agree that theoretical chemistry is in fact physics?

2. Can inorganic chemistry be essentially reduced to physical chemistry and quantum chemistry?

3. What are the main differences between organic chemistry and inorganic chemistry?

The moral of the lesson: the fundamental rules of theoretical chemistry are ultimately explained in principle by physics and physicists could be awarded Nobel prizes in Chemistry. In other words, physicists help to build (or shake) the foundations of chemistry.

References:

1. Curie, M. (1911). Radium and the New Concepts in Chemistry. In Nobel Lectures in Chemistry 1901 – 1921. Singapore: World Scientific.

2. 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.

Section 3–1 Introduction

(Natural philosophy / Relation to other sciences / Love)

In this chapter, Feynman states that he would explain the fundamental problems in the other sciences and “how they get along with physics.” However, it is impossible to deal with the complex, subtle, beautiful matters in these other fields in “so small a space.” In this section, the three interesting points mentioned are natural philosophy, relation to other sciences, and love.

(If you listen to the CD of this Feynman’s lecture, he mentions that it is impossible to explain the fundamental problems in the other sciences within “45 minutes.”)

1. Natural philosophy:

“… physics is the present-day equivalent of what used to be called natural philosophy, from which most of our modern sciences arose (Feynman et al., 1963, section 3.1 Introduction).”

Philosophers may not completely agree with Feynman that physics is equivalent to natural philosophy from which most of the modern sciences arose. In Dictionary of Concepts in the Philosophy of Sciences, there are two definitions of natural philosophy: “1. The name for science until well into the nineteen century. 2. The philosophy study of nature, parallel or complementary to both science and the philosophy of science; this usage is older than modern science but persists in certain philosophical circles (Durbin, 1988, p. 201).” Historically speaking, Newton (1687) formulates three laws of motion in Principia: Mathematical Principles of Natural Philosophy. In the conclusion to the Principia, he writes that, “[a]nd thus much concerning God, to discourse of whom from the appearance of things, does certainly belong to Natural Philosophy (Newton, 1687, p. 442).” In other words, Newton’s notion of natural philosophy includes a role of God in physical phenomena.

Note: As another example, Treatise on Natural Philosophy (Thomson & Tait, 1867) is a physics textbook written by Lord Kelvin and Peter Guthrie Tait. In addition, Truesdell (1966) published a book titled, Six Lectures on Modern Natural Philosophy and tried to revive the term Natural Philosophy.

2. Relation to other sciences:

“… Lack of space also prevents our discussing the relation of physics to engineering, industry, society, and war, or even the most remarkable relationship between mathematics and physics (Feynman et al., 1963, section 3.1 Introduction).”

According to Feynman, it is not possible to discuss the relation of physics to engineering, industry, society, war, and even mathematics within 45 minutes in this lecture. He explains that mathematics is not a natural science because the test of its validity is not experiment. Nevertheless, experimental mathematics is a branch of mathematics in which computation is used to investigate mathematical structures and identify their fundamental properties and patterns. Simply phrased, experimental mathematics has been used to make mathematical predictions such that they can be verified by using computational experiments. Importantly, Feynman path integrals can be applied in financial modeling, and thus, it is also worthwhile nowadays to discuss the relation of physics to finance.

Note: If you listen to the CD of this Feynman’s lecture, he mentions that mathematics is perhaps an unnatural science.

3. Love:

“… We must, incidentally, make it clear from the beginning that if a thing is not a science, it is not necessarily bad. For example, love is not a science. (Feynman et al., 1963, section 3.1 Introduction).”

Feynman says that love is not a science, however, there are studies on the science of love. The feeling of love could be analyzed from the perspective of chemical reactions because human beings are essentially “human molecules.” For instance, there are experiments on hormonal changes of human beings that were falling in love (Marazziti & Canale, 2004). The symptoms of love such as sweaty palms, shaky knees, are sometimes explained to be due to a chemical, “phenylethylamine,” which has been named as the “love molecule.” Although Feynman explains earlier that human molecules and everything can be reduced to atoms, he would possibly argue that our knowledge of love molecules, as well as dopamine, and norepinephrine, are still incomplete.

Four years after delivering this lecture, Feynman (1965) suggests that “[i]f it were possible to state exactly, ahead of time, how much love is not enough, and how much love is over-indulgent, then there would be a perfectly legitimate theory against which you could make tests (p. 159).” Simply phrased, it is difficult to precisely quantify the amount of love.

Note: Interested students should read Liebowitz’s (1983) The Chemistry of Love.

Questions for discussion:

1. How is physics equivalent to natural philosophy?

2. Is mathematics an unnatural science?

3. Can love be explained by science?

The moral of the lesson: students of many other fields find themselves studying physics because of the basic role it plays in all phenomena.

References:

1. Durbin, P. T. (1988). Dictionary of Concepts in the Philosophy of Sciences. Westport: Greenwood.

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.

4. Liebowitz, M., R. (1983). The Chemistry of Love. Boston: Little, Brown, & Co.

5. Marazziti, D., & Canale, D. (2004). Hormonal changes when falling in love. Psychoneuroendocrinology, 29(7), 931-936.

6. Newton, I. (1687/1995). The Principia (translated by A. Motte). New York: Prometheus.

7. Thomson, W., & Tait, P. G. (1867). Treatise on Natural Philosophy. Oxford: Oxford University Press.

8. Truesdell, C. (1966). Six Lectures on Modern Natural Philosophy. Springer-Verlag.