Abstract
In 2016 the LIGO-Virgo collaboration announced “the first direct detection of gravitational waves.” This was to distinguish their result from the indirect observation of Russell Hulse, Joel Weisberg, and Joseph Taylor, which used the decrease in the period of a binary pulsar to “establish, with a high degree of confidence the existence of gravitational radiation as predicted by general relativity.” This raises several interesting questions. One might ask how one can distinguish between direct and indirect observation and whether that distinction is exemplified in the practice of science. One might also ask whether a direct observation has more epistemic weight than an indirect observation. In this essay, I briefly discuss several episodes from the history of modern physics in an attempt to answer those questions. These episodes include Galileo and falling bodies, the discovery of the neutrino, the Higgs boson, and gravitational radiation.
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Source: Galilei, Sidereus Nuncius (ref. 28).

Source: Thomson, “Cathode Rays” (ref. 60), 295.

Source: Thomson, “Cathode Rays” (ref. 60), 296.

Credit: Courtesy of the Cavendish Laboratory.


Source: Thomson, “Cathode Rays” (ref. 60) 304.

Source: Thomson, “Cathode Rays” (ref. 60), 306.

Source: Thomson, “Cathode Rays” (ref. 60), 309.

Source: Sargent, “The Maximum Energy” (ref. 85), 671.

Source: Lawson and Cork, “Radioactive Isotopes of Indium,” (ref. 234). 994.

Source: Sagane et al., “Energy Spectrum” (ref. 234), 558.

Source: Reines et al., “Detection of the Free Antineutrino” (ref. 10), 159.

Source: Reines et al., “Detection of the Free Antineutrino” (ref. 10), 160.


Source: Wu et al., “Experimental Test of Parity Conservation” (ref. 126), 1413.

Source: Wu et al., “Experimental Test of Parity Conservation” (ref. 126), 1414.

Source: Christenson et al., “Evidence for the 2π Decay” (ref. 143), 138.

Source: Christenson et al., “Evidence for the 2π Decay” (ref. 143), 139.

Source: Christenson et al., “Evidence for the 2π Decay” (ref. 143), 139.

Source: Anderson, “The Positive Electron” (ref. 167), 492.

Source: Barnes et al., “Observation of a Hyperon” (ref. 171), 205.

Source: Pevsner et al., “Evidence for a Three-Pion Resonance” (ref. 175), 421.

Source: Pevsner et al., “Evidence for a Three-Pion Resonance” (ref. 175), 422.

Credit: from a talk by Guido Tonelli, LaThuile, March 1, 2011.

Source: CMS, “Observation of a New Boson” (ref. 179), 33.

Source: CMS, “Observation of a New Boson” (ref. 179), 36.

Source: CMS, “Observation of a New Boson” (ref. 179), 35).

Source: CMS, “Observation of a New Boson” (ref. 179), 41.

Source: CMS, “Observation of a New Boson” (ref. 179), 41.

Source: CMS, “Observation of a New Boson” (ref. 179), 42.

Source: CMS, “Observation of a New Boson” (ref. 179), 42.

Source: CERN, “Observation of a New Particle with a Mass of 125 GeV,” http://cms.web.cern.ch/news/observation-new-particle-mass-125-gev (emphasis added).

Source: Weisberg and Taylor, “Gravitational Radiation” (ref. 195), 3.

Source: Weisberg and Taylor, “Gravitational Radiation” (ref. 195), 5.

Source: Abbott et al., “Observation of Gravitational Waves” (ref. 2), 061102-400.

Source: Abbott et al., “Observation of Gravitational Waves” (ref. 200), 061102-2.

Source: Abbott et al., “Observation of Gravitational Waves” (ref. 200), 061102-2.

Source: Abbott et al., “Observation of Gravitational Waves” (ref. 200), 061102-6.
Notes
There are three kinds of neutrinos, those associated with the electron, the muon, and the tau lepton, respectively symbolized ν e , ν μ , and ν τ .
The notation 1H(p,e + ν)2H symbolizes 1H + p → 2H + e + + ν
This is not strictly true. We now know that neutrinos of one type can transform into other types of neutrino during this journey.
Although it was not interpreted in this way, one might speculate whether the measurement of a lower-than-predicted neutrino flux might be considered as evidence for neutrino oscillations. Oscillations had been suggested before the advent of the solar neutrino problem. I suggest that they should not have because the theory of the source, Bahcall’s solar model, was not sufficiently well established at the time. That measurement did, however, encourage the further investigation of neutrino oscillations. My colleague Alysia Marino has remarked that the SNO experiments actually showed only neutrino loss and not neutrino oscillations. Later experiments did, however, show oscillations.
The reliability of sense observations is presumably provided by one’s lifetime of observations that have been proved reliable. Nevertheless, it is known that under certain circumstances; low light, large distance to the object, atmospheric conditions, seeing can be fallible (similarly for hearing). One might recall the old television advertisement, “Is it live or Memorex?” in which the listener cannot distinguish between a live voice or a recording. Although one does not often think it necessary, there are circumstances under which one needs to offer arguments for the credibility of sense observations, just as one does for instrumental observations.
Cooper raises doubt about whether Aristotle actually said this.
The heavier weight would have a larger volume, the radius would be 4.6 times as large, its surface area would be twenty-one times as large, and would offer more air resistance.
This suggests that the experiment might have been performed indoors.
I note that in Millikan’s famous oil-drop experiment, he allowed the drops to fall a short distance and reach terminal velocity, before he started his timing measurements.
One might reasonably regard this as a photographic detection, which certainly requires some argument to establish its credibility.
For a video of Scott’s experiment see https://www.youtube.com/watch?v=KDp1tiUsZw8).
Galileo had described his method for measuring those distances earlier in the Sidereus Nuncias (ref. 28), 40–41.
One might, however, argue that the observation itself demonstrated that the telescope was a reliable instrument. Although some did suggest that the telescope could create specks of light, it is hard to imagine that they would generate a system of spots apparently orbiting Jupiter.
This is an interesting question. Can one separate observation from interpretation?
Thomson did not calculate average values, but they are 0.41 ± 0.07, 0.52 ± 0.06, and 0.87 ± 0.15, for tubes 1, 2, and 3, respectively.
One electron volt is the energy that an electron acquires in passing through a potential difference of one volt.
Fermi later named this particle the neutrino, or little neutral one, to distinguish it from Chadwick’s heavier neutron.
Previously the nucleus was believed to contain only protons and electrons, each of which had spin ½. Thus, the nitrogen nucleus which was composed of fourteen protons and seven electrons would have half-integral spin, but the measured spin was one. Hence the problem. If one added the neutrino as a constituent, the nitrogen nucleus would contain fourteen protons, seven electrons, and seven neutrinos. The spins could then add up to one, and the nucleus would obey Bose statistics.
The Kurie plot graphs √N/f as a function of decay energy, where N is the number of decays with a certain energy and f is a function giving the effect of the Coulomb field of the nucleus on the mission of electrons. It is closely related to the energy spectrum, but had the virtue of being a straight line if the theory was correct.
The veto counter would fire if a charged particle passed through it. This would mean that the event was caused by a charged particle and could not be a neutrino event.
The one-sided probability of a two-standard-deviation effect is 2.5%.
The one-sided probability of a four-standard-deviation effect is 0.0032%.
Fermi’s theory provided an enabling theory for the experiment by showing the expected size of the signal and demonstrating that, in principle at least, the experiment was feasible.
If a particle has angular momentum l then the parity of the wave function is (−1)l.
The θ + decays into two pions and the τ + into three pions.
I was a student in Professor Wu’s nuclear physics course during the spring of 1959.
I use the K 01 − K 02 description rather than the later K 0S and the K 0L description used after the discovery of CP violation. That is the description used in the Christenson et al. paper (ref. 153).
This experiment is sometimes referred to as the Fitch-Cronin experiment, after the two group leaders. They were later awarded the Nobel Prize in physics for this work.
K e3 decay was K → eπν, K μ3 was K → μπν, and K π3 was K → π + π − π 0.
The unusual properties of the K mesons had allowed this calibration.
The empirically-checked Monte Carlo simulation was needed to estimate the background.
Adair and his collaborators had observed far more regeneration than was expected. This result was later shown to be incorrect.
The CPT theorem states that the laws of physics must be invariant under the combination of charge-conjugation, parity, and time reversal operations. A consequence of the CPT theorem was that particles and antiparticles must have the same masses and lifetimes.
It might be reasonable to suggest rather that the CP violation experiment was less direct than the parity violation experiment.
Strangeness is not conserved in the weak interaction.
Protons were distinguished from pions by the observed ionization produced by the particle in the bubble chamber. For tracks with the same momentum the more massive particle, the proton, has a lower velocity. It produces more ionization and darker tracks.
The current statistical criterion for a discovery claim in high energy physics is five standard deviations.
Although (as discussed below) both experimental groups claimed the discovery of a boson, they did not claim that it was the Higgs boson. Most physicists accepted that it was the Higgs boson. For convenience, that is how I shall refer to the particle.
The initial papers of both CMS and ATLAS were based on all of the 7 TeV data and 5 fb−1 of the 8 TeV data. Later papers used the entire 20 fb−1 8 TeV data set.
A jet is a narrow cone of hadrons (strongly interacting particles) and other particles produced by a combination of quarks and gluons, the constituents of elementary particles. Because quarks are confined within particles they cannot exist in free form. Therefore, they fragment into hadrons before they can be directly detected, thereby becoming jets.
This was a local signal, obtained by looking at the data only in the signal region. A global signal uses a larger energy range. In some cases, the latter range might be the energy range shown in their mass plot, but other choices for the range might be used.
An example might help. Suppose you have one hundred boxes and one of them contains a prize. If you pick a single box the probability of winning the prize is 1/100. If you examine thirty boxes your chance of winning the prize is approximately 30/100 (actually 26%). This is the look-elsewhere effect.
A five-standard-deviation effect has a probability of 2.7 × 10−7.
Table 2 showed the expected number of events for different selection criteria for the Higgs signal and the background.
₢ is the difference in the self-gravitational binding energy per unit mass of the two stars.
A slightly different method of estimating background gave a significance of 4.4σ.
In high energy physics, the inclusion of “Observation of” in the title of a paper requires that the observed effect have a statistical significance of at least five standard deviations. “Evidence for” indicates a significance of less than five standard deviations.
The 2017 Nobel Prize in Physics was awarded to Rainer Weiss, Kip Thorne, and Barry Barish of the LIGO Collaboration. The citation was “for decisive contributions to the LIGO detector and the observation of gravitational waves.” It was not for the discovery of gravitational waves.
References
B. R. Abbott, R. Abbott, et al., “Observation of Gravitational Waves from a Binary Black Hole Merger,” Physical Review Letters 116 (2016), 061102-1–16. In this case, the LIGO collaboration is applying the 5 σ criterion for an observation. In high energy physics, this is a requirement for the use of “observation,” which is synonymous with “discovery.”
Russell Hulse and Joseph Taylor, “Discovery of a Pulsar in a Binary System,” The Astrophysical Journal 195 (1975), L51–L53.
Joel Weisberg and Joseph Taylor, “Gravitational Radiation from an Orbiting Pulsar,” General Relativity and Gravitation 13 (1981), 1–6.
Ibid., 1.
Harry Collins, Gravity’s Kiss (Cambridge, MA: MIT Press, 2017).
Bas van Fraassen, The Scientific Image (Oxford: Clarendon Press, 1981), 13–19; Wilfrid Sellars, Science, Perception, and Reality (New York: Humanities Press, 1962), 97.
Dudley Shapere, “The Concept of Observation in Science and Philosophy,” Philosophy of Science 49 (1982), 485–525.
Ibid., 492.
Raymond Davis, Jr., Don S. Harmer, and Kenneth C. Hoffman, “Search for Neutrinos from the Sun,” Physical Review Letters 20 (1968), 1205–9.
C. L. Cowan, Jr., F. Reines, F. B. Harrison, H. W. Kruse, and A. D. McGuire, “Detection of the Free Neutrino: A Confirmation,” Science 124 (1956), 103–4; F. Reines, C. L. Cowan, Jr., F. B. Harrison, A. D. McGuire, and H. W. Kruse, “Detection of the Free Antineutrino,” Physical Review 117 (1960), 159–73.
Arthuer Eddington, Stars and Atoms (New Haven, CT: Yale University Press, 1927), 102.
Nobelprize.org, “The Nobel Prize in Physics, 2002,” accessed July 10, 2017, https://www.nobelprize.org/nobel_prizes/physics/laureates/2002/.
Shapere, “Direct Observation” (ref. 7), 485.
T. Weekes, High-Energy Astrophysics (London: Chapman and Hall, 1969), 161; D. Clayton, Principles of Stellar Evolution and Nucleosynthesis (New York: McGraw-Hill, 1968), 388.
John Bahcall, “Solar Neutrinos I. Theoretical,” Physical Review Letters 12 (1964), 300–302.
Lane Cooper, Aristotle, Galileo, and the Tower of Pisa (Port Washington, NY: Kennikat Press, 1935).
Vivian, quoted ibid., 26.
Ibid., 44–45.
Galileo, Two New Sciences, trans. Stillman Drake (Madison: University of Wisconsin Press, 1974).
Cooper, Aristotle (ref. 16), 68.
Ibid., 66.
Galileo did discuss falling bodies several times in his earlier work. For example, in his 1590 treatise De Motu, he states that at the beginning of its fall a wooden body falls more quickly than a lead body. “If the large amount of air in wood made it go quicker, then as long as it is in the air the wood will move ever more quickly. But experience [or experiment] shows the contrary; for, it is true, in the beginning of its motion the wood is carried more rapidly than the lead; but a little later the motion of the lead Is so accelerated that it leaves the wood behind; and if they are let go from a high tower, precedes it by a long space; and I have often made a test of this.” Quoted in Cooper (ref. 16), 55. This was written at approximately the time Viviani said that Galileo performed the experiment at the Leaning Tower. The experiments also gave very different results from these reported by Galileo in The Discorsi and those stated by Viviani. See also, Stefano Salvia, “From Archimedean Hydrostatics to Post-Aristotelian Mechanics: Galileo’s Early Manuscripts De motu antiquiora (ca. 1590),” Physics in Perspective 19 (2017), 105–50.
Cooper, Aristotle (ref. 16), 79.
Ibid.
Ibid., 29.
Ibid., 31.
Barry Casper, “Galileo and the Fall of Aristole: A Case of Historical Injustice?,” American Journal of Physics 45 (1977), 325–30, on 326.
Galileo Galilei, Sidereus Nuncius, or The Sidereal Messenger, trans. Albert Van Helden (Chicago: University of Chicago Press, 2016), 39–40. All quotes from the Sidereus Nuncias are from this edition.
Letter from Galileo, January 7, 1610, in Stillman Drake, “Galileo’s First Telescopic Observations,” Journal for the History of Astronomy 7 (1976), 153–68, on 158.
Galilei, Sidereus Nuncias (ref. 28), 40.
Letter from Galileo, January 7, 1610, quoted in Drake, 1976 (ref. 29), 155.
Galilei, Sidereus Nuncias (ref. 28), 66.
Ibid., 67.
Ibid., 67–68.
Ibid., 68, emphasis added.
Ibid., 68–69, emphasis added. Note the use of the word “planet” rather than “wandering star.”
Ibid., 85–85.
Ibid., 86. Kepler published his first two laws of planetary motion, 1) the planets move in elliptical orbits with the sun at one focus, and 2) the line joining the planet to the sun sweeps out equal areas in equal times, in his Astronomia Nova in 1609. His third law stating that the ratio of the cube of the radius of the planetary orbit to the square of its period was a constant for all planets (R 3/T 2 = constant) did not appear until his Harmonice Mundi (1619). Galileo might very well have turned this argument around and used the Copernican system to support his observations. At this time, however, I suspect that the Copernican system was not sufficiently well established to be used this way.
Ibid., 86–87.
Galilei, Sidereus Nuncius (ref. 28), 90–91.
Galileo, letter quoted in ibid., 94.
Ibid., 96.
Ibid., 107.
R. C. Stauffer, “Speculation and Experiment in the Background of Ørsted’s Discovery of Electromagnetism,” Isis 48 (1957), 33–50, on 43.
Ibid., 35–36.
Ibid., 40.
Hans Christian Ørsted, “Observations on Magnetism,” in Selected Scientific Works of Hans Christian Øersted, ed. K. Jelved, A. D. Jackson, et al. (Princeton: Princeton University Press, 1998), 379.
H. C. Ørsted, “Observations on Electro-Magnetism,” in Jelved et al. (ref. 47), 430–45, on 432.
H. C. Ørsted, “Experiments on the Effect of the Electric Conflict on the Magnetic Needle,” in Jelved et al. (ref. 47), 413–16.
A. D. Wilson, “Introduction,” in Jelved et al. (ref. 47), xv–xl, on xviii.
Ibid., xix.
R. C. Stauffer, “Persistent Errors Regarding Oersted’s Discovery of Electromagnetism,” Isis 44 (1953), 307–10, on 308; H. C. Ørsted, “Experiments on the Effect of a Current of Electricity on the Magnetic Needle,” in Jelved et al. (ref. 47), 417–20, on 417. In an introduction to a German translation of Ørsted’s Latin paper, Ludwig Wilhelm Gilbert, editor of Annalen der Physik remarked, “What every search and effort had not produced came to Professor Oersted in Copenhagen by an accident during his lectures on electricity and magnetism this past winter.” Quoted in Stauffer, “Persistent Errors” (ref. 52). Ørsted disputed Gilbert’s account. In discussing his lecture he stated, “All my auditors are witnesses that I mentioned the result of the experiment beforehand. The discovery, therefore, was not made by accident, as Professor Gilbert has concluded from the expressions which I made use of in my first announcement.” Ørsted, “Observations on Electro-Magnetism” (ref. 48), 431. This myth persists: “But like many other important discoveries in science, Oersted’s discovery was just a lucky accident (http://www.ck12.org/Physical-Science/Discovery-of-Electromagnetism-in-Physical-Science/lesson/Discovery-of-Electromagnetism-MS-PS/). Even the American Physical Society news states, “Some people have suggested that this was a totally accidental discovery, but accounts differ on whether the demonstration was designed to look for a connection between electricity and magnetism, or was intended to demonstrate something else entirely” (https://www.aps.org/publications/apsnews/200807/physicshistory.cfm/).
Ørsted, “Effect of a Current of Electricity” (ref. 52), 417.
Ibid., 418.
Ørsted, “Effect of the Electric Conflict” (ref. 49), 415.
Ørsted, “Effect of a Current of Electricity” (ref. 52), 419.
Ørsted, “Effect of the Electric Conflict” (ref. 49), 413.
Ørsted, “Effect of a Current of Electricity” (ref. 52), 418.
Ibid.
Joseph John Thomson, “Cathode Rays,” Philosophical Magazine 44 (1897), 293–316.
Ibid., 293–94.
Ibid., 294.
Ibid., 294–95, emphasis added.
Ibid., 296–97.
Ibid., 300–301. The radius of curvature for a charged particle moving in a magnetic field is directly proportional to its momentum and inversely proportional to its charge. Thomson drew no conclusions concerning the mass, velocity, or charge of the cathode rays until after he had determined the mass-to-charge ratio of the rays.
Ibid., 302.
Ibid.
Ibid., 304.
Ibid., 305.
Ibid., 308.
Ibid., 310.
Ibid., 311–312.
Wilfrid Sellars, Science, Perception, and Reality (New York: Humanities Press, 1962), 97.
Charles Ellis and William Wooster, “The Average Energy of Disintegration of Radium E,” Proceedings of the Royal Society (London) A117 (1927), 109–23; Allan Franklin, “Physics Textbooks Don’t Always Tell the Truth,” Physics in Perspective 18 (2016), 3–57.
Ernest Rutherford, “The Scattering of α and β Particles by Matter and the Structure of the Atom,” Philosophical Magazine 21 (1911), 669–88.
Niels Bohr, “Faraday Lecture: Chemistry and the Quantum Theory of Atomic Constitution,” Journal of the Chemical Society 135 (1932), 349–84, on 379.
Ibid.
Ibid., 380.
Ibid. There was a similar problem for the nucleus of 6Li, which was supposed to be composed of six protons and three electrons, but had a spin of one.
Wolfgang Pauli, letter to colleagues, December 14, 1930, reprinted in Abraham Pais, Inward Bound (New York: Oxford University Press, 1986), 315.
James Chadwick, “The Existence of a Neutron,” Proceedings of the Royal Society (London) A136 (1932), 692–708.
Werner Heisenberg, “Uber den Bau der Atomkerne. I,” Zeitschrift für Physik 77 (1932), 1–11; “Uber den Bau der Atomkerne. II,” Zeitschrift für Physik 78 (1932), 156–64; “Uber den Bau der Atomkerne. III,” Zeitschrift für Physik 80 (1932), 587–96.
Enrico Fermi, “Attempt at a Theory of b-Rays,” Il Nuovo Cimento 11 (1934), 1–21; “Versuch einer Theorie der b-Strahlen,” Zeitschrift für Physik 88 (1934), 161–177.
G. Beck, and K. Sitte, “Zur theorie der beta-Zerfalls,” Zeitschrift für Physik 86 (1933), 105–19. Fermi’s theory was not the first quantitative theory of β decay. Beck and Sitte had proposed a theory in which β decay resulted from the creation of an electron-positron pair. The positron was absorbed in the nucleus and the electron emitted, or vice-versa for positron decay. This theory did not conserve energy. It was rejected because it gave an incorrect prediction for the shape of the β-decay energy spectrum.
B. W. Sargent, “The Maximum Energy of the β-Rays from Uranium X and Other Bodies,” Proceedings of the Royal Society (London) A139 (1933), 659–73; “Energy Distribution Curves of the Disintegration Electrons,” Proceedings of the Cambridge Philosophical Society 24 (1932), 538–53.
Sargent, “The Maximum Energy” (ref. 85), 671. Fermi initially considered only “allowed” transitions, those for which the electron and neutrino wave functions could be considered constant over nuclear dimensions. He recognized that “forbidden” transitions would also exist. The decay rate for such transitions would be greatly reduced and the shape of the energy spectrum would differ from that of allowed transitions.
Emil Konopinski, “Beta-Decay,” Reviews of Modern Physics 15 (1943), 209–45. The actual history is far more complex and interesting. Emil Konopinski and George Uhlenbeck almost immediately proposed a competing theory which, for a time, seemed to fit the existing experimental results better than Fermi’s theory. This resulted from a combination of incorrect experimental results and an incorrect experiment-theory comparison. When these problems were corrected the fit to Fermi’s theory was far superior. As Emil Konopinski remarked, “Thus, the evidence of the spectra, which has previously comprised the sole support for the K-U theory, now definitely fails to support it.” Konopinski, “Beta-Decay” (ref. 87), 218.
Niels Bohr, “Conservation Laws in Quantum Theory,” Nature 138 (1936), 25–26, on 26.
George Gamow, Structure of Atomic Nuclei and Nuclear Transformations (Oxford: Clarendon Press, 1937), 132.
E. C. Anderson, “The Reines-Cowan Experiments: Detecting the Poltergeist,” Los Alamos Science 25 (1997), 4–31, http://www.fas.org/sgp/othergov/doe/lanl/pubs/00326606.pdf.
J. S. Allen, The Neutrino (Princeton: Princeton University Press, 1958), 51.
F. Reines, “Neutrinos to 1960—Personal Recollections,” Journal de Physique 43, suppl. C8 (1982), 237–60, on 238–39.
Hans Bethe and Robert. Bacher, “Nuclear Physics,” Reviews of Modern Physics 8 (1936), 82–229, on 188.
H. R. Crane, “The Energy and Momentum Relations in the Beta-Decay and the Search for the Neutrino,” Reviews of Modern Physics 20 (1948), 278–95, on 278.
F. Reines, “The Neutrino: From Poltergeist to Particle,” NobelPrize.org, accessed July 11, 2017, http://www.nobelprize.org/nobel_prizes/physics/laureates/1995/reines-lecture.html, on 203, emphasis added.
Enrico Fermi, Nuclear Physics: A Course Given by Enrico Fermi at the University of Chicago, ed. Jay Orear, A. H. Rosenfed, and R. A. Shulder, rev. ed. (Chicago: University of Chicago Press, 1949).
Robert Leighton, Principles of Modern Physics (New York: McGraw-Hill, 1959), 532. In a footnote on page 532, Leighton references the 1953 Reines-Cowan experiment and states that they “report a probable positive result.” This experiment is discussed below.
Fermi, Nuclear Physics (ref. 96), 85.
F. Reines et al., “Detection of the Free Antineutrino” (ref. 10).
A. L. Leipunski, “Determination of the Energy Distribution of Recoil Atoms During β-Decay and the Existence of the Neutrino,” Proceedings of the Cambridge Philosophical Society 32 (1936), 301–3. Leipunski had investigated the existence of the neutrino earlier by looking at the energy spectrum of recoil nuclei produced in the decay of 11C. He found that the energy of the recoil atoms is considerably greater than would have been expected without neutrinos. Leipunski concluded quite cautiously, “Since both the curves which are to be compared, the energy distribution curve of the positrons from 11C and the distribution curve of the recoil atoms, have not been determined accurately enough, the only conclusion that may be drawn is that these results are in favor of the emission of neutrinos during β decay” (p. 303).
Crane, “The Energy and Momentum Relations” (ref. 94), 293–94. The first operating pile, or nuclear reactor, had been constructed in Chicago during World War II by Enrico Fermi and others as part of the effort to build the atomic bomb. A nuclear reactor used the same nuclear fission process as did the atomic bomb, but under controlled conditions and much more slowly. It produced the same radioactive fission products, which in turn produced antineutrinos.
C. L. Cowan, Jr., F. Reines, F. B. Harrison, E. C. Anderson, and F. N. Hayes, “Large Liquid Scintillation Detectors,” Physical Review 90 (1953), 493–94.
Cowan, Jr., et al., “Detection of the Free Neutrino: A Confirmation” (ref. 10).
Reines et al., “Detection of the Free Antineutrino” (ref. 10).
Cowan et al., “Large Liquid Scintillation Detectors” (ref. 102); Reines et al., “Detection of the Free Antineutrino” (ref. 10).
Reines et al., “Detection of the Free Neutrino” (ref. 10), 159.
Ibid., 159.
Ibid., 159–60.
Ibid., 163.
Ibid., 164.
Ibid., 170.
Ibid., 171.
Ibid., 171.
Ibid., 172.
F. Reines, “Fifty Years of Neutrino Physics: Early Experiments,” in Neutrino Physics and Astrophysics, ed. E. Fiorini (New York: Plenum Press (1982), 11–28.
Reines et al., “Detection of the Free Antineutrino” (ref. 10), 172.
Otto Laporte, “Die Struktur des Eisenspektrums,” Zeitschrift für Physik 23 (1924), 133–75.
Eugene Wigner, “Einige Folgerungen aus der Schrodingerschen Theorie fur die Termstrukturen,” Zeitschrift für Physik 43 (1927), 624–52.
Hans Frauenfelder and Ernest Henley, Nuclear and Particle Physics (Reading, MA: W. A. Benjamin, 1975), 359.
Tsung-Dao Lee and Chen-Ning Yang, “Question of Parity Nonconservation in Weak Interactions,” Physical Review 104 (1956), 254–58, on 254.
T. D. Lee, History of Weak Interactions (New York: Columbia University, 1971), 10. In the 1950s, physicists were confronted by several elementary particles that behaved in unusual ways. They were produced copiously by the strong interactions, but decayed slowly into pions and nucleons by the weak interactions. This was explained by Gell-Mann, and by Nakano and Nishijima (ref. 122). They introduced a property of these elementary particles, which they called strangeness, which was conserved in the strong interactions but not in weak interactions.
Murray Gell-Mann, “Some Remarks on the V-Particles,” Physical Review 92 (1953), 833–34; T. Nakano and K. Nishijima, “Charge Independence for V Particles,” Progress in Theoretical Physics 10 (1953), 581–82; and K. Nishijima, “Charge Independence Theory of V Particles,” Progress in Theoretical Physics 13 (1955), 285–304.
Lee and Yang, “Question of Parity Nonconservation” (ref. 120), 254.
Richard Garwin, Leon Lederman, and Marcel Weinrich, “Observation of the Failure of Conservation of Parity and Charge Conjugation in Meson Decays: The Magnetic Moment of the Free Muon,” Physical Review 105 (1957), 1415–17; Jerome Friedman and Valentine Telegdi, “Nuclear Emulsion Evidence for Parity Nonconservation in the Decay Chain π + - μ + - e +,” Physical Review 105 (1957), 1681–82. Two other experiments, on the sequential decays π → μ → e, were performed by Friedman and Telegdi, “Nuclear Emulsion Evidence” (ref. 124), and by Garwin et al., “Observation of the Failure” (ref. 124). They were an essential part of the evidence that demonstrated parity nonconservation, but will not be discussed here.
Lee and Yang, “Question of Parity Nonconservation” (ref. 120), 255.
C. S. Wu, E. Ambler, R. W. Hayward, D. D. Hoppes, and R. P. Hudson, “Experimental Test of Parity Conservation in Beta Decay,” Physical Review 105 (1957), 1413–15.
Ibid., 1413.
Ibid., 1414.
Ibid., 1413.
Ibid., 1414.
Ibid.
Friedman and Telegdi, “Nuclear Emulsion Evidence” (ref. 124); Garwin et al., “Observation of the Failure” (ref. 124). The effects seen by Friedman and Telegdi had a statistical significance of four standard deviations, those of Wu et al. were thirteen standard deviations, and those of Garwin et al. were twenty-two standard deviations. As my former student, Mark Corske, remarked, “Four standard deviations is strong evidence, thirteen standard deviations is absolute truth, and twenty two standards deviations is the word of God.”
David Halliday, Introductory Nuclear Physics (New York: John Wiley and Sons, 1955), 38.
W. S. C. Williams, An Introduction to Elementary Particles (New York: Academic Press. 1961), 239. Williams does not mention the experiment of Friedman and Telegdi, perhaps an indication that he did not regard it as being as convincing as the other two experiments.
Leonard Schiff, Quantum Mechanics, 2nd ed. (New York: McGraw Hill, 1955), 160.
Leonard Schiff, Quantum Mechanics, 3rd ed. (New York: McGraw Hill, 1968), 254.
Wolfgang Pauli, “Die Allgemeinen Prinzipen der Wellenmechanik” Handbuch der Physik 24 (1933), 83–272.
Ibid., 226.
Jeremy Bernstein, A Comprehensible World (New York: Random House, 1967), 59.
Ibid., 60.
Norman Ramsey, private communication with the author. Ramsey gave me a copy of a letter he sent to Feynman. The story also appears in Frauenfelder and Henley, Nuclear and Particle Physics (ref. 119), 389.
T. D. Lee, private communication with the author, 1985.
James Christenson, James Cronin, et al., “Evidence for the 2π Decay of the K 02 Meson,” Physical Review Letters 13 (1964), 138–40.
G. D. Rochester and C. C. Butler, “Evidence for the Existence of New Unstable Elementary Particles,” Nature 160 (1947), 855–57. Rochester and Butler found V particles, so named because their decays looked like V’s in a cloud chamber. These were later found to be both K mesons and hyperons (spin ½ particles with mass greater than that of the proton).
Gell-Mann, “Some Remarks” (ref. 122); Nakano and Nishijima, “Charge Independence” (ref. 122); Nishijima, “Charge Independence Theory” (ref. 122).
Murray Gell-Mann and Abraham Pais, “Behavior of Neutral Particles under Charge Conjugation,” Physical Review 97 (1955), 1387–89.
Lev Landau, “On the Conservation Laws for Weak Interactions,” Nuclear Physics 3 (1957), 127–31.
Christenson et al., “Evidence for the 2π Decay” (ref. 143).
Ibid., 138. No mention was made of either CP violation of investigating the anomalous regeneration of K 01 mesons from hydrogen, two additional goals that were mentioned in their proposal.
Ibid.
Ibid.
Ibid.
Ibid., 139.
A. Alavi-Harati et al., “Observation of Direct CP violation in K S,L → ππ Decays,” Physical Review Letters 83 (1999), 22–27. This 1999 KTeV experiment found a net yield of 2,607,274 examples of K 0 L decay into two charged pions. Things have improved considerably.
Christenson et al., “Evidence for the 2π Decay” (ref. 143), 140. A group headed by Adair had recently reported anomalously high regeneration of K 01 mesons in hydrogen.
Ibid.
Ibid.
Ibid.
Ibid., 138.
J. W. Cronin, V. L. Fitch, and R. Turlay, private communication.
T. Truong, “Possibility of CP Violation in ΔI = 3/2 Decay of the K 0 Meson,” Physical Review Letters 13 (1964), 358–61, on 358; Robert Sachs, “CP Violation in K 0 Decay,” Physical Review Letters 13 (1964), 286–88, on 286.
Jeremy Bernstein, N. Cabibbo, and T. D. Lee, “CP Invariance and the 2π Decay of the K 02 ,” Physics Letters 12 (1964), 146–48.
John Bell and J. Perring, “2π Decay of the K 02 Meson,” Physics Review Letters 13 (1964), 348–49; K. Nishijima and M. J. Saffouri, “CP Invariance and the Shadow Universe,” Physical Review Letters 14: (1965), 205–7; A. Everett, “Evidence on the Existence of Shadow Pions in K+ Decay,” Physical Review Letters 14 (1965), 615–16; A. Callahan and D. Cline, “Charged Kπ 2 Branching Ratio,” Physical Review Letters 15 (1965), 125–30.
Peter Galison, Image and Logic (Chicago: University of Chicago Press, 1997). These two traditions have now merged into a hybrid tradition, which one might call electronic or digital imaging. An example of this is the CMS (Compact Muon Solenoid) detector discussed below.
Ibid., 22–23.
Kent Staley, “Golden Events and Statistics: What’s Wrong with Galison’s Image/Logic Distinction?,” Perspectives on Science 7 (1999), 196–230.
Carl Anderson, “The Positive Electron,” Physical Review 43 (1933), 491–94. One might regard this episode as a golden “golden” event. Staley has some reservations concerning this. He points out that Anderson’s 1933 paper not only included photographs of four events but also stated that “out of a group of 1300 photographs of cosmic-ray tracks 15 of these show positive particles penetrating the lead, none of which can be ascribed to particles with a mass as large as that of a proton, thus establishing the existence of positive particles of unit charge and of mass small compared with that of the proton” (p. 493).
Staley, “Golden Events” (ref. 166), 215. Anderson named the particle the positron
Anderson, “The Positive Electron” (ref. 167), 491.
Ibid. Although the first option is possible, it is extremely unlikely. Anderson’s earlier identification of the track as a single light particle was the other possibility.
Victor Barnes et al., “Observation of a Hyperon with Strangeness Minus Three,” Physical Review Letters 12 (1964), 204–6, on 204.
Ibid., 204–5.
Ibid., 205.
Ibid., 206.
Aihud Pevsner et al., “Evidence for a Three-Pion Resonance Near 550 Mev,” Physical Review Letters 7 (1961), 421–23.
B. C. Maglić, L. W. Alvarez, A. H. Rosenfeld, and M. L. Stevenson, “Evidence for a T = 0 Three-Pion Resonance,” Physical Review Letters 7 (1961), 178–82.
Pevsner, “Evidence for a Three-Pion Resonance” (ref. 175), 421. These two terms were used interchangeably by particle physicists.
Ibid., 422. A more accurate procedure would have been to estimate the number of ω 0 particles present and subtract it from the total number of events. This would have reduced the background in the η region. One may speculate that the experimenters were being conservative.
CMS Collaboration, “Observation of a New Boson at a Mass of 125 GeV with the CMS Experiment at the LHC,” Physics Letters B 716 (2012), 30–61; ATLAS Collaboration, “Observation of a New Particle in the Search for the Standard Model Higgs Boson with the ATLAS Detector at the LHC,” Physics Letters B 716 (2012), 1–29.
Allan Franklin, Selectivity and Discord (Pittsburgh: University of Pittsburgh Press, 2002), esp. ch. 6.
CMS, “Observation of a New Boson” (ref. 179), 31.
Ibid.
Ibid., 32.
Ibid., 33.
Ibid.
Ibid., 34.
Ibid., 34–35.
Ibid., 36.
Ibid.
Ibid., 43, emphasis added.
CMS Experiment, “Observation of a New Particle with a Mass of 125 GeV,” July 4, 2012, accessed July 11, 2017, http://cms.web.cern.ch/news/observation-new-particle-mass-125-gev, emphasis added.
Russell Hulse and Joseph Taylor, “Discovery of a Pulsar in a Binary System,” The Astrophysical Journal 195 (1975), L51–L53.
Russell Hulse and Joseph Taylor, “A High-Sensitivity Pulsar Survey,” Astrophysical Journal 191 (1974), L59–L61.
Ibid., L51. The importance of this discovery is shown by the award of the 1993 Nobel Prize in Physics to Hulse and Taylor “for the discovery of a new type of pulsar, a discovery that has opened up new possibilities for the study of gravitation.” Nobelprize.org, “The Nobel Prize in Physics 1993,” accessed July 11, 2017, https://www.nobelprize.org/nobel_prizes/physics/laureates/1993/.
Joel Weisberg and Joseph Taylor, “Gravitational Radiation from an Orbiting Pulsar,” General Relativity and Gravitation 13 (1981), 1–6, on 1–2, emphasis added.
Ibid., 2–3.
P. Peters and J. Mathews, “Gravitational Radiation from Point Masses in a Keplerian Orbit,” Physical Review 131 (1963), 435–40.
Weisberg and Taylor, “Gravitational Radiation” (ref. 195), 4.
Ibid., 5.
B. P. Abbott et al., “Observation of Gravitational Waves from a Binary Black Hole Merger,” Physical Review Letters 116 (2016), 061102-1–16.
Ibid., 0611102-1, emphasis added.
Ibid., 0611102-1.
Ibid., 0611102-3–4.
Ibid., 0611102-2.
Ibid., 0611102-5–6.
Ibid., 0611102-7.
Ibid., 0611102-5.
Ibid., 0611102-8.
Harry Collins, Gravity’s Ghost and Big Dog (Chicago: University of Chicago Press, 2013), 242.
Ibid., 190. This discussion was far more extensive, complex, and interesting than the brief account I have given. It has been documented and discussed in detail in Collins, Gravity’s Ghost (ref. 209), chs. 8–12.
Ibid., 254.
Ibid., 264. With apologies to Jacqueline Susann, once may be enough.
Blas Cabrera, “First Results from a Superconductive Detector,” Physical Review Letters 48 (1982), 1378–81.
Collins, Gravity’s Ghost (ref. 209), 198.
Ibid., 198–99.
Ibid., 199.
Ibid., 284.
Harry Collins, Gravity’s Kiss (Cambridge, MA: MIT Press, 2017), 101.
BICEP2 Collaboration, “Detection of B-Mode Polarization at Degree Angular Scales by BICEP2,” Physical Review Letters 112 (2014), 241101-1–25.
Michael J. Mortonson, Uroš Seljak, “A Joint Analysis of Planck and BICEP2 B Modes Including Dust Polarization Uncertainty,” arXiv, May 22, 2014, https://arxiv.org/abs/1405.5857.
Collins, Gravity’s Ghost (ref. 209), 118–19
Nobelprize.org, “Press Release: The Nobel Prize in Physics 1993,” accessed July 11, 2017, http://www.nobelprize.org/nobel_prizes/physics/laureates/1993/press.html, emphasis added.
Collins. Gravity’s Ghost (ref. 209), 147–48.
Ibid., 147. A similar view was expressed to me by Peter Saulson, a former spokesperson for LIGO, in a private conversation.
Ibid., 154–55.
Ibid., 155.
Ibid., 156.
Abbott et al., “Observation of Gravitational Waves” (ref. 200), 061102-8.
Anderson, “The Reines-Cowan Experiments” (ref. 90).
Reines, “Neutrinos to 1960” (ref. 92), 238–39. Reines made this comment after his experimental detection of the neutrino in 1960.
Crane, “Energy and Momentum Relations” (ref. 94), 278.
Reines, “The Neutrino” (ref. 95), 203.
Lee and Yang, “Question of Parity Nonconservation” (ref. 120), 255.
J. Lawson and J. M. Cork, “The Radioactive Isotopes of Indium,” Physical Review 57 (1940), 982–41; Ryokichi Sagane, William L. Gardner, and Harmon W. Hubbard, “Energy Spectrum of the Electrons from μ + Meson Decay,” Physical Review 82 (1951), 557–58.
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Allan Franklin is Professor of Physics Emeritus at the University of Colorado. He has worked on the history and philosophy of physics, particularly on the roles of experiment.
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Franklin, A.D. Is Seeing Believing?: Observation in Physics. Phys. Perspect. 19, 321–423 (2017). https://doi.org/10.1007/s00016-017-0210-y
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DOI: https://doi.org/10.1007/s00016-017-0210-y
Keywords
- experiment
- observation
- Galileo
- neutrino
- Higgs boson
- gravitational radiation
