Classical mechanics was Isaac Newton’s 1687 vision of the world: indestructible matter conducted the forceful energy exchanges propelling the ‘great mechanical machine’ of the universe. Definitively disassembled for inspection and precisely observed, measured and weighed with certainty, scientists would be capable of determining the future and remote past just as certainly. Nothing- in principle- would be unknown to science down to the last indestructible atom. (1)
But while the idea of an ‘atom’ as a fundamental and indivisible ‘pellet’ of matter can be traced back as far as Leucippos in the 5th century B.C.E.(2), growing 19th century experimental evidence and theories of ethereal ‘forces’ and ‘waves’ were gradually prying this supposedly indivisible ‘pellet of matter’ open for scientific inspection.
And in doing so, the elegant structure of classical physics would also begin to unravel at the seams.
Prior to the 19th century even sound and light waves were thought to be mechanical waves of particles (3), But Newton’s idea of light-wave ‘corpuscles’ was challenged by physicist Thomas Young’s early 1800’s double-slit experiment that established, to the dismay of particle theorists, that a beam of light directed through two slits in a barrier produced interference patterns that were splayed across a target on the other side, clearly demonstrating light-wave interference. Light must be waves and not streams of particles.
Along a parallel scientific path another concept of electric and magnetic forces was steadily developing toward convergence with this idea.
Hans Christian Oersted’s philosophy that all forces are integrated produced his 1820 discovery of electromagnetism, the idea of electrical forces generating magnetism, and this in turn led to André Marie Ampére’s finding that these magnetic forces also acted inversely upon electrical forces, generating his 1820 Amprére’s law.
Building upon this in 1830 Michael Faraday discovered that magnetism also produces electricity, and he created the idea of ‘electromagnetic induction’: Faraday’s Law’. (4) And to avoid the possibility that Newton’s gravitational force- action at a distance- would distort his explanations of electro-magnetic forces, in 1846 Faraday suggested [the analogy] that his ‘fields’ were homogenous lines of force’ in space producing light during rapid oscillations. But his theory of electromagnetic fields now needed the refinements of James Clerk Maxwell’s mathematical genius. (Newton, R. p.139)
In 1860 Maxwell enhanced the the conceptsof Faraday and Amprére (that included numerical ratios for calculating the speed of light) and developed his theory of electromagnetic light-radiation. Physics was about to take off in a very big way*. (5)
The mysteries of light, electricity and magnetism were now all rolled up into one theory: electrical fields generate magnetic fields which generate electrical fields perpetually, Maxwell revealed two very rapidly oscillating and self-propagating fields forming continuous waves of light radiations spreading out into space at the first mathematically calculated speed of light.
From the lower frequencies of invisible radio, micro and infrared through the visible frequency spectrum- red, orange, yellow, green, blue, indigo and violet, and up into the higher frequencies of ultraviolet, X-rays and gamma rays, the scientific picture of the world had been irrevocably divided into two contradictory pictures. One of ‘continuous’ wave-radiations and the other of ‘discontinuous’ units of matter- particles.
Electromagnetic radiation was to become the major focus of 19th century physics along with the physical systems of thermodynamics—but the two were destined to collide.
In 1831 Belgian mathematician Adolphe Quetelet was the first to create the new statistical-method that was used by Maxwell and again in 1877 by Ludwig Boltzmann, a pioneerof quantum mechanics. Boltzmann was an adherent of the atomic theory of particle systems (6). He analyzed thermodynamics founder Rudolf Clausius’s concept of entropy and established the statistical nature of the second law of thermodynamics, producing the [two-way] thermodynamic arrow of time asserting Newton’s laws functioned both ways. This is the Second Law of Thermodynamics that is the probabilities of a many-particles-system. (7) (8)
When the constituents of microscopic systems such as Boltzmann’s are used to develop an understanding of macroscopic systems, statistical ‘averaging’ and ‘probabilities’ play a crucial role because any ‘system’ containing trillions of molecules or atoms simply cannot be tracked: uncertainty and statistical probability were entering the scientific picture in the late19th century.
This wasn’t classical causal determinism- this was a statistical proposition of probabilities: trillions of unobservable, randomly and relentlessly flowing atoms generating ‘hot to cold systems’ of gasses producing the disorder of entropy in macroscopic systems (this appearance of ‘disorder’ is actually the lack of causal knowledge that is impossible for us to gain).
Physics was no longer a science of ‘hands-on’ certainty that is described so well with Newton’s mechanics- and in 1900 classical mechanics stalled.
By1900 experimental results in Berlin demonstrated that the Wien’s and Rayleigh-Jeans laws had both profoundly failed when using classical arguments to calculate the thermal energies carried by Maxwell’s electromagnetic spectrum. The laws broke down at the shorter frequency of ultraviolet-waves, where physicists were unable to accurately calculate any further- producing only ‘infinite’, and useless, energy statements. (9)
This is known as the ‘ultraviolet catastrophe’(Kakalios, J. 2009, p. 15)
During that period even the idea of Maxwell’s abstract radiant energy was thoroughly new to 19th century physicists, who were accustomed to the physical ‘units’ of classical mechanical systems (such as Boltzmann’s). And physicists had no idea what a ‘unit’ of radiant energy might even be until the fall of 1900 when Max Planck created his quantum energy unit; the ‘quanta’ of the ‘Planck Constant’. Specifically, Planck proposed the Quantum theory of radiation (10) when he assumed that the minimum energy a wave can carry is always proportional to its frequency; a proportion he stated as E = hv. And this proposition of a ‘finite’ energy unit, or quanta, solved their problems of infinite calculations. (Damour, T., 2009, p. 212)
Atomic physics also made its fundamental début during the late 19th century. In 1897 mysterious ‘rays’ were discovered in the cathode ray tubes of Wilhelm Rontögne while he was experimenting with mineral fluorescence and putting them to imaginative use he produced the world’s first X-ray image- of his wife’s hand. And in England experimenting with his own cathode ray tubes in 1897 J.J. Thomson discovered that the cathode rays themselves could be magnetically deflected: they were tiny charged ‘corpuscles’ that emitted spectral lines— Thomson had discovered electrons. (Oxford University p.24; Newton, R. p. 213)
And Rontögne’s X-rays had also led an inspired Henry Becquerel, who also studied mineral fluorescence, to his discovery of a bizarre emanation from crystal mineral containing uranium. This emanation was neither Rontögne’s x-rays nor something from the field of mineral fluorescence, and he christened this mysterious property ’Les rayons uraniques’ (11).
This was a new field of physics that appealed to an eager young experimental researcher looking to make a name for herself, and along with her physicist husband Pierre,Marie Curie would do just that by adding two new elements to the ‘periodic table of elements’ and creating the concept of atomic radioactive decay.
Currie disagreed with Becquerel’s ’Les rayons uraniques’ as he named them (indicating he thought uranium was the sole source of this new riddle) and after two years of laborious efforts and experimentation the Currie’s were able to extract, isolate and add the two new elements of polonium and radium to the ‘periodic table of elements’, the latter of which gave rise to Marie Currie’s profoundly new theory of radioactivity.
“Radioactivity is an atomic property” she wrote in December of 1898 (Lindley, D. p. 38), and that phenomenon was firmly beyond the reach of 19th century physics. Radioactivity was a spontaneous atomic emanation of random probability; something unknown within a mysterious and puzzlingly deep atomic structure was again defying classical notions of ‘cause and effect’.
“Spontaneity: that was the strange, crucial factor, and a distinctly awkward one it was for scientists inculcated in nineteenth-century traditions… Where was the scientifically essential idea that if something happens, it happens for a reason, because some prior event made it happen? Radioactivity, as far as anyone could tell in 1900, was uncaused, and therefore scientifically uncalled for.” (David Lindley p. 38)
The last piece of surprising experimental information extracted from the atom in the 19th century came in 1898 via a student of J.J. Thomson’s, Ernest Rutherford who built upon the work of the Curries to reveal two distinct types of rays in uranium radiation. The ‘beta particle’, that was soon identified as a fast moving electron and a mysterious alpha particle’; both of which fit Currie’s description: atomic emissions of random probability that occurred for no apparent reason- spontaneity.
The atom’s microscopic depths would yield up secrets only in bits and pieces that science could only understand with the same statistical methods of Ludwig Boltzmann’s second law of thermodynamics, and for the same basic reason:
“If we wanted to know why the …particle was emitted at that particular time we would have to know the microscopic structure of the whole world including ourselves, and that is impossible.” (Werner Heisenberg p.88)
By the turn of the 20th century scientists had penetrated the depths of the physical world far beyond our sensory mediums of perception. And because of this, the measurable and predictable physical forms which were the foundations of Newton’s physics were gone, and physicists found themselves in a vortex of ethereal electromagnetic waves and mystery radioactivity that all converged in the hidden depths of a still unknown—and just as enigmatic- atomic structure.
Yet armed with the 19th century’s gifts of the Universal Planck constant and statistical-mechanics, Albert Einstein would cut the Gordian knot in 1905 and launch quantum physics, while around 1916 Ernest Rutherford and Niels Bohr would experimentally and theoretically launch Nuclear and Atomic physics; all toward the future establishment of quantum mechanics in 1927.
* “From a long view of the history of mankind – seen from, say, ten thousand years from now – there can be little doubt that the most significant event of the 19th century will be judged as Maxwell’s discovery of the laws of electrodynamics.” Nobel Laureate Richard Feynman
References:
(1) Damour, Thibault (2009), Once upon Einstein, trans. by Eric Novak A.K. Peters Ltd., Wellesley, Massachusetts,
(2) Greene, Brian (1999), The Elegant Universe, W.W. Norton & Company, New York, NY.
(3) Heisenberg, W. (1958), Physics and Philosophy, ‘The revolution in modern science’, Prometheus Books, New York, NY (1999)
(4) Kakalios, James (2010), The amazing story of quantum mechanics, Gotham Books, New York, NY.
(5) Lindley, David (2007), Uncertainty; Einstein, Heisenberg, Bohr, and the struggle for the soul of science, Doubleday, New York, NY
(6) Motz, L., Weaver, J.H. (1989), The Story of Physics, Plenum Press, New York and London.
(7) Newton, R. G. (2007), ‘from Clockwork to Crapshoot- a History of Physics’, The Belknap Press of Harvard University Press, Cambridge, MA.
(8) Oxford University Press, ed. Heilbron, J. (2005), The Oxford guide to the History of Physics and Astronomy, Oxford University Press, Oxford, NY.
(9) Wilczek, Frank (2008), The Lightness of Being, N.Y., New York, Perseus Books Group.
Endnotes:
(1) “This vision of scientific omniscience, in which every particle in the universe must follow strict and rational laws, is captured in the famous words of the Marquis de Laplace, one of the leading eighteenth century developers of Newtonianism at its mathematically splendid best:
‘We may regard the present state of the universe as the effect of its past and the cause of its future. An intellect which at any given moment knew all of the forces that animate nature and the mutual positions of the beings that compose it, if this intellect were vast enough to submit the data to analysis, could condense into a single formula the movement of the greatest bodies of the universe and that of the lightest atom; for such an intellect nothing could be uncertain and the future just like the past would be present before its eyes.’” (David Lindley, 2007, p.22)
(2) “First proposed in the fifth century B.C.E. by Leucippos, subsequently adumbrated by Democritus, and later independently reinvented by the Hindus, the notion that the world is made up of unchanging and indestructible atoms had been resurfacing in science for well over two thousand years.” (Roger Newton, 2007, p. 121)
(3) As strange as the idea may seem today even sound waves were once thought to be ‘streams of particles’ until the English physicist John William Strutt brought the field of acoustics to its theoretical completion in the late 1870’s: sound was also found to be a ‘wave’ and not a particle. (Roger Newton, 2007)
“Acoustics, the science of sound, falls at the intersection of several fields, including… thermodynamics, and electromagnetism.” (John Heilbron, 2005)
(4) ‘Electromagnetic induction’ was actually discovered first in the United States by a future Princeton Professor of Natural Philosophy Joseph Henry, but Englishman Faraday published first a year after Henry’s discovery and thus it is ‘’Faraday’s law”.
(5) “… the precise mathematical expressions for Ampére’s and Faraday’s laws both contained within them as a numerical factor the ratio of the different units of electric charge employed in electrostatic and electrodynamic measurements, such as dealing with moving charges in currents, The two German physicists Wilhelm Eduard Weber… and Rudolph Herrmann /Arndt Kohlrausch… discovered in 1855 that the ratio of these units was equal to the speed of light, though they apparently did not regard their discovery as especially significant.” (Roger Newton, 2007, p. 139)
(6) “Boltzmann’s entire work was dedicated to the atomic theory of matter, and he regarded the kinetic theory as an essential part of atomism. At the end of the nineteenth century, however, a few prominent scientists—Ernst Mach and Friedrich Ostwald among them—accepted the kinetic theory but not the atomic constitution of matter. The disagreement centered on the ‘real’ existence of indestructible particles, too tiny ever to be observed. Opponents based the kinetic theory on abstract ‘centers of energy’ and saw no need for atoms or molecules…” (Roger Newton p. 182)
(7) Uncertainty and statistical probability were entering the scientific picture in the mid-19th century.
“‘Probability’ comes into the picture because statistical descriptions are not ‘certain knowledge’ and this disruption of 19th century physics [as ‘definitive knowledge’] was glaringly apparent in the (notorious) second law of thermodynamics regarding the recently coined word ‘entropy’; heat flows only in one direction from hot-to-cold striving for a maximum state of uniformity.
But ‘heat’ is nothing more than the motion of atoms; the more energetic ones colliding with the slower ones reciprocally slowing and speeding one another into an average state of maximized entropy- in the eyes of 19th century physicists that is, who still even in 1896, were debating whether or not atoms even existed.
Boltzmann’s 1877 theorem statistically demonstrated this idea of ‘one-way entropy’ but it was paradoxical to Henri Poincare’s subsequent theorem. Boltzmann’s theorem (contrary to Newton’s ‘timeless’ mechanics) is ‘unidirectional in time’ while Poincare’s says that ‘all’ possible arrangements of atoms must occur (sooner or later) in time which unequivocally declares ‘entropy’ must increase AND decrease- the ‘uncertainty’ of ‘probability’.” (David Lindley, 2007)
(8) Although he wasn’t the first to use the ‘statistical method’ Josiah Willard Gibbs was an American physicist who created (and coined the term) ‘Statistical Mechanics’ beginning with two 1873 thermodynamic papers and then his 1901 book ‘Elementary Principles in Statistical Mechanics Developed with Special Reference to the Rational Foundations of Thermodynamics’. (Roger Newton, 2007, p. 180)
(9) “The dawn of the twentieth century saw the birth of a new era in physical science… The story started with heat radiation, a subject physicists thought they understood and had just brought under control… The German physicist Wilhelm Wien (1864-1928) had been able to show that the most intense radiation was emitted at a wavelength that was inversely proportional to the temperature; this was known as Wien’s displacement law. However, no one had succeeded in justifying this law on the basis of Maxwell’s theory combined with thermodynamics, a glaring failure of basic physical theory…” (Roger Newton, 2007, p. 210-211)
(10) “… the quantum theory of radiation arose because classical physics, as contained in Newton’s laws of motion,in thermodynamics, and in Maxwell’s electromagnetic theory of radiation, cannot correctly describe ‘black-body’ radiation, that is, the continuous spectrum of the energy emitted per second from a 1-cm² hole in the wall of a furnace at a given absolute temperature. This spectrum had been studied experimentally for some years before Planck obtained its correct algebraic formula…” (Lloyd Motz & Jefferson Weaver, 1989 p. 204
“James Clerk Maxwell’s equations described electromagnetic radiation in general, and entropy fixed the equilibrium state. To obtain a theory that agreed with the rapidly improving measurements (the energy distribution of cavity radiation had the practical interest of serving as a universal standard for the efficiency of electric light bulbs), Planck turned to the definition of entropy that Ludwig Boltzmann had employed to describe the behavior of a gas. To bring the definition to bear, Planck calculated as if the sum of the energies of the resonators associated with a given frequency ‘f’ consisted of a very large number of very small elements ‘hf’. (The resonators were fictional oscillators that coupled matter to the radiation field.) The key step in the derivation for Planck was thus an ‘extension’ of the concepts of the mechanical world picture to radiation, not a ‘limitation’ on resonator energy.” (Oxford University Press, 2005, p. 253)
(11) In 1896 Wilhelm Röntgen produced world’s first ‘x-ray image’ through an accidental discovery and it was quickly established that ‘x-rays’ were an electromagnetic radiation shorter in wavelength than visible light and ultraviolet. Also in 1896 Henry Becquerel followed a hunch and serendipitously discovered radioactivity after seeing x-ray images at the French Academy of Sciences in Paris in early 1896. Becquerel was a third generation (Parisian) physicist; they all graduated from École Polytechnique, were all members of Académie Française, all occupants of the chair of physics at the Musée d’Histoire Narurelle. AND they ALL studied ‘fluorescence’, the phenomenon by which certain minerals, after exposure to strong sunlight, are then seen to emit a faint luminosity of their own: Becquerel found something that was neither ‘x-rays’ nor conventional ‘fluorescence’; something new, ’Les rayons uraniques’ he named them. (David Lindley, 2007, pp. 33, 34, 35) (Roger Newton, 2007, p. 214-215)
