Three Scientific Revolutions: How They Transformed Our Conceptions of Reality (18 page)

Then in 1827 the French chemist J. B. A. Dumas devised a method for determining the gas densities at much higher temperatures that enabled him to study a much greater variety of substances at that higher temperature which in turn allowed him to reconcile the combining weights data derived from the Petit-Dulong Law with the relative gas densities obtained from Avogadro's hypothesis that equal volumes of gases do not contain equal numbers of particles. Briefly, the reconciliation could be achieved if, in addition to agreeing there were

polyatomic molecules of the elements . . . it would now have to be further conceded that the polyatomic molecules of the different elements contain different numbers of the respective atoms . . . add[ing] the inability to explain why the molecules of different elements contain different numbers of their respective atoms. (p. 312; brackets added)

It took a little more than a quarter of a century before this phase of atomic physics reached a resolution by the Italian chemist Stanislao Cannizzaro. During that time there continued to be new discoveries despite the prevailing skepticism to accepting the truth of the atomic theory, such as the kinetic explanation of gas pressure as due to the mobility of dispersed particles in the gas and new evidence to support Avogadro's theory of polyatomic particles. Accepting Avogadro's law that equal volumes of similar gases contain the same number of particles of which some were polyatomic, Cannizzaro concluded that it should not be assumed that equal volumes of
different
gases contain the same number of basic particles. But if that were true, the weight of the atoms could not be inferred unless it was known how many atoms were contained in the volume, a near impossibility.

Thus he introduced a different procedure that involved weighing the densities of
various
compound gases containing the same element. Knowing the densities per unit volume of a number of compound gases containing that element, the weight of the element could be determined by what fraction of the weight of the compound was due to that element. Beginning with the smallest ratio, he found that in succeeding weightier compounds the ratios of that element were always in whole numbers. He then realized that he could calculate the
relative weights
of the elementary particles by comparing their ratios in the weights of the various compounds.

If the elementary compound contains one atom of that element this would give the atomic weight of that element. Then following Berzelius' convention that established the atomic weight of hydrogen as the standard of 1, the weights of the other elements relative to hydrogen could be assigned: carbon as 12, oxygen as 16, sulfur as 32, and so forth. As these atomic weights agreed with those derived by the method of specific heats used by Petit and Dulong, this provided strong confirmation of the theory of atomic weights. Thus a half century later thanks to the efforts of preceding experimentalists, Cannizzaro proved Dalton's belief in 1808 of “‘the importance and advantage of ascertaining
the relative weights of the ultimate
particles of both simple and compound bodies
'” (pp. 318–19).

About two decades after Cannizzaro's generally accepted determination of the atomic weights, in 1848 his research culminated in the independent publication respectively of the Periodic Law by Julius Lothar Meyer and the Periodic Table by Dmitri Ivanovich Mendeleev. Mendeleev's table was published in Russian in April 1869 and though Meyer's paper containing his Periodic Law was dated December 1869, it was not published in Germany until 1870. In a Faraday Lecture given to the Fellows of the Chemical Society of the Royal Institution in 1889 Mendeleev gave a succinct but comprehensive summary of what had been achieved up to that time and what could be anticipated in the future.

1. The elements, if arranged according to their atomic weights, exhibit an evident
periodicity
of properties.

2. Elements which are similar as regards their chemical properties have atomic weights which are either of nearly the same value (e.g., platinum, iridium, osmium) or which increase regularly (e.g., potassium, rubidium, caesium).

3. The arrangement of the elements, or of groups of elements, in the order of their atomic weights, corresponds to their so-called
valences
[the combining power of an element] as well as, to some extent, to their distinctive chemical properties—as is apparent, among other series, in that of lithium, beryllium, barium, carbon, nitrogen, oxygen, and iron (brackets added).

4. The elements which are the most widely diffused have small atomic weights.

5. The
magnitude
of the atomic weight determines the character of the element, just as the magnitude of the molecule determines the character of a compound.

6. We must expect the discovery of many yet
unknown
elements—for example, elements analogous to aluminum and silicon, whose atomic weight would be between 65 and 75.

7. The atomic weight of an element may sometimes be amended by a knowledge of those of the contiguous elements. Thus, the atomic weight of tellurium must lie between 123 and 126, and cannot be 128.

8. Certain characteristic properties of the elements can be foretold from their atomic weights.
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This enabled Mendeleev in 1895 to present his Periodic Table consisting of two columns, one vertical and the other horizontal. Both columns listed the elements under the headings given by Berzelius, with the vertical column presenting them according to their atomic weights and chemical properties while the horizontal column listed them in increasing numerals according to their atomic numbers as determined by the number of protons in their nucleus, beginning with hydrogen as 1 since it contains 1 proton. As now written, it appears as H but in a water molecule as H
₂
O (with the
subscript
₂
) because it contains two elements of hydrogen.

What a great progress had been made by chemists since Lavoisier's explicit recognition of oxygen as the combustable gas and the resurrection of the ancient atomic theory of Democritus and Leucippus by Dalton culminating in Mendeleev's Periodic Table. We now await the discovery of new elements and their molecular structure in compounds along with the interior structure of the atom.

Chapter VI

TRANSITION TO THE THIRD REALITY IN THE LATE NINETEENTH AND TWENTIETH CENTURIES

We have just seen how long it had taken and how arduous the task was to replace the Aristotelian and religious worldviews (though religionists still do not accept the fact that there is no longer any plausibility to religious explanations) with the early modern scientific corpuscular-mechanistic explanation of the universe and physiological nature of human beings. Starting with Copernicus in the middle of the sixteenth century, it was not until the latter half of the nineteenth and mainly in the twentieth century that this earlier, more preliminary mechanistic conception of reality was replaced by the third major transition, along with the consequent technological advances.

As American physicist Michio Kaku states in his latest book, “the time was right for the emergence of an Einstein. In 1905, the old physical world of Newton was crumbling in light of experiments that clearly suggested a new physics was about to be born, waiting for a genius to show the way.”
⁵⁷
Though a continuation of the earlier scientific discoveries and theoretical advances of the previous three centuries, it brought about a decisively greater understanding of the world and of human beings due to a much more realistic and extensive conception of the physical universe owing to greatly improved telescopic observations and spectroscopic evidence; deeper probing of the interior structure of the atom; the rejection of Newton's deterministic-mechanistic universe of absolute space and time due to the uncertainty principle in quantum mechanics and Einstein's view of space-time as a four-dimensional field in his general theory of relativity; paradoxes such as the wave-particle duality; and the replacement of “intelligent design” and “special creation” of humans with the confirmation of evolution, brain research (eliminating the soul), and the deciphering of the genetic code.

Ernest Rutherford, the father of nuclear physics, “once said that the rapidity of advance during the years 1895–1915 has seldom, if ever, been equaled in the history of science.” Even if true at that time, Rutherford did not live to witness Hubble's astonishing telescopic discoveries and evidence of the inflationary recession of the universe, Georges Lemaître's anticipation of the Big Bang explanation of the origin of the universe, tunneling microscopes, nuclear fission and fusion, nuclear reactors and particle accelerators, computer technology, genetic decoding and engineering, along with the lunar landing and controlled interplanetary space flights. One can truthfully say there were more new advances in science in the twentieth century than in the entire past history of science that emended Newton's deterministic, absolutistic, mechanistic worldview with a much more extensive and complex conception of reality.

As Einstein and Infeld wrote in 1951:

During the second half of the nineteenth century new and revolutionary ideas were introduced into physics; they opened the way to a new philosophical view, differing from the mechanical one. The results of the work of Faraday, Maxwell, and Hertz led to the development of modern physics, to the creation of new concepts, forming a new picture of reality.
⁵⁸

As we have seen, some of the major changes in physics involved the detection of diffraction patterns supporting the wave theory of light to complement Newton's corpuscular theory; the replacement of the independence of electricity and magnetism with the concept of an electromagnetic field and the recognition that light, too, is an electromagnetic phenomenon; Einstein's introduction of a variable four-dimensional space-time field to replace Newton's conception of gravity as a mutually attractive force between objects; the rejection of indivisible solid atoms for a largely space filled atom conceived in terms of an inner solar structure of subatomic particles with electrical charges that determine the atoms' properties and interactions.

This also included the later discovery that whether light reacts as waves or corpuscles depends on the experimental conditions, thus introducing the wave-particle duality of light; the rejection of the ether as a necessary medium for the transmission of light and gravity; the fact that spatial or temporal measurements are not absolute but relative to the velocity of the measurer and its effect on the measuring device; the discovery of quanta of energy and the uncertainty of the measurements and existence of subatomic particles due to the indeterminate nature of their properties until measured; the red-shift in the light waves from outer space indicative of the recession of the light source and of an expanding universe, along with evidence that at least
our universe
began with a big bang about 13.7 billion years ago; string theory to replace all other theories although as yet there is no evidence to support it; and the possibility of a pluralistic universe with different laws of which ours is only a miniscule extension. It seems there is no end to the future discoveries facing science.

While it is said that “the eighteenth century is the century of Newton,” it is equally true that it was in that century that scientists began the critical task of questioning and testing the fundamental concepts of the Newtonian scientific framework, a crucial function of science that accounts for its success and advancement. For unlike the followers of Aristotle (but not Aristotle himself) who claimed that all knowledge could be found in his works, and religionists who still claim that divinely revealed scripture as interpreted by church authorities contains the ultimate, eternal truth and thus scientific knowledge has only an instrumental value, the obvious advances of science and the tremendous changes in our conception and relation to the world that it has brought about belie this. The task now is to describe these later developments as clearly and simply as possible.

Among the first challenges to Newton's system was his conception of the corpuscular theory of light based on his prismatic discovery of the rays of light and the sharp boundaries of shadows. At the time there was considerable controversy over whether light consisted of waves or of corpuscles and whether it had a finite velocity or was propagated instantaneously. Most continental natural philosophers, such as Hooke and Huygens, defended the wave theory. It was Newton and Olaus Roemer who first succeeded calculating the time for light to reach the earth from the sun to be about eight minutes. Hooke had proposed that light is a form of wave motion in a medium that was supported by Huygens in a lengthy article published in 1690 titled
Traité de la lumière où sont expliquées les causes de ce qui arrive dans la réflexion et dans la réfraction. Et particulièrement dans l'étrange réfraction du cristal d'Islande
(Treatise on light explaining the cause of reflection and refraction. And particularly in the strange refraction of Island crystal). But while Huygens's extensive research was extremely influential on the continent, Newton's prestige in the British Commonwealth was such that his corpuscular interpretation of light was dominate there until it was finally contested in the beginning of the nineteenth century.

As we now know, Thomas Young was among the first to challenge the corpuscular theory in a paper entitled “Outlines of Experiments and Inquiries Respecting Sound and Light” published in the
Philosophical Transactions of the Royal Society
in 1800. Impressed by the similarity of light and sound, he favored the theory that light is transmitted by waves. Along with additional criticisms of the corpuscular theory, his major objection was based on experiments showing that light radiated through small apertures produced diffraction patterns, which offered clear evidence of waves. In a paper titled “On the Theory of Light and Colours” in 1802, he described the light and dark bands in the diffraction patterns in terms now known respectively as constructive (in phase) and destructive (out of phase).
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