The 100 Most Influential Scientists of All Time (25 page)

But Thomson's consistency in his worldview enabled him to apply a few basic ideas to a number of areas of study. He brought together disparate areas of physics—heat, thermodynamics, mechanics, hydrodynamics, magnetism,
and electricity—and thus played a principal role in the great and final synthesis of 19th-century science, which viewed all physical change as energy-related phenomena. Thomson was also the first to suggest that there were mathematical analogies between kinds of energy.

Thomson's scientific work was guided by the conviction that the various theories dealing with matter and energy were converging toward one great, unified theory. He pursued the goal of a unified theory even though he doubted that it was attainable in his lifetime or ever. By the middle of the 19th century it had been shown that magnetism and electricity, electromagnetism, and light were related, and Thomson had shown by mathematical analogy that there was a relationship between hydrodynamic phenomena and an electric current flowing through wires. James Prescott Joule also claimed that there was a relationship between mechanical motion and heat, and his idea became the basis for the science of thermodynamics.

By 1851 Thomson was able to give public recognition to Joule's theory, along with a cautious endorsement in a major mathematical treatise, “On the Dynamical Theory of Heat.” Thomson's essay contained his version of the second law of thermodynamics, which was a major step toward the unification of scientific theories.

Thomson's involvement in a controversy over the feasibility of laying a transatlantic cable changed the course of his professional work. His work on the project began in 1854 when he was asked for a theoretical explanation of the apparent delay in an electric current passing through a
long cable. In his reply, Thomson referred to his early paper “On the Uniform Motion of Heat in Homogeneous Solid Bodies, and its Connexion with the Mathematical Theory of Electricity” (1842). Thomson's idea about the mathematical analogy between heat flow and electric current worked well in his analysis of the problem of sending telegraph messages through the planned 3,000-mile (4,800-kilometre) cable. His equations describing the flow of heat through a solid wire proved applicable to questions about the velocity of a current in a cable.

The Atlantic Telegraph Company's chief electrician E.O.W. Whitehouse claimed that practical experience refuted Thomson's theoretical findings, and for a time Whitehouse's view prevailed with the directors of the company. Despite their disagreement, Thomson participated, as chief consultant, in the hazardous early cable-laying expeditions. In 1858 Thomson patented his telegraph receiver, called a mirror galvanometer, for use on the Atlantic cable.

Thomson's interests in science included not only electricity, magnetism, thermodynamics, and hydrodynamics but also geophysical questions about tides, the shape of the Earth, atmospheric electricity, thermal studies of the ground, the Earth's rotation, and geomagnetism. He also entered the controversy over Charles Darwin's theory of evolution. Thomson opposed Darwin, remaining “on the side of the angels.”

Thomson challenged the views on geologic and biological change of the early uniformitarians, including Darwin, who claimed that the Earth and its life had evolved over an incalculable number of years, during which the
forces of nature always operated as at present. On the basis of thermodynamic theory and Fourier's studies, Thomson estimated in 1862 that more than one million years ago the Sun's heat and the temperature of the Earth must have been considerably greater and that these conditions had produced violent storms and floods and an entirely different type of vegetation. Thomson's speculations as to the age of the Earth and the Sun were inaccurate, but he did succeed in pressing his contention that biological and geologic theory had to conform to the well-established theories of physics.

Thomson's interest in the sea, roused aboard his yacht, the
Lalla Rookh
, resulted in a number of patents: a compass that was adopted by the British Admiralty; a form of analog computer for measuring tides in a harbour and for calculating tide tables for any hour, past or future; and sounding equipment. He established a company to manufacture these items and a number of electrical measuring devices. He also published a textbook,
Treatise on Natural Philosophy
(1867), a work on physics coauthored with Scottish mathematician and physicist Peter Guthrie Tait that helped shape the thinking of a generation of physicists.

(b. April 5, 1827, Upton, Essex, Eng.—d. Feb. 10, 1912, Walmer, Kent)

B
ritish surgeon and medical scientist Joseph Lister was the founder of antiseptic medicine and a pioneer in preventive medicine. While his method, based on the use of antiseptics, is no longer employed, his principle—that bacteria must never gain entry to an operation wound—remains the basis of surgery to this day. He was made a baronet in 1883 and raised to the peerage in 1897.

Lister was the second son of Joseph Jackson Lister and his wife, Isabella Harris, members of the Society of Friends, or Quakers. J.J. Lister, a wine merchant and amateur physicist and microscopist, was elected a fellow of the Royal Society for his discovery that led to the modern achromatic (non-colour-distorting) microscope. While both parents took an active part in Lister's education, his father instructing him in natural history and the use of the microscope, Lister received his formal schooling in two Quaker institutions, which laid far more emphasis upon natural history and science than did other schools. He became interested in comparative anatomy, and, before his 16th birthday, he had decided upon a surgical career.

After taking an arts course at University College, London, he enrolled in the faculty of medical science in October 1848. A brilliant student, he was graduated a bachelor of medicine with honours in 1852; in the same year he became a fellow of the Royal College of Surgeons and house surgeon at University College Hospital. A visit to Edinburgh in the fall of 1853 led to Lister's appointment as assistant to James Syme, the greatest surgical teacher of his day, and in October 1856 he was appointed surgeon to the Edinburgh Royal Infirmary. In April he had married Syme's eldest daughter. Lister, a deeply religious man, joined the Scottish Episcopal Church. The marriage, although childless, was a happy one, his wife entering fully into Lister's professional life.

When three years later the Regius Professorship of Surgery at Glasgow University fell vacant, Lister was elected from seven applicants. In August 1861 he was appointed surgeon to the Glasgow Royal Infirmary, where he was in charge of wards in the new surgical block. The managers hoped that hospital disease (now known as operative sepsis—infection
of the blood by disease-producing microorganisms) would be greatly decreased in their new building. The hope proved vain, however. Lister reported that, in his Male Accident Ward, between 45 and 50 percent of his amputation cases died from sepsis between 1861 and 1865.

In this ward Lister began his experiments with antisepsis. Much of his earlier published work had dealt with the mechanism of coagulation of the blood and role of the blood vessels in the first stages of inflammation. Both researches depended upon the microscope and were directly connected with the healing of wounds. Lister had already tried out methods to encourage clean healing and had formed theories to account for the prevalence of sepsis. Discarding the popular concept of miasma—direct infection by bad air—he postulated that sepsis might be caused by a pollen-like dust. There is no evidence that he believed this dust to be living matter, but he had come close to the truth. It is therefore all the more surprising that he became acquainted with the work of the bacteriologist Louis Pasteur only in 1865.

Pasteur had arrived at his theory that microorganisms cause fermentation and disease by experiments on fermentation and putrefaction. Lister's education and his familiarity with the microscope, the process of fermentation, and the natural phenomena of inflammation and coagulation of the blood impelled him to accept Pasteur's theory as the full revelation of a half-suspected truth. At the start he believed the germs were carried solely by the air. This incorrect opinion proved useful, for it obliged him to adopt the only feasible method of surgically clean treatment. In his attempt to interpose an antiseptic barrier between the wound and the air, he protected the site
of operation from infection by the surgeon's hands and instruments. He found an effective antiseptic in carbolic acid, which had already been used as a means of cleansing foul-smelling sewers and had been empirically advised as a wound dressing in 1863. Lister first successfully used his new method on Aug. 12, 1865; in March 1867 he published a series of cases. The results were dramatic. Between 1865 and 1869, surgical mortality fell from 45 to 15 percent in his Male Accident Ward.

In 1869, Lister succeeded Syme in the chair of Clinical Surgery at Edinburgh. There followed the seven happiest years of his life when, largely as the result of German experiments with antisepsis during the Franco-German War, his clinics were crowded with visitors and eager students. In 1875 Lister made a triumphal tour of the leading surgical centres in Germany. The next year he visited America but was received with little enthusiasm except in Boston and New York City.

Lister's work had been largely misunderstood in England and the United States. Opposition was directed against his germ theory rather than against his “carbolic treatment.” The majority of practicing surgeons were unconvinced; while not antagonistic, they awaited clear proof that antisepsis constituted a major advance. Lister was not a spectacular operative surgeon and refused to publish statistics. Edinburgh, despite the ancient fame of its medical school, was regarded as a provincial centre. Lister understood that he must convince London before the usefulness of his work would be generally accepted.

His chance came in 1877, when he was offered the chair of Clinical Surgery at King's College. On Oct. 26, 1877, Lister, at King's College Hospital, for the first time performed the then-revolutionary operation of wiring a fractured patella, or kneecap. It entailed the deliberate conversion of a simple fracture, carrying no risk to life, into a compound fracture,
which often resulted in generalized infection and death. Lister's proposal was widely publicized and aroused much opposition. Thus, the entire success of his operation carried out under antiseptic conditions forced surgical opinion throughout the world to accept that his method had added greatly to the safety of operative surgery.

(b. June 13, 1831, Edinburgh, Scot.—d. Nov. 5, 1879, Cambridge, Cambridgeshire, Eng.)

S
cottish physicist James Clerk Maxwell was best known for his formulation of electromagnetic theory. He is regarded by most modern physicists as the scientist of the 19th century who had the greatest influence on 20th-century physics, and he is ranked with Sir Isaac Newton and Albert Einstein for the fundamental nature of his contributions. In 1931, on the 100th anniversary of Maxwell's birth, Einstein described the change in the conception of reality in physics that resulted from Maxwell's work as “the most profound and the most fruitful that physics has experienced since the time of Newton.”

The concept of electromagnetic radiation originated with Maxwell, and his field equations, based on Michael Faraday's observations of the electric and magnetic lines of force, paved the way for Einstein's special theory of relativity, which established the equivalence of mass and energy. Maxwell's ideas also ushered in the other major innovation of 20th-century physics, the quantum theory. His description of electromagnetic radiation led to the development (according to classical theory) of the ultimately unsatisfactory law of heat radiation, which prompted Max Planck's formulation of the quantum hypothesis—i.e., the theory that radiant-heat energy is emitted only in finite amounts, or quanta. The interaction between electromagnetic
radiation and matter, integral to Planck's hypothesis, in turn has played a central role in the development of the theory of the structure of atoms and molecules.

Between 1860 and 1865 Maxwell experienced the most productive years of his career. During this period his two classic papers on the electromagnetic field were published, and his demonstration of colour photography took place. He was elected to the Royal Society in 1861. His theoretical and experimental work on the viscosity of gases also was undertaken during these years and culminated in a lecture to the Royal Society in 1866. He supervised the experimental determination of electrical units for the British Association for the Advancement of Science, and this work in measurement and standardization led to the establishment of the National Physical Laboratory. He also measured the ratio of electromagnetic and electrostatic units of electricity and confirmed that it was in satisfactory agreement with the velocity of light as predicted by his theory.

In 1865 Maxwell retired to the family estate in Glenlair. He continued to visit London every spring and served as external examiner for the Mathematical Tripos (exams) at Cambridge. In the spring and early summer of 1867 he toured Italy. But most of his energy during this period was devoted to writing his famous treatise on electricity and magnetism.

It was Maxwell's research on electromagnetism that established him among the great scientists of history. In the preface to his
Treatise on Electricity and Magnetism
(1873), the best exposition of his theory, Maxwell stated that his
major task was to convert British physicist and chemist Michael Faraday's physical ideas into mathematical form. In attempting to illustrate Faraday's law of induction (that a changing magnetic field gives rise to an induced electromagnetic field), Maxwell constructed a mechanical model. He found that the model gave rise to a corresponding “displacement current” in the dielectric medium, which could then be the seat of transverse waves. On calculating the velocity of these waves, he found that they were very close to the velocity of light. Maxwell concluded that he could “scarcely avoid the inference that light consists in the transverse undulations of the same medium which is the cause of electric and magnetic phenomena.”