William Thomson, Lord Kelvin Biography (1824-1907)


William (Lord Kelvin) Thomson is recognized as the premier scientific mind ofthe nineteenth century, and perhaps the greatest thinker since Isaac Newton(1642-1727). He originated new schools of thought in physics, thermodynamics,electronics, and mathematics. He was knighted in 1866 for his work in salvaging the first telegraph cable to span the Atlantic, became wealthy enough toown a 126-ton yacht and an estate, and in 1892 was made Baron Kelvin of Largs.

Thomson was born in Belfast, Ireland, in 1824. The son of a respected mathematician, he was quickly recognized as a child prodigy. When his father was given a professorship at the University of Glasgow, William (then a mere eight years old) would attend lectures. At age 10 he entered the University of Glasgow (as did his 11-year-old brother, James), finishing second in his class. While still in his teens he pursued his graduate degrees at Cambridge and Paris--his first published paper appeared when he was 16 years old. In 1846, the 22-year-old Thomson was appointed (with some help from his father) Professor of Natural Philosophy at the University of Glasgow. There, he was responsiblefor the construction of Britain's first physics laboratory.

It did not take long for the young professor to stir up the European scientific community. Less than a year after his appointment, Thomson announced his findings regarding the age of Earth. Beginning with the assumption that Sun and Earth were once the same temperature, he determined that the time it wouldtake for our planet to cool to its present temperature was somewhere between20 million and 400 million years, and probably very close to 100 million years. This number was much lower than those previously determined by geologists(through by completely different means). Biologists in particular were dismayed, for it meant that all of the evolution of life must now fit within the span of a million years. They began to consider the possibility of evolutionary"leaps"--shortcuts that would dramatically decrease the amount of time needed for life to evolve. Though Thomson's figures were later shown to be incorrect, the furor among biologists led to the theories of evolutionary mutation.

During his studies of the age of our planet, Thomson became intrigued by therelationship between heat and energy. In 1847 he met James Joule (1818-1889),the author of some of the most innovative heat theories of the time; at thatjuncture, however, Joule's work was relatively unknown, particularly in England. Using his tremendous influence Thomson introduced Joule's theories to the Royal Society, giving Joule the recognition he deserved. During the next few years Thomson and Joule worked together, experimenting with the heat and energy of certain gases. One phenomenon they observed was that as a gas was introduced into a vacuum its temperature would drop, and if that drop were enough the gas could be converted to a liquid. Called the Joule-Thomson effect, this phenomenon became the basis for the liquification of most gases and, muchlater, the science of cryogenics.

Thomson's work with Joule continued to feed his curiosity about the nature ofheat. He was especially interested in the work of the French physicist Jacques Charles (1746-1823), who had found that, for every degree celsius below zero a gas was cooled, the volume would decrease by a factor 1/273.16. The implication of this theory was that, at -273.16° C; the volume of the gas would be zero. Scientists were unable to explain exactly why this would happen,just as they were unable to prove Charles's law false. In 1848 Thomson explained the effect in this way: when the temperature of a gas is reduced, so is the energy level of the atoms; as the atoms move less they take up less room,therefore decreasing the volume. At -273.16° C the energy level of the atoms reaches zero--they stop moving, take up almost no space, and their temperature cannot be lowered any further. Because this theory should be true for any substance, Thomson called -273.16° C the absolute zero of temperature.

The most famous application of this idea was Thomson's 1848 invention of an absolute scale of temperature. This scale essentially drops the centigrade scale by 273.16° C, so that zero and absolute zero coincide. Thomson calledhis scale the absolute scale, but after his death it was renamed the Kelvin scale. Zero kelvin (O K) is the lowest possible temperature, or absolute zero.In celsius is equals -273.16° C, and in fahrenheit it equals -459.69° F.

The absolute scale was much easier for scientists to use than centigrade, since it directly took into account energy differences. James Clerk Maxwell (1831-1879) utilized this scale in his formulation of his kinetic gas theory. In1851 Thomson used the scale to show that all energy is eventually converted into unusable heat, and that heat is dissipated into the atmosphere. This concept of degradation was later explored by Rudolf Clausius and was reintroducedin a much clearer and more explicit form as the second law of thermodynamics, stated using the concept of entropy.

During the late 1800s much of the British scientific community was busy working on the first transatlantic cable. Thomson lent his immense knowledge of electrical theory to this effort, inventing a number of ultra-sensitive galvanometers. His theory was that only very low voltages could transmit the telegraph signals at a sufficient rate over such a long cable. This clashed with theviews of E. O. W. Whitehouse, an electrician who had been placed in charge of the project. Using a system of his own design, Whitehouse completed construction of a high-voltage telegraph cable. When tested in 1856, the cable was acomplete failure. After several years of litigation, the transmitters were replaced with Thomson's low-voltage system, and beginning in 1865 the underwater cable provided instant communication across the Atlantic. Thomson was recognized as the man who had rescued a giant financial investment, and was knighted for his work.

During the 1880s Thomson lectured on the virtues of Victorian science, a school of thought that believed that all of the important discoveries in physicshad been completed. So committed was he to this idea that he completely rejected the theories of radioactivity, ignoring and thus missing the onset of thenext great scientific age. He died in 1907 and was buried next to Isaac Newton in Westminster Abbey.

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Alistair Warwick
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Jul 23, 2014 @ 4:16 pm
William Thomson's nationality was Scottish, not English. Please correct this error.

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