“That some form of the meteoric theory is certainly the true and complete explanation of solar heat can scarcely be doubted, when the following reasons are considered: (1) No other natural explanation, except by chemical action, can be conceived. (2) The chemical theory is quite insufficient, because the most energetic chemical action we know, taking place between substances amounting to the whole sun's mass, would only generate about 3,000 years' heat. (3) There is no difficulty in accounting for 20,000,000 years' heat by the meteoric theory. What then are we to think of such geological estimates as [Darwin's] 300,000,000 years for the ‘denudation of the Weald'’?”

“I came into the room which was half-dark and presently spotted Lord Kelvin in the audience, and realized that I was in for trouble at the last part of my speech dealing with the age of the earth, where my views conflicted with his. To my relief, Kelvin fell fast asleep, but as I came to the important point, I saw the old bird sit up, open an eye and **** a baleful glance at me. Then a sudden inspiration came, and I said ‘Lord Kelvin had limited the age of the earth, provided no new source [of heat] was discovered. That prophetic utterance referred to what we are now considering tonight, radium!’ Behold! The old boy beamed upon me.”

See main: Thomson’s search for Carnot’s Reflections

See main: Heat death

See main: Law of dissipation

See main: Atomic theory

See main: Thomson on religion

“Thomson has the gift of translating real facts into mathematical equations and vice versa, a gift which is far rarer than the capacity for finding the solution of a given mathematical problem.”

— Hermann Helmholtz (c.1890), Publication [15]

“With the death of Lord Kelvin, on December 17 [1907], there passes away the grandest figure of contemporary science, and with it closes an epoch in the history of physics. When William Thomson was born, in 1824, Ohm's law of the flow of electric currents had not been discovered, Oersted's discovery of the magnetic action of the current was but four years old, while Faraday's capital discovery of the induction of currents was not to come for seven years. The wave theory of light had been but recently set on its feet by Young and Fresnel, and was not yet thoroughly believed, while the two laws of thermodynamics, perhaps the most important contribution of the nineteenth century, were unknown. All these things Lord Kelvin saw, and a great part of them he was. Probably no one, with the single exception of Helmholtz, born three years earlier, exercised greater influence on the science of the nineteenth century, while to compare the influence of these two great physicists with that of Darwin is as bootless as to question whether the grass is greener than the sky is blue.”

— Arthur G. Webster (1908), “Lord Kelvin”, Dec 22 [14]

“Once Thomson had had accepted the new [dynamical theory of heat] he produced, in the course of a few years, an abundance of new ideas, which were to prove immensely important: many of them in the hands of other men, such as Clausius. Prominent among these ideas were the concept of the ‘energy’ of a body, the insight into the process of dissipation of energy, the establishment of an ‘absolute temperature scale’, the awareness of the importance of ‘transformation’ and ‘equivalence’ and, finally, the expression of the second law of thermodynamics in the mathematical form:

Finally, we note that the function C [Carnot function] was originally proposed as the measure of the work done per degree temperature difference by a unit of heat at a given temperature. It was first visualized by Carnot, refined by Clapeyron, who measured its value at five different temperatures, and by Thomson who, using Regnault’s results, extended the range of measurement an established that it diminished steadily with the temperature. It was brought into the context of the dynamical theory of heat by Clausius and finally related by Joule and Thomson to the reciprocal of the absolute temperature on the thermodynamic scale. If we turn back now to the earlier work and substitute ‘T’ for ‘C’ we can appreciate how close writers like Clapeyron were to the truth.”

— Donald Cardwell (1871), From Watt to Clausius (pgs. 159-60) [16]

“Dead matter cannot become living matter without coming under the influence of matter previous alive.”

— William Thomson (c.1876), statement of his biogenesis philosophy (Ѻ)

“I often say that when you can measure what you are talking about, and express it in numbers, you known something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meager and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely in your thoughts advanced to the stage of science.”

— William Thomson (1883), Publication; cited by James Partington (1911) in Higher Mathematics for Chemical Students (pgs. 2-3)

“It seems to me most probable that the animal body does not act as a thermodynamic engine in converting heat produced by the combination of the food with the oxygen of the inhaled air, but that it acts in a manner more nearly analogous to that of an electric motor working in virtue of energy supplied to it by a voltaic battery. Whatever the nature of these means, whereby mechanical effects are produced in living organisms, consciousness teaches every individual that they are, to some extent, subject to the direction of his will. It appears, therefore, that animate creatures have the power of immediately applying to certain moving particles of matter within their bodies, forces by which the motions of these particles are directed to produce derived mechanical effects.”

— William Thomson (1892), “On the Dissipation of Energy”; cited by Werner Ehrenberg (1967) in “Maxwell’s Demon” (pg. 104); cited by Mae-Wan Ho (1999), out of context, in The Rainbow and the Worm (pgs. 76-77) [17]