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Home > Dictionary of Science Quotations > Scientist Names Index K > Baron William Thomson Kelvin Quotes

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Baron William Thomson Kelvin
(26 Jun 1824 - 17 Dec 1907)

British physicist, mathematician and engineer , born as William Thomson in Ireland, he became an influential physicist, mathematician and engineer who has been described as the Newton of his era.


Science Quotes by Baron William Thomson Kelvin (14 quotes)

Detail from portrait of Lord Kelvin, upper body, seated by artist Sir Hubert von Herkomer
Lord Kelvin
Accurate and minute measurement seems to the non-scientific imagination, a less lofty and dignified work than looking for something new. But nearly all the grandest discoveries of science have been but the rewards of accurate measurement and patient long-continued labour in the minute sifting of numerical results.
— Baron William Thomson Kelvin
Presidential inaugural address, to the General Meeting of the British Association, Edinburgh (2 Aug 1871). In Report of the Forty-First Meeting of the British Association for the Advancement of Science (1872) By xci.
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Do not imagine that mathematics is harsh and crabbed, and repulsive to common sense. It is merely the etherealisation of common sense.
— Baron William Thomson Kelvin
The Six Gateways of Knowledge', Presidential Address to the Birmingham and Midland Institute, Birmingham (3 Oct 1883). In Popular Lectures and Addresses (1891), Vol. 1, 280.
Science quotes on:  |  Common Sense (34)  |  Harsh (2)  |  Mathematics (367)  |  Repulsive (2)

I have no satisfaction in formulas unless I feel their arithmetical magnitude.
— Baron William Thomson Kelvin
From Lecture 7, (7 Oct 1884), in Baltimore Lectures on Molecular Dynamics and the Wave Theory of Light (1904), 76.
Science quotes on:  |  Arithmetic (38)  |  Formula (29)  |  Magnitude (14)  |  Satisfaction (31)

In physical science a first essential step in the direction of learning any subject is to find principles of numerical reckoning and practicable methods for measuring some quality connected with it. I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely in your thoughts advanced to the stage of science, whatever the matter may be.
Often seen quoted in a condensed form: If you cannot measure it, then it is not science.
— Baron William Thomson Kelvin
From lecture to the Institution of Civil Engineers, London (3 May 1883), 'Electrical Units of Measurement', Popular Lectures and Addresses (1889), Vol. 1, 80-81.
Science quotes on:  |  Measurement (112)

Let nobody be afraid of true freedom of thought. Let us be free in thought and criticism; but, with freedom, we are bound to come to the conclusion that science is not antagonistic to religion, but a help to it.
— Baron William Thomson Kelvin
Quoted in Arthur Holmes, 'The Faith of the Scientist', The Biblical World (1916), 48 7.
Science quotes on:  |  Freedom (41)  |  Science And Religion (159)  |  Thought (170)

Mathematics is the only good metaphysics.
— Baron William Thomson Kelvin
Quoted in E. T. Bell, Men of Mathematics, xvii.
Science quotes on:  |  Mathematics (367)  |  Metaphysics (24)

Mathematics is the only true metaphysics.
— Baron William Thomson Kelvin
Silvanus Phillips Thompson, Life of Lord Kelvin (1910), 10. In Robert Ιdouard Moritz, Memorabilia Mathematica; Or, The Philomath's Quotation-book (1914)
Science quotes on:  |  Mathematics (367)  |  Metaphysics (24)

Questions of personal priority, however interesting they may be to the persons concerned, sink into insignificance in the prospect of any gain of deeper insight into the secrets of nature.
— Baron William Thomson Kelvin
As quoted in Silvanus Phillips Thompson, The Life of Lord Kelvin (1910), Vol. 2, 602.
Science quotes on:  |  Deeper (2)  |  Gain (23)  |  Insight (28)  |  Insignificance (7)  |  Interesting (20)  |  Nature (534)  |  Person (38)  |  Personal (16)  |  Priority (3)  |  Prospect (8)  |  Question (159)  |  Secret (44)  |  Sink (6)

Simplification of modes of proof is not merely an indication of advance in our knowledge of a subject, but is also the surest guarantee of readiness for farther progress.
— Baron William Thomson Kelvin
In Lord Kelvin and Peter Guthrie Tait Elements of Natural Philosophy (1879, 1902), Preface.
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The life and soul of science is its practical application, and just as the great advances in mathematics have been made through the desire of discovering the solution of problems which were of a highly practical kind in mathematical science, so in physical science many of the greatest advances that have been made from the beginning of the world to the present time have been made in the earnest desire to turn the knowledge of the properties of matter to some purpose useful to mankind.
— Baron William Thomson Kelvin
From 'Electrical Units of Measurement', a lecture delivered at the Institution of Civil Engineers, London (3 May 1883), Popular Lectures and Addresses Vol. 1 (1891), 86-87.
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The vortex theory [of the atom] is only a dream. Itself unproven, it can prove nothing, and any speculations founded upon it are mere dreams about dreams.
— Baron William Thomson Kelvin
Quoted in Henry Smith Williams, 'Some Unsolved Scientific Problems', Harper's New Monthly Magazine (1899-1900), Vol. 100, 779.
Science quotes on:  |  Atom (164)  |  Proof (136)  |  Speculation (44)  |  Theory (353)

There is nothing new to be discovered in physics now. All that remains is more and more precise measurement.
— Baron William Thomson Kelvin
Webmaster has searched for a primary print source without success. Walter Isaacson likewise found no direct evidence, as he reports in Einstein (2007), 575. However, these sentences are re-quoted in a variety of books and other sources (often citing them as a remark reportedly made by Kelvin in an Address at the British Association for the Advancement of Science in 1900). Although the quote appears noteworthy, it is not included in the major biographical work, the two volumes by Silvanus P. Thomson, The Life of Lord Kelvin (1976). The quote is included here so that this caveat should be read with it.
Science quotes on:  |  Discovery (360)  |  Measurement (112)  |  New (107)  |  Nothing (89)  |  Precision (19)

You, in this country [the USA], are subjected to the British insularity in weights and measures; you use the foot, inch and yard. I am obliged to use that system, but must apologize to you for doing so, because it is so inconvenient, and I hope Americans will do everything in their power to introduce the French metrical system. ... I look upon our English system as a wickedly, brain-destroying system of bondage under which we suffer. The reason why we continue to use it, is the imaginary difficulty of making a change, and nothing else; but I do not think in America that any such difficulty should stand in the way of adopting so splendidly useful a reform.
— Baron William Thomson Kelvin
Journal of the Franklin Institute, Nov 1884, 118, 321-341
Science quotes on:  |  Measurement (112)  |  Metric System (5)

[Referring to Fourier's mathematical theory of the conduction of heat] … Fourier's great mathematical poem ...
— Baron William Thomson Kelvin
In W. Thomson and P. G. Tait, Treatise on Natural Philosophy. Reprinted as Principles of Mechanics and Dynamics (2000), 470.
Science quotes on:  |  Biography (199)  |  Baron Jean-Baptiste-Joseph Fourier (5)  |  Heat (48)  |  Mathematics (367)  |  Poem (76)  |  Theory (353)



Quotes by others about Baron William Thomson Kelvin (9)

The saying often quoted from Lord Kelvin… that 'where you cannot measure your knowledge is meagre and unsatisfactory,' as applied in mental and social science, is misleading and pernicious. This is another way of saying that these sciences are not science in the sense of physical science and cannot attempt to be such without forfeiting their proper nature and function. Insistence on a concretely quantitative economics means the use of statistics of physical magnitudes, whose economic meaning and significance is uncertain and dubious. (Even wheat is approximately homogeneous only if measured in economic terms.) And a similar statement would even apply more to other social sciences. In this field, the Kelvin dictum very largely means in practice, 'if you cannot measure, measure anyhow!'
'What is Truth' in Economics? (1956), 166.
Science quotes on:  |  Economics (19)  |  Measurement (112)  |  Social Science (17)

When Lord Kelvin was in this country [U.S.], he said that nothing interested him so much as Mr. Hewitt's work and his vacuum lamp.
Referring to the mercury lamp invention.
Quoting Kelvin in McClure's Magazine (Jun 1903). In Albert Shaw (Ed.), The American Monthly Review of Reviews (1903), 27, 724.
Science quotes on:  |  Peter Cooper Hewitt (2)  |  Invention (174)

Geologists have not been slow to admit that they were in error in assuming that they had an eternity of past time for the evolution of the earth's history. They have frankly acknowledged the validity of the physical arguments which go to place more or less definite limits to the antiquity of the earth. They were, on the whole, disposed to acquiesce in the allowance of 100 millions of years granted to them by Lord Kelvin, for the transaction of the whole of the long cycles of geological history. But the physicists have been insatiable and inexorable. As remorseless as Lear's daughters, they have cut down their grant of years by successive slices, until some of them have brought the number to something less than ten millions. In vain have the geologists protested that there must somewhere be a flaw in a line of argument which tends to results so entirely at variance with the strong evidence for a higher antiquity, furnished not only by the geological record, but by the existing races of plants and animals. They have insisted that this evidence is not mere theory or imagination, but is drawn from a multitude of facts which become hopelessly unintelligible unless sufficient time is admitted for the evolution of geological history. They have not been able to disapprove the arguments of the physicists, but they have contended that the physicists have simply ignored the geological arguments as of no account in the discussion.
'Twenty-five years of Geological Progress in Britain', Nature, 1895, 51, 369.
Science quotes on:  |  Age Of The Earth (10)  |  Controversy (13)  |  Evolution (342)

I came into the room, which was half dark, and presently spotted Lord Kelvin in the audience and realised 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 cock 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 energy) was discovered. That prophetic utterance refers to what we are now considering tonight, radium! Behold! the old boy beamed upon me.
Speech at the Royal Institution (1904). Quoted in Arthur S. Eve, Rutherford (1939), 107.
Science quotes on:  |  Age Of The Earth (10)  |  Radioactivity (21)  |  Radium (13)

Lord Kelvin was so satisfied with this triumph of science that he declared himself to be as certain of the existence of the ether as a man can be about anything.... “When you can measure what you are speaking about, and express it in numbers, you know something about it....” Thus did Lord Kelvin lay down the law. And though quite wrong, this time he has the support of official modern Science. It is NOT true that when you can measure what you are speaking about, you know something about it. The fact that you can measure something doesn't even prove that that something exists.... Take the ether, for example: didn't they measure the ratio of its elasticity to its density?
In Science is a Sacred Cow (1950), 69-70; 85.
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You and I are just about fit to mend his pens.
[About the young William Thomson (later Lord Kelvin.)]
Remark by Ellis to the mathematician Harvey Goodwin, both examiners, comparing William Thomson's mathematical prowess while still a student at the time of sitting the Tripos Examination (1845). As quoted by Harvey Goodwin in 'A Biographical Memoir', the introduction to Robert Leslie Ellis, William Walton (ed), The Mathematical and Other Writings of Robert Leslie Ellis (1863), xix.
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Why are atoms so small? ... Many examples have been devised to bring this fact home to an audience, none of them more impressive than the one used by Lord Kelvin: Suppose that you could mark the molecules in a glass of water, then pour the contents of the glass into the ocean and stir the latter thoroughly so as to distribute the marked molecules uniformly throughout the seven seas; if you then took a glass of water anywhere out of the ocean, you would find in it about a hundred of your marked molecules.
What is life?: the Physical Aspect of the Living Cell (1944). Collected in What is Life? with Mind And Matter & Autobiographical Sketches (1967, 1992), 6-7.
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The age of the earth was thus increased from a mere score of millions [of years] to a thousand millions and more, and the geologist who had before been bankrupt in time now found himself suddenly transformed into a capitalist with more millions in the bank than he knew how to dispose of ... More cautious people, like myself, too cautious, perhaps, are anxious first of all to make sure that the new [radioactive] clock is not as much too fast as Lord Kelvin's was too slow.
1921 British Association for the Advancement of Science symposium on 'The Age of the Earth'. In Nature (1921), 108, 282.
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The story is told of Lord Kelvin, a famous Scotch physicist of the last century, that after he had given a lecture on atoms and molecules, one of his students came to him with the question, “Professor, what is your idea of the structure of the atom.”
“What,” said Kelvin, “The structure of the atom? Why, don’t you know, the very word ‘atom’ means the thing that can’t be cut. How then can it have a structure?”
“That,” remarked the facetious young man, “shows the disadvantage of knowing Greek.”
As described in 'Assault on Atoms' (Read 23 Apr 1931 at Symposium—The Changing World) Proceedings of the American Philosophical Society (1931), 70, No. 3, 219.
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See also:
  • todayinsci icon 26 Jun - short biography, births, deaths and events on date of Kelvin's birth.
  • todayinsci icon Lord Kelvin
  • todayinsci icon Lord Kelvin - Biography from Famous Men of Science.
  • book icon Degrees Kelvin: A Tale of Genius, Invention, and Tragedy, by David Lindley. - book suggestion.
  • booklist icon Booklist for William Thomson.

Carl Sagan Thumbnail In science it often happens that scientists say, 'You know that's a really good argument; my position is mistaken,' and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion. (1987) -- Carl Sagan
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