Source: Just a Theory: Exploring the Nature of Science (2005), Chapter 2, “Just a Theory: What Scientists Do” (p. 24)
“The laws of classical mechanics represent a mathematical idealization and should not be assumed to correspond to the real laws of nature. … We now have to realize that errors are inevitable (..) a discovery that makes strict determinism impossible.”
[Léon Brillouin, Science and Information Theory, second edition, Academic Press, New York, 1962, 0-48643-918-6, 314]
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Léon Brillouin 4
French physicist 1889–1969Related quotes

[NewsBank, A12, 'Science Guy' Bill Nye defends evolution in debate, St. Paul Pioneer Press, Minnesota, February 5, 2014, Dylan Lovan, Associated Press]

“The laws of nature are but the mathematical thoughts of God.”
The earliest published source found on google books that attributes this to Euclid is A Mathematical Journey by Stanley Gudder (1994), p. xv http://books.google.com/books?id=UiOxd2-lfGsC&q=%22mathematical+thoughts%22+euclid#search_anchor. However, many earlier works attribute it to Johannes Kepler, the earliest located being in the piece "The Mathematics of Elementary Chemistry" by Principal J. McIntosh of Fowler Union High School in California, which appeared in School Science and Mathematics, Volume VII ( 1907 http://books.google.com/books?id=kAEUAAAAIAAJ&pg=PR3#v=onepage&q&f=false), p. 383 http://books.google.com/books?id=kAEUAAAAIAAJ&pg=PA383#v=onepage&q&f=false. Neither this nor any other source located gives a source in Kepler's writings, however, and in an earlier source, the 1888 Notes and Queries, Vol V., it is attributed on p. 165 http://books.google.com/books?id=0qYXAQAAMAAJ&pg=PA165#v=onepage&q&f=false to Plato. It could possibly be a paraphrase of either or both of the following to comments in Kepler's 1618 book Harmonices Mundi (The Harmony of the World)': "Geometry is one and eternal shining in the mind of God" and "Since geometry is co-eternal with the divine mind before the birth of things, God himself served as his own model in creating the world".
Misattributed

“The laws of nature are but the mathematical thoughts of God.”
Attributed to Kepler in some sources (though more recent sources often attribute it to Euclid), such as Mathematically Speaking: A Dictionary of Quotations edited by Carl C. Gaither and Alma E. Cavazos-Gaither (1998), p. 214 http://books.google.com/books?id=4abygoxLdwQC&lpg=PP1&pg=PA214#v=onepage&q&f=false. The earliest publication located that attributes the quote to Kepler is the piece "The Mathematics of Elementary Chemistry" by Principal J. McIntosh of Fowler Union High School in California, which appeared in School Science and Mathematics, Volume VII ( 1907 http://books.google.com/books?id=kAEUAAAAIAAJ&pg=PR3#v=onepage&q&f=false), p. 383 http://books.google.com/books?id=kAEUAAAAIAAJ&pg=PA383#v=onepage&q&f=false. Neither this nor any other source located gives a source in Kepler's writings, however, and in an earlier source, the 1888 Notes and Queries, Vol V., it is attributed on p. 165 http://books.google.com/books?id=0qYXAQAAMAAJ&pg=PA165#v=onepage&q&f=false to Plato. Expressions that relate geometry to the divine "mind of God" include comments in the Harmonices Mundi, e.g., "Geometry is one and eternal shining in the mind of God", and "Since geometry is co-eternal with the divine mind before the birth of things, God himself served as his own model in creating the world".
Disputed quotes

Source: Discipleship (1937), The Righteousness of Christ, p. 122.

in What is Mathematics, in [Hilary Putnam, Mathematics, matter, and method, Cambridge University Press, 1979, 0521295505, 60]

“All mathematical laws which we find in Nature are always suspect to me, in spite of their beauty.”
As quoted in Lichtenberg : A Doctrine of Scattered Occasions (1959) by Joseph Peter Stern, p. 84
Context: All mathematical laws which we find in Nature are always suspect to me, in spite of their beauty. They give me no pleasure. They are merely auxiliaries. At close range it is all not true.