"It is theory which decides what we can observe" -Einstein
"In reality the very opposite happens. It is the theory which decides what we can observe." From Heisenberg, Physics and Beyond, Arnold J. Pomerans, trans. (New York: Harper, 1971), p. 63.
In context:
Heisenberg: "We cannot observe electron orbits inside the atom...Now, since a good theory must be based on directly observable magnitudes, I thought it more fitting to restrict myself to these, treating them, as it were, as representatives of the electron orbits."
"But you don't seriously believe," Einstein protested, "that none but observable magnitudes must go into a physical theory?"
"Isn't that precisely what you have done with relativity?" I asked in some surprise...
"Possibly I did use this kind of reasoning," Einstein admitted, "but it is nonsense all the same....In reality the very opposite happens. It is the theory which decides what we can observe."
(FML: quote also found in Rosamund Zander and Benjamin Zander, The Art of Possibility, (New York: Penguin, 2000), 11)
D.O. Hebb, "Science and the World of Imagination," Canadian Psychology 16 (1975), 4-11 Heisenberg, Physics and Beyond, Arnold J. Pomerans, trans. (New York: Harper, 1971), p. 63.
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[verified 4/17/14]