Editing Theory of everything (section)

===Fundamental limits in accuracy===
No physical theory to date is believed to be precisely accurate. Instead, physics has proceeded by a series of "successive approximations" allowing more and more accurate predictions over a wider and wider range of phenomena. Some physicists believe that it is therefore a mistake to confuse theoretical models with the true nature of reality, and hold that the series of approximations will never terminate in the "truth".<ref>{{cite book|title=The New Cosmic Onion: Quarks and the Nature of the Universe|first=search|last=results|date=17 December 2006|publisher=CRC Press|isbn = 978-1-58488-798-0}}</ref> Einstein himself expressed this view on occasions.<ref>Einstein, letter to Felix Klein, 1917. (On determinism and approximations.) Quoted in Pais (1982), Ch. 17.</ref>