The uncertainty relation does not refer to the past; if the velocity of the electron is at first known and the position then exactly measured, the position for times previous to the measurement may be calculated.

In America, it was decided to attempt the production of atomic bombs with an effort that would constitute a large part of the collective American war effort. In Germany, an effort one thousandth the scale of the American was applied to the problem of producing atomic energy that would drive engines.

The uncertainty principle refers to the degree of indeterminateness in the possible present knowledge of the simultaneous values of various quantities with which the quantum theory deals; it does not restrict, for example, the exactness of a position measurement alone or a velocity measurement alone.

Werner Heisenberg Quotes