If you know that you are not sure, you have a chance to improve the situation. I want to demand this freedom for future generations.

A scientist is never certain. ... We absolutely must leave room for doubt or there is no progress and there is no learning.

Turbulence is the most important unsolved problem of classical physics.

It appears that there are enormous differences of opinion as to the probability of a failure with loss of vehicle and of human life. The estimates range from roughly 1 in 100 to 1 in 100,000. The higher figures come from the working engineers, and the very low figures from management.

The electron is a theory we use; it is so useful in understanding the way nature works that we can almost call it real.

[B]eyond poverty, beyond the point that the material needs are reasonably satisfied, only from within is peace.

Have no respect whatsoever for authority; forget who said it and instead look what he starts with, where he ends up, and ask yourself, "Is it reasonable?"