The Uncertainty of Science
the mass never changes at all. Exciting possibility! It does no harm that
it turned out not to be the case. It was only uncertain, and there is no
harm in being uncertain. It is better to say something and not be sure
than not to say anything at all.
It is necessary and true that all of the things we say in science, all
of the conclusions, are uncertain, because they are only conclusions.
They are guesses as to what is going to happen, and you cannot know
what will happen, because you have not made the most complete
It is curious that the effect on the mass of a spinning top is so
small you may say, "Oh, it doesn't make any difference." But to get a
law that is right, or at least one that keeps going through the successive
sieves, that goes on for many more observations, requires a
tremendous intelligence and imagination and a complete revamping of
our philosophy, our understanding of space and time. I am referring to
the relativity theory. It turns out that the tiny effects that turn up
always require the most revolutionary modifications of ideas.
Scientists, therefore, are used to dealing with doubt and
uncertainty. All scientific knowledge is uncertain. This experience with
doubt and uncertainty is important. I believe that it is of very great
value, and one that extends beyond the sciences. I believe that to solve
any problem that has never been solved before, you have to leave the
door to the unknown ajar. You have to permit the possibility that you
do not have it exactly right. Otherwise, if you have made up your mind
already, you might not solve it.
When the scientist tells you he does not know the answer, he is
an ignorant man. When he tells you he has a hunch about how it is
going to work, he is uncertain about it. When he is pretty sure of how it
is going to work, and he tells you, "This is the way it's going to work,
I'll bet," he still is in some doubt. And it is of paramount importance, in
order to make progress, that we recognize this ignorance and this
doubt. Because we have the doubt, we then propose looking in new
directions for new ideas. The rate of the development of science is not
the rate at which you make observations alone but, much more
important, the rate at which you create new things to test.
If we were not able or did not desire to look in any new direction,
if we did not have a doubt or recognize ignorance, we would not get
any new ideas. There would be nothing worth checking, because we