I first heard this phrasing at the American Geophysics Union Fall Meeting last December. I was reminded of it recently when reading The Pleasure of Finding Things Out: The Best Short Works of Richard P. Feynman.
Science is not in the business of certainty. Many people consider the purpose of science to be the pursuit of “Truth”. Or an effort to understand how the universe works. Both of these things suggest that there is a deterministic answer to the questions science asks. That’s just not true in most cases.
In reality, certainty is not the goal. Consider the Heisenberg Uncertainty Principle, for example. It’s a fundamental concept of Quantum Mechanics that you’ve probably heard about. Basically, the more we know about the position of a particle, the less we can know about the momentum (or velocity) of the particle. There’s an inherent uncertainty in the system such that even if we go looking for the answer, we’ll never be able to pin down both the position and the momentum of the particle at the same time. This is a prime example of the inherent role of uncertainty in science.