He formulated the Heisenberg Uncertainty Principle, which states that it is impossible to know both the position and momentum of an electron with perfect accuracy at the same time. This means we can't predict the exact path an electron will take.
It's important to note that this principle doesn't mean we know nothing about electrons. We can still understand their behavior statistically and predict the probability of finding an electron in a certain region of space. But we cannot know its exact trajectory.
