Pictures of the real thing

Experiments show what is really there. One common method freezes many copies of a protein and images them with an electron microscope, then combines thousands of pictures into one shape.

Where the copies all look alike, the picture is sharp. Where they differ, because a part moves, the picture is blurred. Experiments can also show partners, such as a small molecule in a pocket, that a prediction from one chain cannot.

Prediction and experiment are used together: each is honest about a different weakness.