Michael Riordan makes a good point: If a theory does not eventually lead to testable consequences, theorists are doing metaphysics, not physics. Max Planck used different phrasing to express the same idea: “Experiments,” he said, “are the only means of knowledge at our disposal. The rest is poetry, imagination.” 1
Riordan also suggests that all we are doing is reading the Book of Nature. That image is very powerful, but it cannot be literally correct. If it were, that book would already have been written, a finished work in minute detail. But the book is not finished: Scientists can demonstrate experimentally that we are also inside the book, “through our choices,” as Niels Bohr liked to say. 2 Consequently, we need to move on the razor’s edge by leaving the relativist and postmodernist positions on the one side, and the easy but unreal image of the finished book on the other side, but equidistant.
Including ourselves in the picture creates a serious problem—that is, how to determine the essence of scientific truth, as Riordan says, and how to explain that physics is, nevertheless, objective. Objectivity and truth can be reached in a participatory universe, 3 through different experiments converging in the same result. Let’s look at an example.
The Planck constant h can be experimentally determined by many different procedures that are, in principle, independent of each other. Nevertheless, the experiments all converge in the same value of h (allowing for experimental errors). The probability of this convergence happening by chance tends to zero as the number of experimental procedures increases. This is even more dramatic, given that h is related to some other quantities—for example, the electron charge and mass and the velocity of light. These quantities are also built up by independent confluence that constrains their respective values.
In the history of physics, when three or four independent experimental procedures achieve the same result, with none opposing, that result is considered to be a fact. Such confluent relations are then fundamental and permanent; despite nature’s being a participatory book, they are the precise points in which objectivity and truth enter into physics.
