… according to Einstein the very geometry of space is contingent and variable, its nature at any given point being dependent upon the varying influences of matter and energy throughout the universe upon that point. And here we have the crux of the measurement problem of cosmology. If the structure of space is a contingent aspect of physical influences, then we must first know the nature and distribution of those physical factors before we can know the geometry of any spatial region. But in order to know this distribution of physical factors, we must be able to make accurate and reliable spatial measurements properly to place and relate those contingent, physical influences upon any given point of space. But in order to make accurate and reliable spatial measurements, we must have a robust understanding of the geometry of the spaces in and through which we are measuring. Only with this latter can we understand the effects on our standard unit of measurement of the non-uniform and contingent projective relations of those spaces, and thereby establish a logically meaningful system of conjugacy with the things to be measured. Yet such a robust understanding of the geometry of space is precisely what we do not have, and cannot establish, for it is exactly what GR refuses to grant us. We must know the complete distribution of matter and energy in the universe prior to knowing its geometry. But we must have a comprehensive grasp of this geometry in order to discover this distribution. As Whitehead pointed out, with GR as our theory of space and gravity, we are saddled with a situation where we must first know everything before we can know anything.
… if the very geometry of space is something we cannot know until after we can confidently engage in measurement, then cosmology as a science teeters on the brink of nonsense. For while we must first measure before we can know, GR requires that we know before we can measure.
… And yet, GR appears to be successfully employed in formulating and evaluating cosmological measurements all the time. Indeed, general relativity and quantum mechanics are often held up as the premier examples of the most successful physical theories ever conceived. How are we to reconcile such practical successes with the supposed philosophical issues raised above?
The question almost undoes itself in the asking, for it is a well-known fact that these two theories are mathematically irreconcilable. But it is not just at the small scales of micro-physics that GR runs into problems. At the very large scales of physical cosmology, GR has also proven to be inadequate. In an effort to account for observed phenomena—phenomena of which physicists assume they have meaningful measurements—it has been necessary to reintroduce the idea of the “cosmological constant,” as well as to invent such extravagant new ideas as “dark matter” and “dark energy” in an attempt to account for the evident behavior of the cosmos.
… It was [Whitehead’s] observation that if we do not maintain the separation between geometry and physics, then we lose the logical basis of the rules for conjugacy and projection that make spatial measurement possible. …
So instead of Einstein’s “mono-metrical” approach, as we have termed it, Whitehead proposed what has now come to be known as a “bimetric” solution. Instead of shoe-horning all of the metrical relations into a single tensor (the “gμν”), collapsing geometry and physics, Whitehead’s theory utilized two metrical tensors: His “J” tensor representing the contingent physical relations of gravity and other forces, and his “G” tensor or the necessary spatial relations of geometry. …
… There are now many other members of this class than just Whitehead’s, and many of these theories are known to be viable alternatives to GR. Each of these bimetric theories separates the geometrical relations from the contingent facts of physics, and thus they have the required level of uniformity available to them to permit of the projective relations needed for meaningful measurements.
It is a matter of no great philosophical relevance whether Whitehead’s specific scientific proposal still offers a viable alternative to GR. Whitehead himself never viewed this as anything more than an application of his general philosophical principles. What we have instead is much more interesting: a developed system of philosophical ideas that are well vindicated by an entire family of scientific exemplars that are known to be formally and empirically valid. Moreover, these alternative theories are also much more linear in their formulations. This means that testable predictions can be calculated directly from these theories, and that they are far more easily reconciled with quantum mechanics.
Randall E. Auxier and Gary L. Herstein, The Quantum of Explanation: Whitehead’s Radical Empiricism