“Everybody knows” Einstein’s E = mc2 but not everybody understands it – even some who know what the symbols mean and can use it in physics. Others before Einstein (J.J. Thomson, F. Hasenöhrl) had shown that changes in certain forms of energy would be accompanied by changes in mass in accord with this equation. Relativity tells us that all forms of energy have inertia and that everything with inertia can be converted to different forms of energy. (The title of Einstein’s original paper on this was “Does the Inertia of a Body Depend upon its Energy Content?”) It’s not so much a matter of “converting mass to energy” (or vice versa) as the fact that energy is mass and mass is energy. This is even clearer if (as theorists often do) we choose units so that the speed of light c = 1 and we can write simply E = m.
Mass is a measure of “stuff,” physical substance, and is commonly considered inert. (Hence the word inertia.) Energy, on the other hand, makes things happen. In elementary physics it’s defined as “the ability to do work,” and in advanced dynamics it’s the generator of time development. (The Schrödinger equation of quantum mechanics says that the energy operator of a system produces the temporal change of its wave function.) So E = mc2 could be roughly paraphrased as “stuff happens.”
Now substance and change are basic concepts in two quite different ways of looking at reality. Traditional metaphysics is generally “substantialist: Human beings, God, and everything else are considered in terms of substances or natures which are essentially unchanging – human nature, the divine nature, &c. (In the translation of the Nicene Creed used when I was growing up we confessed that the Son is “of one substance with the Father,” which sounds odd to modern ears.) This is a basically static picture of reality.
An important alternative to such a view in which the idea of change is fundamental is process philosophy, associated especially with Alfred North Whitehead. Here everything is in process, including God. Because of the dynamic character of the world science discloses, and especially because of biological evolution, theology using this approach has had a prominent place in the recent science-theology dialogue.
I am not a process theologian but I think there are worse things to be than that. Conservative Christians are sometimes critical of process theology because it associates God with temporality and change in a fundamental way. But that in itself need not be a problem. A number of modern theologians who are not process types understand God in some sense to “have time” (which does not mean simply being subject to the world’s time) and to have taken the world’s history into the divine life in the Incarnation.
A more serious theological problem is with the understanding of causation in process thought. Here God is a cause of everything but not the sole cause of anything. God is not “omnipotent” in the sense of ultimately doing everything. This is part of its appeal because it helps to deal with the problem of theodicy. (Harold Kushner’s popular book Why Bad Things Happen to Good People is a popular example.) But it also means that there could be no creatio ex nihilo or justification by grace alone. It also seems difficult in this framework to speak of God as Trinity or Jesus as a unique incarnation of God, through some theologians have tried to express these Christian claims in a process context.
We can’t deduce metaphysics from physics, but what we know of the world can certainly be suggestive. What I’ve said about Einstein’s mass-energy equation points to a reality in which both permanence and change are significant. In Whitehead’s philosophy there are both permanent and changing aspects of God, and any substantialist view that takes scripture seriously needs to recognize that time and change were intended by God in creation. (In contrast, some ASA members will remember an absurd statement made at a meeting a few years ago about the second law of thermodynamics going into operation when Eve bit into the apple!)
The really critical theological question that has to be asked of process is whether God has to be involved in process in the same way that the world is. Whitehead thought so, saying that God should not be seen as an exception to the laws of metaphysics but as their supreme exemplification. This assumes, however, that there must be some fundamental resemblance between God and creation, the “analogy of being” that Karl Barth attacked so strenuously. I think Barth was right.
And to close this rather rambling reflection, it’s interesting that Einstein, whose equation I started with, apparently had a basically static view of the world. He was a great admirer of Spinoza, for whom “God” and “nature” were different ways of speaking about the same thing. So if God was unchanging (as Spinoza thought) then nature in its overall aspect would have to be too. Max Jammer, in Einstein’s Religion, suggests that this may have been one motive for Einstein’s addition of a cosmological term to his field equations to make a static universe possible. The further irony is that this term may now explain the accelerating expansion of the universe.