One cannot go beyond the singularities solely by using the general theory of relativity. Because, to a certain extent, the very large encounters the very small in the singularities, it seems necessary to try to explain the singularities by uniting the relativistic theory of gravity with quantum mechanics. Even if this unification has not yet been accomplished, work with its prerequisites has led to sensational hypotheses and suggestions. The alternatives of either an infinitely existing universe or a beginning singularity that cannot be explained scientifically appear to be surmountable within the framework of the indeterminacy of quantum physics, since here, spontaneous events can occur without a causal connection in the classical sense. Hawking, in particular, has been working on the development of a singularity-free model for the universe. According to Hawking, a theory that unites quantum mechanics and gravity must understand quantum theory as the "sum over histories"265 and, according to the theory of relativity, gravitational fields as the curvature of space-time. Proceeding from these conditions, his solution reads: imaginary time266—a time that, with increasing proximity to the beginning, becomes increasingly spacelike and thus ultimately loses its beginning. Within the framework of the uncertainty of quantum physics, Hawking lets the three dimensions of space, along with the imaginary time, form a universe that has neither boundaries nor edges and, yet, is self-contained—a finite space-time without border, comparable to the surface of the earth, only richer by some dimensions. In this case, space-time would have "always" existed, and every physical event could be explained by laws:
There would be no singularities at which the laws of science broke down and no edge of space-time at which one would have to appeal to God or some new law to set the boundary conditions for space-time. One could say: "The boundary condition of the universe is that it has no boundary." The universe would be completely self-contained and not affected by anything outside itself. It would neither be created nor destroyed. It would just BE.267
In models of this type, time is therefore not activated by some type of cause, but rather, it turns itself on, so to speak—an elegant yet speculative theory. Nevertheless, the thought that the universe began with an accidental event on the quantum level, a quantum fluctuation, has become a frequent component of current cosmological theories. Processes in which particles suddenly develop in a vacuum and immediately disappear again are constantly occurring in scientific laboratories. That the entire universe itself could have begun in this manner sounds quite fantastic. There are signs, however, that point in this direction. Thus, there are good reasons to assume that the discussion of cosmological theories that explain the genesis of the universe by a quantum fluctuation will continue.
In some cases, the results, premises, and problems of these theories have been related to theological themes, such as creatio ex nihilo and cosmological eschatology.268 Here, a number of ideas are awaiting theological reflection and reception. Generally, it may be said that theories of this type do not necessarily lead to atheism; instead, they cause what we may call "adeism," that is, a refutation of deism rather than of theism.269 Hawking emphasizes the challenges with which cosmological models based on quantum fluctuation models confront theology. In the same breath that he closes the door on uncritical theistic explanations of the world, he also opens a window here and there for a larger perspective: "Even if science may possibly be able to explain the problem of how the universe began, it cannot answer the question: Why does the universe make the effort to exist?"270 And: "What is it that breathes fire into equations and makes for them a universe to describe?"271
Viewed from a theological perspective, these thoughts bring up the question of how to talk about God. When God is discussed exclusively in connection with the boundary conditions of the universe, it is difficult to reach beyond an image of God of the type that was found in Newton, for example. According to the legacy of Newton, which in this respect is unfor tunate, a God who is linked only to the current boundaries of scientific knowledge will sooner or later inevitably be reduced to a constantly retreating "God of the gaps." Theology certainly does not shut itself off from questions of "a God on the border of the known," but it is just as interested in a "God in the center of the known." While physicists who reflect upon God deal mostly with such boundary questions and thus often presuppose a deistic or an abstract theistic concept of God, theologians tend to be more involved "at the center" of world events, reflecting upon the relation of God in, with, and under things that are happening. To be sure, this difference is not an excuse for avoiding the dialogue about the boundary conditions of the universe, but it can nevertheless explain some of the difficulties of communication that repeatedly threaten to disrupt the discussion.
One of the most easily recognizable difficulties of cosmology is that its insights cannot be verified with absolute certainty by means of experiments. This, in turn, contributes to the extremely hypothetical character of cosmo-logical models, which can therefore also be interpreted very differently, depending on one's viewpoint. For example, if one considers the Big Bang to be the absolute starting point, one can define a universal time using the homogeneity and isotropy of the cosmic background radiation.272 Although we do not know anything about the behavior of such a universal time within Planck time, such a definition would practically satisfy the requirements of physical time measurement. Thus, both absolute time and, in a certain way, an "ether"—in the form of background radiation—would exist again, although the latter would not be a medium, but rather a reference point for the measurement of time and velocity. The question, though, of whether there is actually only one single timescale in the universe has not yet been answered definitively.273
This rather pragmatic interpretation is contradicted by a critical interpretation that, like Hawking, adds quantum physics to the relativistic gravitational theory, but draws other conclusions by basically questioning the continuity of temporality. Against the backdrop of the successive limitation of the concept of time from one level of physical theory to another, this interpretation argues for a collapse of the dynamic concept on the level of quantum gravity.274 In Newton, time was still an absolute, infinite continuum; the special theory of relativity problematized universal simultaneity, the general theory of relativity focused on boundaries for the expansion of time by means of singularities, and quantum theory showed the impossibility of exact access to the measurement of time. Finally, the integration of quantum and space-time theories at and "prior to" the Planck time point to a collapse of the time concept as such. Instead of an entity of universal significance, time in this interpretation is only a local, internal concept.
According to the assumption that the most comprehensive theory always contains the more special ones as a limiting case, it follows: If this critical interpretation applies, the collapse of the dynamic conception in quantum cosmology must be of greater fundamental significance than the evolutionary models for explaining the world. Then the collapse of the dynamic concept in quantum gravity is "not just a detail at some irrelevant scale, because it affects, or should affect, the concepts of space and time as they are used at all levels."275
Repeatedly, experiments have been designed with the aim of circumventing the problem of time. The physicist Julian Barbour provides an example in this direction.276 In 1999, he introduced his theory of a timeless quantum cosmology. He maintains that he has been successful in uniting Einstein's theories of relativity, which deny the existence of a universally valid time, with quantum mechanics, which appears to require such a time. According to Barbour, there is no time. In his eyes, recognizing this represents a revolution in our understanding of the universe. What we consider to be time and movement is illusion. The only things that exist are timeless moments. Barbour considers the notion of a timeline or a time arrow to be unnecessary. Instead, he speaks of "time capsules."277 Such time capsules describe all static formations that generate the impression that a process has occurred. Both the brain seen in its entirety and the earth in its entirety are time capsules. The time capsules can be hidden inside of one another like Russian dolls. In deliberate allusion to the Greek philosopher, the world, which is made of these special moments, is called Platonia. The name is meant to mirror the mathematical perfection and the timeless landscape. Platonia is the arena that, according to Barbour, replaces space and time. Platonia and the quantum-theoretical wave function, as Barbour understands it, form the universe. The philosophy or theology that appears to result from this concept expresses itself in a worship of the "now" or in a pantheistic worldview.278 In Barbour, once again that which has already been addressed several times becomes evident, namely, how short, in many respects, the distance is between mathematics and theology: "It seems that the greatest engine of cultural change—the scientific world-view—rests on a mathematical foundation that, in many respects, is ultimately religious."279 What has been presented in this section indeed deals with ideas that lie within the sphere of what currently constitutes the boundary of cosmologi-cal research and no doubt contains speculative elements. Nevertheless, it is clear that the universe does not have a precisely defined time if one wishes to unite the general theory of relativity with quantum physics. Thus, the possibility "that the evolutionary presentation [of space and time in cosmology] is one of limited validity, and not the most fundamental one"280 cannot just be discarded and must be considered when searching for dynamic relational models for time and eternity. Time would then be something secondary that does not belong to the fundamental laws of the universe and something that more or less had come into being by accident.281 Also, theories about the nonexistence of time will surely be further discussed in the future. If one is successful in finding a theory of everything, the so-called TOE, this theory will probably be timeless (and spaceless) from the beginning. If time is then derived as emergent from such a theory, time would have to be irreversible from the start. Such a concept of time would be in harmony with thermodynamics, which we will consider in the next section.
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