2. THE FIRST VERSION OF THE BLACK HOLE ORIGIN THEORY OF THE UNIVERSE: [SMITH, 1990]

The basic idea behind the Smith [1990] theory is that some black holes have two properties, sucking in matter from one maximal spacetime S1 and spewing forth the matter in a different maximal spacetime S2. Smith's [1990] reads: ". . .one and the same singularity S has the property of sucking in matter (qua black hole singularity) and spewing forth matter (qua big bang singularity). [Smith, 1990: 42].

The big bang singularity in our spacetime is a black hole singularity in another spacetime, and this latter spacetime has a big bang singularity that is a blackhole singularity in yet a third spacetime, and so on ad infintim. This hypothesis, I argued, explains the existence, initial conditions and basic physical constants of our universe.

The explanataion has the following structure. There is some singularity S that has the property of being the big bang singularity in our spacetime M1 and a second property of being a black hole singularity in a different spacetime M2. The singularity S in an endpoint of some timelike and null curves in M2 and the beginningpoint of the timelike and null curves in our spacetime M1. In the spacetime M2, the matter sucked into the black hole is crushed out of existence at the black hole singularity S. But in our spacetime M1, the singularity S explodes and spews forth mass-energy in an expanding spacetime. Not only the mass-energy in our spacetime begins to exist in this big bang explosion, but spacetime itself begins to itself.

Smith's [1990] hypothesizes that the spacetime M2 contains not only the black hole that resulted in our spacetime M1, but many other black holes, say 10 billion. One billion of these ten billion black hole singularities in M2 also have the property of being a big bang singularity of another spacetime M', such that one billion spacetimes are a consequence of the black holes that belong to the spacetime M2. This provides for an inductive-statistical explanation of the initial conditions and basic laws unique to our spacetime M1. For the sake of familiarity let us adopt Hempel's theory of inductive-statistical explanations, I-S explanations, particularly as he later modified it in response to Salmon's argument [1971] that probabilities lower that 1/2 have explanatory relevance. Hempel's modified version [1976], which allows probabilities less than 1/2 into the explanans of I-S explanations, shall be called a neo I-S explanation. A neo I-S explanation explains something in the sense that it predicts it with some degree of probability. Contra Humphreys [1989] and Salmon's later theory [1984], Hempel, the early Salmon and I hold that the explanans need not cite a probabalistic cause of the explanandum. It is sufficient that the explanans lead us to predict the explanadum with some degree of probability. However, in the third, quantum gravity version of this theory, I shall provide a causal explanation of these factors. But for now, let us stay with the 1990 theory.

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Applying established scientific theory to new domains can take us beyond the realm of testable science. For an idea to be outside that realm requires not just that no experiment or observation that could test it is feasible with current technology but that no phenomenon could ever be observed that could illuminate the subject. Physicists’ speculations about universes outside our own observable universe (speculations that I find both fascinating and plausible) are extensions into a realm where tests are impossible, because those other universes are, by definition, outside anything we might ever observe. Such implications from scientific knowledge are not quite at the same level as scientific knowledge in testable domains. I call such speculation scientific metaphysics, to distinguish it from much metaphysical speculation that is clearly not scientific and even contradicts known science. The speculations of scientific metaphysics are constrained and illuminated by the logic of science; they emerge from the same theories that bear on our observable universe and its history. They can lead to new ideas that inform theories of observable phenomena. Some physicists may see the term metaphysics as pejorative, but I do not intend it in that way; I merely wish to distinguish this thinking from that which can be constrained by observations.

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4. A THIRD AND SUCCESSFUL VERSION OF BLACK HOLE ORIGIN COSMOLOGY

Smith [1990] and Smolin [1997] both failed to develop succesful versions of the cosmological natural selection theory. I shall here present in barest outline form a version that I believe can be successfully developed in a detailed way.

Criteria for theory-formation include simplicity, explanatory power, predictive novelty, conservatiness, nonarbitrarness and symmetry, among others. I shall here make use specifically of conservatiness and symmetrry.

A brief and intuitive understanding of conservatiness may be obtaining by saying that a theory T1 is more conservative than a theory T2 if T1 requires less changes in our background or prior scientific beliefs than T2. For example, if theory T2 requires a change only at the periphery of our web of belief, to borrow Quine's metaphor, and T1 requires only a change at the center of our web of belief than, then T2 is more conservative than T1 and, all else being equal, we ought to believe T2 rather than T1.

The symmetry criterion is illustrated by the fact that if we know a situation S1 that instantiates the property F also instantiates the property G, and we know there is another situation S2 that instantiates F and that is all we know about S2 except for the fact that it must instiate either G or H, but not both, then, all else being equal, we ought to belief that situation S2 insitantiates the property G rather than the property H.

In our Black Hole Origin Theory of the universe, we have at the core of this theory the hypothesis that the big bang in our universe is connected to a black hole in another universe. One question we need to ask, but which Smolin does not ask, is what kind of black hole is connected to our big bang? The principles of conservativness and symmetry imply that we should postulate that it is a Kerr black hole (which is a rotating rather than non-rotating black hole).

The reason for this is that all observed black holes in our universe, such as Cygnus X-1, are Kerr Black holes. The other theoretical criteria, explanatory power, preditive novelty, simplicity, etc., do not counterbalance this hypothesis since nothing is gained (in respest of any these criteria of theory formation) by hypothesizing that the black hole is a Schwarschild black hole or a Reissner-Nordstrom black hole. If all else is equal regarding our knowledge of black holes, we ought to believe the black hole that is connected to our universe is a Kerr black hole.

Now comes the most important obstacle to the cosmological natural selection theory, the obstacle that defeated versions one and two of this theory. This is to explain the nature of the connection between the black hole and the big bang of our universe. We recall that version one failed since Johnson, Geroch, Liang and Wald demonstrated the unsuccesfulness of the b-boundary and c-boundary constructions of "singularties" as really existent points on the boundary of a spacetime, leaving version one without an existent reality, a point, that could both be the end-point of a black hole and the beginning-point of a big bang explosion. Version two failed because its postulate that time continues through a black hole into a big bang at the Planck density is inconsistent with the accepted scientific notions that linear time breaks down at the Planck density.

A Kerr black hole is rotating and has a singularity at r = 0. As my first attempt to develop a more satisfactory third version of the Black Hole Origin Theory, I will allow the theoretical criterion of explanatory power to override the criterion of symmetry and conservativeness, since if I postulate that the black hole connected to our big bang is not a normal Kerr black hole, i.e., the type we observe in our universe, but is instead a Kerr vacuum black hole (or, if you prefer, a Kerr white hole), then we will have a type of black hole that can lead to a big bang explosion. A vacuum black hole does not arise from a gravitation collapse If we apply the metric of a normal Kerr black hole to a Kerr vacuum black hole, we will have at r = 0 a disc singularity. The edge of this disk has an infinite curvature, and the rest of the disc is an extendible edge of spacetime. Call the spacetime in which this Kerr vaccuum black hoile exists S1. From the viewpoint of the spacetime S2 into which worldlines can be extended, the Kerr vacuum black hole singularity will be the extendible part of the disk. I hypothesize that this edge of this disk is the big bang singularity of the new spacetime S2.

This Kerr vacuum black hole is not to be confused with the popularly discussed Einstein-Rosen bridge that connects two pre-existing universes [Smith, 1990: 41]; such a bridge invovles two Schwarschild vacuum black hole singularities in two asympotically flat regions of a Minkowski spacetime that connect and form a transient worm-hole between the two spacetime regions. This familiar idea will not help us, since it presupposes rather than explains the existence of the two spactimes that are connected by the wormhole.

The Kerr vacuum black hole gives us a basis to work from, since neither [Smith, 1990] nor [Smolin, 1997] ever explained how a theory of a black hole exploding as a big bang can be mathematically described by a solution to Einstein's equation. For example, Smith [1990: 41] says the major problem with his theory is that "there is no known solution of the equations of GTR that shows a singularity of one of these sorts [i.e. a black hole singularity] to also be a singularity of the other sort [i.e. a big bang singularity]" Smith [1990] is right in only one respect; the Kerr vacuum black hole solution to the Einstein equation does not require that the disk is in fact extended into another spacetime. It implies merely that it is extendible, i.e. that it is physically or nomologically possible for it to be extended. But Smith [1990] is wrong in another respect; he thought there was no solution to the Einstein equation that allowed for the physical or nomological possibility of a singularity that had the property of being both a black hole singuality in one universe and a big bang singularity in a second universe. However, the disk is precisely such a singularity.

Furthermore, Smith was wrong in [1990] in asserting that all vacuum black holes (white holes) are retarded pieces of a big bang singularity. This is required of Schwarzschild vacuum black holes [Misner, Thorne and Wheeler, 1973: 842-843], but not of Kerr vacuum black holes. But note that this issue is in fact irrelevant, which is a point Smith did not grasp in [1990]. For even if all vacumm black hole singularities are retarded pieces of a big bang singularity, the big bang singularity in our universe could have the property of being a vacuum black hole that is a retarded part of the big bang singularity in another universe. There is no necessity for the big bang singularities to be gravitational collapse black hole singularities rather than vacuum black hole singularities.

By identifying the Kerr vacuum black holes as the class of black holes relevant to big bangs, we seem to have made the first step towards developing a third and improved theory of the Black Origin Cosmological Theory.

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