Multiverses and Blackberries
by Martin Gardner
Skeptical Inquirer

[[We have included the first two and final paragraphs]]

The American philosopher Charles Sanders Peirce somewhere remarked that unfortunately universes are not as plentiful as blackberries. One of the most astonishing of recent trends in science is that many top physicists and cosmologists now defend the wild notion that not only are universes as common as blackberries, but even more common. Indeed, there may be an infinity of them!

It all began seriously with an approach to quantum mechanics (QM) called "The Many Worlds Interpretation" (MWI). In this view, widely defended by such eminent physicists as Murray Gell-Mann, Stephen Hawking, and Steven Weinberg, at every instant when a quantum measurement is made that has more than one possible outcome, the number specified by what is called the Schrödinger equation, the universe splits into two or more universes, each corresponding to a possible future. Everything that can happen at each juncture happens. Time is no longer linear. It is a rapidly branching tree. Obviously the number of separate universes increases at a prodigious rate.

[[Final Paragraph]]

The stark truth is that there is not the slightest shred of reliable evidence that there is any universe other than the one we are in. No multiverse theory has so far provided a prediction that can be tested. In my layman's opinion they are all frivolous fantasies. As far as we can tell, universes are not as plentiful as even two blackberries. Surely the conjecture that there is just one universe and its Creator is infinitely simpler and easier to believe than that there are countless billions upon billions of worlds, constantly increasing in number and created by nobody. I can only marvel at the low state to which today's philosophy of science has fallen.

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[[The second article of note is:]]

There was an old lady who swallowed a fly
from the Economist

The universe might make more sense if it was not alone

THE idea of multiple universes is a surprisingly attractive one. Two deep problems would go away if the universe were not, in fact, universal, but were merely one example of an infinitely large class of such objects. These problems are the true nature of the uncertainty principle, and the “anthropic principle”—the coincidence that the universe seems to be set up with precisely the right conditions for human-like life to evolve within it. Unfortunately, the sorts of “multiverse” proposed to resolve these two problems are different.

[[An explanation of why multiverse theories have proliferated throughout Academia]]

For most people, superseding the Copenhagen interpretation of quantum theory probably comes into the “angels dancing on pinheads” category of problem. “Why are we here?” may be a rather more fundamental question. As Sir Martin Rees points out, the conditions for human life to evolve depend on six fundamental physical phenomena—in other words, six numbers—being almost exactly what they are. Yet none of the values of these numbers is implicit in existing physical theory.

Two of the numbers Sir Martin identifies as critical to human existence are omega and lambda. If omega were higher, the universe would have collapsed back in on itself by now; if lower, it would have expanded too fast for galaxies and stars to form. A larger lambda would have had the same effect as a small omega. A third critical number is N. If it were significantly smaller (ie, gravity were more powerful in relation to electromagnetism), only a small, short-lived universe would be possible. A fourth is the number of extended dimensions. Life would be impossible in a two-dimensional universe: there is insufficient scope for the development of complex structures. Less obviously, it would also be impossible in a universe with four large-scale spatial dimensions. Both gravity and electromagnetism are governed by the inverse-square law, that is, their strengths drop with the square of the distance they are acting over. This is a basic consequence of geometry. Add a dimension, and the drop-off would be an inverse cube. That would cause chaos. To take just one example, there would be no stable orbitals for electrons around atoms. Atoms would not exist, so there would be no life.

Two other critical numbers have not been mentioned earlier. Epsilon measures the strong nuclear force. If this were changed, the chemical composition of the universe would be radically different, because the nuclear-fusion reactions that convert hydrogen into heavier elements in stars would produce a different mixture of elements. In particular, there would be very little carbon, which would make it hard for carbon-based life forms to emerge from the primeval soup.

Q is a measure of how tightly the things in the universe that are held together by gravity are bound by that force. It is the ratio between the energy of binding and the energy bound up in the mass of the object (E=mc2 yet again). Its value is about 1:100,000. If it were much smaller than this, the quantum ripples frozen by inflation would not have been attractive enough to act as seeds for the formation of superclusters. The universe would then contain a uniform gas. If it were much larger, most gravitationally bound objects would collapse into black holes—things of such density that not even light can escape their gravitational fields.

There are four competing ideas about why these numbers have the values that they do. One, of course, is that God willed it that way. The second, which is perhaps a non-deistic restatement of the first, is that when the theory of everything is worked out properly, it will be seen that these particular values of these particular constants are necessarily inevitable. The third is that they emerged by blind chance; a happy coincidence. The fourth is that they are actually a mixture of chance and necessity. It is chance that this particular universe fits, but because there is an indefinite (in effect, an infinite) number of universes, each governed by different solutions to string theory, some of those universes (indeed, also an infinite number of them) must have the right conditions for carbon-based life. Of course, life will arise only in those particular universes, so observers will only ever see that set of conditions. They must infer the existence of the others.

[[Concluding paragraph: a critique]]

Like all the best cosmic creation-myths, this one seems testable. Once again, MAP may provide the answer. Inflation would have produced gravitational waves. These should have imprinted the cosmic microwave background with a recognisable pattern in addition to the one created by the frozen quantum fluctuations. Ekpyrosis would have no such consequence. Absence of evidence is not, of course, evidence of absence, but if the predicted pattern is missing, then inflation, which currently lives by the cosmic microwave background, may end up dying by it.

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[ 22 January 2002: Message edited by: Moderator ]