Casey Luskin noted a while back at Evolution News that a recent article in Nature noted that many universes theory is not testable:
Since the early 1980s, some cosmologists have argued that multiple universes could have formed during a period of cosmic inflation that preceded the Big Bang. More recently, string theorists have calculated that there could be 10 [to the]500 universes, which is more than the number of atoms in our observable Universe. Under these circumstances, it becomes more reasonable to assume that several would turn out like ours. It’s like getting zillions and zillions of darts to throw at the dart board, Susskind says. “Surely, a large number of them are going to wind up in the target zone.” And of course, we exist in our particular Universe because we couldn’t exist anywhere else. It’s an intriguing idea with just one problem, says Gross: “It’s impossible to disprove.” Because our Universe is, almost by definition, everything we can observe, there are no apparent measurements that would confirm whether we exist within a cosmic landscape of multiple universes, or if ours is the only one. And because we can’t falsify the idea, Gross says, it isn’t science. (Geoff Brumfiel, “Outrageous Fortune,” Nature, Vol 439:10-12 (January 5, 2006).)
But, Luskin writes, “National Academy of Sciences member and Nobel Laureate Leonard Susskind was given print-space–in fact he had a highlighted box-quote–saying that we should not reject the multi-verse hypothesis on the grounds that it isn’t testable.”
Nature reports:
Susskind, too, finds it “deeply, deeply troubling” that there’s no way to test the principle. But he is not yet ready to rule it out completely. “It would be very foolish to throw away the right answer on the basis that it doesn’t conform to some criteria for what is or isn’t science,” he says. (Geoff Brumfiel, “Outrageous Fortune,” Nature, Vol 439:10-12 (January 5, 2006)
I love it! “It would be very foolish to throw away the right answer on the basis that it doesn’t conform to some criteria for what is or isn’t science …” Why so foolish? Because, while it doesn’t conform to science, it does conform to materialism?
(That said, it is nice to run into Susskind who feels as strongly as I do that “zillions” really IS a number, albeit an indefinite number that was created precisely for math-challenged persons such as me.)
Similarly, in Max Tegmark’s 2003 Scientific American article on the four levels of multi verses, we are told that
Cosmologists infer the presence of Level II parallel universes by scrutinizing the properties of our universe. These properties, including the strength of the forces of nature and the number of observable space and time dimensions, were established by random processes during the birth of our universe. Yet they have exactly the values that sustain life. That suggests the existence of other universes with other values.
So the only reason for the Level II universes’ supposed very existence is to avoid the obvious implications of observable fine-tuning in this one.
Now, of course there is no problem in principle with untestable theories being discussed.
The problem is that the many-universes hypothesis is used as a discussion-stopper – a way to avoid the fine-tuning of the universe.
Here’s what it reminds me of: A small child claiming that “the fairies” broke the vase or stole the cookies. I used to deal with that kind of thing as a childminder and later a young mother on a regular basis.
The real problem isn’t whether fairies exist or act – only a naif or a fool would try discussing that with the child – but whether “the fairies” are used to avoid addressing difficult sets of facts. So with many universes.
When dealing with such data sets from children decades ago, I usually resorted to the following judgement: “Well, if you know so much about the fairies, you must be part of their deplorable gang. You and they can spend the afternoon in your room, and I hope you enjoy each other’s company.”
I suppose if I were going to apply similar reasoning to claims about multiverses, I might say: “Well, you must know a lot about them. Can you arrange a tour of some of the better ones? No need to bother with the complete flops, of course. Moderate flops, we might possibly consider for educational reasons… “