The multiverse as a scientific concept

This article was first posted in two parts on Scientia Salon.

The multiverse concept is often derided as “unscientific” and an example of physicists indulging in metaphysical speculation of the sort they would usually deplore. For example commenters at Scientia Salon have said that the multiverse is “by definition not verifiable and thus outside the bounds of empirical science”, and that “advocates of multiverses seem to be in need of serious philosophical help”. [1]

Critics thus claim that the multiverse amounts to a leap of faith akin to a religious belief. Indeed, the religious often accuse atheistic scientists of inventing the multiverse purely to rebut the “fine-tuning” argument that they say points to a creator god (though the fine-tuning argument is readily refuted in several other ways, and anyhow physicists really don’t care enough about theology these days to let that worry them; further, the concepts leading to a multiverse were developed well before theologians started taking note of the issue).

The purpose of this article is to argue that the multiverse is an entirely scientific hypothesis, arrived at for good scientific reasons and arising out of testable and tested cosmological models. To be clear, I am not asserting that the multiverse has been proven true, even on the balance of probability, but I am asserting that it is a serious scientific concept that will eventually be accepted or rejected on scientific grounds.

Several different concepts could be labelled a “multiverse”, but I am advocating one particular multiverse concept, that arising from what cosmologists call the “eternal inflation” version of Big Bang cosmology. [2] I’ll outline why cosmologists have arrived at this model, which is now a mainstream account of the origin of our universe, and which leads naturally to a multiverse.

Science can indeed answer “why” questions

“Science can answer ‘how’ questions, but religion answers ‘why’ questions”   has become a cliche, oft-quoted by those believing in a proper role for religion even in today’s scientific world. Rarely is this claim argued for, rather it is usually stated as though it were obviously true, a knock-down argument that refutes scientism. The claim is that, while science can tell us how the natural world works, only religion can tell us how the universe came to be and why it was created. Too much emphasis on science is seen as leaving the narrow-minded advocate of scientism as lacking any appreciation of the world of values and emotions and desires and everything that makes life worth living.

The advocate of scientism rejects any such suggestion, considering that values and desires are just as much a property of the natural world as anything else, being the products of highly evolved but entirely natural animals, and thus just as much within the proper domain of science as anything else.

A fine-tuned universe argues for atheism

A favourite and fashionable argument for God is the argument from a fine-tuned universe. The argument is that, were it not for many aspects of our universe being “just right” for us to exist, then we wouldn’t be here, therefore [and that “therefore” is the big leap] the universe must have been fine-tuned to produce us.

Such an argument is advanced by theologians such as Alvin Plantinga and William Lane Craig, while Francis Collins has even gone so far as to claim that Richard Dawkins has admitted that he is troubled by the argument (this led to a witty response by Dawkins).

However, this argument is not just flawed, it actually contains six major flaws. The argument is one of those that is so unconvincing that it never leads anyone to believe in God, it only bolsters the faith of those who already believe, in which state their credulity renders them unable to examine the argument objectively.