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January 31, 2004

How to Challenge Science

The Creationists arrived like clockwork in the comments thread in yesterday's entry, dragging their usual tired armaments of Richard Behe and "Evolution is just a theory" with them because they're apparently under the impression that I'm as ignorant and credulous as they are. I'm not, and I've got the entire corpus of evolutionary biology to back me up, yo. So please, if Behe and a fundamental misunderstanding of what the word "theory" means in the context of science is all you got, please don't come knocking. I've got better things to do.

Such as: Noting an example of how science actually works to challenge existing theory -- not by hauling out bad science performed by people of dubious qualifications in the service of an already-determined result, but by people of experience offering new hypotheses to better fit data about the universe as it exists. As it happens, the popular science magazine Discover has as this month's cover story a fine example of this: A new spin on the creation of the universe.

Let's recap: Currently, the best theory we have on how the universe begun is the Big Bang theory, which says (very basically) that some 13.7 billion years ago the universe sprang into being as a super-dense, super-massive pinprick of matter and energy, which rapidly expanded and cooled over time, forming stars, galaxies and superclusters as it did so. The reason the Big Bang theory is the current leading theory is that it is the theory that best describes the universe as it exists -- it explains the universal background radiation, for example, as well as the percentage of helium present in the universe.

But there are things in the universe which are not easily explained -- for example, the universe seems to be flying apart at an increasing speed over time, necessitating the need for cosmologists to postulate the existence of mysterious "dark energy" -- and there are some kludgy patches that cosmologists have applied to the Big Bang theory to make it work in light of emerging data about the universe. One big kludge is the "inflationary model," which has the universe undergoing an astounding faster-than-light increase in size for a very short (far less than a second) but immensely significant amount of time. The problem with these sort of kludges is that they make the big bang theory significantly more complicated -- and whenever possible, scientists want to find the simplest explanation possible for what they observe.

With that in mind (and here I note I'm skipping over a tremendous amount of information relating to superstring theory and quantum physics), cosmologists Neil Turok, Paul Steinhardt, Burt Ovrut and Justin Khory have suggested a new model of universal creation called the "ekpyrotic universe." In this theory, there is no initial "Big Bang." Instead, our universe exists as a three-dimensional "membrane" floating in a multidimensional space with other similar "branes." At some point, our universe's "brane" collided with another "brane" -- a cosmic crash-up from which was released immense amounts of energy that eventually became the observable universe. The beauty of this theory is that it obviates the need for "dark energy" -- the increasing expansion of the universe is apparently an artifact of the initial collision, and by eliminating the need for a Big Bang, also gets rid of inelegant things like inflationary periods (which, interestingly, was theorized in part by Steinhardt).

(And for those of us who are sort of depressed about the idea of an eventual heat death of the universe, the ekpyrotic universe offers the potential for the universe to begin anew every trillion years or so, as the "branes" that created the universe -- and which drifted apart thanks to the energy released in the collision -- drift together again for another universe-creating crash-up.)

How have cosmologists reacted to this new hypothesis? Well, they are skeptical, of course, as well they should be. Indeed, even its presenters acknowledge that it needs to jump over a number of hurdles before it can claim acceptance -- the review of the cosmologists' professional peers, for example, and the collection of data which can either support or refute the hypothesis. "If weíre right," says Steinhardt in the Discover article, "it will be terrifically exciting. If we turn out to be wrong, thatíll be disappointing, of course, but itís still important to challenge inflation with alternate theories so we can see how robust it really is."

It's also worth noting that before Steinhardt, et al. presented the idea of the "ekpyrotic universe," they spent a year and a half secretly trying to break it -- that is, to look for ways that they could prove it false. "We fully expected the whole idea to fall apart," Turok told Discover.

So, why is this good science?

1. It attempts to explain the observed data collected about the universe.
2. It does not start from a conclusion about the nature of the universe and work its way backward.
3. Those who have presented the hypothesis work in the field and know its intricacies -- indeed, one of of the presenters helped create the current "best-fit" model of the universe.
4. The presenters questioned their own hypothesis extensively and critically over a significant amount of time before presenting it to their peers -- i.e., performed due diligence.
5. They have presented it for peer review and accept the idea that it may be incorrect and recognize the need for data to support their hypothesis.

Should we teach the ekpyrotic universe in our schools alongside the Big Bang, as an alternate theory of the creation of the universe? No -- because there's not enough data to support its hypothesis one way or the other. And certainly if its fundamental theses are disproved by data, it should be tossed aside as a viable theory -- much like the "Steady State" theory was displaced by the Big Bang theory. We might briefly note it as an example of an alternate theory (and I should note that in my own astronomy book, I do just that -- giving it a paragraph in a sidebar about alternate theories), but until it proves itself viable, it doesn't merit displacing the current model or being taught as a "separate-but-equal" alternative.

This is how science is challenged: Thoughtfully, carefully and in service to the universe as it is, not how we wish it to be. Would that all those who wish to their "theories" considered in our places of learning were so devoted to the processes of science, and willing to have it challenged before proclaiming it as a viable "alternative."

Posted by john at January 31, 2004 03:56 PM

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» Is it my breath? from Pharyngula
John Scalzi hammers on the creationism issue, and notices something: The Creationists arrived like clockwork in the comments thread inyesterday's entry, dragging their usual tired armaments of Richard Behe and "Evolution [Read More]

Tracked on January 31, 2004 05:53 PM