WE ARE ALL DESIGNIST NOW:

Recently, a trio of mainstream physicists accused hundreds, perhaps thousands, of other mainstream physicists of Not Doing Science in a very public forum. Their article, published in February's Scientific American2, targets the inflationary universe theory, which, during the past 35 years, has come to be what most physicists use to explain the origin (and present state) of the cosmos. By publishing in SciAm, these authors aren't just asking the vicariously scientific public--you and I--to accept their theory as correct. They are asking us to decide what it means to Do Science.

This whole ordeal goes back to the Big Bang. As in, theory of. It's not terribly controversial, but it has a few problems. In the early 1980s, physicists were trying to make sense of a particularly vexing one: The Big Bang does not explain why the universe is so flat. Flat, in this sense, doesn't mean squashed or thin. It just means that most of the universe is basically an empty, featureless vacuum; galaxies, stars, planets, and whatever you prefer to call Pluto, all are statistical blips. Experiments measuring the breadth of the cosmos had shown there was no way the Big Bang was energetic enough to fling the universe so wide. It ought to be collapsing back in on itself. Instead, the universe is still expanding.

Three physicists--Alan Guth of MIT, Andrei Linde of Stanford, and Paul Steinhardt of Princeton--started working on inflation as a potential solution. Either right before or right after the Big Bang (depends on which inflationary model you accept), there existed a bubble of rapidly expanding inflationary energy. This turbo-charged the Big Bang. The universe opened up wide and flat. It's essentially a vast, uniform nothingness, except some regions of vacuum are ever so slightly more dense than others. These attract atoms, which form molecules, which form dust particles, which form rocks, which attract gases that get so dense they combust, wheedle, spin, orbit ... you know the rest.

Point is, without inflation (or something) the universe would have expanded too slowly, and the gravity from all that matter would have caused it to collapse back in on itself.

Inflation explained that process so well that it came to dominate mainstream physics. It isn't a theory, per se--not like the theory of relativity is a theory. It's more like

a thematically connected group of competing hypotheses, what Guth calls an "umbrella." They share some crucial traits, namely, ripples in the cosmic microwave background radiation. And the hypotheses predict that these traits will conform to certain numerical measurements. Some of these criteria have been met; for instance, in 1998 physicists found proof of dark matter, which accounted for 70 percent of the missing matter that inflation had predicted. Confirming other criteria has been more elusive.

For years, scientists have been looking for precise measurements of a type of gravitational radiation left over from the Big Bang. One recent experiment looking for this so-called B-Mode polarization used a European Space Agency satellite called Planck. And in 2013, scientists interpreting results from Planck said they fit right into one of the inflationary hypotheses.

Eureka? Not according to three other physicists who attended the ESA press conference where the Planck results were announced. They were Avi Loeb, chair of Harvard University's astronomy department; Anna Ijjas, then a grad student and now a post-doc at Princeton's Center for Theoretical Science; and Steinhard, one of the original inflation architects. They felt that the ESA had fit the Planck data to the most convenient inflationary hypothesis. But, crucially, not the simplest. Physics should favor simplicity, and the Planck data actually caused simpler inflationary models to make less sense.

They published a critique of inflation in the journal Physics Letters B--which eventually became the SciAm article--calling out what they saw as errors fitting the Planck data to inflation. They went even further. They pointed out that inflationary energy had never been directly observed, and was therefore hypothetical. Even more vexing to them was the fact that some inflationary models predict the existence of the multiverse, which by definition exists outside this universe's rules and thus cannot be tested using this universe's iteration of science.

But inflation's biggest crime was its flexibility: The authors argue that inflation contains so many hypotheses that you can essentially fit at least one of them around any new data that comes out. In short, inflation can never be disproved. People studying it, therefore, are Not Doing Science.

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