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Our future, our universe, and other weighty topics


Saturday, August 29, 2015

The Latest Cracks in the Cosmological “Just So” Story

The term “just so story” refers to a poorly substantiated narrative in science that is told to explain something. Modern cosmology tells us a “just so” story to try to partially explain why the universe started out in such an exquisitely balanced state. Part of that “just so” story is the theory of cosmic inflation, the narrative that the universe underwent a period of exponential expansion in the first second of its existence. We are told that this special period of super-fast expansion lasted just a fraction of a second. 


Being used to reading triumphalist accounts of modern cosmology, I was pleasantly surprised to read the candid recent account in the very readable book At the Edge of Uncertainty by Michael Brooks, who has a PhD in quantum physics. In his chapter “Complicating the Cosmos,” Brooks paints a picture of a cosmology standard story that is showing many cracks. He cites Michael Turner of the University of Chicago as saying that the cosmic inflation theory is duct-taped and perhaps within a decade of falling apart.

Brooks cites the work of scientist Michael Longo:

Out of 15,000 visible galaxies, roughly 7 per cent more are “left-handed” than “right-handed.” The chances of this being a statistical fluke are about 1 in a million. Especially since, when you look at the southern sky, you see the same effect, but in reverse: more right-handed spirals than left...This means the universe was born with a spin. And if it has a spin, it also has an axis. And if there's one thing the universe isn't meant to have, according to the standard theory, it's an axis. 

Read the account here for a more detailed discussion.  

Brooks then discusses the problems with the Big Bang theory and lithium:

We now know that the cosmos contains one-third the amount of lithium-7 that the Big Bang theory says it should. We also know that there is too much lithium-4, which one less neutron in its nucleus. One thousand times too much, to be precise.

Off by a factor of 1000 – could it be our cosmologists are missing a thing or two (or perhaps 50 or 100)?

Describing a scientific paper by Paul Steinhardt, Anna Ijjas, and Avi Loeb (described by Brooks as Harvard's head of astronomy), Brooks says the following:

The Planck mission has ruled out all but a handful of possibilities for inflation, the paper said. Worse, the ones that disappeared were far more “natural” candidates than the inflation models that provide the best fit to the cosmological data, making them even less likely to be useful resolutions of the horizon problem and the flatness problem.

Brooks then describes an additional huge problem for the cosmic inflation theory created by findings about the Higgs boson. Brooks says, “Once we start adding in solutions to these problems – if we can come up with them – the Big Bang theory will start to look less like a coherent narrative and more like a dreamscape: a mad whirl of disconnected stories.”

Brooks interesting book appeared in 2014, and since then two additional “cracks” may have appeared in our cosmologists' “just so” story of cosmic origins. One is the situation discussed in this paper. The standard assumption of cosmic inflation predicts a universe that is spatially flat, without any spatial curvature. But according to that paper, the latest results from a Baryon Oscillation Spectroscopic Survey (BOSS) are in conflict or “tension” with the idea of a flat universe, and are more consistent with an assumption of a non-flat universe with a positive spatial curvature.

Still another recent “crack” in cosmological assumptions may be the recent discovery of a structure called the largest structure in the universe, “a ring of 9 gamma ray bursts (and hence galaxies) 5 billion light-years across” according to this account. Structures that large simply should not exist, according to thinking such as the cosmic inflation theory and the Cosmological Principle (the idea that the universe is the same no matter which direction we look in).

Perhaps such findings should instill a sense of humility in our cosmologists, and make them less likely to speak as if they understand exactly how the universe got to be this way.