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Changing the Model to Fit the Data, Part 3

In parts 1 and 2 I looked at Danny Faulkner's counterintuitive complaint that scientists are untrustworthy due to their willingness to revise their theories when new evidence warrants it. As an example, Faulkner lists six problems for Big Bang cosmology, then asks why scientists don't simply abandon this model. Faulkner's six problems are the horizon problem, the flatness problem, the smoothness problem, the cosmic age, the increasing expansion rate, and string theory. Mainstream scientists readily acknowledge many of these are, or have been, problems for the Big Bang—although when scientists use the word "problem", they mean it in the sense of a puzzle to be solved rather than an issue that casts doubt on the entire theory or is likely to lead to its abandonment.

The first two problems on Faulkner's list are solved, as Faulkner grudgingly concedes, by cosmic inflation. The third is too, though Faulkner doesn't admit it.

In the late 1970s, a physicist named Alan Guth was studying the problem of magnetic monopoles. Though it didn't make Faulkner's list, this is one of the Big Bang's problems. Magnets, we all know, have two poles, labeled north and south. Bring two magnets together with the same pole facing, and they repel each other. Bring opposite poles together, and they will attract. Theoretically, however, both poles are not necessary to make a magnet. And one of the implications of the Big Bang model is that a large number of monopoles—objects with just one magnetic pole—should have been created in the early universe. But in all the decades of observations since, not one monopole has ever been detected. (Technically, there is a possibility one was detected on Valentine's Day, 1982, but even if genuine, it still leaves them much rarer than they ought to be.)

In 1979 Guth heard a lecture by Steven Weinberg about the Grand Unified Theory, which posited that in the early hot, dense universe the strong and weak nuclear forces and the electromagnetic force were all merged into a single force. These were then split apart during phase transitions. Guth hypothesized that during one of these phase transitions the universe might have gone through a period of supercooling. If this were the case, a false vacuum would have been created, resulting in negative pressure that turned gravity into a repulsive force. As a result, the universe would have entered a state of exponential growth, expanding to many times its original size in a very short time period. Guth was not certain exactly how the universe entered this state—or how it left it—but he realized it would solve the monopole problem. If space had been rapidly stretched in the early universe, the monopoles would be pushed far apart from each other. They would appear to be much less abundant, simply because there is so much more space.

Conversations with his colleagues showed Guth that inflation was not just a potential solution for the monopole problem. Inflation solves the horizon problem, the uniformity of the temperature of the cosmic microwave background radiation. Inflation stretched the universe to the point where regions that had previously been in equilibrium were now isolated from each other. The uniform temperature remains from the equilibrium reached before inflation.

Inflation also solves the flatness problem. The earth is about as spherical as an orange—not a perfect sphere, but close. However, standing on the surface we can't see enough of the earth to perceive its true shape. We have a number of ways to measure it indirectly, but we can't see the earth's true shape because it so big. Likewise, if inflation rapidly stretched the universe to many times its original size, it would appear extremely flat as well.

Finally, inflation solves the structure of large-scale objects, because small fluctuations in the CMB would have been stretched as well, becoming the lumps of matter necessary for gravity to pull together to form galaxies. These small fluctuations were first found by the CoBE spacecraft in the early 1990s, and they were very small indeed, on the scale of about one part in 100,000. Faulkner makes a big deal out of the fact that cosmologists expected the anomalies to be about ten times the size they actually found. And even after admitting that both the WMAP and Planck spacecraft confirmed these findings, Faulkner can't help but refer to the four years CoBE spent mapping the CMB as "meticulous data manipulation." Sounds like sour grapes to me.

Still, inflation has its own challenges. In the end it may turn out to be just a brilliantly creative but misguided idea. But for now, it's a promising avenue for research. And even if it does not end up being the answer, what we've learned from it may point the way to a better solution. And if we find one, Faulkner will likely characterize it as a "rescuing device" and therefore a reason to abandon the Big Bang.

 

Faulkner also lists three problems that cannot be solved by inflation.

String theory made the list apparently because it could potentially result in future modifications to the Big Bang model. Faulkner goes into no detail as to what modifications he has in mind, so I won't either.

The cosmic age problem refers to the results from the independent measurements of the age of the universe and the age of the oldest galactic clusters. At times, calculations showed the galactic clusters to be more than 15 billion years old. A reasonable scientist, looking at the numbers, would suggest re-evaluating the data. Structures of that age cannot exist in a universe that is only 13.8 billion years old. It only makes sense to recheck the measurements. Yet this is the exact thing Faulkner faults the scientists for doing. It's hard to imagine what else he could expect them to do, since objects of such great age aren't possible in a young-earth creationist framework either.

The same is true of the new cosmological constant. When, in the late 1990s, observations of deep-space objects suggested the universe is expanding faster now than it did in the past, it pointed to the existence of a previously unknown force (called "dark energy" because we're still in the dark about what it is and how it works). By repurposing a mathematical term originally invented by Einstein to try to prevent the expansion of the universe, cosmologists can at least describe mathematically what is happening with the expansion, even if we can't directly perceive the cause of it. Again, it means modifying the standard model, but again, I'm not sure what Faulkner would have us do instead. He may not know either; light reaching us from 13 billion years ago isn't allowed in the 6000-year YEC framework.

In his conclusion, Faulkner throws up his hands and calls for the Big Bang theory to be abandoned. I'll explain why that's a mistake that in my next post.

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