Changing the Model to Fit the Data, Part 1

Of all the creationist arguments against mainstream science, perhaps the most perplexing is the complaint that scientists are willing to modify their theories to account for new evidence. Danny Faulkner of Answers in Genesis, interviewed by Carl Wieland and Jonathan Sarfati of Creation Ministries International, was blunt in describing his concerns with Big Bang cosmology.

It is the overwhelmingly dominant model, and they’ve had a few impressive predictions, like the background radiation. But it has many problems—they keep changing the model to make it fit the data we have.

Over on the AiG site, Faulkner goes into more detail about his objections in an article titled Big Bang—The Evolution of a Theory.

So the big bang quickly became the dominant theory of the history of the universe among cosmologists. Since then new observations and ideas have come along that have challenged the big bang. Rather than abandoning the theory, however, cosmologists and astronomers have met each challenge with modifications. In the process, the big bang has morphed into something that little resembles its first incarnation. Many people view these modifications as improvements, but are they really?

Spoiler: Yes they are, really. If they weren't improvements, they wouldn't have been considered in the first place.

But if it needed so many modifications, how did the Big Bang become the dominant model? Let's look at the, ahem, background. As even Faulkner admits, the success of the Big Bang theory is built on the discovery of cosmic microwave background (CMB) radiation in the 1960s.  This uniform black body radiation had been predicted by George Gamow and Ralph Alpher in 1948 as an implication of the Big Bang model. This model—rooted in Edwin Hubble's observation that most of the other galaxies are moving away from ours—posits the universe has expanded from an initial hot, dense state. Gamow realized the initial state would have yielded an isotropic sea of electromagnetic radiation. As the universe expanded, this radiation would have stretched and cooled, but should still be observable wherever we look in the universe, if only we had the tools to see it.

In 1964, astronomers Arno Penzias and Robert Wilson began setting up the Holmdel Horn Antenna, which they had received from Bell Labs. They intended to measure radio signals from the space between galaxies, but their receiver kept picking up microwave static. In an attempt to eliminate the static they methodically removed or neutralized every possible source, including pigeon poop on the antenna, but the static remained. Worse, it seemed to be coming from all directions at once. They contacted Princeton University physicist Robert Dicke, who had been looking for a way to measure the CMB radiation. Dicke, realizing that Penzias and Wilson had found what he had only theorized, told his colleagues, "We've been scooped."

The cosmic background radiation was real, it was in the temperature range predicted by the theorists, it had the expected blackbody spectrum, and it was uniform throughout the universe. No other cosmological model could explain CMB radiation. The Big Bang was vindicated.

But soon, problems arose. The CMB, upon closer inspection, was a little too uniform. In fact, the entire universe was a little too uniform, in a few ways. These are commonly known as the horizon problem, the flatness problem, and the smoothness problem. Faulkner mentions these in his article, then additionally lists (but mislabels) the cosmic age problem and the increasing expansion rate, and concludes his list with string theory. Mainstream scientists readily admit most of these are problems for the Big Bang, although it's important to note that when scientists use the word "problem", they mean it in the sense of a puzzle to be solved, a challenge, and not in the sense of an issue that casts doubt on the entire theory or is likely to lead to its abandonment.

I'm going to follow Faulkner's lead and summarize each of these problems, but unlike Faulkner I'll then look at the possible solutions.

The horizon problem relates to the uniformity of the temperature of the CMB radiation. If we look in one direction and measure the temperature of the CMB as it approaches us, then look in the opposite direction and measure the temperature of the CMB approaching us, we shouldn't expect them to be exactly the same. Slight variations would be normal in a universe that has not reached thermal equilibrium. And it shouldn't have reached equilibrium yet; even in a closed system—the earth's atmosphere, for example—we see relatively wide variations in temperature. And, absent some mechanism for faster-than-light communication,  the radiation as we scan the night sky in one direction has not had time to make contact with radiation from the other direction. Yet whichever direction we look, the CMB is the same temperature.

The flatness problem relates the the density parameter of the universe. If the density of all the matter in the universe were too large, it would eventually create enough gravitational pull to re-collapse the universe. This is known as a closed universe. By contrast, an open universe is one in which the density of matter is too little, and the universe continues expanding forever. In between these scenarios, there is a specific density, known as the critical density, in which the universal expansion eventually (after an infinite amount of time) reaches equilibrium, and stops. This is known as a flat universe.

Of all the possible densities the universe could have, nearly all would result in either a closed or an open universe. It's very unlikely that the density at the very beginning of the universe was exactly the right amount for a flat universe. Yet most measurements, including the very precise measurements from the WMAP spacecraft, indicate that the universe is indeed flat.

The smoothness problem relates to the large-scale structure of the universe. If the universe were as smooth as it appears to be, we shouldn't see matter clumped into large objects like stars and galaxies. The tiny particles scattered throughout the early universe should have been too uniformly distributed to have joined together to create the large-scale structures of today's universe, let alone complex living things. And yet, here we are.

I'm already at more than a thousand words and not even finished with the summary. I'll continue in my next post.