Changing the Model to Fit the Data, Part 4

After summarizing the six problems and (very briefly) mentioning the ways scientists have met these challenges, Faulkner concludes,

Many scientists today think that the big bang model is very successful in that it can explain all sorts of new observations and problems. But it does this by the endless addition of rescuing devices. If a scientific theory can be freely amended to account for any new challenges, then can the theory ever be proved wrong? In science it’s important that an idea be able to be proved wrong, a least hypothetically. A theory that can explain anything and everything, no matter how contradictory, really isn’t science.

Faulkner attempts to discredit the Big Bang with a sleight of hand. He acknowledges that the Big Bang theory has been amended, with success, to meet the observational challenges. He then complains that a valid theory should not be able to "explain anything and everything." But the Big Bang doesn't explain "anything and everything". It only explains the observed universe. The (modified) Big Bang can explain the rate of universal expansion, the uniformity of the CMB radiation, the apparent age of the universe, and numerous other observations—including the size of the observable universe, the existence of quasars only at the far limits of our observation, and the inability to detect the magnetic monopoles that should have been created in the early universe.

But Faulkner doesn't care about any of that. He wants us to abandon the model because the original version wasn't perfect.

In his plea for scientists to abandon the Big Bang, Faulkner draws a comparison with Ptolemy's geocentric model of the universe. Geocentrism was mostly successful in predicting the movement of planets over time, but occasionally a planet would appear to reverse its course and travel in the opposite direction for a short time. Ancient astronomers solved this problem with the concept of epicycles. A planet orbited the earth in a large circle known as the deferent. But at certain points in its orbit, the planet would travel in a smaller circle, known as an epicycle, centered on the deferent. This led to a more accurate model of planetary motion, but further refinements were necessary. Adding a second epicycle within the epicycle improved the model, and adding a third was a further improvement. The Ptolemaic model would eventually be modified to include as many as 28 epicycles in the orbit of a single planet.

Faulkner concludes:

While this feature of endless modification was the reason for the success of the Ptolemaic theory, it eventually was its undoing, because the theory was abandoned largely over its complicated and unwieldy nature. The continued modification of the big bang model is beginning to resemble this cycle. How long will it last?

However, this analogy is fatally flawed. The Ptolemaic model was not undone by its complexity, but by a new model that described planetary motion in a more straightforward way. The heliocentric model, proposed by Nicolaus Copernicus in the 16th century, did away with epicycles entirely. If the sun rather than the earth were the center of the universe, each planet's orbit could be described as a single perfectly circular motion around the sun.

Except when they couldn't. The Copernican model also had its flaws. Tycho Brahe was a wealthy astronomer who plotted the position of Mars over several years. He hired young mathematician Johannes Kepler to calculate the orbit of Mars from this data. But Kepler could not match a circular orbit to the data. Kepler had to use an elliptical orbit to match Brahe's extensive observations. In other words, Kepler changed the Copernican model to fit the data.

Not long after, Dutch physicist Christiaan Huygens developed a system to estimate the distance to other stars. Though his method wasn't perfect, his results indicated the stars were much farther away than was previously believed. Which implied they were suns in their own right, and not objects orbiting our own sun.

Isaac Newton, building on Kepler's and Huygens's insights, and on his own theory of gravity, recognized that no object in the universe could truly be considered the center, because all objects exert a gravitational pull on each other. The center of the universe was "the common centre of gravity of the Earth, the Sun and all the Planets". This required further modification of the Copernican model, to allow for a center that could be outside the sun.

In the 18th century, English astronomer Thomas Wright posited that the stars orbited a common galactic center in the same way that the planets orbited around the sun. German astronomer Johann Heinrich von Mädler located this galactic center in the Pleiades star cluster. This required further revisions to the Copernican model to account for the sun's rotation around the galactic center.

Then in the 20th century, Edwin Hubble demonstrated the existence of other galaxies, and the fact that they were receding from us. This led to the Big Bang and the idea that the universe is homogeneous and isotropic. There is no center.

The only thing remaining from Copernicus' original heliocentric model is the name.

Yet the Copernican model, despite all its modifications—what Faulkner might call "rescuing devices" if young-earth creationism had existed in the 16th century—still describes the orbits of the planets better than any other model.

And the Big Bang describes the expansion of the universe, as well as a host of other observations, better than any other model. If young-earth creationists want scientists to discard the Big Bang, they'll have to come up with a better model.

Don't hold your breath.