Has Cosmic Inflation Been Proved?

Biblical creationists know from Scripture that the universe did not begin in a big bang billions of years ago.

According to the big bang model, the universe suddenly appeared 13.8 billion years ago in a very dense, hot state that expanded into the universe that we see today. Based on this assumption, the big bang model predicted that the universe ought to be filled with radiation in the microwave part of the spectrum having a temperature of only a few Kelvin (K). This radiation, referred to as the Cosmic Microwave Background (CMB), supposedly comes from a time a few hundred thousand years after the big bang. In 1965, two astronomers announced the discovery of a 2.73 K temperature radiation field coming from every direction. This was hailed as proof of the prediction of the big bang model, and so most scientists came to embrace the big bang as the origin of the universe.

Proposing Cosmic Inflation

However, cosmologists realized that there were problems with the CMB. One of these was the horizon problem: the CMB observed from opposite parts of the sky had precisely the same temperature. But how could that be? Those positions opposite one another had never had a chance to exchange heat, so how could they have come into thermal equilibrium (i.e., have the same temperature)?

More than 30 years ago, a theoretical physicist named Alan Guth suggested cosmic inflation to solve the horizon problem. According to the theory of cosmic inflation, 10-34 seconds after the big bang the universe briefly and rapidly expanded, or inflated, to a much larger size with a velocity far faster than the speed of light. This would allow the entire universe initially to be in thermal contact so that it could come into the thermal equilibrium before being pulled out of thermal equilibrium by inflation. Cosmic inflation had the added benefit of solving another difficulty with the big bang, the flatness problem. After much discussion, cosmologists came to embrace cosmic inflation, although there has been no evidence for inflation.

Evidence for Cosmic Inflation?

Today, a team of scientists announced what they think may be the first evidence for cosmic inflation. This work is based upon a certain kind of polarization in the CMB. Like any other electromagnetic radiation, the CMB is a wave phenomenon. Most waves vibrate in all directions, but sometimes waves can vibrate more in one direction than in others. If so, we say that the wave is polarized. Electromagnetic waves can be polarized different ways. Different physical mechanisms can polarize electromagnetic waves differently, so by studying how and to what degree the radiation is polarized, we can gain clues as to what physical mechanisms may have been involved.

According to the big bang model, cosmic inflation may have imprinted a certain kind of polarization in the CMB, and several experiments are now operating to look for the polarization predicted by these models. Today’s announcement is the preliminary result of one of these experiments. However, cosmic inflation is not a single theory, but rather it is a broad theory with an infinite number of variations. Thus, it may not be proper to claim that this discovery proves inflation. Rather, it may merely rule out some versions that cannot be true.

Our Response

This announcement undoubtedly will be welcomed as the long-sought proof of cosmic inflation so necessary to the big bang model. Biblical creationists know from Scripture that the universe did not begin in a big bang billions of years ago. For instance, from God’s Word we understand that the world is far younger than this. Furthermore, we know from Genesis 1 that God made the earth before He made the stars, but the big bang requires that many stars existed for billions of years before the earth did. So how do we respond to this announcement?

First, this announcement may be improperly understood and reported. For instance, in 2003 proof for cosmic inflation was incorrectly reported and a similar erroneous claim was made last year. Second, the predictions that are being supposedly confirmed are very model-dependent: if the model changes, then the predictions change. Inflation is just one of many free parameters that cosmologists have at their disposal within the big bang model, so they can alter these parameters at will to get the intended result. Third, other mechanisms could mimic the signal being claimed today. So, even if the data are confirmed, there may be some other physical mechanism at play rather than cosmic inflation.