For most people, inflation refers to how much money they need to purchase basic goods and to the interest rates on their loans when their government decides to pay its bills by printing more money. The average worker might earn twice as much but discovers he can purchase only about two-thirds as much in the way of goods and services. Hyperinflation occurred in Germany in 1923 (see figure 1). At one point a small glass of beer and one pound of meat cost 4 and 36 billion German marks, respectively.
Figure 1: Hyperinflation
In 1923, German banknotes lost so much value due to inflation that many Germans found them to be an inexpensive substitute for wallpaper. Photo credit: German Government Archives.
The hyperinflation of the German mark is nothing, however, compared to what astronomers believe occurred to the size of the universe between 10-35 and 10-32 seconds after the cosmic creation event. Astronomers conclude that during this extremely brief instant the universe grew in size from one hundred million trillion times smaller than the diameter of a proton to about the size of a grapefruit. That is, the volume of the universe expanded by a factor of 10102 times in less than 10-32 seconds! In big bang cosmology nothing less than such hyperinflation shortly after the universe's birth would allow it to ever possibly support life.
Without the hyperinflation episode the universe would have lacked the uniformity and homogeneity life demands. (For example, the stars and planets needed to support life can form only in an extremely uniform and homogeneous universe.) These necessary characteristics, in turn, demand that light (or heat) everywhere in the universe be thermally connected to light (or heat) everywhere else in the universe. Yet without inflation even in a 14-billion-year-old universe there is not enough time for light to travel the necessary distances to explain such thermal connections.
Inflation is the last scientific prediction of the biblical big bang creation model1 yet to be proven beyond any reasonable shadow of doubt. Young-earth creationist leaders often use doubt about inflation as a tool to deflect criticism of their own creation models, particularly light-travel times in the universe. Critics of the young-earth view point out that if the universe is less than 50,000 years old, then light lacks the time needed to travel from distant galaxies to astronomers' telescopes. In reply, young-earth proponents argue that in the absence of inflation light in the universe cannot be causally connected if the universe is less than 15 billion years old. (It is for this reason that I sometimes refer to myself as a middle-age universe creationist since I hold that the universe is billions of years old, not thousands or quadrillions).
In a recently published article in the Astrophysical Journal, a team of twenty-eight astronomers from the USA, Britain, France, and Chile provided yet more evidence that the universe experienced a brief period of hyperinflation during its infancy.2 The group presented their analysis of two years worth of data from the Background Imaging of Cosmic Extragalactic Polarization (BICEP) instrument, a bolometric polarimeter located at the South Pole (see figure 2). The BICEP instrument's location allows it to take advantage of the extremely cold conditions of Antarctica which guarantee that insufficient water remains in the atmosphere to disturb the quality of the observations.
Figure 2: The BICEP Instrument
The BICEP bolometric polarimeter is the smaller of the two telescopes in this photograph. It is located on the left side of the roof of the two-story building. Photo credit: National Science Foundation
The BICEP experiment's objective is to measure at a high precision level the polarization of the cosmic background radiation left over from the cosmic creation event. Cosmic inflation and the theory of general relativity predict a primordial background of gravitational waves. These gravitational waves, in turn, predict a highly specified signature in the E and B polarization modes of the cosmic background radiation.
The E polarization mode in this radiation was previously detected in the analysis of the 5-year data stream from the Wilkinson Microwave Anisotropy Probe (WMAP) satellite.3 The analysis showed the polarization data from WMAP was consistent with both the inflationary hot big bang creation model and with the universe being dominated primarily by dark energy and secondarily by cold dark matter (the LCDM model). The analysis of the 2-year data stream from the BICEP instrument measured the E-mode to unprecedented precision. It accurately measured the E-mode angular power spectrum from multipole values 21 to 335. It detected for the first time the peak at multipole value = 140 that all inflationary models predicted must exist.
In addition to generating E-mode polarization, gravitational waves produced by the cosmic inflationary episode would induce a B-mode polarization in the cosmic background radiation. Unlike the E-mode, a B-mode detection would yield unambiguous proof for a cosmic inflation event. While an E-mode detection is a necessary requirement for the inflationary hot big bang creation event, there are exotic cosmic models capable of explaining the observed E-mode without inflation. However, only an inflation event could explain a B-mode detection.
The problem for astronomers, though, is that detecting the B-mode polarization in the cosmic background radiation is much more challenging than the E-mode. The WMAP, for example, lacked the sensitivity to even place a meaningful limit on the B-mode polarization. While the analysis of the 2-year data stream from the BICEP observations failed to detect the B-mode, it had sufficient sensitivity to place for the first time a meaningful constraint on the inflationary gravitational wave background. It eliminated several of the more exotic inflationary big bang models.
B- and E-mode polarization in the cosmic background radiation is just one of several tests for cosmic inflation. Two others, for which observational confirmation already exists, are in the values for the geometry of the universe and for what cosmologists term the “scalar spectral index,” a parameter that describes the nature of primordial density perturbations.
All inflationary hot big bang creation models predict the geometry of the universe must be flat or very nearly flat. Perfect geometric flatness is where the space-time surface of the universe exhibits zero curvature (see figure 3). Two meaningful measurements of the universe's curvature parameter, ½k, exist. Analysis of the 5-year database from WMAP establishes that -0.0170 < ½k < 0.0068.4 Weak gravitational lensing of distant quasars by intervening galaxies places -0.031 < ½k < 0.009.5 Both measurements confirm the universe indeed manifests zero or very close to zero geometric curvature and, hence, provide strong evidence for cosmic inflation.
Figure 3: Evidence for the Flat Geometry Predicted by Cosmic Inflation
If the geometry of the space-time surface of the universe is closed, the angular sizes of the hot and cold spots in maps of the temperature fluctuations in the cosmic background radiation will be large. If the cosmic geometry is open, the angular sizes of the hot and cold spots will be small. A flat-geometry universe will exhibit angular sizes in between. Consequently, high sensitivity measurements of the temperature fluctuations in the cosmic background radiation, such as those produced by the WMAP satellite, can determine whether the flat, or nearly flat, cosmic geometry predicted by inflationary hot big bang creation models is correct.
Models of the universe that exclude inflation predict the scalar spectral index must take on a value greater than 1.0. For the simplest cosmic inflation model the scalar spectral index = 0.95. For models invoking a more complex, but not wildly exotic, version of cosmic inflation, the scalar spectral index would fall between 0.96 and 0.97. The latest and best WMAP determination, in combination with the best results from the Sloan Digital Sky Survey and the Supernova Cosmology Project, yielded a scalar spectral index measure of 0.960 ± 0.013.6
Clearly, strong evidence for cosmic inflation already exists. The goal of the BICEP research team, however, is to continue their observational program at the South Pole. In due time they will possess a sensitive enough measurement of the B-mode polarization in the cosmic background radiation to determine exactly what kind of cosmic inflation is responsible for the present-day universe. Such an achievement will definitively establish both cosmic inflation and the theory of general relativity.
We hope this kind of hard scientific proof will help many people change their philosophical and theological objections to the biblically predicted big bang creation model.7 Hopefully, too, it will help proponents of young-earth creationism recognize that [scientific research on God's second book of revelation to humanity, namely the record of nature, is the friend and not the enemy of the Christian faith.8