Does the universe end at the farthest reaches we can observe? If it doesn’t, then what characteristics does this realm beyond the observable universe exhibit? While science fiction authors have written in depth about alternate universes, many scientists want to bring these questions into their arena. To do so, they must posit explanations that account for existing data and predict what future experiments and observations might reveal. The most expedient avenue for such investigations involves inflation and its effect on the cosmic microwave background (CMB) radiation .
A team of Caltech cosmologists recently developed an inflationary model that predicts that the universe is far larger than the region we can see (a Level I multiverse in more technical lingo). Their research seeks to explain a possible asymmetry of the amplitudes of the CMB fluctuations observed by WMAP. Hailed in the popular press as chance to “glimpse before the big bang”, this model makes predictions that will allow cosmologists to better understand the mechanism responsible for the important inflationary era early in the history of the universe.
The pertinent feature of their model utilizes two different scalar fields, instead of one, during the inflationary epoch. One field, the inflaton, drives the inflationary expansion. A second field called the curvaton produces the density fluctuations. Using a two-field approach allows the model to explain the possible asymmetry in the fluctuation amplitudes without disrupting the uniformity seen in the CMB.
Large-scale modes of the curvaton extend beyond the region that inflated to become our observable universe. Thus, different sections of the observable universe can have different values for the curvaton field. These variations lead to different amplitudes for the CMB fluctuations. If this model proves true, it implies that our observable universe represents a small fraction of the total size of the universe. More importantly, this model makes detailed predictions that will be tested by future measurements of the CMB by missions like Planck.
In an earlier TNRTB, I described another piece of data that indicates the universe is much larger than what we can see. Exciting times lay ahead as scientists try to find out just how big the universe is. Regardless of what future results reveal about the physical extent of the universe, RTB expects those results to also provide further demonstration that a supernatural Creator stands as the ultimate cause of this universe.
If you would like to see a question about the multiverse addressed in this forum, send it to firstname.lastname@example.org.