Many universe theory explains a lot of things

Jack Dikian

September 2011

Inflation theory is the theorized extremely rapid expansion of the early universe by a factor of at least 10^78 in volume. The inflationary epoch lasted from 10^36 seconds after the Big Bang to approximately 10^33 seconds. This is a mind-boggling small period of time. It’s 0.000000000000000000000000000000000000 of a second after the big bang.

There are a number of variants to inflation theory or inflation models. An interesting model is the eternal inflation, which says (roughly speaking) that shortly after the Big Bang space-time expanded at different rates in different regions of the early universe, giving rise to bubble universes (that may function with their own separate laws of physics.

Our universe might just be one of many. While the concept is bizarre, it's a possibility, according to scientists who have devised the first test to investigate the idea at Imperial College London. The basic premise of the study is to look for collisions between universes by examining tell tale signs left behind in the cosmic microwave background radiation. This is the diffuse (thermal radiation) light left over from the Big Bang and pervades our universe.

Researchers used data from the Wilkinson Microwave Anisotropy Probe (WMAP) identifying four regions in the universe as promising candidates. However, statistical analyses suggested these patterns were likely to be random, resembling the circular shapes of collisions simply by coincidence. The European Space Agency's Planck satellite data set to be released in 2013, and the researchers plan to look again, surveying in particular the four areas of interest from this study.

A researcher from the University of British Columbia in Canada, agrees that the present data from WMAP is not likely to be precise enough to make a definitive statement, also excited by what the more detailed data from the Planck satellite might revel.

The obvious benefit that a multi-verse theory provides is an explanation for the strange coincidences in our own universe. Many of the fundamental constants such as the strength of gravity and the speed of light, seem perfectly calibrated to produce a universe in which galaxies, stars, planets and even life can form.

The scientists detailed their study in two research papers published recently in the journals Physical Review Letters and Physical Review D.

We are living but on a spec of dust looking out into the darkness

Jack Dikian

September 2011

The more I think about just how much we have been able to infer about the universe we live in the more amazing it all seems. I mean, here we are living on an unassuming rock orbiting a star near the outskirts of a galaxy. Our galaxy is estimated to contain 200 to 400 billion stars. Current estimates guess that there are 100 to 200 billion galaxies in the Universe. The universe is vast and we are living but on a spec of dust looking out into the darkness, looking back in time, and trying to make sense of it all.

The WMAP Explorer mission that launched June 2001 to make fundamental measurements of cosmology is analogies to a trapdoor spider coming out of its silk-lined burrow to examine the perimeter surrounding its burrow before it goes back inside to think about how might other terrains be like, what kind of soils, how small puddles of water be compared to vast oceans, and so on and so forth.

But, that’s exactly what the WMAP has been able to achieve. It has been able to study the properties of our universe as a whole. WMAP has been stunningly successful too, producing our new Standard Model of Cosmology. The 7-year data provide compelling evidence that the large-scale fluctuations are slightly more intense than the small-scale ones, a subtle prediction of many inflation models.

One of the problems the Big Bang theory was not able to explain is the horizon problem. Distant regions of space in opposite directions of the sky are so far apart that, assuming standard Big Bang expansion, they could never have been in causal contact with each other. This light travel time between them exceeds the age of the universe. Yet the uniformity of the cosmic microwave background temperature tells us that these regions must have been in contact with each other in the past.

The Inflation Theory, developed by Alan Guth, Andrei Linde, Paul Steinhardt, and Andy Albrecht, offer a solution to this and several other open questions in cosmology. Inflation supposes a burst of exponential expansion in the early universe, assuming distant regions of the universe were actually much closer together prior to Inflation than they would have been with only standard Big Bang expansion. Thus, such regions could have been in causal contact prior to Inflation and could have attained a uniform temperature.

Other reading

Alan H. Guth & Paul J.Steinhardt, "The Inflationary Universe", Scientific American, May 1984.

Andrei Linde, "The Self-Reproducing Inflationary Universe", Scientific American, November 1994.

Scott Watson, "An Exposition on Inflationary Cosmology", WWWarticle, 2000.

Alan H. Guth, "The Inflationary Universe : The Quest for a New Theory of Cosmic Origins", 1998.