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Quantum Fluctuations and Inflation

Inflation has always been hard to get one’s thoughts around. If nothing can travel faster than light, then how can the universe itself have expanded from submicroscopic to astronomical size in mere moments? The solution — that while nothing can move through space faster than light, space itself knows no such restriction — is still unsatisfying, for we don’t understand how inflation happens, or how it may still affect the accelerating expansion of today’s universe.

The best recent work on these matters has been done through analysis of data from the Wilkinson Microwave Anisotropy Probe (WMAP), using three years worth of observations of the cosmic background radiation. The temperature of that afterglow tells us much about the universe’s age and how it developed, and WMAP can read such temperature fluctuations down to grades finer than a millionth of a degree. The new measurement gives us clues not only about that crucial first trillionth of a second, but also about how and when the first stars began to form. The pattern being studied is less than a hundredth of the strength of the temperature signal that made news three years ago when the early WMAP results came in.

The tiny patterns discernible in the WMAP data, it is believed, eventually emerged into galaxies; at this stage of the infant universe, however, they appear simply as temperature variations within what is otherwise a uniform background light. The new data support the idea that inflation indeed occurred, leading to the formation of the first stars some 400 million years later.

“This is brand new territory,” said WMAP team member Lyman Page of Princeton University in Princeton, N.J. “The polarization data will become stronger as WMAP continues to observe the microwave background. WMAP’s new results heighten the urgency of seeking out inflation’s gravitational wave sign. If gravitational waves are seen in future measurements, that would be solid evidence for inflation.”

So what happened when inflation was triggered? Quantum fluctuations at the subatomic level suddenly became converted into flucuations within matter itself. In a sense, what we see at the largest level in the cosmos around us should, by this theory, reflect the quantum-level characteristics of the early universe, the origin of everything writ large in the sky. And as Page notes above, these fluctuations should also have produced gravitational waves that would have left a signature in the background radiation. Future measurements of the cosmic microwave background from WMAP could confirm inflation, which a mere 25 years ago seemed the wildest of speculations, and now can find support within hard mission data.

Centauri Dreams‘ note: The model that is being confirmed by continuing WMAP analysis is that the normal matter we see around us makes up only 4 percent of the total. It is now thought that 22 percent is in the form of the mysterious dark matter that has yet to be identified, while fully 74 percent exists as dark energy, equally mysterious, and apparently causing a new acceleration, though on a far more sedate scale than the one at the beginning of time. Given that we have a reasonable handle on a mere 4 percent of what makes up the universe, doctrinaire statements about the nature of reality seem increasingly inadvisable!

For more on the WMAP results, click here. These results have also been submitted to the Astrophysical Journal.