Cosmology: "The Universe Is Precisely 13.75 Billion Years Old"

"The Universe Is Precisely 13.75 Billion Years Old"

By Ian O'Neill

"The Universe is 13.75 billion years old, primordial helium has been spotted for the first time and key evidence for the inflationary period immediately after the Big Bang has been found. But not all the new discoveries by NASA's Wilkinson Microwave Anisotropy Probe (WMAP)* appear to fit cosmological theory.

Previously, scientists using data from WMAP measured the time since the Big Bang to be an incredibly precise 13.73 billion years (give or take 0.12 billion years). And now, using the same space-based observatory, the age of the universe has been refined even further, adding another 20 million years to the total (plus or minus 0.11 billion years).

Using data from the first 7 years of operation, this refined universal age could be arrived at. Previously, the first 5 years of WMAP observations were used; the longer the observatory is operational, the longer the exposure time, therefore the results become more precise. This news comes as a series of papers from the WMAP team have been published concerning several different aspects of the observations.

WMAP is constantly surveying the furthermost reaches of the universe, measuring the very faint "echo" of the Big Bang. This echo is known as cosmic microwave background (CMB) radiation, a remnant of the vast energies unleashed as the universe burst into being. By mapping the slight variations of temperature in this background radiation, a lot of information about the conditions of the early universe can be gleaned, but cosmologists aren't only interested how long ago the Big Bang occurred. They are trying to find further evidence for what we believe happened in the moments after the Big Bang and now WMAP is filling in the gaps of our knowledge.

In addition to the precise age measurement, WMAP has been able to detect small acoustic oscillations (the cosmic equivalent to sound waves) in the CMB radiation,** and the signature detected suggests primordial helium was generated in predicted quantities in the early stages of universal evolution. Also, by measuring the fluctuations of the CMB radiation over all scales, there is evidence that suggests there was a very rapid expansion just after the Big Bang. This supports inflation theory and provides further evidence for the mysterious "Dark Energy" that is predicted to permeate through the universe, causing space-time to expand at an accelerated rate.

Although this all sounds great, there's one observation that can't be explained by theory. The amount of CMB radiation spotted near clusters of galaxies is greater than expected. According to theory, CMB photons should interact with these clusters, getting kicked to higher energies. WMAP cannot detect these higher energy photons, so there should be a deficit of CMB photons around clusters. This is not the case and scientists will probably be confused by this for some time to come.

WMAP continues to open our eyes to the nature of our universe by measuring the Big Bang echo, supporting current theories about how the cosmos started out, but challenges other theories as to how CMB radiation should behave. Although the WMAP mission is set to end in the fall of 2010, its results will reverberate for years to come.

*The uncertainties in the measurements don't come from astronomers lack of accuracy, far from it. When measuring cosmic times and distances, very slight errors may creep into the calculations. Some errors might be down to slight instrumental irregularities or fuzziness in datasets, so as a matter of good practice, scientists calculate a "margin for error" in their results. Ideally this margin should be as small as possible, but it will never disappear all together."

- http://news.discovery.com/space/the-universe-is-precisely-1375-billion-years-old.html
Additional information links:
* http://science.howstuffworks.com/hole-in-universe1.htm
** http://science.howstuffworks.com/space-shape3.htm