| Topic: |
Science > Physics |
| User: |
"Sam Wormley" |
| Date: |
17 Mar 2006 05:56:09 PM |
| Object: |
A New Triumph for Inflation |
A New Triumph for Inflation (Physics News Update #769)
http://www.aip.org/pnu/2006/split/769-1.html
The inflationary big bang model has passed a crucial test as
scientists working on the Wilkinson Microwave Anisotropy Probe
released a long-awaited second set of data at a press conference held
March 17.
WMAP was launched in 2001 to map the anisotropies in the cosmic
microwave background (CMB) with far greater precision than the Cosmic
Background Explorer, the predecessor that first discovered the
anisotropies in 1990s.
The earlier release of WMAP data 3 years ago nailed down several
grand features of the universe that had previously been known only
very roughly, including: the time of recombination (380,000 years
after the big bang, when the first atoms were formed); the age of the
universe (13.7 billion years, plus or minus 200 million years); and
the makeup of the universe (with dark energy accounting for 73
percent of all energy -- see PNU 624).
Since that 2003 announcement, WMAP researchers have painstakingly
worked to reduce the uncertainties in their results. The big new
thing in yesterday's announcement, based on three years of data, was
the release of a map of the sky containing information about the
microwaves' polarization (see image at Physics News Graphics).
The microwaves are partly polarized, or oriented, from the time of
their origin (emerging from the so called sphere of last scattering
-- see PNU 591) and partly polarized by scattering, on their journey
to Earth, from the pervasive plasma of mostly ionized hydrogen
created when ultraviolet radiation from the first generation of stars
struck surrounding interstellar gas.
WMAP now estimates that this reionization, effectively denoting the
era of the first stars, occurred 400 million years after the big
bang, instead of 200 million years as had been previously thought.
The main step forward is that smaller error bars, courtesy of the
polarization map and the much better temperature map across the sky
-- with an uncertainty of only 200 billionth of a degree Kelvin --
provide a new estimate for the inhomogeneities in the CMB's
temperature.
The simplest model, called Harrison-Zeldovich, posits that the
spectrum of inhomogeneities should be flat; that is, the
inhomogeneities should have the same variation at all scales.
Inflation, on the other hand, predicts a slight deviation from this
flatness.
The new WMAP data for the first time measures the spectrum with
enough precision to show a preference for inflation rather than the
Harrison-Zeldovic spectrum -- a test that was long-awaited as
inflation's smoking gun.
Papers available on the NASA Web page;
http://map.gsfc.nasa.gov/m_mm/pub_papers/threeyear.html
Image available at Physics News Graphics
http://aip.org/png/2006/253.htm
High resolution images and more information available on the NASA page
http://map.gsfc.nasa.gov/m_mm.html
.
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| User: "tomgee" |
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| Title: Re: A New Triumph for Inflation |
18 Mar 2006 08:27:54 PM |
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Sam Wormley wrote:
A New Triumph for Inflation (Physics News Update #769)
http://www.aip.org/pnu/2006/split/769-1.html
The inflationary big bang model has passed a crucial test as
scientists working on the Wilkinson Microwave Anisotropy Probe
released a long-awaited second set of data at a press conference held
March 17.
SNIP
Since that 2003 announcement, WMAP researchers have painstakingly
worked to reduce the uncertainties in their results. The big new
thing in yesterday's announcement, based on three years of data, was
the release of a map of the sky containing information about the
microwaves' polarization (see image at Physics News Graphics).
SNIP
WMAP now estimates that this reionization, effectively denoting the
era of the first stars, occurred 400 million years after the big
bang, instead of 200 million years as had been previously thought.
The main step forward is that smaller error bars, courtesy of the
polarization map and the much better temperature map across the sky
-- with an uncertainty of only 200 billionth of a degree Kelvin --
provide a new estimate for the inhomogeneities in the CMB's
temperature.
The simplest model, called Harrison-Zeldovich, posits that the
spectrum of inhomogeneities should be flat; that is, the
inhomogeneities should have the same variation at all scales.
Inflation, on the other hand, predicts a slight deviation from this
flatness.
The new WMAP data for the first time measures the spectrum with
enough precision to show a preference for inflation rather than the
Harrison-Zeldovic spectrum -- a test that was long-awaited as
inflation's smoking gun.
The data does not show a "preference for inflation...", as the author
claims, but it simply shows that there is a slight variation from the
simplest model and the IP invention predicts that. It may have been a
crucial test of the IP non-theory, but I would not call it a "triumph"
since it is hardly a resounding success for the IP. The data also
supports my model that does not include an IP. The IP concept has yet
to come up with a reasonable explanation of what caused the inflation.
.
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