Nav: Home

Gravitational Wave Observatory listens for echoes of universe's birth

August 19, 2009

GAINESVILLE, Fla. --- An investigation by a major scientific group headed by a University of Florida professor has advanced understanding of the early evolution of the universe.

An analysis of data from the Laser Interferometer Gravitational-Wave Observatory Scientific Collaboration, or LIGO, and the Virgo Collaboration has set the most stringent limits yet on the amount of gravitational waves that could have come from the Big Bang in the gravitational wave frequency band where LIGO can observe. In doing so, scientists have put new constraints on the details of how the universe looked in its earliest moments.

"Gravitational waves are the only way to directly probe the universe at the moment of its birth; they're absolutely unique in that regard," said David Reitze, a UF professor of physics and the spokesperson for the LIGO Scientific Collaboration. "We simply can't get this information from any other type of astronomy. This is what makes this result in particular, and gravitational-wave astronomy in general, so exciting."

The research is set to appear in the Aug. 20 issue of the journal Nature. Seventeen UF faculty members, postdoctoral associates and graduate students join the paper's authors.

Much like it produced the cosmic microwave background, the Big Bang is believed to have created a flood of gravitational waves -- ripples in the fabric of space and time -- that carry information about the universe as it was immediately after the Big Bang. These waves would be observed as the "stochastic background," analogous to a superposition of many waves of different sizes and directions on the surface of a pond. The amplitude of this background is directly related to the parameters that govern the behavior of the infant universe.

Earlier measurements of the cosmic microwave background have placed the most stringent upper limits of the stochastic gravitational wave background at very large distance scales and low frequencies. The new measurements by LIGO directly probe the gravitational wave background in the first minute of its existence, at time scales much shorter than accessible by the cosmic microwave background.

The research also constrains models of cosmic strings, objects that are proposed to have been left over from the beginning of the universe and subsequently stretched to enormous lengths by the universe's expansion. These strings, some cosmologists say, can form loops that produce gravitational waves as they oscillate, decay and eventually disappear.

Gravitational waves carry with them information about their violent origins and about the nature of gravity that cannot be obtained by conventional astronomical tools. The existence of the waves was predicted by Albert Einstein in 1916 in his general theory of relativity. The LIGO and GEO instruments have been actively searching for the waves since 2002; the Virgo interferometer joined the search in 2007.

The UF LIGO research group built one of the most important and complex parts of the gravitational wave detector, the input optics, said David Tanner, a UF professor of physics. The input optics takes light from the laser, shapes the beam into an ideal form, and directs it to the interferometer at the heart of the gravitational wave detector. UF scientists are working to design and build a second version of the input optics for a major upgrade to LIGO scheduled to go on line in three to four years.

"UF also plays important role in analysis of LIGO data, including searches for sharp bursts of gravitational waves, and for the stochastic background of gravitational waves ... the subject of the just published paper," Tanner wrote in an e-mail.

The authors of the new paper report that the stochastic background of gravitational waves has not yet been discovered. But the nondiscovery of the background described in the Nature paper already offers its own brand of insight into the universe's earliest history.

The analysis used data collected from the LIGO interferometers in Hanford, Wash., and Livingston, La. Each of the L-shaped interferometers uses a laser split into two beams that travel back and forth down long interferometer arms. The two beams are used to monitor the difference between the two interferometer arm lengths.

"Since we have not observed the stochastic background, some of these early-universe models that predict a relatively large stochastic background have been ruled out," said Vuk Mandic, assistant professor at the University of Minnesota and the head of the group that performed the analysis. "We now know a bit more about parameters that describe the evolution of the universe when it was less than one minute old."
-end-


University of Florida

Related Big Bang Articles:

Big brains or big guts: Choose one
A global study comparing 2,062 birds finds that, in highly variable environments, birds tend to have either larger or smaller brains relative to their body size.
Dark matter may be older than the big bang, study suggests
Dark matter, which researchers believe make up about 80% of the universe's mass, is one of the most elusive mysteries in modern physics.
Cincinnati researchers say early puberty in girls may be 'big bang theory' for migraine
Adolescent girls who reach puberty at an earlier age may also have a greater chance of developing migraine headaches, according to new research from investigators at the University of Cincinnati (UC) College of Medicine.
More bang for the climate buck: study identifies hotspots for adaptation funding
Using a combination of crop models and expertise from farmers and others -- and applying them to our current trajectory of high greenhouse gas emissions -- scientists built a tool to assess climate risk vulnerability to help pinpoint communities in need of support for adaptation and mitigation.
Big data takes aim at a big human problem
A James Cook University scientist is part of an international team that's used new 'big data' analysis to achieve a major advance in understanding neurological disorders such as Epilepsy, Alzheimer's and Parkinson's disease.
More Big Bang News and Big Bang Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Erasing The Stigma
Many of us either cope with mental illness or know someone who does. But we still have a hard time talking about it. This hour, TED speakers explore ways to push past — and even erase — the stigma. Guests include musician and comedian Jordan Raskopoulos, neuroscientist and psychiatrist Thomas Insel, psychiatrist Dixon Chibanda, anxiety and depression researcher Olivia Remes, and entrepreneur Sangu Delle.
Now Playing: Science for the People

#537 Science Journalism, Hold the Hype
Everyone's seen a piece of science getting over-exaggerated in the media. Most people would be quick to blame journalists and big media for getting in wrong. In many cases, you'd be right. But there's other sources of hype in science journalism. and one of them can be found in the humble, and little-known press release. We're talking with Chris Chambers about doing science about science journalism, and where the hype creeps in. Related links: The association between exaggeration in health related science news and academic press releases: retrospective observational study Claims of causality in health news: a randomised trial This...