Gravitational Wave Detection Gets A Boost

August 19, 2009 by Fred Bortz

Another blogger here has posted regularly with claims of theories that supersede both Relativity and Quantum Mechanics. I have been his primary challenger, though others have chimed in. Ultimately, I have concluded that his papers are either erroneous or not novel. But at least he has offered a claim that can be tested by observation. Now the possibility of such a test appears to be closer at hand.

His claim is that gravitational waves, which are predicted by the mathematics of General Relativity, do not exist.

Indeed, there has been no direct observation of gravitational waves, but there have also been no observations of events that would be expected to produce detectable gravitational waves. There is strong indirect evidence of gravitational waves, such as the in-spiraling of a binary pulsar system that matches the expectation of the emission of gravitational waves, work which led to the 1993 Nobel Prize in Physics.

But the acid test will be the detection, or non-detection, or gravitational waves from a cosmic event that would be expected to produce a detectable signal. I just got a news release touting a ten-fold increase in sensitivity in the near future, and I reproduce it below.

I hope the other blogger doesn't jump in here to reprise our old arguments, because no matter what he or I think about what is likely to happen down the road, the evidence will tell the tale. Those interested in our earlier discussions are welcome to visit his blog entries and those of "Scruffy".

Fred Bortz
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BRITISH-MADE TECHNOLOGY WILL BOOST
THE SEARCH FOR ELUSIVE GRAVITATIONAL WAVES

UK scientists are helping us edge ever closer to finding the
mysterious, theorized ripples in the fabric of space-time (known as
gravitational waves) with the production of 25 new assemblies for the
LIGO facility -- a network of detectors designed to search for these
elusive waves.

Funded by the US National Science Foundation (NSF), LIGO also allows
us to look inside the most violent events in the Universe and traces
its exotic phenomena in great detail. By increasing the sensitivity of
the LIGO detectors by a factor of ten, the upgrades will greatly
increase our chances of finding gravitational waves and open a new
observational window on the Universe to test our current theories and
models.

The UK’s Science and Technology Facilities Council (STFC) is
contributing £8.5m to this multimillion-dollar upgrade project, named
Advanced LIGO, and is managing the UK’s overall involvement, including
collaboration from the Universities of Glasgow, Birmingham,
Strathclyde and Cardiff. The UK’s deliverables are suspension systems
which help to ensure that the ultra-sensitive silica mirrors at the
heart of the upgraded detector will not be influenced by ground-borne
noise. The detector is sensitive to movements a hundred million times
smaller than an atom so it is vital to ensure that stray noise sources
are eliminated. Technology developed in the European GEO-600 project
is being used to ensure the performance needed by Advanced LIGO.
Shipping of the new parts to the US is currently underway.

The completion of the UK-made upgrades comes as the LIGO Scientific
Collaboration (of which the UK-German GEO600 group is a founding
member) and the Virgo Collaboration announce new results that have
significantly advanced our understanding of the early evolution of the
Universe.

In a paper published in Nature today (20th August) the scientists
explain how LIGO observations have 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, they have narrowed down the possibilities of how the
Universe looked in its earliest moments.

Prof. Jim Hough, UK Principal Investigator for the GEO600 project
said, “This paper helps demonstrate the real excitement and potential
of the field of gravitational wave studies to further our
understanding of the Universe.”

The Big Bang is believed to have created a flood of gravitational
waves when the universe was very young. These waves still fill the
universe today as background “noise”, similar to random ripples on a
pond on a windy day. The strength of this gravitational wave
background is directly related to the way the Universe was in the
first minute after the Big Bang, and the fact that we have not found
any signal so far already tells us the maximum strength which this
background could have.

This information builds on what we’ve learnt from studying the cosmic
microwave background -- heat radiation that tells us the way the
universe was when it was about 380,000 years old. This is still very
young compared with its present 14-billion year age, but much older
than the time period probed by gravitational waves.

“Since we have not observed the gravitational waves from the Big Bang,
some of these early-universe models that predict a relatively large
background of waves have been ruled out,” says Vuk Mandic, assistant
professor at the University of Minnesota.

“We now know a bit more about parameters that describe the evolution
of the universe when it was less than one minute old,” Mandic adds.

Justin Greenhalgh, from the STFC Rutherford Appleton Laboratory, said,
“Once it goes online, Advanced LIGO will allow us to further advance
this research into the evolution of the early Universe. It will be
able to detect cataclysmic events such as black-holes and neutron-star
collisions at 10-times-greater distances and will be sensitive to
sources of extragalactic gravitational waves in a volume of the
universe 1,000 times larger than we can see at the present time. The
new sensitivity of the instruments will propel our work forward and
allow us to reveal more of the hidden mysteries of our Universe.”

David Reitze, a professor of physics at the University of Florida and
spokesperson for the LIGO Scientific Collaboration, added,
“Gravitational waves are the only way to directly probe the universe
at the moment of its birth; they’re absolutely unique in that regard.
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.”

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.

Professor Keith Mason, Chief Executive of the Science and Technology
Facilities Council, said, “The new upgrades for LIGO will greatly
improve our chances of finding gravitational waves. If LIGO detects
them, it will be one of the biggest scientific breakthroughs of our
age and one to which UK scientists contributed a great deal of skills
and expertise. It will also open up a new kind of astronomy that will
allow us to study the Universe in much greater detail in a way that
does not rely on light.”

The analysis used data collected from the LIGO interferometers, a 2 km
and a 4 km detector in Hanford, Washington, and a 4 km instrument in
Livingston, Louisiana. Each of the L-shaped interferometers uses a
laser split into two beams that travel back and forth down long
interferometer arms.

# # #

Nature Paper:
The paper ‘An upper limit on the amplitude of stochastic gravitational
wave background of cosmological origin’ is available from the STFC
press office.

Images:
Images are available from the STFC press office

LIGO:
The LIGO project, which is funded by the National Science Foundation
(NSF), was designed and is operated by Caltech and the Massachusetts
Institute of Technology for the purpose of detecting gravitational
waves, and for the development of gravitational-wave observations as
an astronomical tool.

Research is carried out by the LIGO Scientific Collaboration, a group
of 600 scientists from 12 different countries. The LIGO Scientific
Collaboration interferometer network includes the LIGO interferometers
(including the 2 km and 4 km detectors in Hanford, Washington, and a 4
km instrument in Livingston, Louisiana) and the GEO600 interferometer,
located in Hannover, Germany, and designed and operated by scientists
from the Max Planck Institute for Gravitational Physics and partners
in the United Kingdom funded by the Science and Technology Facilities
Council.

The next major milestone for LIGO is the Advanced LIGO Project, slated
for operation in 2014. Advanced LIGO, which will utilize the
infrastructure of the LIGO observatories, and will be 10 times more
sensitive. Advanced LIGO will incorporate advanced designs and
technologies that have been developed by the LIGO Scientific
Collaboration. It is supported by the NSF, with additional
contributions from the Science and Technology Facilities Council and
the German Max Planck Gessellschaft.

Contacts:
Julia Short
Press Officer
Science and Technology Facilities Council
Tel: +44 (0)1793 442 012
E-mail: Julia.short@stfc.ac.uk

Justin Greenhalgh
STFC
Tel: +44 (0)1235 445 297
E-mail: justin.greenhalgh@stfc.ac.uk