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From: Sam Wormley on 6 Jan 2010 10:41
The North American Nanohertz Observatory for Gravitational Waves
http://arxiv.org/abs/0909.1058

"The North American Nanohertz Observatory for Gravitational Waves
(NANOGrav) is a consortium of astronomers whose goal is the creation of
a galactic scale gravitational wave observatory sensitive to
gravitational waves in the nHz-microHz band. It is just one component of
an international collaboration involving similar organizations of
European and Australian astronomers who share the same goal.
Gravitational waves, a prediction of Einstein's general theory of
relativity, are a phenomenon of dynamical space-time generated by the
bulk motion of matter, and the dynamics of space-time itself. They are
detectable by the small disturbance they cause in the light travel time
between some light source and an observer. NANOGrav exploits radio
pulsars as both the light (radio) source and the clock against which the
light travel time is measured. In an array of radio pulsars
gravitational waves manifest themselves as correlated disturbances in
the pulse arrival times. The timing precision of today's best measured
pulsars is less than 100 ns. With improved instrumentation and
signal-to-noise it is widely believed that the next decade could see a
pulsar timing network of 100 pulsars each with better than 100 ns timing
precision. Such a pulsar timing array (PTA), observed with a regular
cadence of days to weeks, would be capable of observing supermassive
black hole binaries following galactic mergers, relic radiation from
early universe phenomena such as cosmic strings, cosmic superstrings, or
inflation, and more generally providing a vantage on the universe whose
revolutionary potential has not been seen in the 400 years since Galileo
first turned a telescope to the heavens".

Related News Article (includes video)
http://news.discovery.com/space/shimmer-me-this.html

From: Raymond Yohros on 6 Jan 2010 13:06
On Jan 6, 10:41 am, Sam Wormley <sworml...(a)gmail.com> wrote:
> The North American Nanohertz Observatory for Gravitational Waves
>    http://arxiv.org/abs/0909.1058
>
> "The North American Nanohertz Observatory for Gravitational Waves
> (NANOGrav) is a consortium of astronomers whose goal is the creation of
> a galactic scale gravitational wave observatory sensitive to
> gravitational waves in the nHz-microHz band. It is just one component of
> an international collaboration involving similar organizations of
> European and Australian astronomers who share the same goal.
> Gravitational waves, a prediction of Einstein's general theory of
> relativity, are a phenomenon of dynamical space-time generated by the
> bulk motion of matter, and the dynamics of space-time itself. They are
> detectable by the small disturbance they cause in the light travel time
> between some light source and an observer. NANOGrav exploits radio
> pulsars as both the light (radio) source and the clock against which the
> light travel time is measured. In an array of radio pulsars
> gravitational waves manifest themselves as correlated disturbances in
> the pulse arrival times. The timing precision of today's best measured
> pulsars is less than 100 ns. With improved instrumentation and
> signal-to-noise it is widely believed that the next decade could see a
> pulsar timing network of 100 pulsars each with better than 100 ns timing
> precision. Such a pulsar timing array (PTA), observed with a regular
> cadence of days to weeks, would be capable of observing supermassive
> black hole binaries following galactic mergers, relic radiation from
> early universe phenomena such as cosmic strings, cosmic superstrings, or
> inflation, and more generally providing a vantage on the universe whose
> revolutionary potential has not been seen in the 400 years since Galileo
> first turned a telescope to the heavens".
>
> Related News Article (includes video)
>    http://news.discovery.com/space/shimmer-me-this.html
>

great stuff sam!,

i wonder how significant earth gravitation itself
can be in filtering out this very weak form of radiation?

happy new year
r.y
From: dlzc on 6 Jan 2010 14:27
Dear Raymond Yohros:

On Jan 6, 11:06 am, Raymond Yohros <b...(a)birdband.net> wrote:
....
> i wonder how significant earth gravitation
> itself can be in filtering out this very
> weak form of radiation?

That is one of the reasons they are looking off-Earth, I am sure.
LIGO has returned no positive detections to date. The next version of
LIGO may have the same issues.

A 3D web of detectors might do better.

But I don't see how either arrangement can see what equates to a
*torque* applied to the Universe as a whole, since "distance
detections" are based on light propagation, and such detections
individually cannot detect "transverse motion", only "radial motion".

Have to wait for details...

David A. Smith
From: Raymond Yohros on 6 Jan 2010 15:48
On Jan 6, 11:27 am, dlzc <dl...(a)cox.net> wrote:
> Dear Raymond Yohros:
>
> On Jan 6, 11:06 am, Raymond Yohros <b...(a)birdband.net> wrote:
> ...
>
> > i wonder how significant earth gravitation
> > itself can be in filtering out this very
> > weak form of radiation?
>
> That is one of the reasons they are looking off-Earth, I am sure.
> LIGO has returned no positive detections to date.  The next version of
> LIGO may have the same issues.
>

yes, this is the way i see it too. i dont believe ligo has a chance
unless
its some sort of tsunami that can go through d earth like a small
island.
but look at the challenge of doing this on space:
putting lasers floating in space totally out of phase with eachother
at extreme long distances?
is this possible?

maybe gw can be discover indirectly in some other way?

regards
r.y
From: Tom Roberts on 6 Jan 2010 16:14
Raymond Yohros wrote:
> maybe gw can be discover indirectly in some other way?

Yes. They have been indirectly observed in the behavior of the binary pulsars.
They are spinning down at a rate accurately predicted by the emission of
gravitational waves in GR. Hulse and Taylor received a Nobel Prize for this.


Tom Roberts
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