Supernovas, such as the one which created the Crab Nebula, should send out bursts of gravity waves.NASAPosted on 08/22/2009 10:05:51 PM PDT by neverdem
Sensitive search fails to find ripples in space, but boosts hopes for future hunts.
Supernovas, such as the one which created the Crab Nebula, should send out bursts of gravity waves.NASAThe hunt for gravitational waves may not have found the elusive ripples in space-time predicted by Albert Einstein, but the latest results from the most sensitive survey to date are providing clear insight into the origins and fabric of the Universe.
General relativity predicts that gravitational waves are generated by accelerating masses. Violent yet rare events, such as a supernova explosion or the collision of two black holes, should make the biggest and most detectable waves.
A more pervasive yet weaker source of waves should be the stochastic gravitational wave background (SGWB) that was mostly created in the turmoil immediately after the Big Bang, and which has spread unhindered through the Universe ever since.
The Laser Interferometer Gravitational-wave Observatory (LIGO) detectors, based in Washington state and Louisiana, look for these cosmic gravitational waves by measuring any slight disturbance to laser beams that shuttle between heavy mirrors held kilometres apart. Whereas the gravitational wave signal from a distinct event, such as a black-hole merger, would appear as a spike in the LIGO data, the SGWB is a murmur that is more difficult to detect.
“For 40 years they've been saying that gravity waves are around the corner ... I think for the first time that's actually a true statement.”
Michael Turner
University of Chicago, Illinois
Working with the Virgo Collaboration, which runs a gravitational wave detector near Pisa, Italy, the LIGO team has now analysed what their own detector saw between November 2005 and September 2007. Although LIGO did not find any waves, the teams conclude in Nature1 that the SGWB is even smaller than LIGO can currently detect. This result rules out some theoretical models of the early Universe that would generate a relatively large background of gravitational waves.
"This is the first time that an experiment directly searching for gravitational waves is essentially going and making a statement about cosmology, about the evolution of the Universe," says Vuk Mandic, an astrophysicist at the University of Minnesota in Minneapolis, and part of the LIGO team. The data also exclude certain cosmological models involving cosmic strings — hypothetical cracks in the fabric of space that are thinner than an atom but have immense gravitational fields.
The LIGO results reduce the upper limit for the size of the SGWB, which had previously been set by indirect measurements. A relatively large SGWB in the very early Universe, for example, would have had a measurable effect on both the cosmic microwave background radiation left over from that time, and the relative amounts of light elements — such as hydrogen, helium and lithium — created within minutes of the Big Bang.
The LIGO and Virgo collaborations are in the process of merging their scientific efforts, and the teams plan to include data and collaborative work from both experiments in all of their future papers. Detector improvements should help Virgo to match LIGO's sensitivity in the next few years, and a series of upgrades to both experiments should increase their sensitivity to the SGWB by more than a thousand times by 2014 — which astrophysicists say is almost certain to be enough to pin down its quarry at last.
"For some 40 years they've been saying that gravity waves are around the corner," says Michael Turner, an astrophysicist at the University of Chicago in Illinois, who was not involved in the research. "And I think for the first time in 40 years that's actually a true statement."
“Violent yet rare events, such as a supernova explosion or the collision of two black holes, should make the biggest and most detectable waves.”
Unless your presuppositions regarding such objects/events are completely false...
Astro-Space Pings
True enough, if you accept an unproven hypothesis, it’s tough to explain when things don’t work out.
Have any of Einstein’s equations or theories proven to be wrong?
It’s the gravity Tsunami I’m worried about, those
things are too big to surf! Well, maybe not for
the Silver Surfer...
I think the Democrat party is selling them now that Obama has lost his gravitas.
Yes, all of them when applied to subatomic particles. Einstein's theory of relativity applies to very large objects like solar systems and objects traveling near the speed of light. In those cases his theories give accurate results when compared to the measurements. But when applied to subatomic particles his theories do not match the measured results. That is where quantum mechanics come in. Quantum mechanics describes subatomic particles accurately.
Einstein's theory of relative and quantum mechanics contradict each other. They can't both be true, and both are probably false. So the hunt is on for the Theory of Everything (T.O.E.) that will describe both objects moving near the speed of light and subatomic particles. One of the candidates is super string theory. This is strictly theoretical since the proposed strings are too small to detect with instruments. One of the things it predicts is the graviton, a particle of gravity. But the graviton has not shown up yet.
The graviton won’t show up. String theories are garbage science IMO. Even it’s proponents concede that to even begin getting useful results they need to fudge in an extra dimension, M-theory. 11 dimensions to describe a three dimensional, inverse square, phenomenon. The two competing theories currently used work extremely well in there respective fields. The concept and model of gravity is wrong.
FReepmail me if you want on or off my health and science ping list.
Try doing google searches on "Dayton Miller"...
Yup.
Michelson-Morley found a drift, but it was within the margin of error of the experiment, so it was discounted.
What always gets me is that to validate Einstein, they say that there was no drift, but then they come back and say that to validate Einstein, we need gravity waves, which is to say instead of the object accelerating in space, we have space somehow accelerating past the object.
Unfortunately the article seems to miss that obvious point. The most important aspect of the failure to detect gravity waves is that is brings into at least some doubt the validity of Einstein's General Theory of Relativity. That is a very big deal and, IMHO, a source of great embarrassment to the physics community.
Plenty of hard evidence for both.
cosmological constant
“God does not play dice.”
Y’know, I thought I heard somethin’ in the other room...
‘Non-discovery’ of space-time ripples opens door to birth of the Universe
The Times | 8/20/2009 | Mark Henderson
Posted on 08/19/2009 7:20:29 PM PDT by bruinbirdman
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