Gravitational radiation has not been directly detected, there is indirect evidence for its existence.

Not radiation, energy! ;)

Whats the difference?
It's energy that propagates in space and time and is called radiation.

Here is an analogy.

Electromagnetic radiation is a wave that propagates in space and time. Radiation propagation is described by Maxwell's equations and it consists of an electric and a magnetic field that oscillates at a right angle to each other and to the direction.

Electromagnetic radiation occurs in many scientific and technological fields, and has several characteristics, such as wave-particle duality of photons as an energy-carrying quantum.

Maxwell's four equations.

"In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium."

So far we don't have gravitation waves...nor the gravitation particles! To conclude - no radiation...
;)

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non-profit org. Play4Life in Zagreb, Croatia, EU

In 1993 the Nobel prize was assogned to R.A.Hulse and J.H.Taylor for their discovery of binary pulsar PSR B1913+16 whose orbit changes due to the emission of gravitational waves whose energy decreaseas the energy of the double pulsar system. It is true that gravitational waves have not been detected bi LIGO, GEO600, VIRGO and other gravitational wave detectors but Advanced LIGO detectors are being built and will start operation in next fall. Also the eLISA Pathfinder should be launched by a Vega launcher within 2015, although I could not find the launch date.
I remember that the Higgs boson was foreseen in 1964 and discovered in 2012.
Tullio

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[quote]Gravitational radiation has not been directly detected, there is indirect evidence for its existence.

Not radiation, energy! ;)

Whats the difference?
It's energy that propagates in space and time and is called radiation.
"In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium."
So far we don't have gravitation waves...nor the gravitation particles! To conclude - no radiation...
;)

True but your conclusion is probably wrong.
Every object in the universe has a potential energy because of the gravitational pull from objects around it.
Gravitional fields are propagated with the speed of light.
I will call that radiation of gravity and energy.

In 1993 the Nobel prize was assogned to R.A.Hulse and J.H.Taylor for their discovery of binary pulsar PSR B1913+16 whose orbit changes due to the emission of gravitational waves whose energy decreaseas the energy of the double pulsar system. It is true that gravitational waves have not been detected bi LIGO, GEO600, VIRGO and other gravitational wave detectors but Advanced LIGO detectors are being built and will start operation in next fall. Also the eLISA Pathfinder should be launched by a Vega launcher within 2015, although I could not find the launch date.
I remember that the Higgs boson was foreseen in 1964 and discovered in 2012.
Tullio

& in 20+y we haven't seen another example where we can observe GV?

[quote]Gravitational radiation has not been directly detected, there is indirect evidence for its existence.

Not radiation, energy! ;)

Whats the difference?
It's energy that propagates in space and time and is called radiation.
"In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium."
So far we don't have gravitation waves...nor the gravitation particles! To conclude - no radiation...
;)

True but your conclusion is probably wrong.
Every object in the universe has a potential energy because of the gravitational pull from objects around it.
Gravitional fields are propagated with the speed of light.
I will call that radiation of gravity and energy.

just because U call them WHITE...doesn't mean that the color of BLACK is going to change! ;)

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non-profit org. Play4Life in Zagreb, Croatia, EU

Rome was not built in a day. It took 50 years and 12 billion dollars to build LHC to detect the Higgs boson. Advanced LIGO is about to start getting data in fall and we at Einstein@home shall crunch that data. Please be patient.
Tullio

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I will call that radiation of gravity and energy.

just because U call them WHITE...doesn't mean that the color of BLACK is going to change! ;)

Hehehe. Hopefully eLISA Pathfinder will shed some light.

Gravity is the engine behind the universe’s processes, and much of its action is dark. Opening a gravitational window on the universe will let us go further than any alternative. Gravity has its own messenger: Gravitational Waves, ripples in the fabric of spacetime, which travel essentially undisturbed and let us peer deep into the formation of the first seed black holes, exploring redshifts as large as ~ 20, prior to the epoch of cosmic re-ionisation.

https://www.elisascience.org/articles/elisa-mission/gravitational-universe-science-case-elisa

Edit:

eLISA will open the gravitational wave window in space and measure gravitational radiation, from about 0.1 mHz to 100 mHz, a band where the Universe is richly populated by strong sources of gravitational waves.

As a personal note, I published an article about Joseph Weber resonant mass instrument for gravitational waves detection in 1969 on the Mondadori Science Yearbook. I later learned that prof. Edoardo Amaldi, a nuclear physicist, had visited Weber in USA and had come to the conclusion that the effort to detect GW was worthwhile. So he had the Istituto Nazionale di Fisica Nucleare to invest money and time in a series of GW detectors, the final one being the VIRGO interferometer in Cascina di Pisa which is a joint Italian/French cooperation.
Edoardo Amaldi was a member of the Fermi group, and one of the Founding Fathers of both CERN and ESA. I have a biography of him written by Carlo Rubbia.
Tullio

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A question I have had myself, and have seen posted elsewhere, is if gravity propagates at light speed, then how does it escape a black hole? As far as I know, the answer is unknown, but I am seeing such an excellent discussion here, I thought I would ask it.

Steve

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Warning, addicted to SETI crunching!
Crunching as a member of GPU Users Group.
GPUUG Website

AFAIK the only radiation that escapes a black hole is the Hawking radiation. On the NASA site there is a video in which prof. Stephen Hawking explains what happens to you if you fall into a black hole. I humbly leave speech to prof. Hawking, ubi major minor cessat.
Tullio
http://www.nasa.gov/mission_pages/newhorizons/main/index.html

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A question I have had myself, and have seen posted elsewhere, is if gravity propagates at light speed, then how does it escape a black hole? As far as I know, the answer is unknown, but I am seeing such an excellent discussion here, I thought I would ask it.
Steve

Gravity escaping gravity itself?

Another problem to understand (at least to me) is time dilation and how that change our perceptions.
https://en.wikipedia.org/wiki/Gravitational_time_dilation

Objects falling in to a BH are subject to these dilations.
https://en.wikipedia.org/wiki/Time_dilation
Mass in special relativity
https://en.wikipedia.org/wiki/Mass_in_special_relativity
Length contraction.
https://en.wikipedia.org/wiki/Length_contraction

AFAIK the only radiation that escapes a black hole is the Hawking radiation. On the NASA site there is a video in which prof. Stephen Hawking explains what happens to you if you fall into a black hole. I humbly leave speech to prof. Hawking, ubi major minor cessat.
Tullio

But that is not gravitional radiation. The radiation Hawking talks about is how BHs 'evaporate'. Virtual particals created in pairs in empty space. One leaves the event horizon and the other don't.

I never said it was gravitational radiation.
Tullio

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A question I have had myself, and have seen posted elsewhere, is if gravity propagates at light speed, then how does it escape a black hole? As far as I know, the answer is unknown, but I am seeing such an excellent discussion here, I thought I would ask it.

Steve

AFAIK that is the wrong question. My very limited understanding and I very well could be wrong, is that gravity is the distortion of space.

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I agree with that. Gravity is the distortion, but then how would its propagation be limited to the speed of light. Gravity is a property of mass.

Steve

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Warning, addicted to SETI crunching!
Crunching as a member of GPU Users Group.
GPUUG Website

Gravitational waves are ripples in spacetime. They are very weak and Einstein doubted that they could ever be detected. But physicists are trying hard to detect them, because they are the only untested part of Einstein's relativity.
Tullio

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Gravitational waves are ripples in spacetime. They are very weak and Einstein doubted that they could ever be detected. But physicists are trying hard to detect them, because they are the only untested part of Einstein's relativity.
Tullio

I hope I live long enough for them to be detected. This is fascinating stuff. I love thinking to the point, where there is an answer, but none of the evidence makes complete sense. It makes sense, but there are still voids in our understanding.

Steve

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Warning, addicted to SETI crunching!
Crunching as a member of GPU Users Group.
GPUUG Website

That's why I crunch E@H.

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It may take a new step in physics, a theory which includes both relativity and quantum mechanics, to solve this problem. The scientists at GEO600, the German interferometer in Hannover, have included quantum theory in processing the interferometers which use laser light, and laser is a quantum phenomenon, also foreseen by Einstein in 1919 but realized only in the Sixties. It is difficult to find a branch of physics not envisaged by Einstein. Think of the Einstein-Podolsky-Rosen paradox of 1935 which started a whole trend of thought in the search for physical reality. But this would require a book, not a message board
Tullio

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I think that a Gravity wave would require a perturbation in a "Gravitational Field". Electromagnetic waves are a disturbance in the Electro-Magnetic Field.

I agree with that. Gravity is the distortion, but then how would its propagation be limited to the speed of light. Gravity is a property of mass.
Steve

The speed of light is the ultimate speed limit.
Nothing can travel faster not even information.