Question: What are gravitational waves?
About the article "Gravitational wave", section "Sources of gravitational waves".

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Researchers believe that gravitational waves also travel through space, although gravitational waves have never been directly detected.
Not to be confused with gravity waves, gravitational waves are disturbances in the curvature of spacetime, predicted by Einstein's theory of general relativity. 
Amaldi Conferences on Gravitational Waves.
The Edoardo Amaldi Conference series on Gravitational Waves is coordinated by GWIC as the cornerstone conference for the Gravitational Wave Detection community worldwide.
These conferences are held every two years, and move around the world to locations where gravitational wave research is active. 
Detecting gravitational waves.
Difficulties in detection.
Gravitational waves are not easily detectable.
This knowledge gap is primarily due to the massive presence of noise in the low frequencies where antennas currently operate.
Gravitational waves are expected to have frequencies formula_32. 
A gravitational-wave detector is any device designed to measure gravitational waves, tiny distortions of spacetime that are predicted by Einstein's theory of general relativity.
The existence of gravitational radiation is a prediction of general relativity.
Gravitational waves are perturbations in the curvature of spacetime caused by accelerated masses.
Since the 1960s gravitational-wave detectors have been built and constantly improved.
The present-day generation of resonant mass antennas and laser interferometers has reached the necessary sensitivity to detect gravitational waves from sources in the Milky Way.
As of early 2014, no direct detection of gravitational waves has yet been accomplished, although a number of experiments have now added to the evidence that gravitational waves are more than mathematical anomalies of relativity calculations (ref.
the 1993 Nobel Prize in Physics).
On 17 March 2014, astronomers at the Harvard-Smithsonian Center for Astrophysics announced the apparent detection of gravitational waves, which, if confirmed, may provide strong evidence for inflation and the Big Bang. 
In physics, gravitational waves are ripples in the curvature of spacetime that propagate as a wave, travelling outward from the source.
Predicted in 1916 by Albert Einstein to exist on the basis of his theory of general relativity, gravitational waves theoretically transport energy as gravitational radiation.
Sources of detectable gravitational waves could possibly include binary star systems composed of white dwarfs, neutron stars, or black holes.
The existence of gravitational waves is a possible consequence of the Lorentz invariance of general relativity since it brings the concept of a limiting speed of propagation of the physical interactions with it.
Gravitational waves cannot exist in the Newtonian theory of gravitation, in which physical interactions propagate at infinite speed.
Although gravitational radiation has not been "directly" detected, there is "indirect" evidence for its existence.
For example, the 1993 Nobel Prize in Physics was awarded for measurements of the Hulse–Taylor binary system that suggests gravitational waves are more than mathematical anomalies.
Various gravitational wave detectors exist and on 17 March 2014, astronomers at the Harvard–Smithsonian Center for Astrophysics announced that they had detected and produced "the first direct image of gravitational waves across the primordial sky" within the cosmic microwave background, providing strong evidence for inflation and the Big Bang.
Peer review will be needed before there can be any scientific consensus about these new findings.