Gravity waves, also known as gravitational waves, are ripples in the fabric of spacetime caused by certain astrophysical events, such as the collision of black holes or the merger of neutron stars. These waves propagate through spacetime itself, rather than through a medium like the hypothetical ether.
The detection of gravitational waves does not rely on the presence or properties of any medium but rather on the measurement of spacetime distortions caused by the passage of these waves. The primary method used for detecting gravitational waves is through the use of laser interferometry, specifically employing devices known as interferometers.
Interferometers, such as the Laser Interferometer Gravitational-Wave Observatory (LIGO), consist of two or more arms arranged in a specific geometric configuration. A laser beam is split and sent down each arm, and they are reflected back to a central point where they interfere with each other. When a gravitational wave passes through the detector, it causes a small, but measurable, stretching and squeezing of spacetime, which alters the relative lengths of the interferometer arms. This, in turn, affects the interference pattern of the laser light when the beams are recombined.
By precisely monitoring the interference pattern of the laser light, scientists can detect the minuscule changes caused by passing gravitational waves. The technology used in interferometers is extremely sensitive, capable of measuring changes in length at the scale of a fraction of the size of an atomic nucleus.
It's important to note that gravitational waves are not disturbances within a medium, like water waves in an ocean. They are perturbations of the very fabric of spacetime itself. Therefore, the concept of an undetectable or unobservable ether is not applicable to the detection of gravitational waves. The detection and study of gravitational waves provide valuable insights into astrophysics, general relativity, and our understanding of the universe.