Gravitational waves are created when massive objects like black holes move, causing ripples in the fabric of spacetime that can be detected on Earth.

Gravitational waves, while detected by LIGO and predicted to carry energy, present a challenge in general relativity because covariant definitions based on stress energy yield zero energy for pure gravitational waves.

On September 14, 2015, after years of work, LIGO detected its first gravitational wave, a signal from a collision of black holes that occurred over a billion years ago.

LIGO is like a gigantic musical instrument designed to record the shape of the ringing drum of spacetime, allowing scientists to listen to gravitational waves rather than just taking snapshots of them.

One of the most incredible things humans have accomplished is detecting gravitational waves through LIGO, which allows us to observe events from the early universe.

When two black holes merge, they emit gravitational waves, and the final black hole's mass is less than the sum of the original black holes due to energy radiated away as gravitational waves.

Black holes curve space and time around them, creating a gravitational field that affects the movement of objects nearby. When two black holes orbit each other, they create waves in the shape of space that follow their movement, eventually merging into a larger black hole that emits gravitational waves as it settles down.

The final mass of a merged black hole is less than the sum of the two original black holes due to the energy radiated away in the form of gravitational waves, which is not detectable as light but rather as ripples in spacetime.

Sound waves are fluctuations in air movement, similar to waves in water, and they are captured by the ear and processed by the brain to make sense of the environment.