They send out ripples in space-time as extraordinarily large objects collide violently in space, reverberating for billions of years through the universe.

Those gravitational waves, first theorized by Albert Einstein, travel across Earth long after the collisions occur. Over the last five years, these waves have been heard by a series of three-mile-long instruments in Washington, Louisiana, and Italy. The Laser Interferometer Gravitational-Wave Observatory (LIGO) contains the two US detectors, and their partner in Italy is named Virgo.

Einstein predicted that noise and movements on Earth would prevent gravitational waves from ever being observed by us. But he was proven incorrect by these observatories. Cataclysmic collisions between black holes and neutron stars have been observed by scientists. They discovered black holes that shouldn't exist. And they have established the source of almost all the gold, platinum, and silver in the universe.

In October, LIGO and Virgo researchers revealed that these experiments together observed 39 new gravitational-wave events during only six months of observations last year. Scientists have now reported possible gravitational waves 50 times in total.

Here's how Einstein proved right about gravitational waves by astrophysicists and wrong about our ability to detect them.

In 1916, Einstein predicted that gravitational waves would be created by collisions of massive objects, including black holes and neutron stars.

According to his relativity theory, the sheer mass of these objects would distort the space-time fabric, often equal to dozens or even hundreds of suns.

Such objects can immediately transform the mass value of many suns into pure gravitational-wave energy when they collide together.

In every direction, the ripples across space-time from such a violent collision will reverberate, speeding at the speed of light through the universe.

Eventually, the waves could travel through Earth, distorting our time and space, but Einstein figured we'd never sense them.

In the midst of all the noise and vibrations in our world, they appeared too small to pick up.

In an attempt to pick up gravitational waves, researchers constructed two major experiments in the late 1990s.

In Hanford, Washington, one of the L-shaped detectors was installed. Each arm measures 2.5 miles in length. In Livingston, Louisiana, the other was built. They make up one observatory together: LIGO.

There was silence for the first 13 years. But then the LIGO detectors felt their first ripples in space-time, 1.3 billion light-years away from the merger of two black holes.

The discovery proved that Einstein was right about gravitational waves, opening up a new astronomical region. The Nobel Prize in physics was awarded to three researchers who helped formulate the experiment.

Due to the sound, they create in the data, LIGO scientists identify these signals as "chirps".