Recently, there has been a lot of hype in the scientific community about “gravitational waves”, a mysterious wave of disturbance through spacetime itself. But what exaclty is this wave? And why sould we care about it?

The History

When Albert Einstein created his theory of general relativity in 1915, his formula revealed something strange. In general relativity, spacetime behaved like a fabric, where space dictates how matter moves, and matter dictates how space bends. However, Einstein’s formulas predicted ripples through this fabric, behaving like waves. This is exactly gravitational waves which we observe today.

The Detection

When gravitational waves pass a region of spacetime, that region is compressed and rarefacted ever so slightly. This property allows us to detect these waves. A common instrument used for detection is called the “Weber bar”, a long metal bar protected from all seismic movements. When the wave passes through the bar at its resonant frequency, the bar compresses and expands very slightly with the wave, magnifying its action to a detectable level.

The Sources

Many celestial events produce gravitational waves, since these waves are produced when any mass moves through space. However, only a few violent events are strong enough to be detectable. One of the most famous examples of such events is the collision of two neutron stars orbiting eachother. Although these two stars may be in a stable orbit, they continuously lose energy by emitting gravitational waves in their movement. This rate of loss is very slow, only 200 Watts. However, over a cosmological timescale, eventually these two neutron stars will collide into eachother to form a black hole.

Did You Know: Albert Einstein originally didn’t believe in gravitational waves and thought it was an error in his formula?