Predicting Gravitational Waves
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Gravitational Waves and Space
As they travel through space, gravitational waves cause spacetime to change. This means that the shape of an object pulsates as gravitational waves pass through it. Imagine a gravitational wave passing through a book – the book will be stretched and squeezed, stretched and squeezed, etc. At a given time, the distance between the front and back of the book will have increased and the distance between the top and bottom will have decreased.
The strength of the gravitational wave determines how much an object will change in shape. This depends on the type and scale of the event that it came from. Only large-scale events make gravitational waves that we can detect.
To give you an idea of the scales involved, a wave from the collision of two black holes would change space by around 10-18 meters per kilometer. In other words, a gravitational wave from the collision would change the height of the Empire State building by an amount smaller than 1/1000th the width of a proton. That is why gravitational waves are so difficult to detect!
Fortunately, scientists are now able to build instruments that can make such precise measurements.
The width of a proton is a hundred thousandth of the width of an atom, the width of an atom is a millionth of the width of a hair, and the width of a hair is a tenth of one millimeter.
