It was over a century ago that Albert Einstein, in his General Theory of Relativity, made a startling prediction about the nature of energy in our vast universe. Musing on the behaviour of black holes, he suggested that if two were to collide, the combined energy produced would set off a rippling effect in the fabric of the cosmos. And now, after decades of searching, anticipation and trial and error, scientists have finally confirmed the presence of these gravitational waves in space. The discovery is truly transformational, offering a new perspective on space and time and providing a vital consequence of Einstein's theory. Indeed, this week's announcement, from the California Institute of Science and Technology, promises to change the world of astronomy forever.

50 years of searching

The discovery of the presence of gravitational waves in space is the culmination of 50 years of scientific study. Designed in 1979 and built in 2004, the Laser Interferometer Gravitational-Wave Observatory (LIGO) in Livingston, Louisiana, was conceived purely for this purpose and has led to collaborative experimentation on a massive scale. Some 1,000 physicists have been working on the project and wave sensors were also set up in Italy and Germany. LIGO works by sensing areas in space that stretch, even to the minutest degree, using two 4km-long, L-shaped sensors. These two giant interferometers use mirrors to send light waves back and forth. If interference occurs between the waves of light, the scientists can compare the lengths of the arms to such a tiny degree (1/10,000th of the diameter of a proton) that a gravitational wave can be picked up if it happens to be crossing. The tiny nature of these waves, however, has been extraordinarily difficult to detect, as any vibration from thunderstorms, aircraft noise or even far-off earthquakes could overwhelm them.

Exciting discovery

On 14th September, the LIGO detected a signal. Starting at a frequency of 35 Hertz, the vibration then quickened to around 200 Hz before it disappeared a fraction of a second later. The data suggested the collision of two huge masses and a later computer simulation of the raw figures proved it. The data, when modelled, revealed two massive objects, 29 and 36 times the size of our sun, had collided and then come together to form a rippling gravitational wave across space. Black holes are the only explanation for this, as nowhere else can we find so much mass condensed into so little space. As well as providing proof of Einstein's prediction, then, this latest discovery also shows without doubt that black holes exist. Although the team working on the project were excited at the discovery, they first had to prove that the readings were not a hoax or detected by false readings, such was the importance of the find. After a month of checking and cross-checking, scientists had ruled out everything other than a gravitational wave causing the oscillations that had been detected. 

New dawn of understanding

As well as demonstrating proof of Einstein's 100-year old predictions about gravity and space, the discovery of gravitational waves also offers the prospect of an exciting new dawn of our understanding of the cosmos. Deepening what we know about stars and galaxies, if offers the potential to study black holes and giant stars in a way that is measurable. The ability to delve back into space and time could pave the way for the discovery of new phenomena, opening the door on to areas of the universe we know little about. This truly is a transformational discovery.