London: Space-based detector can spot at least two gravitational waves -- ripples in space-time -- each year caused by collisions between supermassive black holes, revealing the initial mass of the seeds from which the first black holes grew 13 billion years ago. A space-based instrument called the Evolved Laser Interferometer Space Antenna (eLISA) detector is set to be launched in 2034. As eLISA will be in space - and will be at least 250,000 times larger than detectors on Earth - it should be able to detect the much lower frequency gravitational waves caused by collisions between supermassive black holes that are up to a million times the mass of our sun. Scientists led by Durham University's Institute for Computational Cosmology ran the huge cosmological simulations that can be used to predict the rate at which gravitational waves caused by collisions between the monster black holes might be detected. The study combined simulations from the EAGLE project - which aims to create a realistic simulation of the known Universe inside a computer - with a model to calculate gravitational wave signals. “Understanding more about gravitational waves means that we can study the universe in an entirely different way. These waves are caused by massive collisions between objects with a mass far greater than our Sun," said lead author Jaime Salcido, PhD student in Durham University. "By combining the detection of gravitational waves with simulations we could ultimately work out when and how the first seeds of supermassive black holes formed,” Salcido added. In February, the international LIGO and Virgo collaborations announced that they had detected gravitational waves for the first time using ground-based instruments and in June reported a second detection. Current theories suggest that the seeds of these black holes were the result of either the growth and collapse of the first generation of stars in the Universe; collisions between stars in dense stellar clusters; or the direct collapse of extremely massive stars in the early Universe. As each of these theories predicts different initial masses for the seeds of supermassive black hole seeds, the collisions would produce different gravitational wave signals. This means that the potential detections by eLISA could help pinpoint the mechanism that helped create supermassive black holes and when in the history of the Universe they formed. “Black holes are fundamental to galaxy formation and are thought to sit at the centre of most galaxies, including our very own Milky Way,” noted co-author professor Richard Bower. “Our research has shown how space-based detectors will provide new insights into the nature of supermassive black holes,” he added. Gravitational waves were first predicted 100 years ago by Albert Einstein as part of his Theory of General Relativity. The research was set to be presented at the Royal Astronomical Society's national astronomy meeting in Nottingham on Monday.