Searching for Einstein's ripples in space and time
Einstein predicted the existence of gravitational waves, ripples in the fabric of space and time, almost a century ago.
Now scientists in Scotland are confident that they will soon be found.
They are part of an international collaboration which is constructing a worldwide network of huge gravitational-wave detectors.
BBC Scotland's science correspondent Kenneth Macdonald explains that their ultimate aim is to be able to "see" across the Universe.