A SCOT has revealed how a US laboratory went into lockdown after the groundbreaking discovery of gravitational waves, also known as ripples in the fabric of spacetime.

Alastair Heponstall is part of the California Institute of Technology (Caltech) instrument science and engineering team which last week announced that it had found ripples in the fabric of spacetime that were first predicte by Albert Einstein a century ago.

Mr Heponstall, originally from Edinburgh, works at the advanced Laser Interferometer Gravitational-Wave Observatory (Ligo).

It spotted the phenomenon which was the collision of two black holes for the first time.

The laser engineer said the facility locked down after Ligo picked up a ripple passing through the earth in September last year.

The distortion in the fabric of spacetime was an echo from the cataclysmic collision of two blackholes more than a billion lightyears away, and exactly what Ligo had been built to find.

But extreme caution had to be taken over the signal, described by some as a 'chirp', to ensure that there was absolutely no doubt about its point of origin.

Mr Heponstall said: "It was picked up at what was the middle of the night here in the US, by a scientist in Germany who was looking at the data Ligo had produced, and it was apparent within minutes what it was.

"Then everything went into lockdown so they could make sure that they knew where all the scientists working on the project were to ensure that there had been no interference in the computers that could have been the source of the signal.

"Because it was the middle of the night there were only one or two people at the detectors, so they knew that no-one could have gone into the rooms and affected anything."

He said the next day all routine meeting were cancelled as all eyes turned to streams of data produced by the observatory to check and recheck its findings.

He added: "Because its is a discovery of this magnitude there had to be absolutely no mistakes before we went public. Just one rogue scientist could have affected the data so they had to be absolutely sure where everyone was and that there had been no interference when the signal was spotted."

Ligo works by firing lasers down two four-kilometre long tubes arranged in an L-shape and bouncing them off precise mirrors, which are among the most sensitive instruments ever built, to measure any variations in their wavelength caused by the "strain" introduced by gravitational waves passing through at a sub-atomic level.

Originally, Mr Heponstall worked on the suspension system designed and built by scientists in Glasgow which holds the mirrors in place and has been credited for making the breakthrough possible.

His other job is to manage lasers fired against the mirrors to prevent many minute warping caused by the beams being measured for vibrations. He said that the project uses "many, many lasers".

Two sites are used by the Ligo project, one in Washington State and another 3,000 km away in Louisiana, and the 'chirp' of the wave reaching earth was recorded at both micro-seconds apart.

It is now hoped that the breakthrough will open a fresh window on the cosmos, with Ligo joining traditional telescopes and radio telescopes in probing the secrets of the universe, including looking for evidence of the Big Bang.

Mr Heponstall said: "Everything produces gravitational waves. Waving your hand in the air produces them. But they are far too weak to detect and only massive events such as that observed in September are detectable at present.

"But now we will keep refining Ligo and make constant improvements to keep looking at see what else is out there."