European Space Agency bids to study gravitational waves
Full marks to Imperial College London (ICL) for their ambitions. In 2015 a European Space Agency (ESA) led mission, named the Laser Interferometer Space Antenna (LISA)-Pathfinder, is giving the university a chance to break new ground in studying gravitational waves.
The university reports that Tim Sumner, Professor of Experimental Astrophysics at ICL, and his colleagues have been investigating the possibility of observing gravitational waves since the early 1990s. They aim to see the ripples of waves likely to be given off by such major cosmic events as the merging of black holes, or even the big bang.
“It opens up a whole new way of doing astronomy,” says Professor Sumner. Over the centuries astronomy has grown to cover more and more of the electromagnetic spectrum, seeing more colours if you like, whether visible light, infrared, X-rays or submillimetre.”
“We’ve come to the realisation that the more ways you look at things, the more you learn. But it is always just looking, it’s always visual. With gravitation waves, some people have said it’s analogous to adding a sound channel; it’s a totally different way of collecting information.”
But how do you look for something that doesn’t give off any light or an electromagnetic signature?
On the Imperial College site Andrew Czyzewski writes:
All types of waves, whether sound waves or ocean waves, create a periodic squashing and stretching effect in the medium in which they are travelling. That also applies to gravitational waves; but because the medium they are travelling in – spacetime – is three-dimensional (really four-dimensional, but we can ignore time in this case) it’s slightly different.
Gravitational wave plus polarizationFirstly imagine a circular cross-section of space with a gravitational wave travelling right through the centre. As the waves pass through the middle of our imaginary spacetime hoop, they first stretch it lengthways (along the y-axis) while squashing it widthways (along the x-axis). Then as the next wave break passes, the reverse happens – it’s stretched in the middle and squashed lengthways, and so on.
LISA-Pathfinder is actually considered a technology demonstration mission. It could be a precursor to a similar, but much bigger experiment.
Should the larger eLISA mission secure funding in an upcoming ESA competition, it could launch in 2028.