Interview

Clashing over noise and waves

Danish scientists express doubts about the breakthrough detection of gravitational waves. A Portuguese physicist explains the controversy.

The take-away

  • Earthly disturbances can affect the instruments that detect gravitational waves
  • It could take years before scientists concur on their understanding of the phenomenon

Scientists at Copenhagen’s Niels Bohr Institute have raised doubts about the first detection of gravitational waves by the Laser Interferometer Gravitational-Wave Observatory (LIGO) in 2015. The allegation: suspicious noise patterns distorted the detection data. Gravitational waves emanate from phenomena like the formation of black holes, but earthly disturbances can affect the two laser interferometers that detect them. The Danish analysis appears to show correlation between earth-originated noise and the breakthrough wave detection. Vítor Cardoso, a former LIGO member and professor at Lisbon’s Instituto Superior Técnico, comments on the Danish doubts.

t14 gravitational waves article - Clashing over noise and waves

How has the physics community reacted?

It is sceptical of the Danish claims because LIGO has 20 years of experience in estimating these noise fluctuations. Some of what the Danes claim was not done was actually investigated by LIGO, and many have said it’s not possible to accurately reproduce just one fragment of the LIGO findings. But I also think that some of those rebuttals are unfair, as it’s indeed impossible to reproduce the background estimates and do a proper analysis because not all of the LIGO data is made public. In short, these claims are important, and need to be looked at – with patience and scientific attitude.

What do these exchanges say about science and real-time public debate?

The timescale for scientific discussions is much longer than that of public interaction. I think it’s good that we’re having this discussion with a large audience, but there’s an important message here: it took science 100 years to make a detection, so it wouldn’t hurt if we take five or 10 years to closely examine the details and understand the consequences.

What’s next?

This will be investigated further only if the Danish paper passes review and is published. LIGO will continue detecting a few events every year, but it’s handicapped by sitting on earth, which is shaking all the time. One solution would be to send detectors into space. The European Space Agency’s eLISA mission will feature three spacecraft, positioned in an equilateral triangle roughly 2 million kilometres apart, that could accomplish this.

Vítor Cardoso, Instituto Superior Técnico Lisboa