Gravitational waves were the first big story on this blog. I like gravitational waves. So when when something about it makes appears on my radar, I listen.
Even if it means it could all be wrong.
Part of the mind-bending difficulty of detecting gravitational waves was solved by looking only at signals appearing in both LIGO observatories. Everything else (traffic, earthquakes, and so on) melts into random static-like background.
That background chatter should be completely independent between the two observatories (because the detector here won’t feel cars 5000 Km away). However, a team from the Niels Bohr Institute in Copenhagen found a different result. They saw a disturbance in the background sweeping through the detectors precisely as gravitational waves passed.
As you can imagine, a lot of math goes in isolating the teensy weensy signal of gravitational waves. The idea is, something could have gone wrong there.
As a result, the estimates of the black hole mergers that produced the gravitational waves are incorrect. Or, in the worst case, that the signal wasn’t a signal at all: LIGO would have detected random background and interpreted it as gravitational waves.
The LIGO team claimed this analysis of the background is flat-out wrong (they were more specific, but I won’t go in those details). Others say it’s possible that the gravitational waves signals were subtracted in such a way that they left a sort of imprint behind.
Though everyone involved displays confidence, nobody has conclusively been proven wrong. It’s an open discussion. But it’s all good: the more scientists check, double check, triple check the results, and discuss the process, the better they understand it. And the better the results get.
The latest observation period—with Italian observatory VIRGO in the mix—recently ended. We’ll see what comes out of that.
If you want more
- The paper on the issue was published on an Open Access journal, so you can just go read it (though it’s not easy)
- You can read some controversy details in famous popular science outlets (quanta, gizmodo). My favorite is Sabine Hossenfelder’s piece on Forbes
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