Late Wave

It took only one scientist to predict them but a thousand to get them confirmed (1004 to be precise). I guess if the confirmation of gravitational waves couldn’t draw me out of my blogging hiatus nothing could, although I am obviously catching a very late wave. The advantage of this – I can compile and link to all the best content that has already been written on the topic.

Of course this latest spectacular confirmation will unfortunately not change the mind of those quixotic individuals who devote themselves to fight the “wrongness” of all of Einstein’s work (I once had the misfortune of encountering the maker of this abysmal movie. Safe to say I had more meaningful conversations talking to Jehovah Witnesses).

But given the track record of science news journalism, what are the chances that this may be a fluke similar to the BICEP news that turned out to be far less solid than originally reported? Or another repeat of the faster than light neutrino measurements?

The beauty of a direct experimental measurement as performed by LIGO, is that the uncertainty can be calculated statistically. Since this is a “5-sigma” event, this means the signal is real with a 99.9999% probability. The graph at the bottom shows that what has been measured matches a theoretically expected signal from a black hole merger so closely that the similarity is immediately compelling even for a non-scientists.

But more importantly, unlike faster than light neutrinos, we have every reason to believe that gravitational waves exist. There is no new physics required, and the phenomenon is strictly classical, in the sense that General Relativity produces a classical field equation that unlike Quantum Mechanics adheres to physical realism. That is why this discovery does nothing to advance the search for a unification of gravity with the other three forces. The importance of this discovery lies somewhere else, but is no less profound. Sabine Hossenfelder says it best:

Hundreds of millions of years ago, a primitive form of life crawled out of the water on planet Earth and opened their eyes to see, for the first time, the light of the stars. Detecting gravitational waves is a momentous event just like this – it’s the first time we can receive signals that were previously entirely hidden from us, revealing an entirely new layer of reality.

The importance of this really can’t be overstated.  The universe is a big place and we keep encountering mysterious observations. There is of course the enduring puzzle of dark matter, lesser known may be the fast radio bursts first observed in 2007 that are believed to be the highest energy events known to modern astronomy.  Until recently it was believed that some one-off cataclysmic events were the underlying cause, but all these theories had to be thrown out when it was recently observed that these signals can repeat.  (The Canadian researcher who published on this recently received the highest Canadian science award, and the CBC has a nice interview with her).

We are a long way off from having good spatial resolution with the current LIGO setup. The next logical step is of course to simply drastically increase the scale of the device, and when it comes to Laser interferometry this can be done on a much grander scale then with other experimental set-ups (e.g. accelerators).  The eLISA space based gravitational wave detector project is well underway. And I wouldn’t yet count out advanced quantum interferometry as a means to drastically improve the achievable resolution, even if they couldn’t beat LIGO to the punch.

After all, it was advanced interferometry that had been driving the hunt for gravitational waves for many decades. One of its pioneers, Heinz Billing, was determined to bring about and witness their discovery, reportedly stating that he refused to die before the discovery was made.  The universe was kind to him, so at age 101 he is still around and got his wish.


LIGO measurement of gravitational waves. Shows the gravitational wave signals received by the LIGO instruments at Hanford, Washington (left) and Livingston, Louisiana (right) and comparisons of these signals to the signals expected due to a black hole merger event.