A century ago, Albert Einstein predicted in his General Theory of Relativity, that the space-time fabric of which the universe was formed could be measured through the ripples produced by events led by high-mass bodies, such as black holes. But he passed away without being able to prove it.
To this day, Einstein’s dream has been fulfilled. The first detection of gravitational waves occurred at the beginning of 2016, and since then successive detections have taken place that have not stopped adding points to the Relativity marker.
A landmark discovery that has come about thanks to a decades-long project, LIGO ( Laser Interferometer Gravitational-Wave Observatory ), which used a pair of gigantic laser interferometers to measure how the wave’s gravity passed through Earth. Rainer Weiss, Barry Barish and Kip Thorne spearheaded the project, which has led to them being awarded the 2017 Nobel Prize in Physics.
But what are these gravitational waves? The scientific popularizer Javier Santaolalla is an engineer, a doctor in particle physics and a former researcher at CERN (European Organization for Nuclear Research), he explains this concept with a very simple metaphor: the space-time fabric is actually a flexible fabric that is it can fold and it can be folded.
Like a flexible tarp, you can hit it. If you hit it with great force, a wave is generated in the fabric, just as if you throw a stone into a pond.
This wave propagates through all space and reaches us; that gravitational wave is a space-time wave . And it is precisely how we can measure it, as a stretching or compression of space-time locally.
The fifth detection of gravitational waves, announced in October 2017, is the most surprising in all of history, since it has been produced, instead of by waves, by light ; light from the merger of two neutron stars, rather than the earlier black hole-derived detections that had been made thus far. Black holes do not emit light, so it was hoped that neutron stars could also cause and detect this physical phenomenon, as has eventually been proven.
The detection of gravitational waves is a milestone in science that will mark the roadmap to develop the new physics. And, to understand it, we have experts with the gift of the word, such as Javier Santaolalla so that the language of science is accessible to everyone.
