Updated:
Save
It doesn’t always happen, but from time to time a scientific event occurs that makes the entire planet stop for a few minutes and, far from wars, economic disasters, pandemics or sporting successes, focus on knowledge, on the importance of cooperation and in the most innovative ideas of Science. That is precisely what happened yesterday when, for the first time, the world was able to see an image of Sagittarius A*, the large black hole that resides at the center of our galaxy. Six simultaneous conferences took place around the world and revealed, at the same time, the historical image, a true demonstration, and more in these times, of what international cooperation can achieve.
At first glance, it’s just a blurry photo, a kind of donut with the center engulfed in darkness and surrounded by a bright orange ring.
But behind that image there are long years of work by a team of more than 300 people from scientific institutions around the world. A work that is destined to reveal one of the most unknown aspects of the functioning of the Universe in which we live.
It goes without saying that this image is the first of a whole series of photographs to come. In the future, the images will be increasingly clear and focused, achieved by fine-tuning both the hardware and the software that made it possible to obtain the first one. And not only static photographs will arrive, but videos in which, also for the first time, we will be able to see directly how matter falls and disappears forever in the jaws of these insatiable ‘space monsters’.
In 2019, the same team that has now obtained the first photo of Sagittarius A* already showed us that of another black hole 1,500 times larger: the one in the center of the galaxy M87, 55 million light-years away. This black hole has a mass equivalent to that of 6,500 million suns, much more than Sagittarius A*, which ‘only’ has four million solar masses and which is also much closer, just 27,000 light years from us.
Still, it has been much more difficult to get the image of ‘our’ black hole than that of that distant galaxy. The main reason is that the position of the Earth relative to Sagittarius A* is not as favorable for observation as that of M87. Between us and the central black hole of the Milky Way, in fact, there is a real ‘wall’ made of billions of stars and huge, dark clouds of dust and gas, very abundant in the central regions of the galaxy, that do not allow us to distinguish what is behind.
Even so, the scientists of the EHT (Event Horizon Telescope) collaboration have achieved it, noting an unprecedented success. The EHT is a ‘virtual’ telescope that is the size of our planet, something that is achieved by adding the capacities of eight large radio telescopes scattered around the world. The result, as was already shown in 2019 and has been shown again now, is truly spectacular.
But why are these photographs important? Undoubtedly, there is an emotional part in all this, which is to finally be able to see something that has been studied for several decades by indirect methods and complex mathematics. “Seeing is believing” said almost 2,000 years ago the apostle thomas, refusing to take Jesus’ resurrection for granted until he could see for himself his empty tomb. And the same now applies to Sagittarius A*.
This Thursday, more than a century after Einstein’s theory of general relativity hinted at the existence of black holes, those impossibly dense regions of space continue to capture everyone’s imagination. To find them, astronomers have for decades tracked the orbits of countless stars around massive unseen companions, always assuming that black holes were responsible for these erratic motions. But they had never been able to see one.
Until now it was, at best, elegant solutions to Einstein’s equations, who were not even entirely sure that black holes really existed. And in many cases, those later solutions seemed too extreme to be true, despite all the indirect evidence.
But now everything has changed. With an image in hand, all of this can be studied just like any other real physical object, and not just as a series of complicated mathematical abstractions. In fact, the structure revealed in the Sagittarius A* image will no doubt help confirm the accuracy of general relativity, and perhaps also reveal how material around a black hole sometimes falls into it and sometimes acquires the energy necessary to move away in the form of huge spiral jets. Black holes are the only places in the universe where the cosmos makes ‘knots’ that we can untie. We have studied them, we have theorized about them and now, finally, we can see them. The image is a brilliant confirmation of more than a century of purely theoretical work.
From now on, observations that no one dared even dream of before will be possible. For example, the scale study of the horizon of black holes, the invisible ‘border’ from which nothing, once crossed, can escape again. From now on, it will be possible to ask a lot of new questions that were not even conceivable before. The promises for the future are enormous.
www.abc.es
George is Digismak’s reported cum editor with 13 years of experience in Journalism