Out of sight, out of mind Sagittarius A*

I was watching a newscast on May 13 when the announcer advanced that it was imminent that a “historic news” in the field of science. Naturally, that piqued my interest. What could it be? During the same newscast, the answer came: it had just been reported that an image of the black hole found in thein the center of our galaxya, the Milky Way. Communication was very well orchestrated; As far as I know, at least seven press conferences were called, including one in Madrid.

Isn’t it the final destiny of the Milky Way, and that of all galaxies, to be engulfed by their corresponding cosmic wells?

At the one held in Garching (Germany), Sara Issaoun, the astrophysicist, stated that “today, at this moment, we have direct evidence that this object is a black hole.” “Direct Evidence”, yes, but deep down, “direct” is relative. I don’t think any expert had previously doubted that a supermassive black hole existed at the center of the Milky Way.

Messier 87

On April 26, 2019, when I dedicated this weekly article to the photograph that had just been shown of the black hole M87*located in the center of the Messier 87 galaxy, from which we are separated by 55 million light-years, I already wrote that there were rumors, which spread to the press, that a photograph of Sagittarius A* was also going to be presented.

Even the very cautious Royal Swedish Academy of Sciences decided to award half of the 2020 Nobel Prize in Physics to Reinhard Genzel and Andrea Ghez “for the discovery of a supermassive compact object in the center of our galaxy. Such familiarity with the existence of Sagittarius A* was also recognized in one of the six articles dedicated to explaining the details of the photograph of this black hole, published in a special issue of Astrophysical Journal Letters: “We present –announces– the first image of the black hole of the Galactic Center: Sagittarius A*.

Well-studied astrophysical object

Identified almost 50 years ago, it is the closest supermassive black hole candidate, and it is among the most studied astrophysical objects.” If a photograph of this black hole had not been obtained in April 2019, it is because the task was much more complex than that of M87*. It is not the same to make observations of a galaxy far from ours, than to look towards its center, since in this case the observations are hindered by star matter that separates us from that center, 26,000 light-years away from us.

It has been necessary to combine images from eight radio-observatories, distributed throughout the globe (one of them on Pico Veleta in Sierra Nevada). The photograph now obtained constitutes, without a doubt, a scientific-technical achievement extraordinary; allows us to deduce that the mass of this black hole is four million times that of the Sun, and that its diameter is 44 million kilometers.

A monstrosity that suggests all kinds of reflections. Given the ability to gravitational pull of an object as massive as Sagittarius A*, will it not be the final fate of the Milky Way, and possibly all galaxies, to be engulfed by their corresponding mysterious cosmic wells? And, of course, where does the trapped matter “fall”? Given that there can no longer be any doubt about the existence of black holes, if there are fundamental questions in physics and cosmology, this is one of them.

Light in the darkness

It is certain that in such an answer you will have to intervene quantum physics, since inside the black hole the distances involved end up belonging to the scale of quantum phenomena, but even so our mind is disoriented before such a fact. “In our imagination – wrote Heino Falcke and Jörg Römer in a book focused on the photograph of M87*, although they also alluded to Sagittarius A*, The light in the darkness (Debate, 2021)– black holes symbolize the devouring nothingness, a limit where all life and all understanding ceases, the vision of the gates of hell”.

Could they be channels of communication with the other universes in whose existence more and more scientists believe? Or if we abandon the somewhat local galactic perspective and think of the whole of the Universe, couldn’t its end be an ultra-mega-black hole? After all, deep down it is not an idea that is too different from that of the origin of the Universe in a no less mysterious Big Bang.

Big Science

But I want to go back to the May 13 announcement. Accepting that the news is important, the fact that it is not surprising leads to some reflections. On the one hand, the publicity aspect: increasingly, scientists, especially those involved in large studies (the so-called Big Science) –and the international collaboration in the Event Horizon Telescope project, generator of the photograph, is–, they need to highlight the results they obtain, make them have the greater social relevanceIt’s possible, something not too difficult given the media’s thirst for spectacular news.

Is communication technique –and advertising– it has been used several times in recent times: precisely ten years ago to announce that the Higgs boson had been found, an essential piece for the so-called Standard Model in high-energy physics; in February 2016 to present the first detection of gravitational waves, and to present the aforementioned photograph of M87*. In all three cases, it was undoubted novelty. But the Sagittarius A* photo ad does not possess this novelty property: it uses an already existing technique and confirms something well known.

Our house’

In a certain sense, it could be said that the relevance that is being given to it is adjusted to the current spirit of the time, in which images have acquired an overwhelming presence. Perhaps the old Spanish saying, “Eyes that do not see, heart that does not feel” –understanding by “heart” the ability to “visualize” intellectually–, is also valid for science. Although perhaps the ultimate reason for this new celebration of the photograph of a black hole is what Falcke and Römer said in their book: “Neither the Higgs boson nor the gravitational waves had triggered the emotions that the photograph of M87*” . Now history repeats itself, reinforced because it is the central black hole of our “home”, the Milky Way.

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