Of Julia Bertotto Rome, 6 December 2022 – Stefano Giovanardi he is an astronomer, science popularizer and scientific curator of the astronomical museum and planetarium in Rome, as well as a cosmic narrator of the evocative shows that the projections offer to his visitors. We went to visit him in one of the most magical places in the capital, where the celestial vault opens up glittering before our eyes, in the name of wonder and mystery.
Professor Giovanardi, what is the state of current knowledge on space? I know we could talk for days, but…how far have we gone?
In my opinion, astrophysics follows two directions, one that runs fast and makes giant strides, one that goes slower but is solid and allows us to hold something acquired in our hands. The way forward is the search for extra-solar planets and life in space, we are analyzing their atmospheres, they are giant leaps in technological and cognitive terms. In twenty years we have compiled a catalog of 5,000 extra-solar planets. Another very fast-moving sector is black hole research, this year we obtained that magnificent photo of the black hole that is at the center of our galaxy, an extraordinary technological and international collaborative effort.
And what about fairly firm and stable acquaintances?
We learned about stars and their functioning already with quantum physics in the first half of the twentieth century, and since then the theory of stellar evolution has become one of the safest things we know. Another thing we know for sure from the last century about our universe is that it is expanding.
Or it’s astounding to think that until 1929 we didn’t know anything about the nature of galaxies, whether they were clusters within the Milky Way or whether they were somewhere else far away. This is what we can say we currently know. We also know where this expansive thrust of the universe comes from, i.e. from the Big Bang, but we absolutely do not know what cosmic condition it will lead us to. The most plausible scenario is that of an endless expansion.
Cosmological theories all agree on the initial “big bang” model.
Basically yes. The cosmic microwave background, which comes uniformly from every direction in the sky, is very solid evidence. There are currently no more valid theories than the Big Bang to explain where this signal comes from. All the energy contained in the universe, which then composed light, matter, particles, did not pour into the universe like a liquid in a container, but generated the universe itself. Before the Big Bang there was no universe; it makes no sense to speak of a before the Big Bang because before there was no before, there was neither space nor time. Just as it makes no sense to ask what is outside the universe because there is no outside. Since the Big Bang, space has started to expand and time to flow, and they haven’t finished doing it yet. Luckily for us!
Shiva’s eternal cosmic dance is still going on, the god is still dancing to the beat of this electromagnetic music. But let’s get to what we don’t know.
A little socratically we can say that since 1998 we know that we know practically nothing about space: dark energy. This charming and sinister name gives us the idea of vagueness. We know that it is the predominant form of energy in the cosmos because it accounts for roughly 65%-69% of the universe. This is quite disheartening for a researcher. 96% of this unknown is dark energy and 23-25% dark matter.
It means that we only reasonably know what makes up 4% of the universe. Sometimes it seems to me that our state of knowledge is almost humiliating for our intelligence.
And in that 4% there are nebulas, socks, walruses, our politicians…
We can try to be humble, (da humus, earth), that is, rooted in our condition of the unknown, without feeling mortified.
Yes, also because the unknown is the very reason for research and for every passion.
Is the future of humanity on the red planet (where we already grow onions)?
The Chinese tried to bring a greenhouse to the hidden side of the moon, with cotton seeds they even germinated, but they lasted a day because the greenhouse didn’t hold up and broke.
Transferring humanity to Mars is a dream that science fiction has cherished for years, but realizing it is beyond our means at the moment. Elon Musk has claimed that by 2054 he will establish a city of a million people on Mars. It seems blatantly outside of any rosy forecast. Even taking a crew of a few people to Mars is today a very difficult undertaking. Mars is the most mechanically colonized planet, it is invaded by probes, even if half of those we sent us didn’t make it. But it’s really complicated to send a human being there, and a series of ethical questions also arise if it is a matter of sending someone there. We have already been returning to the Moon for a long time with the Artemis mission in its infancy and not before 2025-2026. In short, for Mars, we have to wait.
About Socrates and philosophy. Giordano Bruno was somehow right when he spoke of innumerable (never mind the infinitive-them infinite) universes and worlds?
He spoke of innumerable suns and worlds, and he certainly wasn’t wrong about that. Today we have cataloged 5,000 but we know there are billions. In our galaxy alone there are a hundred billion stars and each one also has a planet around it, let alone if there isn’t one that bears some resemblance to ours. Thanks to the James Webb telescope we will know more. These worlds are inhabited by living beings added Bruno; here on this we cannot yet affirm in a documented way that he was right. It is probable according to data and estimates that he is right but we must be cautious as we do not have direct evidence. Let us then add patience to humility.
In short, Bruno had taken more of us five centuries ago than Musk today. However, the Holy See has never rehabilitated his figure, unlike that of Galileo, certainly not for this but for other “doctrinal” reasons. And speaking of patience, which takes time: the physicist Carlo Rovelli in the essay “The order of time” offers us a concept of time bordering on our cognitive abilities. Not an identical time everywhere, which flows at a constant cadence independent of us, but a relational time, which changes with the mass of the bodies and according to how much they weigh, curving the fabric of space-time.
This speech has to do with the theory of relativity. It is certainly true that time does not flow uniformly for everyone, but it is also true that the plot of space-time deforms according to the relative speed of two actors, only if the difference in speed at which each travels is really great measures the occurrence of a phenomenon, only then can it measure it differently. But this happens if one of the speeds in question is very high, like the speed of light.
So we have no way of perceiving these differences as our speed does not reach these measures. If she traveled at the speed of light we could notice this inhomogeneity of time. In short, for us human beings it is irrelevant. But it’s not for Cinema, which has produced wonderful films like Interstellar on the basis of these discoveries, tricks of science and above all of nature, of which art uses to narrate a change of fate or avoid great pain.
To me, who personally believe I have a strong spirituality, that question has always seemed ridiculous: “Is there life on other planets?”. I know that intelligent and complex life is meant – not just microorganisms – but I believe that life is the condition of the very existence of the cosmos. He would never have given himself a universe died. It is not an organic but an ontological fact, let’s say in the philosophical sphere. If the universe has manifested itself in its material form, it is in short only a consequence of the fact that there is a life, a spirit from which it expresses itself.
I find this way of perceiving reality very fascinating, but one immediately stumbles upon the great difficulty of defining what life is. Is it a function? So is that which breathes alive? What is reproduced? What do you think? And how is it measured? How do you grab it?
Descartes considered animals as non-living machines as he saw them as automatons. Our hair is organic but not alive.
A star becomes protein so even if it wasn’t alive it will. As a scientist, are you able to reconcile the idea of a divine plan or do you see in the stars only a chain of causes and effects devoid of a teleological proceeding and an eschatological aim?
It is not personally imperative for me to reconcile these two aspects because, as I said, we still don’t know what it means life but not because you find the question reductive. We are once again faced with an enigma like dark energy, and perhaps we need to find new probes or new words to understand each other. I suspend judgment but I want to say that I don’t see hostility between a spiritual vision and a conception that has more reservations about this feeling. Indeed, I see fantastic planets to explore.
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Onions on Mars, on the red planet with Elon Musk? Interview with the astronomer Giovanardi