Saturday evening with Christophe Galfard worked from the ground level on to broaden our perspective on the Universe as far as science has been capable to carry us. Allow us to begin: Everything we know in the universe, interacts with light. Astrophysics began in the simplest form with the observation of the sky and its luminaries: Sun, Moon, stars. In the 16th century, the Danish astronomer Tycho Brahe began to gaze up at the night sky, but was unable to interpret the full scope of his observations without the help of a mathematician. The man who came into play was the person who allowed us to understand how the planets move: Johannes Kepler.
And in the 17th century, along came Newton with the groundbreaking idea of a Universal law of gravitation. “The universe became accessible to our imagination,” because we understood that the same laws that governed on Earth could do so in the heavens, explains Galfard. Newton’s understanding of gravity was a precedent for the imminent growth of our notion of the Solar System, for his laws allowed scientists to realize that there must be a body interfering with the orbit of the planet Uranus. This is how Neptune was discovered in 1843 based purely on mathematical calculations.
Then came Einstein, who through the general theory of relativity was able to explain the orbit of planet Mercury, which had up to then been an anomaly. He also set a speed limit to the Universe: the speed of light. An understanding of how information –that is, light– travels through space and time. So the theory of relativity tackled our understanding of gravity, and quantum theory has done so of matter. How to reconcile both? As science advanced, a Swiss named Fritz Swicky, who spent a very long time with his eyes in the lens of a telescope, realized that there’s something wrong with the way galaxies moved, a warning which set a huge question mark at the end of the conversation.
In the 1970s a woman called Vera Rubin shed some light on the matter to introduce the role of darkness in our Universe. More sophisticated telescopes had shown us that unsurmountable numbers of starts exist within galaxies, and galaxies, as most things in the universe, are spinning around. According to Newton and Einstein, the outskirts of galaxies, the speed at which things advance should be slower, but Rubin discovered that this is not so. The stars in the galaxy all advance at the same speed. If Newton’s laws legitimized the existence of Neptune, and Einstein explained the orbit of Mercury, there must be something we’re not contemplating that accounts for 80% of the matter in the known universe. Dark Matter is that which brakes the first rule we learned with Galfard: everything interacts with light. Dark Matter does not. This undefined element in the nature of the Universe affects the way everything within our galaxy moves in ways we cannot explain.
Galfard’s lesson was drawing to its end under a splendid night sky in the courtyard of Centro de Formación de la Cooperación Española. “We are standing on the shores of the discoveries of great scientists,” said Galfard. This accounts for why we have the biggest questions in history yet. But “despite our questions, we can understand the history of the Universe.” Galfard encouraged the audience to keep their curious minds alive and in defense of the importance of learning science: “if we stop teaching science, in two generations, the Earth becomes flat.” The disciple of the great Stephen Hawking ending with an exciting statement: “We’re aware that there’s something else that might show us new horizons in Space and time.”