Each and every one of us is familiar with the force of gravity. It keeps us firmly planted on Earth, it is the force against which we must fight every morning to get out of bed, and it is the reason why climbing a staircase or a mountain requires effort. Thanks to gravity, we glide down snow-covered slopes on our skis, water flows from the mountains to the sea, and apples fall from trees. According to legend, this phenomenon played a significant part when Isaac Newton developed the first mathematical description of universal gravitational attraction, realizing that the same force that makes those apples fall also choreographs the celestial ballet of planets, stars and galaxies.
Without gravity, the moon would not orbit the Earth, the Earth would not revolve around the Sun, and galaxies would not exist. Newton’s profound contribution was to realize that gravity acts on all matter, at every moment, everywhere, in every corner of the Universe. It is universal!
Gravitation is also mysterious and counter-intuitive. The modern theory describing it is general relativity, developed by Albert Einstein in the years following 1910, and published in 1915. According to general relativity, space and time form a structure in which geometry is curved, far from our everyday experience of the world. In the most extreme cases, gravity gives rise to objects as exotic as black holes, from which no signal can escape. It is also at the origin of gravitational waves, discovered very recently thanks to detectors of incredible precision. Another strange aspect of gravity is that it does not behave like the other forces of nature, electromagnetism for example, which are very successfully described by quantum theories. So far, scientists have not yet succeeded in finding the necessary tools to unify gravity with the other forces in a single theoretical framework.
Reconciling gravity with quantum theory is perhaps the most pressing of challenges for today’s physicists. Stephen Hawking showed some years ago that there are links between the two, but despite nearly a century of effort and research, physicists have yet to find the key to integrating the force of gravity into the world of the infinitesimally small described by quantum mechanics.
The 2018 edition of the Wright Colloquium will explore gravitation in all its aspects. Our speakers will discuss its use for interplanetary journeys, to the comet Churyumov-Gerasimenko for example, on which a probe was successfully landed in 2014. Gravitational extremes like black holes and gravitational waves will be discussed, as will the measurement of gravitational waves in detectors for which the boldest superlatives do not suffice. And we will explore the complex links between gravitation and the quantum world. These themes will be the topics of five lectures given every evening of the week from 5-9 November at Uni Dufour.
Every evening, before the public talks, the Scienscope of the University of Geneva will be presenting animations that illustrate in a simple and fun way the concept of Gravity in physics, biology as well as mathematics. Theses animations will take place from 17:30 to 18:30 in front of the Auditorium Piaget, Uni Dufour.