What reality does science tell us about? With Christophe Galfard

Edited by Charles Pépin

“I want to tell you the story of the truth or rather, the story of a man. He is a scientist who seeks the truth, or at least who seeks to know what reality is made of. Imagine in a white coat in his laboratory, but more often than not, he is in a shirt, not necessarily white, at his desk, sometimes even in his underpants, making equations.Each of his hypotheses is a question posed to the world, in front of him is the accumulation of equation packages, which very often does not yield anything, will sometimes make it possible to formulate a new hypothesis. Afterwards it will be necessary to check. (…) “

To talk about science and wonder, and what science can tell us about reality, Christophe Galfard, PhD in theoretical physics, lecturer and author, especially author of the bestseller The universe at your fingertips sold more than a million copies worldwide, is a guest in “Under the Sun of Plato”, in the cave of France Inter.

What reality does science tell us about?

This episode is about the black hole, the cosmos, the infinitely large, the infinitely small, dark matter …

Who is Christophe Galfard?

A very gifted math student, so gifted that he, as Charles Pépin explains, was advised to go and see the great Stephen Hawking, who then took him as a student at Cambridge, and then he became his collaborator.

How did it go from hard research to popularization for the general public with conferences, shows, books? This desire came to him in part from his frequentment of Stephen Hawking. He explains: “Stephen Hawking, for those who do not know him, is one of the most famous scientists, at least in the Anglo – Saxon world of the 20th century. He revolutionized our view of black holes and wrote a book that was a absolute bestseller with more than 20 million copies sold, which is called A short time history and so basically, who opened a hole, or rather a bridge, that built a bridge between theoretical physics, the scientists who were supposed to be in their ivory tower somewhere, and the general public. “

He helped him write lectures for the general public, and it fascinated him.

54 min

The very big ones and the very small ones

There are initially two theories, two areas of research, which Christophe Galfard explains: “We have two great theories, two great principles, one that applies to everything that is gravity, very large, rather questions about the whole cosmos and something else about what is smaller, what is inside us, matter, light, etc. and what we call quantum physics. These two theories are completely separate. There is the small one and there is the big one, it is very good, they work really well. We have never had theories that worked as well as these two to discover things we did not know. These theories allow us to look into the unknown and then go and verify that this vision actually works.

In his book The universe at your fingertipshe speaks of a possible unity. There are places in space where these two theories meet:

“Black holes where you have something very big, like a giant star that has shrunk and become tiny. And the Big Bang, the origin of our universe or our whole reality was a small place.”

But what is a black hole? “It simply came to our notice then. We have places in our universe where there is not much energy. Black holes are places where there is too much energy concentrated in a tiny spot. And we know, for example, that black holes can be born when giant stars explode and pull their nucleus together at the time of the explosion. Bam, the heart is contracted and after a while there is so much energy, so much gravity that the surface of the heart itself collapses about itself. It is as if you are walking on the ground and the ground is slipping under your feet to fall. Falling, falling to infinity, almost. “

The Milky Way: a dust

He uses in his book The universe at your fingertips an image so that we can represent the size scales:

“When you look at the sky at night, you see that there are stars everywhere. And then a little white ribbon, which we call the Milky Way. It turns out that the Milky Way, that’s the name of our galaxy. It’s not just the name of the galaxy. this white ribbon, it turns out that all the stars you see in the night sky belong to the Milky Way, so to get an idea of ​​what this road looks like, I take in the book the example of 300 cardboard boxes, about one cubic meter, one meter times a meter, filled with fine sand.And you spread these grains of sand on the Place de la Concorde, in a spiral around the obelisk, and it gives us our own galaxy. The Milky Way and the Sun are just one of those grains of sand. Inside this construction and galaxies like it, we know at least 1,000 billion.

Listen to the interview in its entirety …

Some books by Christophe Galfard

51 min

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