We are still lost in the cosmos. “ The more we learn about nature, the stranger it becomes ”

I thought: this is my path for decades to come, ”says Hans Plets (1968). But the Flemish astronomer moved from university to the Belgian KNMI and recently became CEO of a company that trains air traffic controllers. “My parents laughed: your gaze descends from the stars to the ozone layer and now finally to the ground.”

Somewhere along the way, Plets threw himself into the question of what we can actually know – and scientists like him now know a lot, from the structure of the universe to the smallest reality we exist in. Plets follows in his book in sober and clear prose Lost in reality 25 centuries of thinking about what we know and if we can know it.

I believe that among the dozens of philosophers you deal with, from ancient Greece to the present day, I find one that really touches you: the British Enlightenment philosopher David Hume.

“Yes, handsome man! But when I went to study philosophy, I was very angry with him for breaking everything I thought I could know. I had looked for scientific knowledge. How can you ask yourself that tomorrow the sun will rise again? Don’t we all know that? No, we don’t know. Or not with absolute certainty. Hume became the disappointment for me.

It did not diminish the feeling of being lost for Plets. The reader of his book gets this dizzying awareness as the story progresses. Especially when Plets describes modern physics. For outsiders, this is inaccessible terrain, where you have little to look for if you are not familiar with tensor calculus, complex number theory, Hilbert spaces, functional analysis, and theories. some ropes. Plets writes that there is an unprecedented gap between the reality we live in every day, the nanoreality of the little ones and the cosmos. “On a cosmos scale, nature behaves differently from what we are used to with our five senses and on our scale. Mass and movement distort malleable space and time, which you have to merge into space-time. There is no absolute space, no absolute clock. You cannot objectively verify whether two events in space-time are occurring simultaneously. Mass is a form of energy.

At the smallest level, measurement is a tricky task, because measurement itself influences the measurable. Localization makes way for statistics – you can talk about the probability that an electron is somewhere, but the more precisely you want to determine where exactly, the less you know about its speed. Far from certainties.

So you are always lost.

“Yes, the more we learn about nature, the stranger it becomes. We used to live in a comfortable universe, where God took care of him, now we have just enough sense to realize that we are an extra in a cosmos that is not tailor-made for us. Hume’s disappointment has remained, his skepticism is like a stone in my shoe.

Yet knowledge is increasing, it is a search for The Theory that explains everything.

“Until recently, I wanted us to go at full speed in this research and for billions to go to CERN, the Geneva research institute equipped with a particle accelerator. This wants to build even faster facilities, so that we can penetrate deeper into the secrets of the little ones. But the latest major breakthroughs in theorizing on this subject have been delayed by decades. Slowly, we also fear that some properties of nature cannot be explained further. Desperation in the ranks of contemporary physicists is increasing noticeably.

“I am charmed by the thought of German physicist Sabine Hossenfelder. She says: we have lost track. Particle physicists and cosmologists watch with colored glasses, they expect too much that reality will conform to what we mathematically think “too good to be wrong”, that there is symmetry in everything. Hossenfelder would like to take a break for a moment. I will repeat it to him, even if it does not suit my impatient nature.

For those who want to know how everything works, Plet’s book is a disillusionment. “We have an idea of ​​the nature of about 95% of our universe, we barely have a grasp of consciousness, we don’t know how many dimensions reality is made up of, we don’t really understand why time moves so inexorably around. and why things are like this. they are. the most basic level.

Above all, there is a lot to not know, you write that the laws of nature are not suited to human measure. This orientation is therefore lacking. At the end of your book, you allude to meaning.

“Yes, in the last few decades scientists have hit the traditional areas of meaning, religion and metaphysics with the hammer. Scientists are gradually realizing that something must therefore be substituted for it. In this context yes, here I present the poetic naturalism of the American physicist Sean Carroll, he has a sense of aesthetics, ethics, but also ambitions and disillusions. But all this without contradicting the ideas of science. As far as I’m concerned, this is a valid first attempt to look at everything that makes our life scientifically valid.

It looks pretty bare and abstract. Are you going to expand on this in a future book?

“Well, I actually got a request from the editor to write about alien life, the chances of that happening. Let me address this.

Hans Plets, Lost in reality. Man in search of his place in the cosmos, Sterck and De Vreese; 288 pages € 25.95.