Guido Tonelli: science has solved Hamlet's dilemma

It is not so intuitive, however, to understand why - from a state of order - there was this fluctuation that created disorder.

Actually, the so-called state of order, on the microscopic level, is quite chaotic: if one could see the vacuum state, one would see a continuous swirl of fluctuations, what we call the quantum foam. It is an ordered chaos, dominated by the laws of randomness and quantum mechanics. One of these bubbles, if it extracts a small amount of matter - strange particles we call infratons - from the vacuum and places them in a tiny portion of space-time if it happens by chance that the positive energy required to extract the particles from the vacuum is equal and opposite to the negative energy with which space-time is impregnated by the presence of this matter, the system has zero total energy and therefore can evolve for indefinite times. It does not close again. If the energy were positive, it would have to fall back in. It is a simple and at the same time incredible mechanism and it is the simplest solution that contemporary science investigated for decades until the total energy of the universe was measured and it was surprisingly discovered that the total energy of the universe is zero. Suddenly this made it possible to understand where the first instants originated from.

But the amazing thing is to realise that even today, the universe, i.e. 200 billion galaxies each containing 100 billion stars and dust and gas and dark energy and dark matter, and an enormous material structure, is still a vacuum state.

The void is full...

In fact, our worldview, the one developed by the early Greek wise men, led us to underestimate an element that we have only recently begun to investigate. Our vision has focused on the solid, on material objects. We, for example, see the Sun and the Earth, a large star around which the planet orbits, and pay no attention to the space-time that encloses them. We have a prejudice of ignoring the container in which physical phenomena occur, but this container plays a decisive role: it is the space-time deformed by the presence of the Sun that produces the Earth's orbit around the Sun. When people began to consider the role of space-time in the dynamics of the universe, starting with Einstein, it was discovered that space-time is also a material structure that contains energy, that vibrates and oscillates, that produces gravitational waves that can propagate to disproportionate distances, all of which took 100 years of study, and this is the key that made us suddenly realise that if we consider the role of space-time, which is the negative energy, the energy of gravitational attraction between planets, galaxies etc, and the positive energy, concentrated in the full, in the masses of the planets or galaxies, these two components are complementary, they cancel each other out, exactly as happened in the primordial bubble where everything was born. So full and empty, being and non-being, are two sides of the same coin, you cannot separate them. Being and non-being coexist interpenetrate, matter and emptiness are closely connected, fullness and emptiness are aspects of the same phenomenon.

In the book he writes being is not being....

Yes, you have to remove the 'o' and put the 'is' and you solve the Hamletic dilemma.

What role did the discovery of the Higgs boson play?

We have seen that the void is the cradle of the universe. The deeper understanding of the void, the journey we took into the void, made us realise our origin. It is as if it has given us an enormous gift. The other gift is having realised that the universe is a state of emptiness. We are indebted to emptiness because to emptiness we owe our origin and emptiness is our essence can deep, of this universe of which we ourselves are a part. But there is a third gift of the vacuum that we discovered more recently, in 2012, when we discovered the Higgs boson. Then we realised that the vacuum also plays a decisive role in defining the particular material structure that our universe has taken on. This is the electroweak vacuum, not a vacuum-void but a vacuum enriched by the presence of this field that is the Higgs field. Ever since it installed itself in the entire universe, which happened in the very first moments, immediately after the Big Bang, the electro-weak vacuum has changed everything. That chaotic universe in which myriads of massless elementary particles flew everywhere could never have built the wonder that surrounds us: stars, planets, plants, human beings. All these material forms arise from the interaction of the electroweak vacuum with elementary particles. By interacting with the electro-weak vacuum, the elementary particles acquire different masses: as the force of their interaction with the electro-weak vacuum differs, they acquire different masses, and this mechanism is fundamental to the construction of permanent material structures. Without the electroweak vacuum, protons or neutrons could not form where light quarks are held together by gluons. These primordial building blocks are the basis for the construction of the first material structures. Without that particular interaction that electrons have with the electroweak vacuum, one could not explain the light mass that electrons have and that allows them to orbit around nuclei to form atoms. It all stems from there. From there, hydrogen gas, stars, galaxies, planets, rocks, seas, plants, animals, human beings will form: it is the basis of an endless chain of successive generations of persistent material structures. At the origin is the gift that the electroweak vacuum gave us, giving this universe a wonderful material structure that is what surrounds us.

What can come from understanding emptiness?

This is a very topical challenge because it is as if for 2500 years we had concentrated on matter: we understood in great detail its composition, its microscopic structure, and yet we neglected the other component, space-time, which contains matter. Now that we have understood the importance of the vacuum, of space-time, if we were able to study in depth the laws that regulate its most intimate structure, on the one hand we could find answers to some of the great questions of contemporary science - perhaps the secret of quantum gravity, which we have not yet been able to describe, is hidden there - and, on the other, if we look at the technologies that we have been able to develop once we understand the detailed structure of matter, all the technologies that have been developed over the last hundred years thanks to quantum mechanics, we can get an idea of what might come from knowing the most intimate laws of the vacuum, of space-time. We must imagine that the day mankind succeeds in understanding the most detailed workings of the most intimate structures of the vacuum, unimaginable technologies can be born from there, and this is the challenge to which the researchers of the next generations are called.