Prologue

It is 6 October 1570. In England, Guy Fawkes is a newborn baby in his mother’s arms and Queen Elizabeth I is feeling the sting of her excommunication from the Catholic Church. In Italy, the once-great Jerome Cardano, now sixty-nine years old and feeling it, is also about to fall foul of the religious establishment.

He is in Bologna for a meeting of the city’s syndics, the governing officials who pronounce on civil law. Jerome hopes to persuade them of his innocence — that he has not, as the Milanese College of Physicians has suggested, committed sodomy and incest. Forbidden to enter Milan to plead his case, his only hope is the Bolognese syndics. But his hope is misplaced and he seems to have no concept of just how impossible his position has become. In the public’s eyes, he is now a madman. In Milan, he was spotted begging for alms at the gates of the College of Physicians — where he once held the office of rector. There are moments when Jerome is overcome by his new misfortune, by his hunger, and by the ignominy of his position, and is found loudly cursing in the streets. It doesn’t help that he has taken to wearing a gift given to him many years earlier by the Archbishop of Scotland: a belted plaid that he wraps around his waist and secures with a leather belt, throwing the rest of the heavy mottled cloth over his shoulder. No one in Italy has ever seen — let alone worn — anything quite like it. Who can blame the locals for laughing?

How the mighty fall. Just two decades earlier, this man was summoned all the way to Edinburgh to treat the Archbishop’s asthma. On his long journey to Scotland, the physicians to the French king had organised for Jerome to speak at a series of conferences in Paris. Then, while in Edinburgh, the courtiers of the young King Edward VI of England had begged him to come to London and provide a medical consultation for the ailing royal youth. Not satisfied merely to tap Jerome’s medical skill, they prevailed upon him to construct the royal astrological chart. He left Edinburgh a rich and celebrated man; he left London even richer. On his journey home, he travelled via all the major cities of Europe, entertained by noblemen and the ambassadors of the Holy Roman Emperor.

Now he has no money to pay for lodgings and spends his nights in an abandoned hovel where the wind whistles through the gaps in the walls. What is left of the roof creaks ominously above his head. Every evening, before he goes to sleep, the celebrated physician, the royal astrologer, the inventor of numerous machines and mathematical abstractions — among them probability theory — eyes the rotten beams. He attempts a calculation of the likelihood of the building’s collapse. There is a part of him that would welcome such a swift end.

But morning comes and the building still stands. His stomach empty and groaning, Jerome emerges warily into the light and looks down the street. He has woken in a good mood. There is a lightness in his stride as he sidesteps a mangy, sleeping dog — he has developed a phobia of dogs that he will attempt to explain in the pages of his autobiography — and turns towards the city centre. Today, he will see the Bolognese syndics and they will listen to him. These are not like the petty, sour-faced goats that rule over Milan. From tomorrow, he will be permitted to earn his living again. And then, across the road, he sees someone staring at him. At first, the disfigured, bearded features of Nicolo Tartaglia are not clear. But then the man known as The Stammerer steps forward, and with him steps a cohort of the city guard, their armour gleaming in the early morning sun.

‘There he is,’ Tartaglia says. His words are barely discernible, so profound are the childhood injuries to his face. But the gleam in his eye is unmistakable. ‘Arrest him.’

As the guard moves to cross the street, another figure is revealed. Watching with a cold, intense gaze is Aldo, Jerome’s youngest son. Slowly, the young man turns and walks away. But not before the father sees a sly smile, a grin that celebrates a long-sought revenge, bloom on the face of his only surviving child.

ψ

Have you ever wanted to understand the universe? Once that desire burns away at your soul — really burns — there’s no going back. That’s why some people dedicate their lives to physics. Or to philosophy. Or to Buddhism. Or to mathematics. They are all searching for answers. I am not saying that they are all ultimately following the same path — I know which I think is the best bet — but none is able to satisfy everybody.

I chose physics as my path to enlightenment. Some prefer the teachings of Jesus. Others go for Krishna or Kabbalah. My friend Jerome Cardano — indulge me, for we have spent a lot of time together — opted for astrology. He didn’t ever really trust it, though. Jerome used to worry at astrology, to work it hard, to ask difficult questions of it. I’m not convinced everyone does the same, even with physics — a predicament that provides much of the reason for this book.

I am a physicist. My expertise, such as it is, is in quantum mechanics, the theory that describes how the world works on microscopic scales. My interest in Jerome arises from the fact that he used his sharp mind to unearth the mathematical pillars on which quantum theory, our most successful scientific guide to the universe, is founded. Astrology and quantum physics rattling around in one Renaissance skull — who’d have thought?

Jerome would be happy that I am introducing him to you: his work, his mind, and his life. He always wanted to be famous; by the age of twelve, he had decided to dedicate himself to creating something that would bring him lasting renown. That you know next to nothing about him points to one of his many dashed hopes.

He hoped also to make his fortune at the gambling table. Despite inventing probability theory for just that purpose, he gambled away his marital bed and all his wife’s jewellery. Then there was his hope that his wife, Lucia, would live a long and happy life. For all the good doctor’s successes in treating others, he could do nothing to halt her death after just fourteen years of marriage. He hoped that his elder son would be a successful physician. Unfortunately, Giovanni’s marriage into a family of gangsters made that particular aspiration particularly optimistic, and the young man’s execution for murder, a plot twist that broke Jerome’s heart, put an end to that hope. Jerome also hoped for grandchildren, but ended up raising only the grandchild of a man who tried to ruin him.

The one thing for which he held no hope was probably his most important and lasting creation. It is the square root of a negative number, something we now call the imaginary number. Though it initially seemed like nothing more than a strange mathematical abstraction, it has turned out to be essential to understanding how the universe holds together.

It was a privilege to be the one to tell him.

You’re probably thinking that I have lost my mind. You might be right. My obsession with Jerome has, in the last few years, taken me over. I have a mind that has been schooled in quantum physics and trained to think rationally, dissecting facts and ideas dispassionately. And here I am, not only celebrating a Renaissance astrologer, but talking as if we are contemporaries.

To me, though, it makes sense. I talk to Jerome. He talks to me. These conversations take place in my head, true, but they are informed by his writings, and by things written about him. We are intellectual contemporaries. We are both rational, both seeking to understand the universe, both convinced that nobody has a good grasp of it yet. We both believe that space and time — time, in particular — are not what you and I have been raised to believe they are. So, yes, this book is not quite what you have come to expect from a science writer with my training and history. But I can’t help that. In my head I have visited Jerome in his prison cell. And maybe it is not just in my head. Within the books that Jerome wrote after his release I see unmistakable traces of my visits.

Perhaps you should walk away before I drag you into this madness.