Helgoland by Carlo Rovelli
It’s not very often that I read a book that blows my mind. Helgoland by Carlo Rovelli is one such. Carlo Rovelli is an Italian Theoretical Physicist and he has written several popular science books. Helgoland is my first one and I believe that now there will be several more.
The book is in three parts. The first one is the story of discovery of quantum physics. The book gets its name from the German island Heligoland (or Helgoland). Our encounter with Helgoland starts with a young Werner Heisenberg looking out to the sea and thinking whether he has solved it. Heisenberg at that time was suffering from a bout of hay fever and he chose Helgoland as the place to rest and recuperate. The island has no trees and no pollens. Essentially, no allergens which could exacerbate his condition. Here he stayed for a few months and worked out the problem that was given to him by Niels Bohr. Rovelli says –
“Niels Bohr was already a renowned scientist. He had written formulas, simple but strange, that predicted the property of chemical elements, even before measuring them…..
Above all, these formulas had about them something that was truly absurd. They assumed, for no good reason, that the electrons orbited around the nucleus only on certain precise orbits, at certain precise distance from the nucleus, at certain precise energies – before magically leaping from one orbit to another. The first quantum leaps. Why only these orbits? Why these incongruous leaps from one orbit to another? What force could possibly cause such bizarre behaviour as this?”
This was the problem that Heisenberg grappled with on Helgoland. And while thinking about these in his isolation, he hit upon the idea of observables. Again Rovelli, trying to imagine Heisenberg’s thought process;
“We cannot find new laws of motion to account for Bohr’s orbits and his leaps? Fine, let’s stick with the laws of motion…… without altering them.
Let’s change, instead, our way of thinking about the electron. Let’s give up describing its movement. And Let’s describe only what we can observe: the light it emits. Let’s base everything on the quantities that are observable.”
At the time, there was already a philosophical undercurrent based on observables. There were ongoing philosophical discussions on the relation between reality and experience among the Austrian and German Philosophers at the beginning of 20th century. Ernst Mach, who had a decisive influence on Einstein, insisted that knowledge had to be based solely on observations, freed of any implicit metaphysical assumptions. You can only know what you can perceive. If it is not in your perception, you don’t truly know it. Heisenberg took the same approach and discovered his mechanics when looking only at observables.
He saw the behavior of electrons, and replaced the physical variables in Bohr’s formulas with a table of numbers. Rows for orbits of departure and Columns for orbits of arrival during these quantum leaps. The maths worked. On 7th June, 1925 something began to click. Heisenberg has written –
“Suddenly I no longer had any doubts about the consistency of the new quantum mechanics that my calculations described.
At first, I was deeply alarmed. I had the feeling that I had gone beyond the surface of things and was beginning to see a strangely beautiful interior.”
It does read and feel like a moment of revelation – “Gone beyond the surface of things”. Heisenberg’s matrix was then validated by other scientists. Wolfgang Pauli does the maths and ascertains that it works. In parallel, Paul Dirac independently arrives at the same conclusion as Heisenberg.
The matrix works, but the calculations based on matrix manipulation are difficult. A more elegant solution will be – if the electron was not a particle but a wave form with probabilities attached to the event of it being at some place. And we meet Erwin Schrodinger with his wave equation.
If you have ever been interested in the evolution of science or if you have studied science in your undergraduate program (like yours truly), you get to meet all of those characters from your text books in a colorful representation of their life. For example, Pauli is the arrogant one while Schrodinger is promiscuous. Rovelli takes you on a journey like no other, and you are left amazed that it all really happened. He takes you inside the minds of some of the greatest scientists the world has seen and you struggle along with them to come to terms with the reality, as it is. And by the end of your reading, you also realize that Rovelli himself is no less than these brilliant minds of yore.
The story of quantum mechanics has an illustrious cast of characters. Einstein, Niels Bohr, Werner Heisenberg, Wolfgang Pauli, Max Born, Erwin Schrodinger, Max Planck, Pascual Jordan, Paul Dirac, Louis de-Broglie; all of them make their appearance in this story of discovery of quantum mechanics.
The book is eminently fascinating just for this part one itself. The discovery of quantum mechanics changed science forever and scientists all over the world are still trying to understand its meaning fully.
In the second and third parts of the book Rovelli takes us through the implications of the quantum mechanics through some popular interpretations. He introduces the concept of superpositions, of which the most famous example is Schrodinger’s cat. He then speaks about the many worlds interpretation of quantum and some other theories with which he doesn’t agree. Finally, he introduces the relational interpretation of the quantum.
In the next two posts, we will examine the worlds of Quantum entanglement and the relational interpretation.
2 thoughts on “Helgoland by Carlo Rovelli”
Quite fascinating
Thanks Jaya, it is.