Helgoland: Making Sense of the Quantum Revolution (2021)
Carlo Rovelli (1956)
233 pages
Since quantum theory’s formulation and elaboration during the first half of the 20th century, it has had a remarkable run of success. Its predictions have been validated to ever higher levels of accuracy by increasingly complex experiments, and its developments have dramatically deepened scientists’ understanding in a wide variety of fields. More concretely, its practical applications have had a revolutionary impact on many of the devices in our daily lives, from the improvement of even the most mundane home appliances to the development of an ever-expanding bonanza of technical marvels.
And yet, despite all this success, the physical interpretation of quantum mechanics has remained an enigma, with a number of its predictions – and the experimental results that have confirmed them – contradicting our deeply-rooted intuitions about how the physical world behaves.
While many physicists over the years have narrowed their focus onto the technological opportunities quantum mechanics has offered, others have been unwilling to ignore the theory’s enigmatic consequences for our understanding of the fundamental nature of reality, and so have sought explanations for its bestiary of confounding implications. This latter group, according to physicist Carlo Rovelli in his book Helgoland, can roughly be divided into two camps: those who postulate mind-bending theories that maintain our physical intuition at a cost of introducing seemingly unverifiable features, and those who postulate equally mind-bending theories that require us to set aside our physical intuition. Given the strangeness of the observed phenomena, either path requires a bold imagination.
In his book, which has the subtitle Making Sense of the Quantum Revolution, Rovelli summarizes the theoretical development and experimental validation of quantum mechanics, as well as the enduring debates over its interpretation. He then outlines his own theory for what quantum mechanics reveals about the fundamental nature of the world, and describes its surprising consequences, before concluding with a captivating exploration of the striking similarities of his proposed explanation to understandings in other fields.
The book opens with the story that gives it its title: Werner Heisenberg’s stay during the summer of 1925 on the North Sea Island of Helgoland. Heisenberg came to the island seeking a quiet, isolated spot in which to develop a theory that could explain Niels Bohr’s surprising formulas describing properties of electrons. Bohr’s equations accurately predicted aspects of the observed behavior of electrons, but also indicated that an electron can only take on discrete orbits around the atom, making quantum leaps to go from one orbit to another. The concept that nature could be discrete at some fundamental level rather than continuous, though now seriously entertained, at that time represented a tectonic shift in physicists’ views of reality.
Unfortunately, Bohr’s equations gave no hint as to what force or forces could explain his shocking results, and it was this question that Heisenberg wrestled with during his sojourn on Helgoland. Rovelli writes that Heisenberg eventually had
the idea. An idea that could only be had with the unfettered radicalism of the young. The idea that would transform physics in its entirety – together with the whole of science and our very conception of the world. An idea, [Rovelli] believe[s], … that humanity has not yet fully absorbed. (8)
Helgoland, in fact, represents Rovelli’s attempt to help readers “absorb” the fundamental shift quantum mechanics seems to require to our understanding of the world.
Heisenberg’s idea, as Rovelli describes it, was to shift from trying to “find the force capable of causing the bizarre behavior of electrons” (8) – that is, how an electron makes quantum leaps – to writing formulas that fully describe the observed phenomena of the electron, such as the light it emits when it moves. Ultimately, the equations Heisenberg developed described the behavior of the electron more fully than Bohr’s formulas could, but did not at all resolve the question of how the described behavior occurred.
Rovelli provides an introduction to Heisenberg’s formulation, and its subsequent development into quantum mechanics by Heisenberg as well as others associated with Bohr, and describes some of the numerous experimental results that have supported it. He also reviews the struggle over the interpretation of the theory, at the heart of which lies Heisenberg’s decision to let go of the search for
how the observed behavior occurs and focus instead on formulating a description for
what is observed. This debate continues to the present day, and has been explored in a string of books, such as Adam Becker's recent
What Is Real? (my review linked to at right).
Central to these debates has been a particularly unnerving aspect of quantum theory, one that has been backed-up by many experimental results: the locations of tiny particles appear to be probabilistic. Rovelli notes that, in response to this, some physicists have developed interpretations of quantum theory that maintain our intuitive, deterministic expectation for the physical world; in so doing, however, they end up relying on unverifiable structures such as multiverses (see, for example, physicist Max Tegmark's
Our Mathematical Universe, my review linked to at right) or hidden (indeterminable) variables.
Ultimately, Rovelli finds these deterministic formulations of quantum theory unconvincing, and he argues that, instead of trying to force quantum theory to match our intuitive desire for a deterministic reality, physicists should be open to new ways of thinking about the fundamental nature of reality. Over the middle section of the book, he describes the interpretation he finds most plausible: that bits of matter cannot be described in isolation, in the sense of being objects having particular properties; rather, objects are defined by their relation to one another.
[Quantum theory] describes how every physical object manifests itself to any other physical object. How any physical entity acts on any other physical entity. …
To understand nature, we must focus on these interactions rather than on isolated objects. (75)
Thus, for Rovelli, the entire physical world is defined by interrelationships between objects, rather than by properties associated with individual objects. In this way of thinking about the world,
“everything exists solely of the way in which it affects something else. When the electron does not interact with anything, it has no physical properties. It has no position; it has no velocity.” (79)
And the electron is simply a specific example; for Rovelli the same principle applies to all objects, of any size. In this he includes himself, as well as his readers: in his view we, each of us, only have particular properties in relation to other objects that we interact with.
And his theory has several startling consequences, including that for a given object, its properties can be vary, depending on its interrelationships with other objects. In particular, quantum theory leads to the conclusion that “a fact might be real with respect to you and not real with respect to me,” (81) and so that “no universal set of facts exists.” (96) Here, Rovelli uses the word fact to represent property. And lest this sounds a little too much like support for the alternative facts crowd, he brings in the quantum concept of entanglement, due to which, he demonstrates, when two observers view a property of (i.e., a fact about) an interaction between two other objects, they will necessarily observe the same property.
Rovelli notes that the debate over these fundamentally opposed points of view – matter having universal properties versus only having properties based on relationships with other objects – has existed in the context of a broader set of controversies that arose in the twentieth century, in areas such as philosophy and politics.
He describes disputes in the early Soviet Union that were percolating around the same time as the development of quantum theory, and that themselves grew out of philosophical divisions of the early 20th century. In particular, he recounts a falling out between Lenin, who held to the idea “that ‘there is nothing in the world except matter in motion in space and in time,’ and that we can arrive at ‘absolute truths’ through knowledge of matter,” and his former colleagues, such as Bogdanov, who felt that “things are much more subtle than naïve materialism would have it.” (127)
Lenin won these debates, of course, though Rovelli pointedly notes that in the long run, Bogdanov’s prediction “that Lenin’s dogmatism would … prevent [the Russian Revolution] from evolving further [and] render it sclerotic, [proved] prophetic.” (130) Rovelli argues that our deeply engrained physical intuition of the nature of reality have led to a similar sclerosis, one that threatens to hold back progress in physics: “what are these ‘most rooted metaphysical convictions’ of ours, if not what we have become accustomed to believe precisely by handling stones and pieces of wood?” (136)
In a plea to not get trapped in our “most rooted metaphysical convictions,” Rovelli asks us to accept that our long-standing convictions about nature may need to be reconsidered.
Turning to a much earlier historical period, Rovelli discovers similarities to his proposal that the physical world is defined by relationships in ancient philosophical traditions that describe our conscious perception of the world as happening through relationships. He references the work of the Buddhist philosopher Nāgārjuna, who lived in the second century CE, and who claimed, according to Rovelli, that
there is no ultimate or mysterious essence to understand – that is the true essence of our being. “I” is nothing other than the vast and interconnected set of phenomena that constitute it, each one dependent on something else.
Based on this understanding, “there is no sense, argues, in looking for an ultimate substratum.” As with Rovelli’s relational theory of reality, for Nāgārjuna all things exist “only in interdependence with something else.” (152-154) (An engaging and accessible review of the Buddhist conceptions of consciousness and the self, and its apparent validation by recent research in neuroscience and psychology, can be found in Robert Wright’s
Why Buddhism Is True; my review linked to at right.)
Of course, Rovelli’s plea that we be open to the possibility that our intuition of nature as deterministic may be incorrect is a bit of a two-way street. Though he certainly seems justified in being unpersuaded by the seemingly unverifiable assumptions of the theories that have been proposed to-date to explain quantum physics in a way that maintains our expectation of determinism, that is not sufficient in itself to decide that determinism must be thrown out. Yes, we should be open to considering understandings of reality that are not deterministic – such as Rovelli’s relational model – and more generally that align with experimentally validated theories that run counter to our fundamental physical intuitions. But physicists’ have often enough before been misled into thinking they had reached the most basic level of understanding, and so a determinist can perhaps still argue, to quote Monty Python, “I’m not dead yet.”
Rovelli concludes his book with a fascinating exploration of recent developments in scientists’ conceptualization of consciousness. He describes the idea of relevant relative information: ‘information’ in the mind that is ‘relative’ – “generated by the interactions that weave the world” (168) – and ‘relevant’ – “its presence or absence influences my survival” (173). In this view, human consciousness is thought to be an encoding – if incredibly, and nearly unimaginably complex – of relevant relative information about our interrelationships with other physical objects.
Noting the parallels to his own relational interpretation of quantum mechanics, Rovelli concludes that:
Meaning and intentionality are only particular cases of the ubiquity of correlations. There is a continuity between the world of meanings in our mental life and the physical world. Both are relations. (176)
But, while the similarities are indeed striking, such a relational understanding of consciousness doesn’t seem to require the physical world to also be fundamentally defined by relationships. Rovelli himself makes clear that the view of consciousness as being an emergent property of the complexity of our brain’s relevant relative information processing capability has no direct connection to quantum physics, noting in particular that he doesn’t find the idea that “electrons and protons have a kind of proto-consciousness … persuasive.” (164)
Ultimately, however, whether or not a reader leaves convinced of Rovelli’s proposed view of physical reality as fundamentally tied to interrelationships between objects, Helgoland provides an engaging history of quantum theory and its interpretations, and a fascinating exploration of conscious. As has been the case in others of Rovelli’s works (my reviews linked to below), his sparkling and engaging prose make approachable what is perhaps one of the most challenging fields for lay readers to venture into. And by contextualizing the development of quantum mechanics within the broader history of our evolving understanding of the physical world, as well as the philosophical and political milieu of the twentieth century, Rovelli thrills as well as explains.
Other notes and information:
As part of his argument in support of the concept that "the qualities of an object are born from the interaction with something else," Rovelli compares it to "naïve materialism, according to which all mental phenomena are reducible to the movement of matter." He also refers to this as "naïve realism," which he dismisses as "intuitively difficult to reconcile with subjective experience." (184) And yet, elsewhere in the book, Rovelli claims that it is a mistake to allow our intuitive experience to lead us to believe that there must be a deterministic explanation underlying quantum mechanics, writing: "Our prejudices concerning how reality is made are just the result of our experience. Our experience is limited." (136) He seems to be wanting to have it both ways: dismiss our relying on our subjective experience when it contradicts quantum theory, but call upon it to support his proposed concept of objects being defined by their interactions.
Links here to my reviews of other books by Carlo Rovelli:
Have you read this book, others by this author, or even similar ones by other authors? I’d enjoy hearing your thoughts.
Other of my book reviews: FICTION Bookshelf and NON-FICTION Bookshelf
