Giorgio Parisi - In A Flight Of Starlings (Allan Lane, 2023) ****

Giorgio Parisi won the Nobel Prize in Physics in 2021 for his “discovery of the interplay of disorder and fluctuations in physical systems from atomic to planetary scales.”

In this short book he describes, explains and muses on complex systems, such as the flight of starlings, which is only the subject of the first chapter. His writing is simple, elegant and accessible, and easy to understand for the lay reader. 

He explains how as a young researcher he was encouraged to focus on just a few subjects instead of "concentrating on a few important ones. On the one hand this was obviously good advice, but on the other it was precisely by studying many things at once that I was able to make connections between different fields, the basis of many later discoveries"(p. 46). Next to starlings, we learn about the boiling of water and phase transitions, spin glasses, quantum physics, metaphors in physics and how ideas are born. Each chapter is worth reading, even if the first chapter on the flight of starlings was why I bought the book. The essence is about Parisi's work in complex system and the interaction of the various elements that they consist of. 

"In the context of physics, 'exchanging information' is equivalent to 'being subject to forces'. But generally speaking - given that the model can be applied to many fields of study, from physics and biology to economics and so on - there are many objects whose behavior depends on the behavior of other objects that are more or less in proximity to them, given that objects that are too far apart from each other cannot exchange information" (p. 47)

Not surprisingly, scientists from other disciplines are not always too happy when experts from other fields intrude in their area of interest. Just like anthropologists and sociologists hated the biologists who started with sociobiology, here the biologists are sometimes not all too happy when physicists come on their turf, when of course this cross-breeding is where the fun is. 

"We defined new standards of investigation in biology by using techniques originated and developed in statistical physics to solve complex and disordered problems. Not all biologists ap­preciated this incursion into their territory: some have shown themselves to be very interested in the results, while others have found our investigations to be too short on biology and top-heavy with math. The work was rejected by various journals that are probably kicking themselves now. After the great success of our first· article, which was cited in almost two thousand scientific publications, many others have followed." (p.17)

 And of course that's also where the value of analysing complex systems comes from. Understanding their workings at a very basic and abstract level, amplifies their use across contexts and areas of interest. 

"The actual world is disordered, and as we said at the start, many situations in the real world can be described as a large number of elementary agents that interact with each other. These interactions can be schematized with simple rules, but the results of their collective action are sometimes really unpredictable. The elementary agents can be spins, atoms or molecules, neurons, cells in general-but also websites, financial traders, stocks and shares, people, animals, components of ecosystems, and so on. 

Not all interactions between elementary agents generate dis­ordered systems. Disorder is born from the fact that certain ele­mentary entities behave differently from others: some spins try to go in opposite directions; certain atoms are different from most others; certain financial actors sell shares that others are buy,ing; some dinner guests actively dislike others who have been invited and want to sit as far away from them as possible. In all these disordered cases, the mathematical and conceptual tool I found is indispensable for tackling the problems associated with them." (p.80)

The book is an easy read, but with a very important topic. 

Thomas Hertog - On The Origin Of Time (Torva, 2023) ****

Belgian physicist Thomas Hertog had the privilege to work with Stephan Hawking during the last decade of his life, and this book tries to capture the essence and the changes in Hawking's thinking over the years, but it is also a testimony of friendship and admiration for the great physicist. 

The book starts with the paradoxes that philosophers and scientists have struggled with for thousands of years: why is there such a thing as life? is there a plan behind it? and why are there laws that govern us? Hertog narrates well, exceptionally well for such a complex, confusing and hard to understand subject. He starts by going back in time, human time, to the ancient Greeks and builds his narrative up with the building blocks that we are familiar with. So far, so good, and we as lay people can still follow. 

One of the leading characters in Hertog's book is his fellow countryman George Lemaître, the physicist and priest whose concept of the expanding universe led to a breakthrough in theoretical physics and astronomy. It took some time, but eventually Einstein became also convinced that Lemaître was correct. In this way Hertog takes us from each step to the next step, a new theory, new findings, challenges, and corrections, which lead to new theories. It is a great ode to the power of science and to the open-mindedness of scientists who through debate and correspondence accept that other viewpoints and findings are more accurately reflecting the complex realities out there. 

But he also describes the changes in Hawking's own theories and perspectives, possibly challenged by himself only, thinking ever deeper into the nature of our universe. Hertog tries to explain all this by using drawings and analogies, but they only lead us so far in understanding the complexity of what the theories entail. Without the mathematics, it is hard to fathom what they are really talking about (not that we would understand it with the mathematics, of course). 

I can only encourage readers to keep reading, even of some of the findings are incomprehensible. 

"STEPHEN'S NO-BOUNDARY MODEL of the beginning-conceived from the top down!-is key to realize the fundamentally historical perspective on physics and cosmology that I have advocated, a view of physics that in­cludes the genesis of the laws. The no-boundary hypothesis predicts that if we trace the primordial universe as far back in time as we possibly can, its structural properties continue to evaporate and transmute and that this extends, ultimately, to time itself. Time would initially have been melded with space into something like a higher-dimensional sphere, closing the universe into nothingness. This led the early Hawking, still reasoning in a causal bottom -up fashion, to proclaim that the universe was created from nothing. But Hawking's final theory offers a radically different interpreta­tion of this closure of spacetime at the big bang. The later Hawking held that this nothingness at the beginning is nothing like the emptiness of a vacuum, out of which universes may or may not be born, but a much more profound, epistemic horizon involving no space, no time, and, crucially, no physical laws. "The origin of time" in Stephen's final theory is the limit of what can be said about our past, not just the beginning of all that is. This view is especially borne out by the holographic form of the theory where the dimension of time and hence the basic notion of evolution, the epitome of reductionist concepts, are seen as emergent qualities of the universe. From a holographic viewpoint, going back in time is like taking an increasingly fuzzy look at the hologram. One quite literally sheds more and more of the information that it encodes until, well, one runs out of qubits. That would be the beginning."(p. 257) 

Fascinating, mind-boggling, and utterly perplexing. 

I can only encourage readers to read it. 

Brian Cox - Forces Of Nature (William Collins, 2017) ***

Physicist Brian Cox produced and presented one of the most beautiful and educational documentaries on the nature of our nature, answering questions about things that are so everyday that we rarely ask questions about them, such as: why do snow crystals have the form they have or why is the sky blue?

He takes the reader on a fascinating journey from the most obvious and easy to understand things in a step-by-step approach to more complex matter, such as the nature of space and time, or the deepest essence of light, or the origin of life and free will. Cox is a wonderful guide in all this, keeping a big picture view, and once in a while digging deeper in the complexity of our nature.

In passing, he also advocates for more investments in basic research, to help us understand the deepest questions about our universe, even if they do not immediately result in economic or social benefits. I can only support that vision.

I can recommend both the documentary (the quality filming by the BBC is as usual astonishing) and the book. Both really are complementary.

Sean Carroll - The Big Picture - On the Origins of Life, Meaning and the Universe Itself (One World, 2017) *****

Sean Carroll is a theoretical physicist at the California Institute of Technology, the author of several popular science books and an award-winning scientist.

"The Big Picture" does exactly what its hugely ambitious title promises, and in the space of 433 pages. Quite a feat. He starts with with the deepest level of reality, with the Big Bang, the cosmos and the smallest particles in our universe and our daily lives. He demonstrates how everything is matter or energy. He expands on how scientists from the ancient Greeks tried to come to grasps with this elusive reality, how delving deeper provided answers yet created even more questions.

He expands on what we can know and how. He writes about the nature of science, of doubt and observation. How extremely difficult it is to understand and explain reality. How different levels of description fail to convey the exact nature of reality. How we have to accept uncertainty. And probability instead of accuracy.

In part three he goes into the "essence" of reality. Why does the universe exist at all? What are the smallest particles, how do they come into existence, and how do they interact? Carroll is confident that the big picture that we have today, the "Core Theory", is the correct one. This quantum field theory unites the standard model of physics and the general relativity. Our present understanding of quantum gravity includes everything we experience in our daily lives. it's the quantum field theory of the quarks, electrons, neutrinos, all the families of fermions, electromagnetism, gravity and nuclear forces, and the Higgs. "A thousand years from now we will have learned a lot more about the fundamental nature of physics, but we will still use the Core Theory to talk about this particular layer of reality (...) the laws of physics underlying everyday life are completely known". He concedes that "it's not the most elegant concoction that has ever been dreamed up in the mind of a physicist, but it's been spectacularly successful at accounting for every experiment ever performed in a laboratory here on earth".

On the cause of the universe or the question "why is there something instead of nothing?", he turns the situation around to account for the real findings in physics: "there is not a moment in time when there is no universe, and another moment in time when ther is; all moments in time are necessarily associated with an existing universe. The question is whether there can be a first such moment, an instant of time prior to which there were no other instants. That's a question our intuitions aren't up to addressing. 
Said another way: even if the universe has a first moment in time, it's wrong to say that it "comes from nothing". That formulation places into our mind the idea that there was a state of being called "nothing", which then transformed into the universe. That's not right; there is no such thing as "transforming". What there is, simply, is a moment of time before which there were no other moments."

Not surprisingly, in this universe, there is no need for a god who created all this. The implications of the Core Theory are also clear for the existence of a soul : it just cannot possibly exist, and as a consequence, there is no possibility for something such as life after death to exist. We are all matter.

Then he takes us a step further, into the realm of life. How it began. Sure, Carroll is not a biologist, but he looks at biology with the mind of a physicist. He looks at how complexity can arise, and how the laws of entropy are completely compatible with it.

Then he looks at consciousness and the latest findings of neuroscience and cognitive sciences. Again, many questions remain about how the brain works, about how consciousness is created out of the electrical signals that are transmitted between the neurons in our brain.

In the final chapters he talks about the world, about morality. And here too, Carroll's words are wise, and well-substantiated.

It is by all means an amazing book, not only by the scope of the author's knowledge, the depth of his insights, the fluency with which he describes it, but also because of his scientific open-mindedness and care for humanity. Some could argue that it's a little too much, that a physicist should stick to his territory and not go beyond his field of knowledge. But why not? Physics has given us answers to questions that philosophers and theologians had been struggling with since forever. Few philosophers will understand quantum physics, but philosophy can be understood by physicists, just like morality. I think it's wonderful that someone dares make the connection between all the sciences. As long as its critical and well-informed, they should all be doing that.

Essential reading in any school in the world, regardless of the subjects chosen.

Carlo Rovelli - Reality Is Not What It Seems (Penguin, 2017) ****

In this great book, physicist Carlo Rovelli explains what we know about reality, and how it can be interpreted. It's a wonderful journey into the nature of science itself, about what we know and don't know, and about what we can know. In our universe there are one billion galaxies with each around 1 billion stars, and our world is just one planet of those stars. In the middle of our galaxy, there is a black hole that is one million times the size of our sun, and that swallows up entire "solar systems" like a whale eats little fish (I checked this, and they do eat small fish, and not only plankton, which I thought).

He gives an overview of a number of theories that are currently used to describe the facts and findings of modern physics. What comes out loud and clear is that our universe is finite.

Rovelli gives a historic overview of theories about our world, and how they involved over time. He does this in a very readable and accessible way, often using anecdotes and discussions from the life of the physicists who shaped our current thinking.

Rovelli ends the book with some musings on the nature of science. He says that the only thing that's infinite is our ignorance. And that's maybe a good thing too. "Science is not reliable because it provides certainty. It's reliable because it provides us with the best answers we have at present. Science is the most we know so far about the problems confronting us. It is precisely this openness, the fact that it constantly calls current knowledge into question, which guarantees that the answers it offers are the best so far available."

There is a lot we don't know yet. And that's a message which still offers mystery and humility.

Lawrence Krauss - A Universe From Nothing (Simon & Schuster, 2012) ****

Why is there something rather than nothing? The major question that has been driving philosophical thought and theology for thousands of years.

Lawrence Krauss tries to give a glimpse of what might look like an answer. And if anybody can know, it's him. With degrees of physics of MIT and Harvard, he is now professor of cosmology at the University of Arizona.

He gives many examples of things that come to existence from nothing, which is really common at the level of the smallest components of our quantum world. And because the big universe out there is only an assembly of these small particles, there is no need for a cause to exist. That is just the way it is. "Ultimately, this question may not be more significant or profound than asking why some flowers are red and some are blue".

Obviously, before getting there, Krauss takes us on an interesting - and often personal - journey, creating a big picture of insights from quantum physics to the consequences of this weird world for a better understanding of our universe. He explains it in a layman's language, without any need for prior understanding of mathematics or physics. Nevertheless, it remains quite a feat to grasp the latest theories, for the simple reason that it's impossible for us to picture them with our macro-world perspective. How can you understand what a "multiverse" might look like. Or how can you understand a closed universe, one in which if you could see far enough, you would be looking at the back of your own head? How can you understand anti-matter?

One thing is certain for him. Even if we do not understand all aspects of our world and universe, there is no need for a "god" to have created it. There is not only no need for it, it would make the whole even more complex and more unlikely.

Interesting reading if you're interested in the most profound question of our existence.

Lawrence Krauss - The Greatest Story Told ... So Far (Simon & Schuster, 2017) ****

"The Greatest Story Ever Told" obviously refers to the bible, but that is just fiction, so Krauss brings us the wonderful story of science and matter, which is the real "Greatest Story Ever Told ... So Far", allowing for new scientific insights to change our current beliefs.

Krauss takes you along to the very tiniest particles of matter, and beyond that, explaining how to even can exist, and explaining what we don't understand. And despite his genuine efforts to include the layman among his readership, by inventing analogies and visual explanations to give us a glimpse of what mathematics or what the Large Hadron Collider has revealed, the outcome is still as mystifying as it was before. But luckily not only to me, but also for particle physicists and astrophysicists who look in wonder at their findings, probably even more surprised than I am, because they can understand at least part of it : "Not only have our explorations revealed the existence of dark matter, which is likely composed of new elementary particles not yet observed in accelerators, but far more exotic still, we have discovered that the dominant energy of the universe resides in empty space - and we currently have no idea how it arises" .

But that makes it fascinating. Not an easy to read book, but fascinating stuff.

John Freely - Before Galileo - The Birth Of Modern Science in Medieval Europe (Overlook Duckworth, 2013) ***½

John Freely is een Amerikaans fysicus die in zijn "Before Galileo" de geschiedenis van de fysica brengt, en dan met name de wereldbeelden die ervoor nodig waren om ook wetenschappelijke vooruitgang te maken.

In zijn eerste hoofdstukken schetst hij de ongelooflijke ontdekkingen en hypotheses die door de Grieken werden geformuleerd, en dan vooral op het vlak van sterrenkunde en wiskunde. Hij gaat lang door op het belang van de Arabische geleerden om de klassieke traditie verder te zetten, om dan dankzij vertalingen uit het Arabisch terug ingang te vinden in het werk van Thomas Aquinas, Roger Bacon, Robert Grosseteste en anderen om dan te culmineren in het werk van Copernicus en Galileo.

Een mooi en overzichtelijk werk.