Book review and thoughts — “The Constants of Nature” by John D Barrow

Aditya Gaonkar
5 min readApr 20, 2021

I open this post by posing the following question: We know that a neutron is very slightly more massive than a proton. What if the reverse was the scenario, i.e. proton is more massive than a neutron? A neutron in isolation will decay into a proton, electron and other stuff with a half life of around 14 minutes. This happens because as the neutron is slightly more massive and thus more energetic than the proton, it wants to go to a lower energy state, thus ending up decaying into a proton. A proton is as stable a particle as they come, happy news for us as a hydrogen atom is a proton and an electron, making everything around us possible. Now, if in a hypothetical universe a proton was a wee bit more massive than a neutron, disaster could ensue as we would never get the normal hydrogen we all know and love because the protons would decay into neutrons. You might point out that the isotopes of hydrogen could still exist, but things could very well be extremely different. For example, heavy water is made of an isotope of hydrogen and is stable, but it isn’t conducive to many of the subtle biochemical processes necessary for life as we know it. A neutron being very slightly more massive than a proton has ended up being rather consequential for our existence.

The above scenario is one flavour of the kind of stuff this book deals with, which is asking “alright, what if the various fundamental constants took different values than what we observe them to be?”. The answer the book provides, mainly by referencing various scientific papers is kind of unsettling, as the various scenarios considered converge to one conclusion: our very existence is quite fortuitous, depending on many of these constants taking the values they take. Mess around with these constants and I wouldn’t be here writing this post.

This discussion might prompt the question: Alright, what if we adjusted the laws of the nature so that the mess caused by the change of the constants is rectified or something can be salvaged? Unfortunately, the book doesn’t answer this question. I presume that the author and indeed all the scientific papers the book references assume that the basic equations governing everything remain the same. I’m not really sure if people have pursued this line of inquiry, or if it’s a variable which makes the problem at hand intractable. This in my opinion is one shortcoming of the book.

The book also details at length the fascination many heavyweights of modern physics had with the values of these constants and some of their work with it, which makes for some fascinating reading. Also considered briefly is the question of why we have 3 spatial and 1 time dimensions, the implications of this scenario on our existence and what if some truly crazy scenarios happened? (for example, 2 time dimensions. Don’t even ask me how this would work in practice!)

Overall, I really enjoyed this book. Maybe me having an interest in modern physics added a value to my reading, although I don’t think one needs to know those things to understand this book (you can always google to know about the fine structure constant and what it’s significance is!). If you want to know where science currently hits a limit in explaining why we even exist, this book is a must read. It won’t give you answers, but it will give you food for thought and great material for deep philosophical discussions with your friends. One drawback the book suffers from is that it sometimes veers off into tangents and needs more focus from the reader.

Will physics ever be able to answer these questions? My thoughts are ambiguous about this. On one hand, considering how we always have seemed to make progress in answering questions, even if it takes centuries to achieve it, it might very well be possible to find answers. However another part of my head says that we probably are approaching a paradigm of questions which are way more deeper than anything we’ve ever considered as a species and so directly connected to our existence that we can never answer this. Only time will tell what will happen.

Equally interesting to think about is what form the potential answers might take. When one looks back at history, I suspect we will not really like the answers we might get. Consider how unsettling the heliocentric theory was, when compared to the conventional wisdom and dogma of the middle ages. Another example is the funny fact that while Isaac Newton wrote down a successful equation to calculate the force of gravity, he was as clueless as anyone else of that era was when asked “alright, how does this thing even work?”. To get the answer to this profound question, we had to wait for more than two centuries for another era defining genius to come along and basically shatter our very perspective of how space and time behave. Even now, both the theories of relativity can be deeply unsettling to study. Consider how quantum mechanics and quantum field theory forced us to accept that at the subatomic level you can never determine anything and only talk in terms of probabilities at best. This is a notion so deeply unsettling that Einstein remarked “God doesn’t play dice with the universe” and never really reconciled with this view of things. He even posed the famous EPR paradox to challenge quantum mechanics, but this beast of a theory ate that up and threw out the absolutely insane concept of quantum entanglement! Modern physics relies on theories which challenged the existing intuition about fundamental things like space, time, determinism of events and definitely do confound newcomers even now. This precedent is why I think that the most probable scenario of getting answers to the kind of questions we ask here demands that we further suspend our intuition and belief.

It will not be proper without ending this post by discussing a rather controversial idea and an equally ridiculous (in my eyes, at the very least) counter to this. The fact that the laws of nature and the constants associated with them need to take rather specific forms gives some credence to the idea of “intelligent design”, which leads to the idea that god does exist. This is rather unsettling for scientists, and with good reason as it can lead one down a terrifying rabbit hole. As a counter (sort of), some string theorists propose the idea of a multiverse as a consequence of string theory, with each member of the multiverse having it’s own uniquely valued fundamental constants. To many other scientists, this idea is ridiculous as there is zero experimental and observational evidence for string theory. I’m reminded of a statement Einstein purportedly told Georges Lemaitre, who first proposed the Big Bang theory: “Your calculations are correct, but your physics is atrocious.”, which might apply to string theory (ultimately Einstein turned out to be wrong in making that statement!). Even if it’s proven to be true, string theory has implications which we probably will struggle to digest, just as we’ve struggled with relativity and quantum mechanics.

Hope this post encourages some of you to pick up this book. Give it a read and do drop your thoughts in the comments!

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Aditya Gaonkar

IC Design Engineer. Retired FC Barcelona fan. Interested in physics, mathematics, philosophy, memes, epic fantasy. IIT Madras and Columbia University alum.