REVIEW: The God Equation

Introduction

Professor Michio Kaku is a theoretical physicist and author of several popular science books. The God Equation is his latest book, published in 2021, with another one following in 2023, called Quantum Supremacy. I first heard of him through the science podcast StarTalk with Neil deGrasse Tyson, where professor Kaku would occasionally appear as a guest. I remember him having a very pleasant voice and attitude, it was always fun listening to physics experts explain the world around us, or geek out about the latest sci-fi movie. When I saw his book discounted at a fair, I decided to give it a go. I always enjoy seeing some historical background on physics and how the theories we today take for granted came about.

Modeling the World

The basic idea of this book is to give a kind of road map, an overview of big breakthroughs in physics, explaining physical concepts and important individuals along the way. As far as ancient Greece, there was the idea that our world consists of tiny particles, and that we can describe nature using mathematics. With the demise of the ancient civilizations, a lot of that was lost. We went through the Middle Ages where superstition often took a leading role, and science took a backseat. History has proven more than once that even if you come along with brilliant, groundbreaking ideas, they may not catch on. Your idea has to come in a time when the defining spirit of that age is ready to accept it. Scientists that lived in such times, and were skillful and lucky enough to get their ideas through, are the ones we remember.

When talking about physics, I think it is often overlooked in our education system to explain the concept of a physical or mathematical model. Our world is endlessly complicated, and it is impossible to explain a phenomenon by taking into account everything. Luckily, we don’t have to. In fact, a lot of things we don’t even know we have to take into account, since we are limited with our 5 senses and current state of knowledge. So how do we deal with this? We create a model – we simplify the thing we want to observe or explain, we create an ideal situation (which we know doesn’t exist in the real world), and we represent it with a mathematical formula. Once we have our theory on paper, in the form of a mathematical formula, we go back to the real world, conduct an experiment, and see how well our model holds up with the real world experiment. A good theory is one that is simple, can describe a phenomena in a lot of different scenarios, and is accurate enough. Those theories are the ones we learn in physics textbooks. So when we see those physics equations, what we really see are human thought constructions that model some phenomena in nature, using mathematics as nature’s language.

In this book we go very briefly through some of the most important theories, as the theme of the book is unification, or search for a theory that would explain all phenomena in the universe in a coherent fashion. The first big unification comes from one of the greatest scientists of all time – Issac Newton.

Unification 1 – Newton

Before Newton, it was believed that one set of rules governs the earth, and another set of rules the heavens. Allegedly, the famous apple story (it falling on his head is probably not true) prompted Newton to think about whether the thing that causes the apple to fall is the same thing that keeps the Moon in orbit. If you fire a canon from the top of a mountain, the canon ball will eventually hit the ground. If you fire it at a higher velocity, it will travel further before hitting the ground. If you imagine firing it with higher and higher velocities, eventually the canon ball will travel all around the earth and come back to your position, similarly to the Moon’s orbit. Newton concluded that the physical laws that govern motion on Earth and those in space are one and the same, thus creating the first big unification of physics. He postulated his Three Laws of Motion and his Theory of Gravity, introducing the concept of Force, and thus creating a framework for all of physics at the time. His theory was simple, easy to use, and applicable in more ways than we can think of. It gave answers to a lot of questions that have been mysteries for centuries. It also paved the way for the Industrial Revolution.

We later found that there are some extreme cases in which Newton’s Laws cannot be used, like when traveling at a velocity close to the speed of light, or in the physics of subatomic particles (quantum mechanics). However, that does not take away one bit from Newton’s theory as one of the greatest accomplishments of the human mind.

Unification 2 – Faraday and Maxwell

The next big unification of physics followed 200 years after Newton, when Micheal Faraday paved the way for James Clerk Maxwell, who defined the theory of electromagnetism, thus showing that electricity and magnetism are two sides of the same force. We then learned that visible light is an electromagnetic wave, and just one part of the electromagnetic spectrum. Faraday’s and Maxwell’s discoveries led to the age of electricity, something we all take for granted today.

Unification 3 – Einstein

I will also mention our favorite scientist, Albert Einstein, who gave us two more unifications – that of space and time (we now call spacetime) and that of matter and energy, described by his famous equation E = mc², where E is energy, m is mass, and c is the speed of light (300 000 000 m/s). The General Theory of Relativity is our current best theory of Gravity, and is often considered ‘beautiful’ in a mathematical sense. By the way, this is the theory which makes GPS possible, so the next time you use google maps, you can thank Einstein!

Einstein’s theories deserve websites for themselves, so I will not go into more detail here, but just post a link to one of the videos on the topic. You notice I got a little bit into the actual substance of the book in the last few sections. In this way, I just wanted to give you an idea of what to expect. There are not too many details on every topic, but rather quite a brief overview of the ‘biggest moments’ in physics. After Einstein, we jump into some more unifications, quantum mechanics, and then into possible all-unifying theories.

So what are we Unifying?

At this stage you might be asking yourself: ‘OK, but what exactly are we unifying? What is this theory of everything?’

We now know about four fundamental forces in the Universe:
1) Gravity
2) The electromagnetic force
3) The strong nuclear force
4) The weak nuclear force

Our theory for gravity is Einstein’s General Relativity, while the other 3 forces are described by Quantum Mechanics. So, General Relativity and Quantum Mechanics are the two theories upon which all of modern physics rests. Those theories have been validated numerous times and work really well in their respective fields (most situations require the use of only one of them). However, they are not compatible with each other, and do not work in some cases, for example in regions of black holes. The next goal would be to unify those two theories and get a complete theory which would describe all aspects of the Universe.

The String Theory

One proposition for such a theory is the String theory, the idea that reality is made up of infinitesimal vibrating strings, smaller than atoms, electrons or quarks. Professor Kaku is one of the co-founders of the theory and has been dealing with the topic since 1968. String theory way exceeds my understanding of physics, so I will leave the explanations to professor Kaku. In the book he gives a basic overview and presents some challenges and still open questions. At the end, he also gives his opinion on some fundamental philosophical questions.

There is no deep dive into string theory in the book, but you do get some basic information, like that string theory involves math that only works in 10 dimensions (say what?). To be honest, I felt the book still needed that one sentence, one simple explanation in layman’s terms of what string theory actually is. I recommend watching the video from Kurzgesagt if you’re interested in a brief summary.

The Book Structure

The book has seven chapters, with a lot of sub-chapters. It can be easy to get lost in the chapters, as to me, it felt more like one big overview, and I didn’t really feel that chapter division. It was still surprisingly easy to read. You can approach it as a quick read-through, and be OK with not understanding absolutely everything. Just hearing the story, the names of some theories, and scientists can be informative, and get you some points on the next pub quiz. That said, it can be a bit hard to follow, especially in the second half. Some concepts in quantum mechanics are not really something you deal with on a daily basis, so maybe some more explanations of that would be beneficial.

I got the feeling that the book is not hugely ambitious in it’s undertaking, and that’s OK. It sets out to cover a lot of ground, but not to go into too much detail. As a popular science book on physics, it does provide the reader with some refreshment on classic theories, and some cool info on modern physics and current trends. So all in all, I think it succeeds in what it sets out to accomplish.

Conclusion & Verdict

Reading The God Equation was a lot more fun than I anticipated. It is written pretty well, and is not too hard to read in terms of pure readability. It gives a nice overview of big breakthroughs in physics from the point of view of unification. The concepts are not explored in depth, but can serve well as quick reminders or starting points for further individual exploration for the reader. It gives one possibility for an unifying theory in the form of string theory, making sure to inform the reader when it moves from facts to assumptions.

Even though the concepts were not explained in too much detail, I do think the overall enjoyment of the book depends on the user’s background in physics. Some of the earlier chapters are not too bad, but in the second half of the book we deal with quantum mechanics. It felt as if some background in the field was assumed, and I would have liked to see a bit more explanations there. Then again, it is quantum mechanics, so maybe there is no easy way to write about it?

Overall, I would say this is a very solid popular science book on physics. It can be read pretty causally, you can learn something, and have some references for further exploration. I would recommend it to physics and science enthusiasts, or anyone who wants to add some popular science to their yearly reading list. If you’re not really a fan of physics, you’ll probably want to skip this one. And if you’re still wondering what the God Equation is, don’t worry, physicists are wondering too.

Rating: 4/5