When you are done with work and other commitments you might find some time to do other stuff. You might be wondering what to do with that time. Well, if your brain won’t calm down and it’s too late to go outside then you could do worse than wondering about why a world of rocks, trees, frogs and humans exists in the first place. Subjects that are grounded in the real world - from geology to agriculture, psychology to medicine, and engineering to economics - segment the world into chewable chunks and are themselves fields of specialist endeavour. Yet they all reference more fundamental aspects of human enquiry even if they choose not to delve into the details. A sociologist might reference the work of a field biologist studying baboons. A field biologist knows a lot about the Krebs cycle even if she doesn’t explicitly reference it. A biochemist studying oxidation in the Krebs cycle knows about atomic orbitals but might not understand the math that comes with it. And - somewhere down a dark hall - a physicist smirks as, finally, someone in the real world wants to talk to him.
Theoretical physicists, like their philosophising friends, dive deep into the fundamental nature of things. Some philosophers agonise over epistemology and ontology. Just as some physicists struggle with where their math takes them. Thankfully, that’s their problem. Not ours. Fortunately many also take the time to educate those that seek scholarship and a few even write books for the merely curious.
This book about classical physics is written by a physicist and educator well-known for being resolute about how concepts in physics should be presented and understood. For the average punter physics is not an easy topic to engage with. So the remarkable thing about this book is how readable it is. The chapters do progress rapidly and, for a book aimed at a popular audience, exposes the reader to a lot of math. This brevity and that dreaded four letter word means a step up in attention but the math is kept superficial and the arguments easy to follow. Taking classical physics into the 20th century also means that there are occasional leaps of faith. Lucky for me I am as malleable with my math as I am with my grasp of reality. Replace the plus (+) sign with a minus (-) sign in Pythagoras’ theorem? Puh! I can do that.
There aren’t many jolts like this and the accompanying explanations give some coherence to the otherworldliness that is modern physics. Indeed, the author shows how the reality we experience is skewed by dimensional and temporal restrictions and encourages the reader to take a step back and rethink everything from first principles. First, by re-examining our understanding of how objects move through space; then by adding dimensional time; before tackling the mapping of manifolds. Nevertheless this book is only accessible to a wide audience because noobs like me have the ability to tap into content created by some incredible online educators. Key words are highlighted in bold text so when I can’t follow the argument for “metric tensor” then I know what term to look up. Tap.. tap.. tap.. and, bingo! 3Blue1Brown walks me through the essence of linear algebra (which is not as dry as it sounds) before I move on to tensors and differential geometry (although Dialect does an excellent summary).
This is a small book on a big topic. Physics students spend years grappling with these ideas and some will devote an entire career within and/or expanding its boundaries. For a popular science book the first instalment of “Biggest Ideas in the Universe” imposes a rigour that is first surprising, then challenging, then satisfying. It does not tell us everything about the physics of space, time and motion. Of course not. What we get is an exciting glimpse closely attended by a more considered perspective of the mind-bending beauty and magnitude encapsulated in such conceptualisations. The target audience with high school math and a history of wandering the vagaries of physics is delivered a series of well explained chapters that starts with a ball rolling down a hill and ends with General Relativity. As such the book flows seamlessly. The perspective is unapologetically that of a physicist and the intuitions gained come with solid, logical grounding. That’s gold.
I would mention that the chapter on Time is not as poignant than the rest of this excellent book. But it is the only section that reads like a series of statements and commentary. Time is an incredibly difficult concept to come to grips with and because each chapter anticipates the next I think I was expecting an impossible revelation. In any case I got through the chapter, moved on to Spacetime - where the above equation dropped (lending Time a dimensional context) - and the world of classical physics continued to reveal itself.
It’s not everything. But it is thunderingly good.
Sean Carroll’s book on Quanta and Fields - the second in this series of “Biggest Ideas in the Universe” - comes out on the 1st of October.
https://www.preposterousuniverse.com/biggestideas/
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