DK - The Physics Book, Big Ideas Simply Explained

I fell in love with physics as a boy when I discovered that this was the subject that best provided answers to many of the questions I had about the world around mequestions like how magnets worked, whether space went on forever, why rainbows form, and how we know what the inside of an atom or the inside of a star looks like. I also realized that by studying physics I could get a better grip on some of the more profound questions swirling around in my head, such as: What is the nature of time? What is it like to fall into a black hole? How did the universe begin and how might it end?

Now, decades later, I have answers to some of my questions, but I continue to search for answers to new ones. Physics, you see, is a living subject. Although there are many things we now know with confidence about the laws of nature, and we have used this knowledge to develop technologies that have transformed our world, there is still much more we do not yet know. That is what makes physics, for me, the most exciting area of knowledge of all. In fact, I sometimes wonder why everyone isnt as in love with physics as I am.

But to bring the subject aliveto convey that sense of wonderrequires much more than collecting together a mountain of dry facts. Explaining how our world works is about telling stories; it is about acknowledging how we have come to know what we know about the universe, and it is about sharing in the joy of discovery made by the many great scientists who first unlocked natures secrets. How we have come to our current understanding of physics can be as important and as joyful as the knowledge itself.

This is why I have always had a fascination with the history of physics. I often think it a shame that we are not taught at school about how concepts and ideas in science first developed. We are expected to simply accept them unquestioningly. But physics, and indeed the whole of science, isnt like that. We ask questions about how the world works and we develop theories and hypotheses. At the same time, we make observations and conduct experiments, revising and improving on what we know. Often, we take wrong turns or discover after many years that a particular description or theory is wrong, or only an approximation of reality. Sometimes, new discoveries are made that shock us and force us to revise our view entirely.

One beautiful example of this that has happened in my lifetime was the discovery, in 1998, that the universe is expanding at an accelerating pace, leading to the idea of so-called dark energy. Until recently, this was regarded as a complete mystery. What was this invisible field that acted to stretch space against the pull of gravity? Gradually, we are learning that this is most likely something called the vacuum energy. You might wonder how changing the name of something (from dark energy to vacuum energy) can constitute an advance in our understanding. But the concept of vacuum energy is not new. Einstein had suggested it a hundred years ago, then changed his mind when he thought hed made a mistake, calling it his biggest blunder. It is stories like this that, for me, make physics so joyous.

This is also why The Physics Book is so enjoyable. Each topic is made more accessible and readable with the introduction of key figures, fascinating anecdotes, and the timeline of the development of the ideas. Not only is this a more honest account of the way science progresses, it is also a more effective way of bringing the subject alive.

I hope you enjoy the book as much as I do.

Jim Al-Khalili