When Amanda Gefter asked the cosmologist Kip Thorne to explain John Wheeler’s ideas on the universe and physical reality, Thorne was dismissive. “I think we [physicists] are less in a position to probe those issues than philosophers are…I steer clear of asking what is ultimate reality.” But Gefter was not to be dissuaded. Her quest to understand what physics has to say about that “ultimate reality” is the subject of her book Trespassing on Einstein’s Lawn and, on balance, I think she makes a good job of it. I certainly felt that I learned something, even though the book, like the quest itself, has some ups and downs along the way.

Gefter’s story begins when she is in high school. Disillusioned by her science classes, she is encouraged by her father to tackle the more “philosophical” ideas within physics – ideas about cosmology, gravity and quantum mechanics, as well as classic questions such as “What is nothing?” and “Where did the universe come from?” Gradually, Gefter and her father begin delving into physics together, seeking the answers to the universe more or less as a hobby. And while she goes on to study philosophy and creative writing (rather than science) at university, she later becomes a science writer as a pretext for continuing her quest – a quest in which she slowly realizes that the universe is far less “real” than we could ever imagine.

Initially, Gefter’s narrative reads like a very ordinary coming-of-age story, and aspects of it feel rather forced and unremarkable. She does, however, flag up some interesting issues. One is the importance of showing children the relevance of science at school, beyond simply abstract facts. Children need to understand how what they are learning fits into the real world, particularly the world with which they are familiar. Without this, the facts have no meaning. Another is “impostor syndrome”, which leads talented, intelligent people to believe they are not good enough and will soon be “found out” by colleagues or superiors. Gefter saw her transition from student to writer as extraordinary because she felt that she was just pretending. In truth, I think many people – especially, but not exclusively, women – experience this. Awed by our colleagues’ intelligence or performance, we end up always feeling like we are winging it.

Once Gefter embraces her own status as a bona fide science writer, her story somehow becomes more compelling. The concept of her journey resonated with me, as I have recently undertaken a similar one myself (although in my case, I have been learning about the Northern Lights rather than cosmology). Finding things out on this scale can be a transformational experience and is as much about the people as the physics, so it was good to hear about the physicists Gefter met along the way. I enjoyed the stories about Wheeler, the Los Alamos physicists and Einstein peering through ­Hubble’s telescope; indeed, there could have been more.

The narrative ties back nicely to discussions between Gefter and her father many years previously, showing not only how the small seed he planted had grown and blossomed, but also how his early ideas related to what physicists think about reality.

One of the first things that Gefter learns during her quest is that scientific theories aren’t about “things” at all. Instead, they are about mathematical structure. Our interpretations of theories – such as “gravity is a force that masses exert on one another from a distance” (Newton), or “gravity is the local curvature of space–time” (Einstein) – are just different stories we contrive to make sense of the maths. This helps to explain why Newtonian gravity looks the same as Einstein’s gravity in the low-energy limit. Newton was not wrong; he was simply looking at a small corner of the picture. The overall structure is the same.

Reading this reminded me of an anecdote I heard from another physicist at a conference. He had been visit­ing the cathedral in Seville, Spain, when he noticed that the floor he was standing on was laid out in a beautiful star pattern. He took a picture of it. Then he lifted the focus of his camera and took a picture of the rest of the floor. At this point he realized that the floor was not made of stars at all, but was a black-and-white pattern of squares and triangles. Only when viewed in isolation did small patches look like stars. The global view changed the picture.

This global view may help us reconcile classical physics with modern physics, but when it comes to the universe, there is no “God’s-eye” view. There are just different reference frames, and this problem lies at the heart of the incompatibility between general relativity and quantum mechanics. In relativity, observers are inside the system (space–time), whereas in quantum mechanics they are outside making the measurements. But to view the universe from outside is impossible.

While studying in London, Gefter realizes that what is real is what survives the translation between reference frames – in other words, what is invariant. She draws an analogy with languages. “Love” and “amor”, she points out, are not totally different things simply because they look different. The terms refer to the same thing. The underlying structure (the concept) is what is real, not the word itself (the description). Similarly, anything real must survive the translation between observers’ reference frames. Armed with this knowledge, Gefter and her father go on a search for invariance.

The middle of the book becomes somewhat convoluted, presenting multiple views from different physicists and using extensive dialogue. This confusion is compounded by the use of jargon and acronyms, which often make it difficult to grasp the essence of an exchange. Fortunately there are helpful summaries in the last chapters. Gefter also has some nice, almost poetic, ways of ­expressing things, as in phrases such as “the gravitational lifeblood of stars and galaxies” and she gives good, simple analogies for difficult concepts. She should, however, be careful of the lazy use of cliché in descriptions, and her style was often too colloquial for my taste. One can, I think, have an authentic “voice” without resorting to expletives.

During her quest, Gefter learns that many concepts we regard as invariant are, in truth, observer-dependent. Acknowledging this is difficult because it requires us to drop long-held assumptions, equivalent to recognizing the speed of light as finite. Even Einstein, who made the mental leap to formulate rela­tivity, had trouble accepting quantum mechanics. The concepts are tricky and counter-intuitive, but ultimately Gefter’s book is an enlightening journey through the extremes of modern physics to the edge of the universe.

• 2014 Bantam £18.49/$28.00hb 432pp