In 1974, when I was 11 years old, I purchased my first book with my own money earned from a low-paying newspaper delivery job. The book was “Black Holes: The End of the Universe?” by John Taylor. The subtitle caught my attention as I had never heard of black holes before. At that time, these enigmatic cosmic entities were only a theoretical concept. However, fifty years later, there is ample evidence to prove their existence. Italian physicist Carlo Rovelli, known for his bestselling books on quantum mechanics, time, and the nature of reality, combines all three topics in his latest work. In this book, he takes us on a journey deep inside a black hole. With his adept storytelling skills, Rovelli begins by explaining the formation of black holes, making this mind-boggling ride an enthralling experience.
Eventually, stars deplete their fuel and stop emitting light. At this stage, their own gravitational force causes them to compress. Our sun will eventually become a white dwarf, with its mass compressed to the size of Earth. However, some stars are so massive that their collapse continues until they reach a singularity, a point where the laws of physics no longer apply. A black hole is a singularity surrounded by an event horizon, a boundary that only allows one-way movement and shields it from the rest of the universe. Anything that gets too close to the black hole will be unable to escape and will be pulled into it, ultimately being crushed out of existence. This is the commonly accepted explanation, but Rovelli challenges it in his thought-provoking and densely packed narrative, which may require multiple readings to fully grasp.
Einstein’s general theory of relativity suggests that the interior of a black hole takes on the shape of a funnel, which becomes increasingly longer and narrower over time. At the bottom of the funnel sits the remaining core of the star that collapsed to form the black hole. Rovelli argues that the collapsing star never actually reaches the bottom, but continues to fall due to the effects of gravity on time. As space and time are transformed into a cloud of quantum possibilities, a black hole can potentially turn into a white hole, with time running in reverse. Rovelli explains that white holes are what we would see if we could film a black hole and play the footage backwards.
Perplexed? Well, it’s challenging enough to convey in a book, let alone a review. Even some experts struggle to fully understand these perplexing and counterintuitive concepts. And while Rovelli avoids the technical language of a physicist, he does allow readers to skip certain sections. Fortunately, Einstein himself gives us some leeway, stating, “imagination is more important than knowledge.” However, this does not mean that you will finish White Holes with less knowledge than when you started – Rovelli effectively captures the awe and peculiarity of the universe. But by the end, you may feel inclined to relax with a drink and relish the sensation of your mind returning to its usual shape.