This book was written by British mathematical physicist Roger Penrose in 2016. I had previously read his works "The Road to Reality" and "The Emperor's New Mind," both of which were quite difficult to understand, with a lot of deep content and many unique viewpoints, suitable for those with a certain foundation in mathematics and physics to study carefully.
The main content of this book includes questioning string theory, an in-depth introduction to quantum mechanics, some musings on cosmology, and an introduction to the original theory of twistors.
I had previously read many popular science articles and watched videos on string theory, which are indeed very fashionable and attractive, and could be a potential grand unified theory. However, the biggest problem is that it is difficult to observe and verify through experiments; the additional dimensions are mainly a mathematical necessity and are hard to experience in reality.
Quantum mechanics is relatively easier to understand; I have read many popular science articles on it. Although many aspects are counterintuitive, many can be verified through experimental observation and are widely applied in life. The view that things are not deterministic but probabilistic also aligns with my belief in the existence of free will.
The focus of cosmology is the Big Bang theory, the evolution of black holes, and the singularity theorem. Penrose won the 2020 Nobel Prize in Physics for "discovering that the formation of black holes is a robust prediction of general relativity." General relativity theoretically allows for the existence of black holes, and Penrose proved within the framework of general relativity that under very broad conditions (the main condition being that the energy of the collapsing matter is non-negative), black holes can indeed form, enclosing a singularity; this is the singularity theorem. In Penrose's topological proof, the trapping surface does not need to have spherical symmetry. Once a trapping surface appears, matter collapses toward the singularity, making the singularity and event horizon inevitable. Black holes and singularities are almost a necessity under general relativity, meaning that in a complex reality, gravitational collapse of sufficiently large mass will inevitably lead to black holes.
Twistor theory is a mathematical tool pioneered by Penrose primarily used to solve the integration of general relativity and quantum mechanics. It represents points in four-dimensional spacetime (Minkowski space or Euclidean space) as complex numbers in three-dimensional complex space, namely in the twistor space. This part requires mathematical understanding beyond my grasp, necessitating a relearning of projective geometry and complex number theory, and I truly cannot delve deeper into it.
Overall, in recent years, physics has not made significant breakthroughs theoretically; rather, it has been more about patching up quantum theory and general relativity. For substantial development, resources cannot be concentrated mostly on a few popular theories like string theory; instead, more people need to propose new viewpoints and new questions, pushing the development of physics through detailed calculations and meticulous experimental observations.