Review: Seven Brief Lessons on Physics

ters, beginning with 'The most beautiful theories' which discusses relativity and some history behind the unification of various theories throughout the 20th century. The description of black holes, which are the result of massive stars collapsing under their own weight, causing extreme bending of space to the extent that an actual hole is created (crazy right?) left me particularly dazzled. I was struck by the section on gravitational fields too, which turn out to be the same as our idea of 'space'. Furthermore, 'space' is not separate from the everyday matter we are familiar with, but another constituent part, which flexes and twists. Rovelli goes on to describe how this can be seen in the way planets orbit a star: the Sun bends space around it, and Earth orbits around the Sun to race against the inclines of space, much like a ball rolling on a curved sheet.

The following chapter discusses quantum mechanics in a delightfully simple way, where we learn of Einstein’s breakthrough when he discovered light comes in packets called photons, rather than as a continuous field. The implications this has on energy impact us daily, as it turns out all elements on the periodic table which make up our surrounding matter correspond to exact quantum mechanical solutions for allowed energy spacings in atoms. able and perhaps at one point didn’t exist. Statistical physics also gets an important mention here, where readers discover exactly how important heat is to our perception of time and why exactly putting a cold spoon in a hot coffee cup makes the spoon heat up rather than the coffee cool down.

Later chapters embark on a brief history of the human understanding of the cosmos, from the belief that our Earth was flat in the era of the Ancient Greek philosophers, through to the Earth-centred model of the solar system in Medieval times, through to the discovery of galaxies outside the Milky Way in the 1930s and up to the expanding universe we are familiar with today. This flows surprisingly smoothly to a chapter on particles and the mysterious phenomenon of dark matter. While it cannot be directly seen, its existence has been inferred from the behaviour of galaxies, which appear not to have enough mass to stay together without flinging themselves into pieces, unless an extra unseen mass provides the necessary gravitational attraction to keep them together. The last few chapters tackle some big mysteries of modern physics, from missing particles to 'bouncing' universes occurring before the Big Bang to the surprising fact that time is immeasur-

The book ends with a philosophical chapter that brings the focus back on humanity in a heart-warming and humbling closing, reminding us that we are not mere observers of our surroundings but active constituents of it. At a mere 79 small pages (with a comfortably large font), this little book is well worth a read on a warm summer evening, perhaps under a twinkling sky, to ponder about the universe as we experience it.