Philosophical paradoxes are said to arise if we can reverse our path in time, going to the past to correct mistakes or leverage successes. Our observations are always that the Arrow of Time points from the past toward the future no matter how long you wait you'll never find yourself back before you started waiting if you spill coffee from a cup, you never see it climb back into the cup. If Time is, or is not, reversible, why should that be? The bidirectional Arrow of Time, deeply embeded in early science and in science fiction, is unsettling. The same is true of Maxwell's equations of electromagnetism. Is this an illusion, as Einstein suggested? Is time simply thee in a complete sequence with all possibilities already determined, so we just experience what must be experienced? Is Time reversible so we can go back? Newtonian mechanics offers no assistance on these questions: for Newtonian physics time is reversible: you can run his equations backward to pinpoint the location of a celestial object at any previous time. The Mayans were great record keepers!īut today we sense an Arrow of Time-Time inexorably proceeds from the past into the future. Thus the future was known by the past: if you record events during one cycle, you know them for future cycles. To them, time was repetitive-each cycle simply reproduced earlier cycles. The Mayans thought of Time as a rotating wheel, like a clock, that returns to its original place, thus starting another 260-year cycle.

Our understanding of Time is inextricably linked to our culture and to our understanding of the world around us (our science). I also read portions of Brian Greene's excellent new book Until the End of Time just to be sure I got it right. So this review focuses on those questions, which are the subject of the books. But I've traveled that path several times and my interest is in the basic questions that led me to the book: What is Time? Is Time irreversible? What do those questions even mean? For those who want a review of scientific advances from Newton forward, it is an excellent read. The Arrow of Time is a very interesting exposition of the history of science, much of it not relating directly to the notion of the arrow of Time. Naturally, I began thinking about time, not just what to do with it but, more importantly, what is it? This led me to The Arrow of Time: A Voyage Through Science to Solve Time's Greatest Mysteries (1990) by Peter Coveney and Roger Highfield. At this moment I, like you, am quarantined in my home and admonished about any outside contact. It's the Spring of 2020, the year of the Coronavirus.

The Arrow of Time by Peter Coveney