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Review of: “REALITY IS NOT WHAT IT SEEMS” by Carlo Rovelli For those who have an even casual interest in modern physics or “science” this is a truly remarkable book. Rovelli is able to take highly complex problems and express them in a way which can make them accessible to even those who think that mathematics is simply something you use to figure out how much change you should get at the supermarket or doing the highly difficult calculation of how much to tip on a restaurant bill. Over the years I have read literally dozens of books written for the nonscientist about special and general relativity, quantum mechanics, Brane theory, String Theory, Information Theory and quantum loop gravity. This is the first time I have encountered one which makes some real sense about these abstract concepts and clearly answers a question which has bothered me throughout this quest for knowledge: Is there such a thing as quantum time or is time simply a construct, an invention we use to measure the concurrence between different events. Spoiler Alert. Not only does quantum time exist it appears to be a requirement for healing the conflict between relativity and quantum mechanics. As most readers are aware Einstein’s theories of both general and special relativity are remarkably accurate and have passed every test to which they have been subjected as long as they apply to very large things. Quantum mechanics, the strange physics of the very small, is also exceedingly accurate in its predictions as long as it stays within its “range.” However these two great theories fail miserably when combined. This failure results from the combined mathematics giving results that result in answers that are infinite. A big no no in both mathematics and reality. According to Rovelli this can be overcome by the basic understanding that all “things” are quantized. That is there is a smallest possible size for the most basic of concepts including space and time. You may of heard about something called Zeno’s paradox. This can be stated in many ways but let’s take something that we do every day. Most of us when we get out of bed go to the bathroom. A rather basic task, which some may find harder than others to achieve and yet we are almost always able to achieve that goal. So what is paradoxical about that? Well when I get up in order to get to the bathroom I have to go half way say to my chair. That seems easy enough. But then from my chair I once more have to go half way to my final goal, the bathroom. So far I am seem to be doing okay, but am I? Now, unfortunately, I start thinking; how many half ways are there from the point I have reached to that elusive bathroom? Oh oh I exclaim I can keep on cutting this distance in half an infinite number or times. If so not only can I not reach the bathroom I could not have even begun to get out of bed, the initial place I began. What’s the solution? Am I forever stuck at one place and if not why not. The solution is the quantum of space. Space itself cannot be infinitely divided in half because there is indeed a smallest piece of space which is called the Plank length or unit. The Plank unit is very, very small but is greater than zero or in other words finite. No matter how hard I try to divide this unit it stays the same length and the concept of half of it is impossible and I am therefore not bound by infinity of lengths. I am free to do one of my most basic obligations of the day. Well if there is indeed a smallest possible piece of space how about time. Most of us have heard about the concept of space time. I had until recently mistakenly believed that the concept of space time was an invention of Einstein. It was actually proposed by another mathematician, Minkowski and is therefore referred to as Minkowski’s space time. The rational for this is highly complex but if this postulate had a bearing on reality could time itself actually be quantized. That would mean that time is not simply a way of measuring things but has a physical reality as well. I assume by now you have guessed that indeed there in a quantum of time beyond which there is no way to divide time. That length of time is the time it takes for a photon traveling at the speed of light (c) to travel on plank unit. A very, very, very small bit of time but a bit that is indeed finite. Thus we have removed from the equations of physics the two things that have always been considered infinite and make them finite. The result is that there are no infinities no matter what the conditions are in the universe, everything is finite. Whether at the Big Bank itself or at any place in the universe there are no infinities only finites are allowed. If you are interested in an accessible (understandable) description of how this comes about read Reality Is Not What It Seems. I doubt this will change anything in my life or yours except that I sleep better since I no longer have to worry about not being able to get to the bathroom the next morning.