, and for something that small, even the light hitting it would give it a kick that would change its motion. As a result, its velocity now becomes uncertain. Of course, with larger entities, like you and me, light can’t knock us around. But the principle holds; there is an eventual limit to how much we can know about any object in this universe. Our knowledge of even the tiniest particle in the universe is fundamentally limited by a quantum trade-off!
Figure 2.1 The process of determining the position of a subatomic particle, such as an electron, changes its velocity because even the energy of the light used to observe it gives it a kick.
But the strangest thing about the uncertainty principle is that all observable physical parameters come in pairs called conjugate variables, for which if one is measured very precisely, inevitably some precision is lost in the other. It is kind of like most married couples, both can never seem to be happy at the same time! Well, the name can’t be a coincidence—after all, a married couple is a “conjugal” pair! Position and velocity happen to be just one such pair, but there are many others, like energy and time, for example. Interestingly enough, each member of a conjugate pair affects its partner, but not necessarily members of other pairs. So, for example, we can measure the position and the time both as precisely as we want to, likewise the momentum and the energy—no uncertainty trade-offs there. Now if that seems bizarre, just think about marital conjugal pairs; the happiness of a wife might correlate with her husband’s but is independent of how the neighbors are feeling.
The uncertainty principle is a primary reason why the quantum view of the universe is so very different from the classical view. In the classical worldview defined by Sir Isaac Newton, you could know everything about any object in the universe completely and up to arbitrary precision—well at least in principle. This led to a deterministic view of the world, which strongly influenced the cultural and philosophical outlook in the centuries that followed Newton. The universe was viewed as a clockwork mechanism, so that if you knew the initial position and velocity of every particle in the universe and the forces acting among them, you could, in principle, predict how the drama of the universe would play out for all eternity.
The trouble with this deterministic view is that it did not leave any room for free will or matters of chance. If you bought into that picture, then you will have to believe that everything in the universe (including all our lives) were predetermined at the origin of the universe! So certainly some change of view was inevitable. Yet nobody could have expected the magnitude of the change that was to come! The quantum view à la the uncertainty principle really took us all the way to the other extreme: Now instead of the universe being completely deterministic, it turns out that, at the subatomic level, everything is governed by uncertainties and laws of chance. Forget about predetermining the fate of the universe, the uncertainty principle tells us that we cannot even precisely determine the fate of one single tiny electron!
In retrospect, the classical deterministic view of the world was an unrealistic one at many levels. For one, it simply does not agree with any of our life experiences. In a predetermined universe, chance can be eliminated, so you could, in principle, know it all. Well then, if you could know it all ahead of time, you could also arrange to have it all. Yeah, right! The reality is that in life we can never have it all, and our lives are indeed governed by chance, much more than we would like to admit. Life is chock-full of trade-offs, just like the uncertainty principle. And as with the uncertainty principle in nature, all the desirable and worthwhile things in life seem to come in conjugate pairs, with a built-in catch so that you can never get enough of both—because too much of one always means sacrificing on the other. In the language of quantum physics, we just say that conjugate pairs do not commute.
My favorite one is the “time versus money conjugate pair”; you never can seem to have all the money you want and the time to spend it simultaneously. Barring a few lucky individuals—those who came into large inheritances, like the idle aristocrats in the novels of P. G. Wodehouse, or those lucky few who made their pile young and retired early—the rest of us with high financial ambitions have to slog at it for most of our lives, leaving very little time to play with the money as we struggle to push up our net worth higher. On the other hand, if you have no financial ambitions, and you are completely content with living in a barrel—like Diogenes of ancient Greece—and with having nothing at all—like the naked fakirs in the Himalayas—you will likely have all the time in the world, but of course not much money to measure that time with. In the quantum jargon, time and money just do not commute!
Then, take the whole marriage thing, for instance. Not so long ago, the popular comedian, Chris Rock, a keen observer of human behavior, had this to say about marriage: You can either be “single and lonely” or be “married and bored.” Without perhaps realizing it, he was touching a bit on the uncertainty principle, because I think that captures another one of life’s great trade-offs. If you stay single, you can continue to play the field, you can hit the bars on the weekends, date several people in a single year at varying levels of intimacy, and move on when you are bored (assuming that you have the charm and the social skills to get someone to go out with you in the first place). At the end of every day, when you leave your workplace, you are free as a bird, you can do anything you want in your pad. If you happen to be a guy for whom a regular cleaning schedule is thing of mystery, there would be no wife to question your notions of cleanliness; if you planned for days to watch that game on Monday night, you would not be cajoled and manipulated into watching the mushy sitcom instead. And vice versa, if you are a woman who likes your nest to be organized and pretty, there is no one to mess up your place, no badly aimed urine all over your toilet, and if one night you felt like having a good cry watching The Bridges of Madison County, there is no danger of some insensitive lout switching channels just as Clint Eastwood is driving away from that last crossroad.
So, it is all great, you are completely free to enjoy yourself and live as you want to—that is, until you hit those weekends with no dates and cannot find any friends to hang out with; you are rained in and you do not even feel like watching television because it reminds you of all that is missing in your life; worse still, you are middle-aged now and getting dates is not as easy or as much fun as it used to be—and all your friends are married with kids and busy with their lives. Then you might start wishing for a family and kids yourself. You might have enjoyed the single life, but all along there was this risk of eventually ending up lonely and depressed. Not to mention that you probably have shortened your life by excessive partying, drinking, and smoking in the name of socializing.
Well, those are the trade-offs for the single life. There is plenty to say about the other side as well, the married life. I read somewhere that married guys are among the largest consumer demographics of the adult industry in America. So I am assuming all is not so quiet on that domestic front. For sure, married people envy their single friends often, and perhaps that is why they always try so hard at matchmaking; you know that if you are single after a certain age, and most of your friends are married, they will harass you about getting married, and they will keep on trying to set you up with someone—usually with people you do not want to meet. I think married people simply cannot bear to see all the fun their single friends are having that they themselves are missing out on, while they are doing household chores amidst whiny kids and intolerable spouses. So they try to ruin that fun for their single friends, by getting them married, as well. But hey, if you can survive all that and make it through the tough times, you will have very little time to get depressed and lonely, partly because you will never be alone for any length of time to indulge in either. And in your middle age, when the kids are off to college and doing well, you will be so proud and happy, and the spouse of many years has now become someone you cannot imagine living without. So when your still-single friends, the ones you used to envy a decade ago, stop by, they will linger over the photographs of your kids and wonder what went wrong in their lives.
While on the topic of family life, one can also apply the uncertainty principle to having kids. Sure, they can make you smile and make you proud and might rally around you (if you are lucky) in your old age, but then you have to be prepared to go through those sleepless nights and the trips to the doctor, the PTA meetings, soccer practice, piano lessons, and pretty much sacrifice many of the best years of your life to take care of their needs while they grow up.
Other trade-offs in life have a closer semblance to another set of conjugate variables in quantum physics. The energy–time uncertainty principle is just as fundamental as the position–velocity one we talked about. And in quite the same way, the more precisely we specify the total energy in a system, the less precisely can we define the time scale associated with it. This is somewhat trickier than the other sets of uncertainty-bound conjugate pairs in physics, because unlike position or velocity or even energy, time is not a characteristic of an object, be it an electron or a human being. Time, like space, is more like a background against which all other things play out. One way to understand the energy–time uncertainty principle is as follows: All fundamental particles have some intrinsic energy as a part of their quantum identity, just as your height, eye color, and other characteristics identify you. And the more precisely you want to know the energy of a particle, the more time you need to do the measurement. Therein lies the trade-off: The more precise your knowledge of the energy, the less precisely can you pinpoint the time when you actually have that knowledge, and, vice versa, the less time you spend in measuring that energy, the more precisely you can specify the exact moment of the energy measurement, but then you have to sacrifice the accuracy of the energy value you have.
As you will see often in this book, the human implications and the life-parallels of many of nature’s laws have already been distilled (albeit unwittingly) into some of our traditional aphorisms. A real-life analog of the energy–time uncertainty principle is the well-known figure of speech, “jack of all trades, master of none,” because effortless virtuosity requires time and dedication. To master anything—to minimize the uncertainty in your knowledge of a subject—you need to dedicate an immense amount of time; whereas if you are fickle and spend only a short time on any particular interest, you will be just another jack at it, never a master. Beethoven was the genius that he was because he had the dedication to perfect his art, and he sacrificed much in his life along the way. Einstein worked on general relativity for ten grueling years. Thomas Alva Edison was a workaholic who only slept a few hours a night, and his long and persistent efforts changed our world. A famous musician once commented wryly about his skills that, “It is not easy to make it look easy.” That is so very true. There is no uncertainty in virtuoso performers playing their instruments; they are sure of how to play and what to play—it all flows. But behind it all, lies years and years of hard work and sacrifice and obsessive drive to get there.
Well, I could rant forever about all the trade-offs in life, and I am sure you can come up with many more of your own, but here are just a few of my favorite ones to convince you that the spirit of the uncertainty principle indeed defines our lives:
• The bigger and more lavish the wedding, the shorter the marriage lasts; think of celebrity weddings!
• The more magnificent the house, the less time people seem to spend in it. Many large mansions are owned by rich folks who own multiple homes and only spend a few weeks or months at each. On the other hand, the small suburban houses with kids stacked on bunk beds seem to be always full of people and life.
• The more spectacular the kitchen, the less cooking is usually done in it. The best cooking always seems to come from your grandma’s humble, old-fashioned kitchen; whereas in that beautiful thousand-handle state-of-the-art kitchen, the only handle that is probably used is the one for the microwave.
• Women complain about guys being either interesting and attractive, but unfaithful and deceitful, or very dependable and reliable, but boring and unattractive. Guys have similar complaints as well; women they can easily get are never the ones they are attracted to, and the ones that are attractive are always out of reach.
• You like the peace and security of the country—great quality of life and great for raising kids—but then you risk becoming bored out of your mind often and missing out on all the culture and excitement of the big cities. A place in the scenic boonies is great until you have an emergency that requires urgent care. Move to the city, and you could get all the excitement and activities you could ever want, but then you need to deal with traffic, crime, and a whole bunch of other everyday hassles.
• You get drunk and feel at the top of the world for a few hours, and then you wake up with the worst hangover the next morning—and perhaps next to some loathsome stranger!
• You are the cool kid in your high-school class, spend all your time partying and chasing girls, could not care less about your studies, and think life is so good that you might even drop out of school—but then you risk ending up like Al Bundy in Married with Children. The nerds and geeks who seem to have no life, no dates, and are bullied daily at school are the ones who might end up as the Bill Gates or the Steve Jobs of the future.
• You have a lot of stuff and you always have to worry about losing it, or you don’t have a care in the world—and you probably have nothing to lose, either.
• Throughout history, people who settled down in villages and towns, nations and countries, could count on a better quality of life in general. But when the nomadic tribes, the so-called barbarians, invaded, the barbarians had a huge tactical advantage, and they usually won with devastating success and then disappeared with all the loot. The cities and nations could, and did, send out huge armies after them, but could never find them! This was true when Rome fell, when Genghis Khan ravaged the known world, and it is true now, as the civilized nations try to battle terrorists and combat guerilla warfare.
But at the end, a bit of uncertainty in life is perhaps good for us. That is what makes life exciting and interesting. It is also the source of hope. You might not want to know everything about everything—the reality can be quite painful sometimes—like what the future really holds or what people really think about you. Besides, much of our plans and dreams of life are built upon the premise of uncertainty and the absence of complete knowledge. Romance is all about uncertainty; without it, there would have been no Casablanca or Doctor Zhivago or the powerful final sequence of The Third Man. In an absolutely certain world, all the romance you will have will be children’s fairy tales. Likewise, there would have been very little drama and suspense; Hitchcock might as well have been making cartoons. And not just in movies, even in real life, doesn’t much of the excitement and romance in our life ultimately arise from innate uncertainties that surround us?
If uncertainties of life ever get you down, it might help to remember that it is not just your life; uncertainties define the universe at the most fundamental scale. Even in the world of physics that purports to be so exact, in the end we’re really working with probabilities. It is all a game of chance from the smallest scale to the scale of our everyday lives, and we just have to weigh the probabilities, as there is always a trade-off; it’s just that in physics, we have formulae for those trade-offs. In real life, we have to make ours up as we go along.