This column is ultimately a review of A Guess at the Riddle: Essays on the Physical Underpinnings of Quantum Mechanics, the short new book by David Z Albert, a philosopher at Columbia University and (as I found out last week) the graduate advisor of the founding editor of 3QuarksDaily, S. Abbas Raza. Unlike Raza, I have never met Albert, but my parasocial relationship with his work is midway through its second decade, which I am now acknowledging upfront.
I first became aware of David Z Albert when I was an undergraduate at a small Lutheran college in rural Iowa. On its top floor, the Wartburg College library had a large painting of Martin Luther, our hero, overseeing a bonfire of Catholic theology. But in the basement, where the unburnt books were held, I found a copy of Albert’s 1992 debut, Quantum Mechanics and Experience. The book’s style seemed wholly unusual to me. As a physics student, I wasn’t accustomed to books that were at once about science but somehow separate from it. I was impressed how Albert had retained only enough detail for a conceptual critique. I didn’t know, then, that its peculiar patois was just that of the analytic philosophers, with Albert merely adopting an eccentric dialect of that communal tongue.
In my last column for 3QD, I wrote about how quantum models work. A physical system is associated with a quantum state. As time passes, the quantum state changes according to a deterministic rule, the Schrodinger equation, branching smoothly into distinct outcomes. At the end, you compare how much of the wave-function—what percentage of its total squared amplitude—is parked in each possible branch, and this gives you the probability of observing each outcome.
Quantum Mechanics and Experience is a book about the measurement problem in quantum mechanics, which (roughly) is the question of how nature decides which one of the predicted possibilities within the final quantum state we actually end up observing. Albert’s book wasn’t my first exposure these issues—I had read Nick Herbert’s 1987 book, Quantum Reality, a few years earlier—but it represented the first time I got the sense that these issues were still debated, and still up for grabs. Read more »
If you spend any time doing science, you might notice that some things change when you close the door to the lab and walk into the theory suite.
In the laboratory, surprising things happen, no doubt about it. Depending on the type of lab you’re working in, you might see liquid nitrogen boiling out from a container, solutions changing color only near their surfaces, or microorganisms unexpectedly mutating. But once roughly the same thing happens a few times in a row, the conventional scientific attitude is to suppose that you can make sense of these observations. Sure, you can still expect a few outliers that don’t follow the usual trends, but there’s nothing in the laboratory that forces one to take any strong metaphysical positions. The surprises, instead, are of the sort that might lead someone to ask, Can I see that again? What conditions would allow this surprise to reoccur?
Of course, the ideas discussed back in the theory suite are, in some indirect way, just codified responses to old observational surprises. But scientists—at least, young scientists—rarely think in such pragmatic terms. Most young scientists are cradle realists, and start out with the impression that there is quite a cozy relationship between the entities they invoke in the theory suite and the observations they make back in the lab. This can be quite confusing, since connecting theory to observation is rarely so straightforward as simply calculating from first principles.
The types of experiments I’ve had been able to observe most closely involve electron microscopes. For many cases where electron microscopes are involved, workers will use quantum models to describe the observations. I’ve written about quantum models a fewtimesbefore, but I haven’t discussed much about how quantum physics models differ from their classical physics counterparts. Last summer, I worked out a simple, concrete example in detail, and this column will discuss the upshot of that, leaving out the details. If you’ve ever wondered, how exactly do quantum models work?—or even if you haven’t wondered, but are wondering now that I mention it—well, read on. Read more »
This is the second in a series of posts about J. Robert Oppenheimer’s life and times. All the others can be found here.
In the fall of 1922, after the New Mexico sojourn had strengthened his body and mind, Oppenheimer entered Harvard with an insatiable appetite for knowledge; in the words of a friend, “like a Goth looting Rome”. He wore his clothes on a spare frame – he weighed no more than 120 pounds at any time during his life – and had striking blue eyes. Harvard required its students to take four classes every semester for a standard graduation schedule. Robert would routinely take six classes every semester and audit a few more. Nor were these easy classes; a typical semester might include, in addition to classes in mathematics, chemistry and physics, ones in French literature and poetry, English history and moral philosophy.
The best window we have into Oppenheimer’s personality during his time at Harvard comes from the collection of his letters during this time edited by Alice Kimball Smith and Charles Weiner. They are mostly addressed to his Ethical Culture School teacher, Herbert Smith, and to his friends Paul Horgan and Francis Fergusson. Fergusson and Horgan were both from New Mexico where Robert had met them during his earlier trip. Horgan was to become an eminent historian and novelist who would win the Pulitzer Prize twice; Fergusson who departed Harvard soon as a Rhodes Scholar became an important literary and theater critic. They were to be Oppenheimer’s best friends at Harvard.
The letters to Fergusson, Horgan and Smith are fascinating and provide penetrating insights into the young scholar’s scientific, literary and emotional development. In them Oppenheimer exhibits some of the traits that he was to become well known for later; these include a prodigious diversity of reading and knowledge and a tendency to dramatize things. Also, most of the letters are about literature rather than science, which indicates that Oppenheimer had still not set his heart on becoming a scientist. He also regularly wrote poetry that he tried to get published in various sources. Read more »
I began reading Anthony Zee’s most famous book, Quantum Field Theory in a Nutshell, at Muncher’s Bakery in Lawrence, Kansas, where, as a would-be quantum field theorist in 2010, Zee’s book taught me to evaluate Gaussian integrals. Zee made it all seem almost trivial, but his fast style belied the true expectation that his book would be read slowly, pen in hand, the reader studiously working their way from one line to the next. You couldn’t escape the sense that Zee was a very clever man, if not a very sympathetic teacher. This was a book whose readers would select it. If they couldn’t proceed, well, who was really to blame?
I never did become a quantum field theorist, though that’s hardly Zee’s fault. (At that point, I barely had the patience to sit and eat a donut.) Thankfully, Zee has now published an even swifter book, Quantum Field Theory, As Simply as Possible, which readers of this column will be happy to know I actually finished.
On the first page, Zee comments wryly that popular physics books jumped straight from quantum mechanics to string theory—so this book fills the quantum field theory gap. Now, if you are not a physicist, you may not know what quantum field theory is. This review is for you. Unfortunately, Zee’s new book probably isn’t. For whom then, is QFT, as Simply as Possible (henceforth: QFT, ASAP) written? My own answer is that it’s perfect for a past version of myself, just way too late for that bakery. Read more »
Physicists writing books for the public have faced a longstanding challenge. Either they can write purely popular accounts that explain physics through metaphors and pop culture analogies but then risk oversimplifying key concepts, or they can get into a great deal of technical detail and risk making the book opaque to most readers without specialized training. All scientists face this challenge, but for physicists it’s particularly acute because of the mathematical nature of their field. Especially if you want to explain the two towering achievements of physics, quantum mechanics and general relativity, you can’t really get away from the math. It seems that physicists are stuck between a rock and a hard place: include math and, as the popular belief goes, every equation risks cutting their readership by half or, exclude math and deprive readers of a deeper understanding. The big question for a physicist who wants to communicate the great ideas of physics to a lay audience without entirely skipping the technical detail thus is, is there a middle ground?
Over the last decade or so there have been a few books that have in fact tried to tread this middle ground. Perhaps the most ambitious was Roger Penrose’s “The Road to Reality” which tried to encompass, in more than 800 pages, almost everything about mathematics and physics. Then there’s the “Theoretical Minimum” series by Leonard Susskind and his colleagues which, in three volumes (and an upcoming fourth one on general relativity) tries to lay down the key principles of all of physics. But both Penrose and Susskind’s volumes, as rewarding as they are, require a substantial time commitment on the part of the reader, and both at one point become comprehensible only to specialists.
If you are trying to find a short treatment of the key ideas of physics that is genuinely accessible to pretty much anyone with a high school math background, you would be hard-pressed to do better than Sean Carroll’s upcoming “The Biggest Ideas in the Universe”. Since I have known him a bit on social media for a while, I will refer to Sean by his first name. “The Biggest Ideas in the Universe” is based on a series of lectures that Sean gave during the pandemic. The current volume is the first in a set of three and deals with “space, time and motion”. In short, it aims to present all the math and physics you need to know for understanding Einstein’s special and general theories of relativity. Read more »
At the close of the 20th century, the logical end-point of physics seemed clear: unify all physical phenomena under the umbrella of a single, unique ‘Theory of Everything’ (ToE). Indeed, many were convinced that this goal was well within reach: in his 1980 inaugural lecture Is the end in sight for theoretical physics?, Stephen Hawking, the physicist perhaps most closely associated with the quest for the ToE in the public eye, speculated that this journey might be completed before the turn of the millennium.
More than twenty years after, a ToE has not manifested—and moreover, seems in some ways more distant than ever. Confidence in the erstwhile ‘only game in town’, string/M-theory, has been waning in the face of floundering attempts to make contact with the real world. Without much hope of guidance from experiment, some have even been questioning whether the theory is ‘proper science’ at all—or, conversely, whether it requires a reworking of scientific methodology towards a ‘post-empirical’ framework from the ground up. But in the wake of string theory’s troubles, no other contender has risen up to take center stage. Read more »
As someone who has been interested in both classical music and the history of physics for a long time, I have been intrigued by comparison of the styles between the two art forms. I use the term “art form” for physics styles deliberately since most of the best physics that has been done represents high art.
Just like with classical music, physics has been populated by architects and dreamers, careful workmen and inspired explorers, bursts of geniuses and sustained acts of creativity. It is worth spending some time discussing what the word “style” might even mean in a supposedly objective, quantitative field like physics where truth is divined through precise measurements and austere theories. The word style simply means a way of thinking, calculation and experiment, an idiosyncratic method that lends itself individually or collectively to figuring out the facts of nature. The fact is that there is no one style of doing physics, just like there is no one style of doing classical music. Physics has blossomed when it has benefited from an unpredictable diversity of styles; it has stagnated when a particular style hardened into the status quo. And just like classical music goes through periods of convention and experimentation, deaths and rebirths, so has physics.
If we take the three great eras of classical music – baroque, classical and romantic – and the leading composers pioneering these styles, it’s instructive to find parallels with the styles of some great physicists of yore. Johann Sebastian Bach who is my favorite classical musician was known for his precise, almost mathematical fugues, variations and concertos. Read more »
Zombies have become a mainstay of philosophy as much as of pulp fiction—a confluence that it would be fallacious to assume implies some further connection between the two, naturally. Zombies are beings that act in many ways like living humans—they move around, they interact with the world, and they, to generally horrific effect, consume resources for sustenance—not ending up as which is the typical goal of the protagonists of various kinds of zombie media. Yet, they lack the crucial quality of actually being alive, instead generally being considered merely ‘undead’.
Zombies are thus creatures of lack, creatures that have been robbed of some quality we otherwise think essential. Consider, for instance, the notion of the soulless zombie: a being which, despite acting and reacting just like any other human being—in fact, we might stipulate, in a way exactly paralleling your actions and reactions—lacks a ‘soul’ of any kind. If this is imaginable, then, the argument goes, there’s nothing that you’d actually need a soul for—and hence, we can strike it from the list of essential qualities without any resulting deficit.
A counterpoint to this particular argument is the floating man thought experiment of Ibn Sina (often Latinised as Avicenna), the eleventh century Persian polymath and physician. Ibn Sina imagines being created ‘at a stroke’, fully formed, in a state of free fall, and in darkness. Lacking any external sensory impression, one would still be certain of one’s own existence. But if there is nothing physical one could be conscious off absent such sensory data, then that sensation of being aware of one’s own self must be a sensation of something non-physical—the soul, or Nafs in the Quran. To Ibn Sina, then, the soulless zombie would merely show that the world is not exhausted by the physical, by our behaviors and reactions to external stimuli. Read more »
Imagine, if you will, that I own a reliably programmable qubit, a device that, when prepared in some standard and uncontroversial way, has a 50/50 probability of having one of two outcomes, A or B. Now imagine also that I have become convinced of my own telekinetic powers.
Suppose that the qubit has been calibrated within an inch of its life, and I have good reason to believe that the odds for the two possible outcomes, A or B, are in fact equally matched. My telekinetic powers, on the other hand, are weak—not strong enough to make heads explode like that guy in Scanners, nor strong enough to levitate chalk like in Matilda. Yet neither am I powerless. If I reign myself in—no more than a few attempts per night (I take care not to tire myself), and no counting tries when my juju’s off (remember, my gifts are unremarkable)—then I have been able, through intense concentration and force of will, to favor outcome A just slightly, just barely bumping its odds up, let’s say, from 50.0% to 50.1%.
Squinting, I claim statistical significance. But when I share these findings with you, my scientifically trained colleague, you are unimpressed.
The physicist Philip W. Anderson, winner of the Nobel Prize in 1977, has lingered in the broader scientific imagination for two main reasons—reasons, depending on your vantage, that cast him either as a hero, or as a villain.
The heroic Anderson is the author of “More Is Different,” the 1972 essay that wittily dismisses the idea that the laws of physics governing the microscopic constituents of matter are by themselves enough to capture the full richness of the world. His vision of science as a “seamless web” of interconnections led to his becoming one of the public faces of so-called “complexity science,” and a founding member of the Santa Fe Institute.
The villainous Anderson is remembered for taking this position—the position that the low-level laws of physics do not exhaust fundamental physics—in front of Congress. Anderson’s tart exchanges with Steven Weinberg before the Senate debating the merits of the Superconducting Super Collider (SSC) begin a new biography, A Mind Over Matter: Philip Anderson and the Physics of the Very Many, by Andrew Zangwill. When the SSC was canceled, Anderson, who argued that the funds would be better spent on a wider variety of projects, became a target of physicists’ ire, despite his lack of any significant political influence. (Weinberg’s last book of essays, which I reviewed, extensively discussed the politics of the SSC.)
But Anderson, who died just last year, was much more than just a hero or villain. A Mind Over Matter makes the case that Anderson was “one of the of the most accomplished and influential physicists of the twentieth century.” In presenting the evidence, Zangwill, who is himself a notable physicist, gives us a tour of condensed-matter physics, the science that deals with the properties of materials not atom-by-atom but roughly 1023 particles at a time, a subject where Anderson’s influence continues on. Read more »
Considered the epitome of genius, Albert Einstein appears like a wellspring of intellect gushing forth fully formed from the ground, without precedents or process. There was little in his lineage to suggest genius; his parents Hermann and Pauline, while having a pronounced aptitude for mathematics and music, gave no inkling of the off-scale progeny they would bring forth. His career itself is now the stuff of legend. In 1905, while working on physics almost as a side-project while sustaining a day job as technical patent clerk, third class, at the patent office in Bern, he published five papers that revolutionized physics and can only be compared to Isaac Newton’s burst of high creativity as he sought refuge from the plague. Among these were papers heralding his famous equation, E=mc^2, along with ones describing special relativity, Brownian motion and the basis of the photoelectric effect that cemented the particle nature of light. In one of history’s ironic episodes, it was the photoelectric effect paper rather than the one on special relativity that Einstein himself called revolutionary and that won him the 1922 Nobel Prize in physics.
But in judging Einstein’s superlative achievements, both in terms of his birth and his evolution as a physicist, it is easy to think him of him as an entirely self-made genius. Nothing could be further from the truth. Einstein stood on the proverbial shoulders of giants – Newton, Mach, Faraday, Maxwell, Lorentz, among others – men who had laid the foundations of physics for two centuries before him and who he always had effusive praise for. But quite apart from learning from his intellectual ancestry, Einstein also honed useful habits and personal qualities that enabled him to triumph in his work. Too often when we read about brilliant men and women, there’s a tendency to enshrine and emphasize pure intellect and discard the personal qualities, as if the two were cleanly separable. But the fact of the matter is that raw brilliance and qualities are like genes and culture, each feeding off of each other and nurturing each other’s growth and success.
As psychologist Angela Duckworth described in her book “Grit”, genius without effort and determination can fail, or fail to live up to its great promise at the very least. And so it was for Einstein. Which makes it a matter of curiosity at the minimum ,and more promisingly a tool for measurably enhancing the efficiency of our own more modest work, to survey the personal qualities that Einstein embodied that made him successful. So what were these? Read more »
James Clerk Maxwell, whose theory of electromagnetism occupies the same physics pedestal as Newton’s theory of gravity, was by all accounts a good-humored and generous man, and a fairly confusing lecturer. Here is a story about Maxwell (admitted to be apocryphal in the math notes that recount it) that suggests something of his character:
Maxwell was lecturing and, seeing a student dozing off, awakened him, asking, “Young man, what is electricity?” “I’m terribly sorry, sir,” the student replied, “I knew the answer but I have forgotten it.” Maxwell’s response to the class was, “Gentlemen, you have just witnessed the greatest tragedy in the history of science. The one person who knew what electricity is has forgotten it.”
This anecdote—this joke—is improved for those who know Maxwell as the preeminent early theorist of electricity. After all, if Maxwell didn’t know how to define electricity, what hope was there for his students?
At risk of over-explaining it, this anecdote gestures toward a piece of insider knowledge. You don’t need to know everything to construct a mathematical theory, and mathematical theories can be more robust than the systems they have been constructed to describe. As I’ve written elsewhere, mathematical techniques that are useful in one area of science tend to be useful in in other areas, not as an exception, but as a rule. Read more »
Progress in science often happens when two or more fields productively meet. Astrophysics got a huge boost when the tools of radio and radar met the age-old science of astronomy. From this fruitful marriage came things like the discovery of the radiation from the big bang. Another example was the union of biology with chemistry and quantum mechanics that gave rise to molecular biology. There is little doubt that some of the most important future discoveries in science in the future will similarly arise from the accidental fusion of multiple disciplines.
One such fusion sits on the horizon, largely underappreciated and unseen by the public. It is the fusion between physics, computer science and biology. More specifically, this fusion will likely see its greatest manifestation in the interplay between information theory, thermodynamics and neuroscience. My prediction is that this fusion will be every bit as important as any potential fusion of general relativity with quantum theory, and at least as important as the development of molecular biology in the mid 20th century. I also believe that this development will likely happen during my own lifetime.
The roots of this predicted marriage go back to 1867. In that year the great Scottish physicist James Clerk Maxwell proposed a thought experiment that was later called ‘Maxwell’s Demon’. Maxwell’s Demon was purportedly a way to defy the second law of thermodynamics that had been proposed a few years earlier. The second law of thermodynamics is one of the fundamental laws governing everything in the universe, from the birth of stars to the birth of babies. It basically states that left to itself, an isolated system will tend to go from a state of order to one of disorder. A good example is how a bottle of perfume wafts throughout a room with time. This order and disorder was quantified by a quantity called entropy. Read more »
In November 1918, a 17-year-student from Rome sat for the entrance examination of the Scuola Normale Superiore in Pisa, Italy’s most prestigious science institution. Students applying to the institute had to write an essay on a topic that the examiners picked. The topics were usually quite general, so the students had considerable leeway. Most students wrote about well-known subjects that they had already learnt about in high school. But this student was different. The title of the topic he had been given was “Characteristics of Sound”, and instead of stating basic facts about sound, he “set forth the partial differential equation of a vibrating rod and solved it using Fourier analysis, finding the eigenvalues and eigenfrequencies. The entire essay continued on this level which would have been creditable for a doctoral examination.” The man writing these words was the 17-year-old’s future student, friend and Nobel laureate, Emilio Segre. The student was Enrico Fermi. The examiner was so startled by the originality and sophistication of Fermi’s analysis that he broke precedent and invited the boy to meet him in his office, partly to make sure that the essay had not been plagiarized. After convincing himself that Enrico had done the work himself, the examiner congratulated him and predicted that he would become an important scientist.
Twenty five years later Fermi was indeed an important scientist, so important in fact that J. Robert Oppenheimer had created an entire division called F-Division under his name at Los Alamos, New Mexico to harness his unique talents for the Manhattan Project. By that time the Italian emigre was the world’s foremost nuclear physicist as well as perhaps the only universalist in physics – in the words of a recent admiring biographer, “the last man who knew everything”. He had led the creation of the world’s first nuclear reactor in a squash court at the University of Chicago in 1942 and had won a Nobel Prize in 1938 for his work on using neutrons to breed new elements, laying the foundations of the atomic age. Read more »
There is a sense in certain quarters that both experimental and theoretical fundamental physics are at an impasse. Other branches of physics like condensed matter physics and fluid dynamics are thriving, but since the composition and existence of the fundamental basis of matter, the origins of the universe and the unity of quantum mechanics with general relativity have long since been held to be foundational matters in physics, this lack of progress rightly bothers its practitioners.
Each of these two aspects of physics faces its own problems. Experimental physics is in trouble because it now relies on energies that cannot be reached even by the biggest particle accelerators around, and building new accelerators will require billions of dollars at a minimum. Even before it was difficult to get this kind of money; in the 1990s the Superconducting Supercollider, an accelerator which would have cost about $2 billion and reached energies greater than those reached by the Large Hadron Collider, was shelved because of a lack of consensus among physicists, political foot dragging and budget concerns. The next particle accelerator which is projected to cost $10 billion is seen as a bad investment by some, especially since previous expensive experiments in physics have confirmed prior theoretical foundations rather than discovered new phenomena or particles.
Fundamental theoretical physics is in trouble because it has become unfalsifiable, divorced from experiment and entangled in mathematical complexities. String theory which was thought to be the most promising approach to unifying quantum mechanics and general relativity has come under particular scrutiny, and its lack of falsifiable predictive power has become so visible that some philosophers have suggested that traditional criteria for a theory’s success like falsification should no longer be applied to string theory. Not surprisingly, many scientists as well as philosophers have frowned on this proposed novel, postmodern model of scientific validation.Read more »
A rare and happy coincidence today: The birthdays of both John Archibald Wheeler and Oliver Sacks. Wheeler was one of the most prominent physicists of the twentieth century. Sacks was one of the most prominent medical writers of his time. Both of them were great explorers, the first of the universe beyond and the second of the universe within.
What made both men special, however, was that they transcended mere accomplishment in the traditional genres that they worked in, and in that process they stand as role models for an age that seems so fractured. Wheeler the physicist was also Wheeler the poet and Wheeler the philosopher. Throughout his life he transmitted startling new ideas through eloquent prose that was too radical for academic journals. Most of his important writings made their way to us through talks and books. Sacks the neurologist was far more than a neurologist, and Sacks the writer was much more than a writer. Both Wheeler and Sacks had a transcendent view of humanity and the universe, a view that is well worth taking to heart in our own self-centered times.
Their backgrounds shaped their views and their destiny. John Wheeler grew up in an age when physics was transforming our view of the universe. While he was too young to participate in the genesis of the twin revolutions of relativity and quantum mechanics, he came on stage at the right time to fully implement the revolution in the burgeoning fields of particle and nuclear physics. Read more »
The sun was setting on a cloudless sky, the gulls screeching in the distance. The air was bracing and clear. Land rose from the blue ocean, a vague apparition on the horizon.
He breathed the elixir of pure evening air in and heaved a sigh of relief. This would help the godforsaken hay fever which had plagued him like a demon for the last four days. It had necessitated a trip away from the mainland to this tiny outcrop of flaming red rock out in the North Sea. Here he could be free not just of the hay fever but of his mentor, Niels Bohr. Perched on the rock, he looked out into the blue expanse.
For the last several months, Bohr had followed him like a shadow, an affliction that seemed almost as bad as the hay fever. It had all started about a year earlier, but really, it started when he was a child. His father, an erudite scholar but unsparing disciplinarian, made his brother and him compete mercilessly with each other. Even now he was not on the best terms with his brother, but the cutthroat competition produced at least one happy outcome: a passion for mathematics and physics that continued to provide him with intense pleasure.
He remembered those war torn years when Germany seemed to be on the brink of collapse, when one revolution after another threatened to tear apart the fabric of society. Physics was the one refuge. It sustained him then, and it promised to sustain him now.
If only he could understand what Bohr wanted. Bohr was not his first mentor. That place of pride belonged to Arnold Sommerfeld in Munich. Sommerfeld, the man with the impeccably waxed mustache who his friend Pauli called a Hussar officer. Sommerfeld, who would immerse his students not only in the latest physics but in his own home, where discussions went on late into the night. Discussions in which physics, politics and philosophy co-existed. His own father was often distant; Sommerfeld was the father figure in his life. It was also in Sommerfeld’s classes that he met his first real friend – Wolfgang Pauli. Pauli was still having trouble attending classes in the morning when there were all those clubs and parties to frequent at night. He always enjoyed long discussions with Pauli, the ones during which his friend often complimented him by telling him he was not completely stupid. It was Pauli who had steered him away from relativity and toward the most exciting new field in physics – quantum theory.