Day 315: Einstein’s Dice and Schrödinger’s Cat

This is the tale of two brilliant physicists, the 1947 media war that tore apart their decades-long friendship, and the fragile nature of scientific collaboration and discovery.

When they were pitted against each other, each scientist was a Nobel laureate, well into middle age, and certainly past the peak of his major work. Yet the international press largely had a different story to tell. It was a familiar narrative of a seasoned fighter still going strong versus an upstart contender hungry to seize the trophy. While Albert Einstein was extraordinarily famous, his every pronouncement covered by the media, relatively few readers were conversant with the work of Austrian physicist Erwin Schrödinger.

Those following Einstein’s career knew that he been working for decades on a unified field theory. He hoped to extend the work of nineteenth-century British physicist James Clerk Maxwell in uniting the forces of nature through a simple set of equations. Maxwell had provided a unified explanation for electricity and magnetism, called electromagnetic fields, and identified them as light waves. Einstein’s own general theory of relativity described gravity as a warping of the geometry of space and time. Confirmation of the theory had won him fame. However, he didn’t want to stop there. His dream was to incorporate Maxwell’s results into an extended form of general relativity and thereby unite electromagnetism with gravity.

Every few years, Einstein had announced a unified theory to great fanfare, only to have it quietly fail and be replaced by another. Starting in the late 1920s, one of his primary goals was a deterministic alternative to probabilistic quantum theory, as developed by Niels Bohr, Werner Heisenberg, Max Born, and others. Although he realized that quantum theory was experimentally successful, he judged it incomplete. In his heart he felt that “God did not play dice,” as he put it, couching the issue in terms of what an ideal mechanistic creation would be like. By “God” he meant the deity described by seventeenth-century Dutch philosopher Baruch Spinoza: an emblem of the best possible natural order. Spinoza had argued that God, synonymous with nature, was immutable and eternal, leaving no room for chance. Agreeing with Spinoza, Einstein sought the invariant rules governing nature’s mechanisms. He was absolutely determined to prove that the world was absolutely determined.

Exiled in Ireland in the 1940s after the Nazi annexation of Austria, Schrödinger shared Einstein’s disdain for the orthodox interpretation of quantum mechanics and saw him as a natural collaborator. Einstein similarly found in Schrödinger a kindred spirit. After sharing ideas for unification of the forces, Schrödinger suddenly announced success, generating a storm of attention and opening a rift between the men.

You may have heard of Schrödinger’s cat—the feline thought experiment for which the general public knows him best. But back when this feud took place, few people outside of the physics community had heard of the cat conundrum or of him. As depicted in the press, he was just an ambitious scientist residing in Dublin who might have landed a knockout punch on the great one.
The leading announcer was the Irish Press, from which the international community learned about Schrödinger’s challenge. Schrödinger had sent them an extensive press release describing his new “theory of everything,” immodestly placing his own work in the context of the achievements of the Greek sage Democritus (the coiner of the term “atom”), the Roman poet Lucretius, the French philosopher Descartes, Spinoza, and Einstein himself. “It is not a very becoming thing for a scientist to advertise his own discoveries,” Schrödinger told them. “But since the Press wishes it, I submit to them.”

The New York Times cast the announcement as a battle between a maverick’s mysterious methods and the establishment’s lack of progress. “How Schrödinger has proceeded we are not told,” it reported.

For a fleeting moment it seemed that a Viennese physicist whose name was then little known to the general public had beaten the great Einstein to a theory that explained everything in the universe. Perhaps it was time, puzzled readers may have thought, to get to know Schrödinger better.

Today, what comes to mind for most people who have heard of Schrödinger are a cat, a box, and a paradox. His famous thought experiment, published as part of a 1935 paper, “The Present Situation in Quantum Mechanics,” is one of the most gruesome devised in the history of science. Hearing about it for the first time is bound to trigger gasps of horror, followed by relief that it is just a hypothetical experiment that presumably has never been attempted on an actual feline subject.

Schrödinger proposed the thought experiment in 1935 as part of a paper that investigated the ramifications of entanglement in quantum physics. Entanglement (the term was coined by Schrödinger) is when the condition of two or more particles is represented by a single quantum state, such that if something happens to one particle the others are instantly affected.

Inspired in part by dialogue with Einstein, the conundrum of Schrödinger’s cat presses the implications of quantum physics to their very limits by asking us to imagine the fate of a cat becoming entangled with the state of a particle. The cat is placed in a box that contains a radioactive substance, a Geiger counter, and a sealed vial of poison. The box is closed, and a timer is set to precisely the interval at which the substance would have a 50–50 chance of decaying by releasing a particle. The researcher has rigged the apparatus so that if the Geiger counter registers the click of a single decay particle, the vial would be smashed, the poison released, and the cat dispatched. However, if no decay occurs, the cat would be spared.

According to quantum measurement theory, as Schrödinger pointed out, the state of the cat (dead or alive) would be entangled with the state of the Geiger counter’s reading (decay or no decay) until the box is opened. Therefore, the cat would be in a zombielike quantum superposition of deceased and living until the timer went off, the researcher opened the box, and the quantum state of the cat and counter “collapsed” (distilled itself) into one of the two possibilities.

~~Einstein’s Dice and Schrödinger’s Cat: How Two Great Minds Battled Quantum Randomness to Create a Unified Theory of Physics -by- Paul Halpern

Day 132: Book Excerpt: Brilliant Blunders

In his masterwork Principia, first published in 1687, Isaac Newton noted that “a globe of red hot iron equal to our earth, that is, about 40,000,000 feet in diameter, would scarcely cool in an equal number of days, or in above 50,000 years.” Realizing he could not easily square this result with his religious beliefs, Newton was quick to add, “But I suspect that the duration of heat may, on account of some latent causes, increase in a yet less proportion than that of the diameter; and I should be glad that the true proportion was investigated by experiments.”

Newton was not the only seventeenth-century scientist to think about this problem. The famous philosophers Descartes and Gottfried Wilhelm Leibniz also discussed the cooling of the Earth from an initially molten state. However, the first person who appears to have taken seriously Newton’s advice about an experimental investigation—and who in addition was imaginative enough to attempt to use the cooling problem to estimate the age of the Earth—was the eighteenth-century mathematician and naturalist Georges-Louis Leclerc, Comte de Buffon.
Buffon was a truly prolific character who was not only an accomplished scientist but also a successful businessman. He is perhaps best known for the clarity and forcefulness with which he presented a new method for approaching nature. His monumental lifework, Histoire Naturelle, Générale et Particulière (Natural History, General and Particular)—thirty-six-volumes of which were completed during his lifetime (with eight more published posthumously)—was read by most of the educated people of the day in Europe and North America. Buffon’s aim was to deal in succession with topics ranging from the solar system, the Earth, and the human race to the different kingdoms of living creatures.

In his mental excursion into the Earth’s physical past, Buffon assumed that the Earth started as a molten sphere after having been ejected from the Sun due to a collision with a comet. Then, in the true spirit of an experimentalist, he was not satisfied with a purely theoretical scenario—Buffon proceeded immediately to manufacture spheres of different diameters and to measure accurately the time it took them to cool down. From these experiments he estimated that the terrestrial globe solidified in 2,905 years and cooled down to its present temperature in 74,832 years, even though he suspected that the cooling time could be much longer.

Eventually, however, it was not pure Newtonian physics that brought the problem of the Earth’s age into the limelight. The surge in the study of fossils in the eighteenth century convinced naturalists such as Georges Cuvier, Jean-Baptiste Lamarck, and James Hutton that both the paleontological and the geological records required the operation of geological forces over exceedingly long periods of time. So long, in fact, that, as Hutton has put it, he found “no vestige of a beginning, no prospect of an end.”

In view of the increasing difficulty of trying to cram the entire history of the Earth into the biblical mere few thousand years, some of the more religiously inclined naturalists (but not only them) opted to rely on catastrophes such as floods as agents of rapid changes. If great expanses of time were to be denied, catastrophes appeared to be the only vehicle that could significantly shape the Earth’s surface almost instantaneously. To be sure, the distribution of marine fossils provided clear evidence for the action of flooding and glaciation in the Earth’s geological past, but many of the ardent catastrophists were at least partially motivated by their unwavering loyalty to the biblical text rather than by the scientific attestation. Richard Kirwan—one of the well-known chemists of the day—articulated this position clearly. Kirwan pitted Hutton directly against Moses in describing how dismayed he was to observe “how fatal the suspicion of the high antiquity of the globe has been to the credit of Mosaic history, and consequently to religion and morality.”

The situation started to change dramatically with the publication of Charles Lyell’s three-volume Principles of Geology in the years 1830–33. Lyell, who was also Charles Darwin’s close friend, made it clear that the catastrophist doctrine was far too frail to last as a compromise between science and theology. He decided to put aside the question of the origin of the Earth and to concentrate on its evolution. Lyell argued that the forces that sculpted the Earth—volcanism, sedimentation, erosion, and similar processes—remained essentially unchanged throughout the Earth’s history, both in their strength and in their nature. This was the idea of uniformitarianism that inspired Darwin’s concept of gradualism in the evolution of species. The basic premise was simple: If there was one thing that these slow-acting geological forces needed in order to have an appreciable effect, it was time. Lots of it. Lyell’s followers have almost abandoned the notion of a definite age altogether in favor of the rather vague “inconceivably vast” time. In other words, Lyell’s Earth was one that was almost in a steady state, with snail’s-pace changes operating over a nearly infinite time. This principle starkly contrasted with the theological estimates of some six thousand years.

To a certain extent, the world view of an immeasurably extended geological age permeated Darwin’s The Origin, even though Darwin’s own attempt to estimate the age of the Weald—the eroded valley stretching across the southeastern part of England—turned out to be disastrously flawed, and he eventually retracted it. Darwin envisaged for evolution a long sequence of phases, lasting perhaps ten million years each. There was, however, one important difference between Darwin’s stance and those of the geologists. While he indeed required long periods of time for evolution to run its course, he insisted on a directional “arrow of time”; he could not be satisfied with a steady state or a cyclical progression, since the concept of evolution gave time a clear trend. But a controversy was starting to brew. It was not between Darwin and Lyell personally, nor even between geology and biology in general, but between a champion of physics on one side and some geologists and biologists on the other. Enter one of the most eminent physicists of his time: William Thomson, later known as Lord Kelvin.
On April 28, 1862, Kelvin (then still Thomson) read to the Royal Society of Edinburgh a paper entitled “On the Secular Cooling of the Earth.” This paper followed closely on the heels of another article published just the month before, with the title “On the Age of the Sun’s Heat.” Thomson made clear from the opening sentence that this was not going to be just another forgettable technical essay. Here was a hard-line attack on the geologists’ assumption about the unchanging nature of the forces that had shaped the Earth:

For eighteen years it has pressed on my mind, that essential principles of Thermodynamics have been overlooked by those geologists who uncompromisingly oppose all paroxysmal hypotheses, and maintain not only that we have examples now before us, on the earth, of all the different actions by which its crust has been modified in geological history, but that these actions have never, or have not on the whole, been more violent in past time than they are at present.

While the phrase “pressed on my mind” was somewhat of an overdramatized exaggeration, it was certainly true that Kelvin’s first papers on the topics of heat conduction and the distribution of heat through the body of the Earth were written as early as 1844 (when he was a twenty-year-old student) and 1846, respectively. Even before his seventeenth birthday, Thomson succeeded in spotting a mistake in a paper on heat by an Edinburgh professor.

Kelvin’s point was simple: Measurements from mines and wells indicated that heat was flowing from the Earth’s interior to its surface, implying that the Earth was an initially hotter planet that was cooling. Consequently, Kelvin argued, unless some internal or external energy sources could be shown to compensate for the heat losses, clearly no steady state, or repeating, identical geological cycles, were possible.

~~Brilliant Blunders (From Darwin to Einstein) -by- Mario Livio

Day 80 : Book Excerpt : The Hidden Reality: Parallel Universes and the Deep Laws of the Cosmos

In the far reaches of an infinite cosmos, there’s a galaxy that looks just like the Milky Way, with a solar system that’s the spitting image of ours, with a planet that’s a dead ringer for earth, with a house that’s indistinguishable from yours, inhabited by someone who looks just like you, who is right now reading this very book and imagining you, in a distant galaxy, just reaching the end of this sentence. And there’s not just one such copy. In an infinite universe, there are infinitely many. In some, your doppelgänger is now reading this sentence, along with you. In others, he or she has skipped ahead, or feels in need of a snack and has put the book down. In others still, he or she has, well, a less than felicitous disposition and is someone you’d rather not meet in a dark alley.

And you won’t. These copies would inhabit realms so distant that light traveling since the big bang wouldn’t have had time to cross the spatial expanse that separates us. But even without the capacity to observe these realms, we’ll see that basic physical principles establish that if the cosmos is infinitely large, it is home to infinitely many parallel worlds—some identical to ours, some differing from ours, many bearing no resemblance to our world at all.
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“Your mathematics is correct, but your physics is abominable.” The 1927 Solvay Conference on Physics was in full swing, and this was Albert Einstein’s reaction when the Belgian Georges Lemaître informed him that the equations of general relativity, which Einstein had published more than a decade earlier, entailed a dramatic rewriting of the story of creation. According to Lemaître’s calculations, the universe began as a tiny speck of astounding density, a “primeval atom” as he would come to call it, which swelled over the vastness of time to become the observable cosmos.

Lemaître cut an unusual figure among the dozens of renowned physicists, in addition to Einstein, who had descended on the Hotel Metropole in Brussels for a week of intense debate on quantum theory. By 1923, he had not only completed his work for a doctorate, but he’d also finished his studies at the Saint-Rombaut seminary and been ordained a Jesuit priest. During a break in the conference, Lemaître, clerical collar in place, approached the man whose equations, he believed, were the basis for a new scientific theory of cosmic origin. Einstein knew of Lemaître’s theory, having read his paper on the subject some months earlier, and could find no fault with his manipulations of general relativity’s equations. In fact, this was not the first time someone had presented Einstein with this result. In 1921, the Russian mathematician and meteorologist Alexander Friedmann had come upon a variety of solutions to Einstein’s equations in which space would stretch, causing the universe to expand. Einstein balked at those solutions, at first suggesting that Friedmann’s calculations were marred by errors. In this, Einstein was wrong; he later retracted the claim. But Einstein refused to be mathematics’ pawn. He bucked the equations in favor of his intuition about how the cosmos should be, his deep-seated belief that the universe was eternal and, on the largest of scales, fixed and unchanging. The universe, Einstein admonished Lemaître, is not now expanding and never was.

Six years later, in a seminar room at Mount Wilson Observatory in California, Einstein focused intently as Lemaître laid out a more detailed version of his theory that the universe began in a primordial flash and that the galaxies were burning embers floating on a swelling sea of space. When the seminar concluded, Einstein stood up and declared Lemaître’s theory to be “the most beautiful and satisfactory explanation of creation to which I have ever listened.” The world’s most famous physicist had been persuaded to change his mind about one of the world’s most challenging mysteries. While still largely unknown to the general public, Lemaître would come to be known among scientists as the father of the big bang.
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Einstein began work on general relativity around 1907, a time when most scientists thought gravity had long since been explained by the work of Isaac Newton. As high school students around the world are routinely taught, in the late 1600s Newton came up with his so-called Universal Law of Gravity, providing the first mathematical description of this most familiar of nature’s forces. His law is so accurate that NASA engineers still use it to calculate spacecraft trajectories, and astronomers still use it to predict the motion of comets, stars, even entire galaxies.

Such demonstrable efficacy makes it all the more remarkable that, in the early years of the twentieth century, Einstein realized that Newton’s Law of Gravity was deeply flawed. A seemingly simpleminded question revealed this starkly: How, Einstein asked, does gravity work? How, for example, does the sun reach out across 93 million miles of essentially empty space and affect the motion of the earth? There’s no rope tethering them together, no chain tugging the earth as it moves, so how does gravity exert its influence?

In his Principia, published in 1687, Newton recognized the importance of this question but acknowledged that his own law was disturbingly silent about the answer. Newton was certain that there had to be something communicating gravity from place to place, but he was unable to identify what that something might be. In the Principia he gibingly left the question “to the consideration of the reader,” and for more than two hundred years, those who read this challenge simply read on. That’s something Einstein couldn’t do.

~~The Hidden Reality: Parallel Universes and the Deep Laws of the Cosmos -by- Brian Greene