In the spring of 1959 Bohr granted everett an interview in Copenhagen. They met several times during a six-week period but to little effect: Bohr did not shift his position, and everett did not reenter quantum physics research. The excursion was not a complete failure, though. One afternoon, while drinking beer at the hotel Østerport, everett wrote out on hotel stationery an important refinement of the other mathematical tour de force for which he is renowned, the generalized Lagrange multiplier method, also known as the everett algorithm. The method simplifies searches for optimum solutions to complex logistical problems—ranging from the deployment of nuclear weapons to just-in-time industrial production schedules to the routing of buses for maximizing the desegregation of school districts. In 1964 everett, pugh and several other wseg colleagues founded a private defense company, lambda corporation. Among other activities, it designed mathematical models of anti-ballistic missile systems and computerized nuclear war games that, according to pugh, were used by the military for years. Everett became enamored of inventing applications for bayes theorem, a mathematical method of correlating the probabilities of future events with past experience.
Essence: 50 of the most Inspiring African-Americans
The questions that he brought up were important. Nuclear Military Strategies, princeton awarded everett his doctorate nearly a year after he had begun his first project for the pentagon: calculating potential mortality rates from radioactive fallout in a nuclear war. He soon headed the mathematics division in the pentagons nearly invisible but extremely influential weapons Systems evaluation Group (wseg). Everett advised high-level officials in the eisenhower and Kennedy administrations on the best methods for selecting hydrogen bomb targets and structuring the nuclear triad of bombers, submarines and missiles for optimal punch in a nuclear strike. In 1960 he helped write wseg. 50, a catalytic report that remains classified to this day. According to everetts friend writers and wseg colleague george. Pugh, as well as historians, wseg. 50 rationalized and promoted military strategies that were operative for decades, including the concept of Mutually Assured Destruction. Wseg provided nuclear warfare policymakers with enough scary information about the global effects of radioactive fallout that many became convinced of the merit of waging a perpetual standoff—as opposed to, as some powerful people were advocating, launching preemptive first strikes on the soviet Union, China. One final chapter in the struggle over everetts theory also played out in this period.
In April 1957 everetts thesis committee accepted the writing abridged version—without the splits. Reviews of Modern Physics published the shortened version, entitled Relative state formulation of quantum Mechanics. In the same issue, a companion paper by Wheeler lauded his students discovery. When the paper appeared in print, it slipped into instant obscurity. Wheeler gradually distanced himself from association with everetts theory, but he kept in touch with the theorist, encouraging him, in vain, to do more work in quantum mechanics. In an interview last year, Wheeler, then 95, commented that everett was disappointed, perhaps bitter, at the nonreaction to his theory. How I wish that I had kept up the sessions with everett.
Reviews of Modern Physics, he nashville wrote: The copenhagen Interpretation is hopelessly incomplete because of its a priori reliance on classical physics. As well as a philosophic monstrosity with a reality concept for the macroscopic world literature and denial of the same for the microcosm. While Wheeler was off in Europe arguing his case, everett was in danger of losing his student draft deferment. To avoid going to boot camp, he decided to take a research job at the pentagon. He moved to the washington,. C., area and never came back to theoretical physics. During the next year, however, he communicated long-distance with Wheeler as he reluctantly whittled down his thesis to a quarter of its original length.
For one thing, Wheeler was troubled by everetts use of splitting humans and cannonballs as scientific metaphors. His letter revealed the copenhagen-ists discomfort over the meaning of everetts work. Stern dismissed everetts theory as theology, and Wheeler himself was reluctant to challenge bohr. In a long, politic letter to Stern, he explicated and excused everetts theory as an extension, not a refutation, of the prevailing interpretation of quantum mechanics: I think i may say that this very fine and able and independently thinking young man has gradually come. So, to avoid any possible misunderstanding, let me say that everetts thesis is not meant to question the present approach to the measurement problem, but to accept it and generalize. Everett would have completely disagreed with Wheelers description of his opinion of the copenhagen interpretation. For example, a year later, when responding to criticisms from Bryce. Dewitt, editor of the journal.
The best biographies and autobiographies ever written
But the branching process happens regardless of whether a human being is present. In general, at each interaction between physical systems the total wave function of the combined systems would tend to bifurcate in this way. Todays understanding of how the branches become independent and each turn out looking like the classical reality we are accustomed to is known as decoherence theory. It is an accepted part of standard modern quantum theory, although not everyone agrees with the everettian interpretation that all the branches represent realities that exist. Everett was not the first physicist to criticize the copenhagen energy collapse postulate as inadequate. But he broke new ground by deriving a mathematically consistent theory of a universal wave function from the equations of quantum mechanics itself.
The existence of multiple universes emerged as a consequence of his theory, not a predicate. In a footnote in his thesis, everett wrote: From the viewpoint of the theory, all elements of a superposition (all branches) are actual, none any more real than the rest. The draft containing all these ideas provoked a remarkable behind-the-scenes struggle, uncovered about five years ago in archival research by Olival Freire,., a historian of science at the federal University of Bahia in Brazil. In the spring of 1956 everetts academic adviser at Princeton, john Archibald Wheeler, took the draft dissertation to copenhagen to convince the royal Danish Academy of Sciences and Letters to publish. He wrote to everett that he had three long and strong discussions about it with Bohr and Petersen. Wheeler also shared his students work with several other physicists at Bohrs Institute for Theoretical Physics, including Alexander. Wheelers letter to everett reported: your beautiful wave function formalism of course remains unshaken; but all of us feel that the real issue is the words that are to be attached to the quantities of the formalism.
Breaking with Bohr and heisenberg, he dispensed with the need for the discontinuity of a wave-function collapse. Everetts radical new idea was to ask, what if the continuous evolution of a wave function is not interrupted by acts of measurement? What if the Schrödinger equation always applies and applies to everything—objects and observers alike? What if no elements of superpositions are ever banished from reality? What would such a world appear like to us? Everett saw that under those assumptions, the wave function of an observer would, in effect, bifurcate at each interaction of the observer with a superposed object.
The universal wave function would contain branches for every alternative making up the objects superposition. Each branch has its own copy of the observer, a copy that perceived one of those alternatives as the outcome. According to a fundamental mathematical property of the Schrödinger equation, once formed, the branches do not influence one another. Thus, each branch embarks on a different future, independently of the others. Consider a person measuring a particle that is in a superposition of two states, such as an electron in a superposition of location a and location. In one branch, the person perceives that the electron is. In a nearly identical branch, a copy of the person perceives that the same electron is. Each copy of the person perceives herself or himself as being one of a kind and sees chance as cooking up one reality from a menu of physical possibilities, even though, in the full reality, every alternative on the menu happens. Explaining how we would perceive such a universe requires putting an observer into the picture.
Biographies of Great Men of, god
Many of thesis the founders of quantum mechanics, notably bohr, werner heisenberg and John von neumann, agreed on an interpretation of quantum mechanics—known as the copenhagen interpretation— to deal with the measurement problem. This model of reality postulates that the mechanics of the quantum world reduce to, and only find meaning in terms slogan of, classically observable phenomena—not the reverse. This approach privileges the external observer, placing that observer in a classical realm that is distinct from the quantum realm of the object observed. Though unable to explain the nature of the boundary between the quantum and classical realms, the copenhagenists nonetheless used quantum mechanics with great technical success. Entire generations of physicists were taught that the equations of quantum mechanics work only in one part of reality, the microscopic, while ceasing to be relevant in another, the macroscopic. It is all that most physicists ever need. Universal wave function, in stark contrast, everett addressed the measurement problem by merging the microscopic and macroscopic worlds. He made the observer an integral part of the system observed, introducing a universal wave function that links observers and objects as parts of a single quantum system. He described the macroscopic world quantum mechanically and thought of large objects as existing in quantum superpositions as well.
A wave function can be thought of as a list of all the possible configurations of a superposed quantum system, along with numbers that give the probability of each configurations being the one, seemingly selected at random, that we will detect if we measure the. The wave function treats each element of the superposition as equally real, if not necessarily equally probable from our point of view. The Schrödinger equation delineates how a quantum systems wave function will change through time, an evolution that it predicts will be smooth and deterministic (that is, with no randomness). But that elegant mathematics seems to contradict what happens when humans observe a quantum system, such as an electron, with a scientific instrument (which itself may be regarded as a quantum-mechanical system). For at the moment of measurement, the wave function describing the superposition of alternatives appears to collapse into one member of the superposition, thereby interrupting the smooth evolution of the wave function and introducing discontinuity. A single measurement outcome emerges, banishing all the other possibilities from classically described reality. Which alternative is produced at the moment of measurement appears to be arbitrary; its selection does not evolve logically from the information- packed wave function of the electron before measurement. Nor essay does the mathematics of collapse emerge from the seamless flow of the Schrödinger equation. In fact, collapse has to be added as a postulate, as an additional process that seems to violate the equation.
this way, the young man challenged the physics establishment of the day to reconsider its foundational notion of what constitutes physical reality. In pursuing this endeavor, everett boldly tackled the notorious measurement problem in quantum mechanics, which had bedeviled physicists since the 1920s. In a nutshell, the problem arises from a contradiction between how elementary particles (such as electrons and photons) interact at the microscopic, quantum level of reality and what happens when the particles are measured from the macroscopic, classical level. In the quantum world, an elementary particle, or a collection of such particles, can exist in a superposition of two or more possible states of being. An electron, for example, can be in a superposition of different locations, velocities and orientations of its spin. Yet anytime scientists measure one of these properties with precision, they see a definite result—just one of the elements of the superposition, not a combination of them. Nor do we ever see macroscopic objects in superpositions. The measurement problem boils down to this question: How and why does the unique world of our experience emerge from the multiplicities of alternatives available in the superposed quantum world? Physicists use mathematical entities called wave functions to represent quantum states.
At least that is fruit how his history played out in our fork of the universe. If the many-worlds theory that everett developed when he was a student at Princeton University in the mid-1950s is correct, his life took many other turns in an unfathomable number of branching universes. Everetts revolutionary analysis broke apart a theoretical logjam in interpreting the how of quantum mechanics. Although the many-worlds idea is by no means universally accepted even today, his methods in devising the theory presaged the concept of quantum decoherence— a modern explanation of why the probabilistic weirdness of quantum mechanics resolves itself into the concrete world of our experience. Everetts work is well known in physics and philosophical circles, but the tale of its discovery and of the rest of his life is known by relatively few. Archival research by russian historian Eugene Shikhovtsev, myself and others and interviews I conducted with the late scientists colleagues and friends, as well as with his rock-musician son, unveil the story of a radiant intelligence extinguished all too soon by personal demons. Ridiculous Things, everetts scientific journey began one night in 1954, he recounted two decades later, after a slosh or two of sherry. He and his Princeton classmate Charles Misner and a visitor named Aage petersen (then an assistant to niels Bohr) were thinking up ridiculous things about the implications of quantum mechanics. During this session everett had the basic idea behind the many-worlds theory, and in the weeks that followed he began developing it into a dissertation.
Creative courage for young hearts: 15 Emboldening
Editor's Note: This story was originally printed in the. December 2007 issue of, scientific American and mother is being reposted from our archive in light of a new documentary on pbs, parallel Worlds, parallel lives. Hugh everett iii was a brilliant mathematician, an iconoclastic quantum theorist and, later, a successful defense contractor with access to the nations most sensitive military secrets. He introduced a new conception of reality to physics and influenced the course of world history at a time when nuclear Armageddon loomed large. To science-fiction aficionados, he remains a folk hero: the man who invented a quantum theory of multiple universes. To his children, he was someone else again: an emotionally unavailable father; a lump of furniture sitting at the dining room table, cigarette in hand. He was also a chain-smoking alcoholic who died prematurely.