Posts Tagged ‘atomic bomb’
“In our society (that is, advanced western society) we have lost even the pretence of a common culture”*…
In 1959. C.P. Snow gave a now-famous series of lectures (quickly published): The Two Cultures, lamenting the cleaving of Western culture into spheres of science and humanities, neither of which could clearly understand, thus effectively communicate with the other. Jeroen Bouterse reminds us that Snow had a predecessor…
Several years before C.P. Snow gave his famous lecture on the two cultures, the American physicist I.I. Rabi wrote about the problem of the disunity between the sciences and the humanities. “How can we hope”, he asked, “to obtain wisdom, the wisdom which is meaningful in our own time? We certainly cannot attain it as long as the two great branches of human knowledge, the sciences and the humanities, remain separate and even warring disciplines.”
Rabi had been interested in science since his teenage years, and grown up to be a Nobel-prize winning physicist. He had also been an important player in the Allied technological effort during World War II, as associate director of the ‘Rad Lab’: the radiation laboratory at MIT that developed radar technology. The success of Rad Lab, Rabi later reflected, had not been a result of a great amount of theoretical knowledge, but of the energy, vitality, and self-confidence of its participants. In general, Rabi’s views on science and technology were somewhat Baconian: science should be open to the unexpected, rather than insisting on staying in the orbit of the familiar.
In Rabi’s accounts of his time leading Rad Lab, he would also emphasize the way in which he insisted on being let in on military information. “We are not your technicians”, he quoted himself, adding: “a military man who wants the help of scientists and tells them half a story is like a man who goes to a doctor and conceals half the symptoms.” Indeed, the key to understanding Rabi’s worries about the two cultures – he would go on to embrace Snow’s term – is his view of the role science ought to play in public life. Scientists should not just be external consultants, delivering inventions or discoveries on demand or listing the options available to the non-specialist. In some stronger sense, they should be involved in directing policy decisions.
Even more than Rabi’s positive experience with the military during the war, his views were informed by his frustration with the lack of agency scientific experts were able to exercise in the immediate aftermath. Already in 1946, he complained in a lecture that scientists had been used to create the atom bomb, but they had not been consulted about its use, and the fact that many of them had been opposed to it had made no difference. “To the politician, the scientist is like a trained monkey who goes up to the coconut tree to bring down choice coconuts.”
This feeling would increase with the decision to develop a hydrogen bomb. In 1949, Rabi was one of eight experts in the General Advisory Committee (GAC) to the Atomic Energy Commission (AEC), in which capacity he co-signed a unanimous report arguing that the ‘Super’ should not be built. (Rabi, together with Fermi, signed a minority opinion to the effect that the US should first get the USSR to pledge that it would not seek to develop an H-bomb.)
Rather than signaling to the world that he sought to avoid an arms race, however, President Truman did the opposite: without knowing that it was even possible, he announced publicly that the US would “continue its work on all forms of atomic weapons, including the so-called hydrogen or super-bomb.” Rabi would never forgive Truman…
… in the context of Rabi’s broader thinking about science in modern culture, as he came to develop and express it in the decades after the war [the] was not just that more technical expertise needed to be brought to the decision tables; the point was that scientists should make their moral views heard. In the atomic age, where science created so much power, science’s representatives should wield some of that power. From the perspective of the scientists, this was because the atom bomb had demonstrated beyond doubt that science was not a disinterested search for objective truth; it had consequences, and scientists should accept responsibility for those consequences. They should consider not just the means, but the goals…
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It is a soft law in two cultures discourse that precisely those who most bewail the chasm between science and the humanities end up deepening it. In Rabi’s case, the reason is that he believed in the two cultures; he believed there was something special about the culture and tradition of modern natural science that was a source of wisdom and strength, and that in many ways the project of the humanities was its opposite. Understanding of nature was progressive and forward-looking, was a matter of hope and optimism, while understanding of the human world was old, had already been achieved in ancient societies, and was more a matter of transmission than of innovation. Historian of physics Michael Day notes that over time, Rabi talked less about merging the two traditions and more about putting science at the center of education…
In spite of this, I think Rabi saw correctly that picturing science and the humanities as opposing forces helped him to identify a real fault line in modern culture. The notion that science has to stay on one side of the fact-value-distinction, while the humanities are closer to the actual formation of values, was not a figment of his imagination, and it did stand in the way of his cultural ideals. While not quite the synthesis between the two sides that he sometimes claimed to aim for, the answer he gave – that neither science nor the humanities, nor committees ‘discover’ values, but that values are immanent in activities, in ways of life; that the age of science came with the scientific way of life, with its own values, and that these values were potentially culture-defining – was compelling…
… there remains something inspiring in Rabi’s vision of a common quest for knowledge and understanding, of people working together in activities that are both exciting and important, and of a society that takes those people and their projects not as resources to be exploited, but as models to be emulated.
“The atom bomb and the two cultures: I.I. Rabi on the sciences and the humanities,” from @jeroenbou in @3QD. Eminently worth reading in full.
(Image above: source)
* C. P. Snow, The Two Cultures
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As we search for synthesis, we might send insightful birthday greetings to Walter Kohn; he was born on this date in 1923. A theoretical physicist and theoretical chemist, he shared the 1998 Nobel Prize in Chemistry (with John Pople); Kohn was honored for his development of density functional theory, which made it possible to calculate quantum mechanical electronic structure by equations involving electronic density (rather than the much more complicated many-body wavefunction). This computational simplification led to more accurate calculations on complex systems and to many new insights, and became an essential tool for materials science, condensed-phase physics, and the chemical physics of atoms and molecules.
“Reality is merely an illusion, albeit a very persistent one”*…
In an excerpt from his new book, The Rigor of Angels: Borges, Heisenberg, Kant, and the Ultimate Nature of Reality, the estimable William Egginton explains the central mystery at the heart of one of the most important breakthroughs in physics–quantum mechanics…
For all its astonishing, mind-bending complexity– for all its blurry cats, entangled particles, buckyballs, and Bell’s inequalities– quantum mechanics ultimately boils down to one core mystery. This mystery found its best expression in the letter Heisenberg wrote to Pauli in the fevered throes of his discovery. The path a particle takes ‘only comes into existence through this, that we observe it.’ This single, stunning expression underlies all the rest: the wave/particle duality (interference patterns emerge when the particles have not yet been observed and hence their possible paths interfere with one another); the apparently absurd liminal state of Schrodinger’s cat ( the cat seems to remain blurred between life and death because atoms don’t release a particle until observed); the temporal paradox (observing a particle seems to retroactively determine the path it chose to get here); and, the one that really got to Einstein, if the observation of a particle at one place and time instantaneously changes something about the rest of reality, then locality, the cornerstone of relativity and guarantee that the laws of physics are invariable through the universe, vanishes like fog on a warming windowpane.
If the act of observation somehow instantaneously conjures a particle’s path, the foundations not only of classical physics but also of what we widely regard as physical reality crumble before our eyes. This fact explains why Einstein held fast to another interpretation. The particle’s path doesn’t come into existence when we observe it. The path exists, but we just can’t see it. Like the parable of the ball in the box he described in his letter to Schrodinger, a 50 percent chance of finding a ball in any one of two boxes does not complete the description of the ball’s reality before we open the box. It merely states our lack of knowledge about the ball’s whereabouts.
And yet, as experiment after experiment has proven, the balls simply aren’t there before the observation. We can separate entangled particles, seemingly to any conceivable distance, and by observing one simultaneously come to know something about the other–something that wasn’t the case until the exact moment of observing it. Like the beer and whiskey twins, we can maintain total randomness up to a nanosecond before one of them orders, and still what the one decides to order will determine the other’s drink, on the spot, even light-years away.
The ineluctable fact of entanglement tells us something profound about reality and our relation to it. Imagine you are one of the twins about to order a drink (this should be more imaginable than being an entangled particle about to be observed, but the idea is the same). From your perspective you can order either a whiskey or a beer: it’s a fifty-fifty choice; nothing is forcing your hand. Unbeknownst to you, however, in a galaxy far, far away, your twin has just made the choice for you. Your twin can’t tell you this or signal it in any way, but what you perceive to be a perfectly random set of possibilities, an open choice, is entirely constrained. You have no idea if you will order beer or whiskey, but when you order it, it will be the one or the other all the same. If your twin is, say, one light-year away, the time in which you make this decision doesn’t even exist over there yet. Any signals your sibling gets from you, or any signals you send, will take another year to arrive. And still, as of this moment, you each know. Neither will get confirmation for another year, but you can be confident, you can bet your life’s savings on it–a random coin toss in another galaxy, and you already know the outcome.
The riddles that arise from Heisenberg’s starting point would seem to constitute the most vital questions of existence. And yet one of the curious side effects of quantum mechanics’ extraordinary success has been a kind of quietism in the face of those very questions. The interpretation of quantum mechanics, deciding what all this means, has tended to go unnoticed by serious physics departments and the granting agencies that support them in favor of the ‘shut up and calculate’ school, leading the former to take hold mainly in philosophy departments, as a subfield of the philosophy of science called foundations of physics. Nevertheless, despite such siloing, a few physicists persisted in exploring possible solutions to the quantum riddles. Some of their ideas have been literally otherworldly.
In the 1950s, a small group of graduate students working with John Wheeler at Princeton University became fascinated with these problems and kept returning to them in late-night, sherry-fueled rap sessions. Chief among this group was Hugh Everett III, a young man with classic 1950s-style nerd glasses and a looming forehead. Everett found himself chafing at the growing no-question zone that proponents of the Copenhagen interpretation had built around their science. Why should we accept that in one quantum reality, observations somehow cause nature to take shape out of a probabilistic range of options, whereas on this side of some arbitrary line in the sand we inhabit a different, classical reality where observations meekly bow to the world out there? What exactly determines when this change takes place? ‘Let me mention a few more irritating features of the Copenhagen Interpretation,’ Everett would write to its proponents: ‘You talk of the massiveness of macro systems allowing one to neglect further quantum effects … but never give any justification for this flatly asserted dogma.’…
A fascinating sample of a fascinating book: “Quantum Mechanics,” from @WilliamEgginton via the invaluable @delanceyplace.
Further to which, it’s interesting to recall that, in his 1921 The Analysis Of Mind, Bertrand Russell observed:
What has permanent value in the outlook of the behaviourists is the feeling that physics is the most fundamental science at present in existence. But this position cannot be called materialistic, if, as seems to be the case, physics does not assume the existence of matter…
via Robert Cottrell
See also: “Objective Reality May Not Exist, Quantum Experiment Suggests” (source of the image above).
* Albert Einstein
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As we examine existence, we might spare a thought for Otto Frisch; he died on this date in 1979. A physicist, he was (with Otto Stern and Immanuel Estermann) the first to measure the magnetic moment of the proton. With his aunt, Lise Meitner, he advanced the first theoretical explanation of nuclear fission (coining the term) and first experimentally detected the fission by-products. Later, with his collaborator Rudolf Peierls, he designed the first theoretical mechanism for the detonation of an atomic bomb in 1940.
“In our world of big names, curiously, our true heroes tend to be anonymous”*…
Now let us praise a man who should be famous…
Alfred Lee Loomis was a lawyer, a banker, a socialite, possibly one of the most influential physical scientists of the twentieth century, and can reasonably claim to have done more than any other civilian to bring a swift end to World War II. And yet, in the intervening decades, he’s faded into obscurity.
Loomis’s story is one of incredible intellect, unimaginable wealth, a breadth of ability that spanned from the abstract and theoretical across to the practical and logistical, and an unbelievable knack for knowing the right people and putting them into contact with one another. He applied these generational talents relentlessly to the hardest problems facing science throughout the first half of the twentieth century. He deserves to be far better known…
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To be more specific…
Alfred Lee Loomis (November 4, 1887 – August 11, 1975) was an American attorney, investment banker, philanthropist, scientist, physicist, inventor of the LORAN Long Range Navigation System and a lifelong patron of scientific research. He established the Loomis Laboratory in Tuxedo Park, New York, and his role in the development of radar and the atomic bomb contributed to the Allied victory in World War II. He invented the Aberdeen Chronograph for measuring muzzle velocities, contributed significantly… to the development of a ground-controlled approach technology for aircraft, and participated in preliminary meetings of the Manhattan Project.
Loomis also made contributions to biological instrumentation. Working with Edmund Newton Harvey he co-invented the microscope centrifuge, and pioneered techniques for electroencephalography. In 1937, he discovered the sleep K-complex brainwave. During the Great Depression, Loomis anonymously paid the Physical Review journal’s fees for authors who could not afford them….
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As Nobel Laureate Luis Alvarez noted…
… after the turn of the century, university scientists found it possible to earn a living teaching students, while doing research “on the side.” So the true amateur has almost disappeared—Alfred Loomis may well be remembered as the last of the great amateurs of science. He had distinguished careers as a lawyer, as an Army officer, and as an investment banker before he turned his full energies to the pursuit of scientific knowledge, first in the field of physics, and later as a biologist. By any measure that can be employed, he was one of the most influential physical scientists of this century. In support of that assessment, one can note: (1) his election to
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this Academy when he was 53 years old, (2) his honorary degrees from prestigious universities, (3) his crucial wartime role as director of all NDRC-OSRD radar research in World War II, and (4) his exceedingly close personal relationships with many of the leaders of American science and government in the mid-twentieth century…
The financier who became a scientist and helped win World War II: Alfred Lee Loomis. For more, see Jennet Conant’s Tuxedo Park: A Wall Street Tycoon and the Secret Palace of Science That Changed the Course of World War II. (Conant is the grandaughter of James B. Conat– in the photo above– chemist, President of Harvard, and friend/collaborator of Loomis).
* Daniel J. Boorstin
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As we applaud awesome amateurs, we might send insightful birthday greetings to Edward Williams Morley; he was born on this date in 1838. A chemist who was first to precisely determine the atomic weight of oxygen, he is probably best remembered for his collaboration with the physicist Albert A. Michelson. In what we call the Michelson–Morley experiment (actually a number of experiments conducted between April and July in 1887), they attempted to detect the luminiferous aether, a supposed medium permeating space that was thought to be the carrier of light waves; their method was the very precise measurement of the speed of light (in various directions, and at different times of the year, as the Earth revolved in its orbit around the Sun). Michelson and Morley always found that the speed of light did not vary at all depending on the direction of measurement, or the position of the Earth in its orbit– the so-called “null result.”
Neither Morley nor Michelson ever considered that these null results disproved the hypothesis of the existence of “luminiferous aether.” But other scientists began to suspect that they did. Almost two decades later the results of the Michelson–Morley experiments supported Albert Einstein’s strong postulate (in 1905) that the speed of light is a constant in all inertial frames of reference as part of his Special Theory of Relativity.
“It can be argued that in trying to see behind the formal predictions of quantum theory we are just making trouble for ourselves”*…
Context, it seems, is everthing…
… What is reality? Nope. There’s no way we are going through that philosophical minefield. Let’s focus instead on scientific realism, the idea that a world of things exists independent of the minds that might perceive it and it is the world slowly revealed by progress in science. Scientific realism is the belief that the true nature of reality is the subject of scientific investigation and while we may not completely understand it at any given moment, each experiment gets us a little bit closer. This is a popular philosophical position among scientists and science enthusiasts.
A typical scientific realist might believe, for example, that fundamental particles exist even though we cannot perceive them directly with our senses. Particles are real and their properties — whatever they may be — form part of the state of the world. A slightly more extreme view is that this state of the world can be specified with mathematical quantities and these, in turn, obey equations we call physical laws. In this view, the ultimate goal of science is to discover these laws. So what are the consequences of quantum physics on these views?
As I mentioned above, quantum physics is not a realistic model of the world — that is, it does not specify quantities for states of the world. An obvious question is then can we supplement or otherwise replace quantum physics with a deeper set of laws about real states of the world? This is the question Einstein first asked with colleagues Podolski and Rosen, making headlines in 1935. The hypothetical real states of the world came to be called hidden variables since an experiment does not reveal them — at least not yet.
In the decades that followed quantum physics rapidly turned into applied science and the textbooks which became canon demonstrated only how to use the recipes of quantum physics. In textbooks that are still used today, no mention is made of the progress in the foundational aspects of quantum physics since the mathematics was cemented almost one hundred years ago. But, in the 1960s, the most important and fundamental aspect of quantum physics was discovered and it put serious restrictions on scientific realism. Some go as far as to say the entire nature of independent reality is questionable due to it. What was discovered is now called contextuality, and its inevitability is referred to as the Bell-Kochen-Specker theorem.
John Bell is the most famous of the trio Bell, Kochen, and Specker, and is credited with proving that quantum physics contained so-called nonlocal correlations, a consequence of quantum entanglement. Feel free to read about those over here.
It was Bell’s ideas and notions that stuck and eventually led to popular quantum phenomena such as teleportation. Nonlocality itself is wildly popular these days in science magazines with reported testing of the concept in delicately engineered experiments that span continents and sometimes involve research satellites. But nonlocality is just one type of contextuality, which is the real game in town.
In the most succinct sentence possible, contextuality is the name for the fact that any real states of the world giving rise to the rules of quantum physics must depend on contexts that no experiment can distinguish. That’s a lot to unpack. Remember that there are lots of ways to prepare the same experiment — and by the same experiment, I mean many different experiments with completely indistinguishable results. Doing the exact same thing as yesterday in the lab, but having had a different breakfast, will give the same experimental results. But there are things in the lab and very close to the system under investigation that don’t seem to affect the results either. An example might be mixing laser light in two different ways.
There are different types of laser light that, once mixed together, are completely indistinguishable from one another no matter what experiments are performed on the mixtures. You could spend a trillion dollars on scientific equipment and never be able to tell the two mixtures apart. Moreover, knowing only the resultant mixture — and not the way it was mixed — is sufficient to accurately predict the outcomes of any experiment performed with the light. So, in quantum physics, the mathematical theory has a variable that refers to the mixture and not the way the mixture was made — it’s Occam’s razor in practice.
Now let’s try to invent a deeper theory of reality underpinning quantum physics. Surely, if we are going to respect Occam’s razor, the states in our model should only depend on contexts with observable consequences, right? If there is no possible experiment that can distinguish how the laser light is mixed, then the underlying state of reality should only depend on the mixture and not the context in which it was made, which, remember, might include my breakfast choices. Alas, this is just not possible in quantum physics — it’s a mathematical impossibility in the theory and has been confirmed by many experiments.
So, does this mean the universe cares about what I have for breakfast? Not necessarily. But, to believe the universe doesn’t care what I had for breakfast means you must also give up reality. You may be inclined to believe that when you observe something in the world, you are passively looking at it just the way it would have been had you not been there. But quantum contextuality rules this out. There is no way to define a reality that is independent of the way we choose to look at it…
“Why is no one taught the one concept in quantum physics which denies reality?” It’s called contextuality and it is the essence of quantum physics. From Chris Ferrie (@csferrie).
* “It can be argued that in trying to see behind the formal predictions of quantum theory we are just making trouble for ourselves. Was not precisely this the lesson that had to be learned before quantum mechanics could be constructed, that it is futile to try to see behind the observed phenomena?” – John Stewart Bell
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As still we try, we might relatively hearty birthday greetings to Sir Marcus Laurence Elwin “Mark” Oliphant; he was born on this date in 1901. An Australian physicist who trained and did much of his work in England (where he studied under Sir Ernest Rutherford at the University of Cambridge’s Cavendish Laboratory), Oliphant was deeply involved in the Allied war effort during World War II. He helped develop microwave radar, and– by helping to start the Manhattan Project and then working with his friend Ernest Lawrence at the Radiation Laboratory in Berkeley, California, helped develop the atomic bomb.
After the war, Oliphant returned to Australia as the first director of the Research School of Physical Sciences and Engineering at the new Australian National University (ANU); on his retirement, he became Governor of South Australia and helped found the Australian Democrats political party.
“As far as the laws of mathematics refer to reality, they are not certain; and as far as they are certain, they do not refer to reality.”*…
Quantum computing is all the rage. It seems like hardly a day goes by without some news outlet describing the extraordinary things this technology promises. Most commentators forget, or just gloss over, the fact that people have been working on quantum computing for decades—and without any practical results to show for it.
We’ve been told that quantum computers could “provide breakthroughs in many disciplines, including materials and drug discovery, the optimization of complex manmade systems, and artificial intelligence.” We’ve been assured that quantum computers will “forever alter our economic, industrial, academic, and societal landscape.” We’ve even been told that “the encryption that protects the world’s most sensitive data may soon be broken” by quantum computers. It has gotten to the point where many researchers in various fields of physics feel obliged to justify whatever work they are doing by claiming that it has some relevance to quantum computing.
Meanwhile, government research agencies, academic departments (many of them funded by government agencies), and corporate laboratories are spending billions of dollars a year developing quantum computers. On Wall Street, Morgan Stanley and other financial giants expect quantum computing to mature soon and are keen to figure out how this technology can help them.
It’s become something of a self-perpetuating arms race, with many organizations seemingly staying in the race if only to avoid being left behind. Some of the world’s top technical talent, at places like Google, IBM, and Microsoft, are working hard, and with lavish resources in state-of-the-art laboratories, to realize their vision of a quantum-computing future.
In light of all this, it’s natural to wonder: When will useful quantum computers be constructed? The most optimistic experts estimate it will take 5 to 10 years. More cautious ones predict 20 to 30 years. (Similar predictions have been voiced, by the way, for the last 20 years.) I belong to a tiny minority that answers, “Not in the foreseeable future.” Having spent decades conducting research in quantum and condensed-matter physics, I’ve developed my very pessimistic view. It’s based on an understanding of the gargantuan technical challenges that would have to be overcome to ever make quantum computing work…
Michel Dyakonov makes “The Case Against Quantum Computing.”
* Albert Einstein
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As we feel the need for speed, we might recall that it was on this date in 1942 that a team of scientists led by Enrico Fermi, working inside an enormous tent on a squash court under the stands of the University of Chicago’s Stagg Field, achieved the first controlled nuclear fission chain reaction… laying the foundation for the atomic bomb and later, nuclear power generation.
“…the Italian Navigator has just landed in the New World…”
– Coded telephone message confirming first self-sustaining nuclear chain reaction, December 2, 1942.
Illustration depicting the scene on Dec. 2, 1942 (Photo copyright of Chicago Historical Society)
Indeed, exactly 15 years later, on this date in 1957, the world’s first full-scale atomic electric power plant devoted exclusively to peacetime uses, the Shippingport Atomic Power Station, reached criticality; the first power was produced 16 days later, after engineers integrated the generator into the distribution grid of Duquesne Light Company.
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