Posts Tagged ‘uncertainty principle’
“I visualize a time when we will be to robots what dogs are to humans. And I am rooting for the machines.”*…
Readers will know of your correspondent’s fascination with the remarkable Claude Shannon (see here and here), remembered as “the father of information theory,” but seminally involved in so much more. In a recent piece in IEEE Spectrum, the redoubtable Rodney Brooks argues that we should add another credit to Shannon’s list…
Among the great engineers of the 20th century, who contributed the most to our 21st-century technologies? I say: Claude Shannon.
Shannon is best known for establishing the field of information theory. In a 1948 paper, one of the greatest in the history of engineering, he came up with a way of measuring the information content of a signal and calculating the maximum rate at which information could be reliably transmitted over any sort of communication channel. The article, titled “A Mathematical Theory of Communication,” describes the basis for all modern communications, including the wireless Internet on your smartphone and even an analog voice signal on a twisted-pair telephone landline. In 1966, the IEEE gave him its highest award, the Medal of Honor, for that work.
If information theory had been Shannon’s only accomplishment, it would have been enough to secure his place in the pantheon. But he did a lot more…
In 1950 Shannon published an article in Scientific American and also a research paper describing how to program a computer to play chess. He went into detail on how to design a program for an actual computer…
Shannon did all this at a time when there were fewer than 10 computers in the world. And they were all being used for numerical calculations. He began his research paper by speculating on all sorts of things that computers might be programmed to do beyond numerical calculations, including designing relay and switching circuits, designing electronic filters for communications, translating between human languages, and making logical deductions. Computers do all these things today…
The “father of information theory” also paved the way for AI: “How Claude Shannon Helped Kick-start Machine Learning,” from @rodneyabrooks in @IEEESpectrum.
* Claude Shannon (who may or may not have been kidding…)
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As we ponder possibility, we might send uncertain birthday greetings to Werner Karl Heisenberg; he was born on this date in 1901. A theoretical physicist, he made important contributions to the theories of the hydrodynamics of turbulent flows, the atomic nucleus, ferromagnetism, superconductivity, cosmic rays, and subatomic particles. But he is most widely remembered as a pioneer of quantum mechanics and author of what’s become known as the Heisenberg Uncertainty Principle. Heisenberg was awarded the Nobel Prize in Physics for 1932 “for the creation of quantum mechanics.”
During World War II, Heisenberg was part of the team attempting to create an atomic bomb for Germany– for which he was arrested and detained by the Allies at the end of the conflict. He was returned to Germany, where he became director of the Kaiser Wilhelm Institute for Physics, which soon thereafter was renamed the Max Planck Institute for Physics. He later served as president of the German Research Council, chairman of the Commission for Atomic Physics, chairman of the Nuclear Physics Working Group, and president of the Alexander von Humboldt Foundation.
Some things are so serious that one can only joke about them
Werner Heisenberg
“I knew I shoulda taken that left turn at Albuquerque”*…
Looney Tunes without Looney Tunes: “Looney Tunes Backgrounds.”
[TotH to This Isn’t Happiness]
* Bugs Bunny
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As we contemplate context, we might send uncertain birthday greetings to Werner Karl Heisenberg; he was born on this date in 1901. A theoretical physicist, he made important contributions to the theories of the hydrodynamics of turbulent flows, the atomic nucleus, ferromagnetism, superconductivity, cosmic rays, and subatomic particles. But he is most widely remembered as a pioneer of quantum mechanics and author of what’s become known as the Heisenberg Uncertainty Principle. Heisenberg was awarded the Nobel Prize in Physics for 1932 “for the creation of quantum mechanics.”
During World War II, Heisenberg was part of the team attempting to create an atomic bomb for Germany– for which he was arrested and detained by the Allies at the end of the conflict. He was returned to Germany, where he became director of the Kaiser Wilhelm Institute for Physics, which soon thereafter was renamed the Max Planck Institute for Physics. He later served as president of the German Research Council, chairman of the Commission for Atomic Physics, chairman of the Nuclear Physics Working Group, and president of the Alexander von Humboldt Foundation.
Some things are so serious that one can only joke about them
Werner Heisenberg
“Reality is that which, when you stop believing in it, doesn’t go away”*…
Quantum mechanics arose in the 1920s, and since then scientists have disagreed on how best to interpret it. Many interpretations, including the Copenhagen interpretation presented by Niels Bohr and Werner Heisenberg, and in particular, von Neumann-Wigner interpretation, state that the consciousness of the person conducting the test affects its result. On the other hand, Karl Popper and Albert Einstein thought that an objective reality exists. Erwin Schrödinger put forward the famous thought experiment involving the fate of an unfortunate cat that aimed to describe the imperfections of quantum mechanics.
In their most recent article, Finnish civil servants Jussi Lindgren and Jukka Liukkonen, who study quantum mechanics in their free time, take a look at the uncertainty principle that was developed by Heisenberg in 1927. According to the traditional interpretation of the principle, location and momentum cannot be determined simultaneously to an arbitrary degree of precision, as the person conducting the measurement always affects the values.
However, in their study Lindgren and Liukkonen concluded that the correlation between a location and momentum, i.e., their relationship, is fixed. In other words, reality is an object that does not depend on the person measuring it. Lindgren and Liukkonen utilized stochastic dynamic optimization in their study. In their theory’s frame of reference, Heisenberg’s uncertainty principle is a manifestation of thermodynamic equilibrium, in which correlations of random variables do not vanish.
“The results suggest that there is no logical reason for the results to be dependent on the person conducting the measurement. According to our study, there is nothing that suggests that the consciousness of the person would disturb the results or create a certain result or reality,” says Jussi Lindgren…
The full story at: “A new interpretation of quantum mechanics suggests that reality does not depend on the person measuring it.”
* Philip K. Dick
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As we admire amateur achievement, we might spare a thought for another profoundly-gifted amateur, James Prescott Joule; he died on this date in 1889. A seminal physicist and mathematician, he did “his science” in his free time; in his day job, he managed his family’s brewery.
Joule studied the nature of heat, and discovered its relationship to mechanical work– work that was prompted by his concern as a brewer to get the most from his steam (and later electric) engines. This led to the law of conservation of energy, which in turn led to the development of the first law of thermodynamics. The SI derived unit of energy, the joule, is named for him.
Joule’s earliest published work met with substantial resistance, as it depended on very precise measurements of heat that most in his audience believed infeasible– but that Joule, drawing on his brewer’s craft, had in fact achieved.
He worked with Lord Kelvin to develop an absolute thermodynamic temperature scale, which came to be called the Kelvin scale. Joule also conducted experiments on magnetostriction, via which he found the relationship between the current through a resistor and the heat dissipated, which is known as Joule’s first law.
“The true sign of intelligence is not knowledge but imagination”*…
Perhaps Arthur C. Clarke was being uncharacteristically unambitious. He once pointed out that any sufficiently advanced technology is going to be indistinguishable from magic. If you dropped in on a bunch of Paleolithic farmers with your iPhone and a pair of sneakers, you’d undoubtedly seem pretty magical. But the contrast is only middling: The farmers would still recognize you as basically like them, and before long they’d be taking selfies. But what if life has moved so far on that it doesn’t just appear magical, but appears like physics?
After all, if the cosmos holds other life, and if some of that life has evolved beyond our own waypoints of complexity and technology, we should be considering some very extreme possibilities. Today’s futurists and believers in a machine “singularity” predict that life and its technological baggage might end up so beyond our ken that we wouldn’t even realize we were staring at it. That’s quite a claim, yet it would neatly explain why we have yet to see advanced intelligence in the cosmos around us, despite the sheer number of planets it could have arisen on—the so-called Fermi Paradox…
Caleb Scharf on the possibility that alien life could be so advanced it is indistinguishable from physics: “Is Physical Law an Alien Intelligence?”
For a very different perspective (albeit, one seemingly rooted in a more narrowly-defined understanding of “life”), see “A Key Evolutionary Step May Mean Intelligent Alien Life Doesn’t Exist in the Universe.”
* Albert Einstein
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As we think through the thought experiment, we might send uncertain birthday greetings to Werner Karl Heisenberg; he was born on this date in 1901. A theoretical physicist, he made made important contributions to the theories of the hydrodynamics of turbulent flows, the atomic nucleus, ferromagnetism, superconductivity, cosmic rays, and subatomic particles. But he is most widely remembered as a pioneer of quantum mechanics and author of what’s become known as the Heisenberg Uncertainty Principle. Heisenberg was awarded the Nobel Prize in Physics for 1932 “for the creation of quantum mechanics.”
During World War II, Heisenberg was part of the team attempting to create an atomic bomb for Germany– for which he was arrested and detained by the Allies at the end of the conflict. He was returned to Germany, where he became director of the Kaiser Wilhelm Institute for Physics, which soon thereafter was renamed the Max Planck Institute for Physics. He later served as president of the German Research Council, chairman of the Commission for Atomic Physics, chairman of the Nuclear Physics Working Group, and president of the Alexander von Humboldt Foundation.
Cracking the uncrackable code?…
Heisenberg’s uncertainty principle, a foundational tenet of quantum mechanics, is essentially the assertion that when one tries to measure one aspect of a particle precisely, say its position, one necessarily “blurs out” one’s ability to know with any precision its speed– or vice versa. Indeed, Heisenberg’s original word for the phenomenon translates better as “indeterminacy”–raising the prospect of a physical world whose nature is, beyond some incomplete point, unknowable.
Still, as mysterious as the concept is, it has offered a tantalizingly-concrete prospect: the “uncrackable” codes of quantum cryptography. If “listening in” distorts the message, then the eavesdropper is out of luck.
But now, as the BBC reports, researchers at the University of Toronto have raised some serious uncertainty about the Uncertainty Principle itself:
The Heisenberg uncertainty principle is in part an embodiment of the idea that in the quantum world, the mere act of measuring can affect the result.
But the idea had never been put to the test, and a team writing in Physical Review Letters says “weak measurements” prove the rule was never quite right…
This problem with the act of measuring is not confined to the quantum world, explained senior author of the new study, Aephraim Steinberg of the University of Toronto.
“You find a similar thing with all sorts of waves,” he told BBC News. “A more familiar example is sound: if you’ve listened to short clips of audio recordings you realise if they get too short you can’t figure out what sound someone is making, say between a ‘p’ and a ‘b’.
“If I really wanted to say as precisely as possible, ‘when did you make that sound?’, I wouldn’t also be able to ask what sound it was, I’d need to listen to the whole recording.”
The problem with Heisenberg’s theory was that it vastly predated any experimental equipment or approaches that could test it at the quantum level: it had never been proven in the lab.
“Heisenberg had this intiuition about the way things ought to be, but he never really proved anything very strict about the value,” said Prof Steinberg.
“Later on, people came up with the mathematical proof of the exact value.”…
In 2011, they carried out a version of a classic experiment on photons – the smallest indivisible packets of light energy – that plotted out the ways in which they are both wave and particle, something the rules strictly preclude.
This time, they aimed to use so-called weak measurements on pairs of photons, putting into practice an idea first put forward in a 2010 paper in the New Journal of Physics.
Photons can be prepared in pairs which are inextricably tied to one another, in a delicate quantum state called entanglement, and the weak measurement idea is to infer information about them as they pass, before and after carrying out a formal measurement.
What the team found was that the act of measuring did not appreciably “blur out” what could be known about the pairs.
It remains true that there is a fundamental limit of knowability, but it appears that, in this case, just trying to look at nature does not add to that unavoidably hidden world.
Or, as the authors put it: “The quantum world is still full of uncertainty, but at least our attempts to look at it don’t have to add as much uncertainty as we used to think!”…
“There’s actually a lot of technology that relies on quantum uncertainty now, and the main one is quantum cryptography – using quantum systems to convey our information securely – and that mostly boils down to the uncertainty principle.”
A pdf of the University of Toronto group’s paper is here.
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As we reconsider the benefits of entanglement, we might spare a thought for Pieter van Musschenbroek; he died on this date in 1761. A one-time student of Isaac Newton (who helped transmit Newton’s ideas through Europe), van Musschenbroek was a professor of mathematics, philosophy, astronomy, and medicine. (Those were the days…) Fascinated by electrostatics, he used what he learned from his father, an accomplished designer and manufacturer of scientific instruments, to build the first capacitor (that’s to say, device that can store an electric charge), the Leyden Jar– named for the city that was home to van Musschenbroek’s university.
Leyden jar construction
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