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To: Kevmo

The de Broglie - Bohm theory is dead. Dead dead dead, The experiments of Hanbury Brown and Twiss decisively refuted it back in the 1950s.

Invest instead in my plan to extract sunlight from cucmbers (5 brownie points for catching the reference).


6 posted on 09/11/2011 10:32:56 PM PDT by John Locke
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To: John Locke

The de Broglie - Bohm theory is dead. Dead dead dead, The experiments of Hanbury Brown and Twiss decisively refuted it back in the 1950s.
***No mention of Hanbury nor Twiss on Wikipedia. Sounds like they could use an expert like you.

http://en.wikipedia.org/wiki/Bohmian_mechanics

This article needs attention from an expert on the subject. See the talk page for details. WikiProject Physics or the Physics Portal may be able to help recruit an expert. (November 2009)


8 posted on 09/11/2011 10:41:23 PM PDT by Kevmo (Turning the Party over to the so-called moderates wouldn't make any sense at all. ~Ronald Reagan)
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To: John Locke; Lurker; All; y'all; et al

http://en.wikipedia.org/wiki/Pilot_wave

History

In his 1926 paper,[2] Max Born suggested that the wave function of Schrödinger’s wave equation represents the probability density of finding a particle.

From this idea, de Broglie developed the Pilot Wave theory, and worked out a function for the guiding wave. He presented the Pilot Wave theory at the 1927 Solvay Conference.[3] However, Wolfgang Pauli raised an objection to it at the conference, saying that it did not deal properly with the case of inelastic scattering. De Broglie was not able to find a response to this objection, and he and Born abandoned the pilot-wave approach.

Later, in 1932, John von Neumann published a paper claiming to prove that all hidden variable theories were impossible.[4] (A result found to be flawed by Grete Hermann three years later, though this went unnoticed by the physics community for over fifty years).

One would expect that, after such a bad start, this theory would disappear without trace. However, in 1952, David Bohm became dissatisfied with the prevailing orthodoxy, and rediscovered de Broglie’s Pilot Wave theory. Bohm developed the Pilot Wave Theory into what is now called the De Broglie-Bohm theory.[5]

The de Broglie-Bohm theory itself might have gone unnoticed by most physicists, if it had not been championed by John Bell, who also countered the objections to it. In 1987, John Bell[6] rediscovered Grete Hermann’s work, and thus showed the physics community that Pauli’s and von Neumann’s objections really only showed that the Pilot Wave theory did not have locality; in fact, no quantum-mechanical theories have locality, so these objections did not invalidate the Pilot Wave theory.

The de Broglie-Bohm theory is now considered by some to be a valid challenge to the prevailing orthodoxy of the Copenhagen Interpretation, but it remains controversial.

Yves Couder and co-workers recently discovered a macroscopic pilot wave system in the form of walking droplets. This system exhibits behaviour of a pilot wave, heretofore considered to be reserved to microscopic phenomena.[7]


9 posted on 09/11/2011 10:47:26 PM PDT by Kevmo (Turning the Party over to the so-called moderates wouldn't make any sense at all. ~Ronald Reagan)
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To: John Locke
for something that's "dead dead dead dead", it sure seems to be getting up and walking around pretty good.
A quantum take on certainty
Physicists show that in the iconic double-slit experiment, uncertainty can be eased .
http://www.nature.com/news/2011/110602/full/news.2011.344.html
Edwin Cartlidge
The double-slit experiment shows the dual wave-particle nature of photons.GIPHOTOSTOCK/SCIENCE PHOTO LIBRARY
An international group of physicists has found a way of measuring both the position and the momentum of photons passing through the double-slit experiment, upending the idea that it is impossible to measure both properties in the lab at the same time .

In the classic double-slit experiment, first done more than 200 years ago, light waves passing through two parallel slits create a characteristic pattern of light and dark patches on a screen positioned behind the slits. The patches correspond to the points on the screen where the peaks and troughs of the waves diffracting out from the two slits combine with one another either constructively or destructively .

In the early twentieth century, physicists showed that this interference pattern was evident even when the intensity of the light was so low that photons pass through the apparatus one at a time. In other words, individual photons seem to interfere with themselves, so light exhibits both particle-like and wave-like properties.
However, placing detectors at the slits to determine which one a particle is passing through destroys the interference pattern on the screen behind. This is a manifestation of Werner Heisenberg's uncertainty principle, which states that it is not possible to precisely measure both the position (which of the two slits has been traversed) and the momentum (represented by the interference pattern) of a photon .

What quantum physicist Aephraim Steinberg of the University of Toronto in Canada and his colleagues have now shown, however, is that it is possible to precisely measure photons' position and obtain approximate information about their momentum1, in an approach known as 'weak measurement' .

Steinberg's group sent photons one by one through a double slit by using a beam splitter and two lengths of fibre-optic cable. Then they used an electronic detector to measure the positions of photons at some distance away from the slits, and a calcite crystal in front of the detector to change the polarization of the photon, and allow them to make a very rough estimate of each photon's momentum from that change.
Average trajectory
By measuring the momentum of many photons, the researchers were able to work out the average momentum of the photons at each position on the detector. They then repeated the process at progressively greater distances from the slits, and so by "connecting the dots" were able to trace out the average trajectories of the photons. They did this while still recording an interference pattern at each detector position .

Intriguingly, the trajectories closely match those predicted by an unconventional interpretation of quantum mechanics known as pilot-wave theory, in which each particle has a well-defined trajectory that takes it through one slit while the associated wave passes through both slits. The traditional interpretation of quantum mechanics, known as the Copenhagen interpretation, dismisses the notion of trajectories, and maintains that it is meaningless to ask what value a variable, such as momentum, has if that's not what is being measured.
Steinberg stresses that his group's work does not challenge the uncertainty principle, pointing out that the results could, in principle, be predicted with standard quantum mechanics. But, he says, "it is not necessary to interpret the uncertainty principle as rigidly as we are often taught to do", arguing that other interpretations of quantum mechanics, such as the pilot-wave theory, might "help us to think in new ways" .

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David Deutsch of the University of Oxford, UK, is not convinced that the experiment has told us anything new about how the universe works. He says that although "it's quite cool to see strange predictions verified", the results could have been obtained simply by "calculating them using a computer and the equations of quantum mechanics" .

"Experiments are only relevant in science when they are crucial tests between at least two good explanatory theories," Deutsch says. "Here, there was only one, namely that the equations of quantum mechanics really do describe reality."
But Steinberg thinks his work could have practical applications. He believes it could help to improve logic gates for quantum computers, by allowing the gates to repeat an operation deemed to have failed previously. "Under the normal interpretation of quantum mechanics we can't pose the question of what happened at an earlier time," he says. "We need something like weak measurement to even pose this question."



10 posted on 09/11/2011 11:16:51 PM PDT by Kevmo (Turning the Party over to the so-called moderates wouldn't make any sense at all. ~Ronald Reagan)
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To: John Locke
I confess thay I had to look it up.

And even though there is a Belgian band (MekanOrganiK) that has an album named "How to extract sunlight from Cucumbers" -

I believe your reference has to do with the novel "Gulliver's Travels".

12 posted on 09/11/2011 11:40:37 PM PDT by airborne (Paratroopers! Good to the last drop!)
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