Thanks ETL.
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Posted on 10/29/2017 4:12:12 PM PDT by ETL
'Delayed-choice' test, a first with spacefaring photons, affirms light can behave like a wave or a particle.
Light is two-faced: Sometimes it behaves like a wave, sometimes like a particle. Now, scientists have shown that light’s shifty disposition persists even after trekking thousands of kilometers into space and back again, researchers report October 25 in Science Advances.
Depending on how light is measured, it can either be particle-like, lighting up a camera pixel, for example, or wavelike, interfering with other waves like ripples on the surface of water. It’s one of the many oddities of quantum mechanics. Before light is measured, quantum theory suggests, it is in a particle-wave limbo, neither purely one nor the other.
Physicists have tested this idea by performing “delayed-choice” experiments in the lab, in which researchers send light into a device and randomly choose whether or not to flip a switch that seems to retroactively change the light’s behavior (SN: 5/30/15, p. 9). In one configuration, the light travels down two paths at once and acts like a wave, interfering with itself. In the other, the light acts like a particle, taking a single path. That choice of configuration can be made even after the light has already traveled through the device but before being measured, revealing that light remains in quantum limbo until it is finally detected.
For the first time, physicist Paolo Villoresi of the University of Padua in Italy and colleagues took the technique into space. The researchers sent light through a lab apparatus and up to a satellite equipped with reflectors, which bounced the light back down to the device. While the light was in transit, the scientists used a random number generator to determine whether to configure their apparatus so that the light would behave like a particle or a wave. The light performed as expected, verifying that quantum mechanics holds even over the round trip into space and back.
Wave–particle duality is the concept in quantum mechanics that every particle or quantic entity may be partly described in terms not only of particles, but also of waves.
It expresses the inability of the classical concepts "particle" or "wave" to fully describe the behavior of quantum-scale objects. As Albert Einstein wrote:[1]
"It seems as though we must use sometimes the one theory and sometimes the other, while at times we may use either. We are faced with a new kind of difficulty. We have two contradictory pictures of reality; separately neither of them fully explains the phenomena of light, but together they do."
Through the work of Max Planck, Einstein, Louis de Broglie, Arthur Compton, Niels Bohr and many others, current scientific theory holds that all particles also have a wave nature (and vice versa).[2]
This phenomenon has been verified not only for elementary particles, but also for compound particles like atoms and even molecules.
For macroscopic particles, because of their extremely short wavelengths, wave properties usually cannot be detected.[3]
Although the use of the wave-particle duality has worked well in physics, the meaning or interpretation has not been satisfactorily resolved; see Interpretations of quantum mechanics.
Bohr regarded the "duality paradox" as a fundamental or metaphysical fact of nature. A given kind of quantum object will exhibit sometimes wave, sometimes particle, character, in respectively different physical settings. He saw such duality as one aspect of the concept of complementarity.[4]
Bohr regarded renunciation of the cause-effect relation, or complementarity, of the space-time picture, as essential to the quantum mechanical account.[5]
Werner Heisenberg considered the question further. He saw the duality as present for all quantic entities, but not quite in the usual quantum mechanical account considered by Bohr. He saw it in what is called second quantization, which generates an entirely new concept of fields which exist in ordinary space-time, causality still being visualizable.
Classical field values (e.g. the electric and magnetic field strengths of Maxwell) are replaced by an entirely new kind of field value, as considered in quantum field theory. Turning the reasoning around, ordinary quantum mechanics can be deduced as a specialized consequence of quantum field theory.[6][7]
The wave-particle duality of photons
http://photonterrace.net/en/photon/duality/
You are a light unto my path...
Particle or wave.
My physical walk or
Spiritual journey.
Science once again that science works
How can they waste millions of dollars on this when the climate is changing???
/sarc
Climate Change? We need NASA muslim outreach. /sarc
Interesting.
Psi ...
Related...
NONLOCALITY AND ENTANGLEMENT
Another of the remarkable features of the microscopic world prescribed by quantum theory is the idea of nonlocality, what Albert Einstein rather dismissively called “spooky actions at a distance”.
This was first described in the “EPR papers” of Einstein, Boris Podolsky and Nathan Rosen in 1935, and it is sometimes referred to as the EPR (Einstein-Podolsky-Rosen) paradox.
It was even more starkly illustrated by Bell’s Theorem, published by John Bell in 1964, and the subsequent practical experiments by John Clauser and Stuart Freedman in 1972 and by Alain Aspect in 1982.
Nonlocality describes the apparent ability of objects to instantaneously know about each other’s state, even when separated by large distances (potentially even billions of light years), almost as if the universe at large instantaneously arranges its particles in anticipation of future events.
Thus, in the quantum world, despite what Einstein had established about the speed of light being the maximum speed for anything in the universe, instantaneous action or transfer of information does appear to be possible.
This is in direct contravention of the “principle of locality” (or what Einstein called the “principle of local action”), the idea that distant objects cannot have direct influence on one another, and that an object is directly influenced only by its immediate surroundings, an idea on which almost all of physics is predicated.
Nonlocality suggests that universe is in fact profoundly different from our habitual understanding of it, and that the “separate” parts of the universe are actually potentially connected in an intimate and immediate way.
In fact, Einstein was so upset by the conclusions on nonlocality at one point that he declared that the whole of quantum theory must be wrong, and he never accepted the idea of nonlocality up till his dying day. ...”
http://www.physicsoftheuniverse.com/topics_quantum_nonlocality.html
Continued...
Nonlocality occurs due to the phenomenon of entanglement, whereby particles that interact with each other become permanently correlated, or dependent on each other’s states and properties, to the extent that they effectively lose their individuality and in many ways behave as a single entity.
The two concepts of nonlocality and entanglement go very much hand in hand, and, peculiar though they may be, they are facts of quantum systems which have been repeatedly demonstrated in laboratory experiments.
For example, if a pair of electrons are created together, one will have clockwise spin and the other will have anticlockwise spin (spin is a particular property of particles whose details need not concern us here, the salient point being that there are two possible states and that the total spin of a quantum system must always cancel out to zero).
However, under quantum theory, a superposition is also possible, so that the two electrons can be considered to simultaneously have spins of clockwise-anticlockwise and anticlockwise-clockwise respectively. If the pair are then separated by any distance (without observing and thereby decohering them) and then later checked, the second particle can be seen to instantaneously take the opposite spin to the first, so that the pair maintains its zero total spin, no matter how far apart they may be, and in total violation of the speed of light law.
Despite Einstein’s misgivings about entanglement and nonlocality and the practical difficulties of obtaining proof one way or the other, Irish physicist John Bell attempted to force the issue by making it experimental rather than just theoretical.
Bell’s Theorem, published in 1964, and referred to by some as one of the most profound discoveries in all of physics, effectively showed that the results predicted by quantum mechanics (for example, in an experiment like that described by Einstein, Podolsky and Rosen) could not be explained by any theory which preserved locality.
The subsequent practical experiments by John Clauser and Stuart Freedman in 1972 seem (despite Clauser’s initial espousal of Einstein’s position) to definitively show that the effects of nonlocality are real, and that “spooky actions at a distance” are indeed possible.
In theory, the concepts of entanglement and nonlocality may have applications in communications and even teleportation, although these ideas are still largely hypothetical at this stage. Due to the effects of the uncertainty principle, the mere act of observing the properties of particles at a quantum level (spin, charge, etc), disturbs the quantum system irrevocably, and this would appear to prevent us from using this system as a means of instantaneous communication.
However, Anton Zeilinger’s work at two observatories in the Canary Islands has shown promising indications that entangled particles can indeed be reconstituted in a different place (although the leap from this to a teleportation device of the kind envisaged in Star Trek is a profound one).
http://www.physicsoftheuniverse.com/topics_quantum_nonlocality.html
So when do we reach the point where we can, with the correct knowledge, just say “abracadabra” and make things appear and disappear? I’m not really making fun...think about it!
Nicely played
How do you know when a physicist is tired? Psi dot psi
Mind boggling stuff.
Can’t really understand it, but it suggests that as far as current physics goes (to quote Peter Gabriel) “Well, there’s a hole in there somewhere.”
Or as Einstein said, “God does not play dice with the universe.” But in fact he not only plays dice with the universe, but he throws them into a place you can’t see.
God has a sense of humor, but Werner Heisenberg was uncertain about this. This gave him a quantum of solace until he observed his solace and it changed what he observed though he really thought he had observed it and thus altered his solace.
I suspect he drank a lot after this. :)
You’re welcome, and thank you!
It’s all so frickin’ annoying...
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