New Evidence Could Overthrow the Standard View of Quantum Mechanics

[BADecker]

New Evidence Could Overthrow the Standard View of Quantum Mechanics

This is exactly what the standard view of quantum mechanics, often called the Copenhagen interpretation, asks us to believe. Instead of the clear-cut positions and movements of Newtonian physics, we have a cloud of probabilities described by a mathematical structure known as a wave function. The wave function, meanwhile, evolves over time, its evolution governed by precise rules codified in something called the Schrödinger equation. The mathematics are clear enough; the actual whereabouts of particles, less so. Until a particle is observed, an act that causes the wave function to "collapse," we can say nothing about its location. Albert Einstein, among others, objected to this idea. As his biographer Abraham Pais wrote: "We often discussed his notions on objective reality. I recall that during one walk Einstein suddenly stopped, turned to me and asked whether I really believed that the moon exists only when I look at it."

Read more at http://www.wired.com/2016/05/new-support-alternative-quantum-view/.

[Wilikon]

But there’s another view—one that’s been around for almost a century—in which particles really do have precise positions at all times. This alternative view, known as pilot-wave theory or Bohmian mechanics, never became as popular as the Copenhagen view, in part because Bohmian mechanics implies that the world must be strange in other ways. In particular, a 1992 study claimed to crystalize certain bizarre consequences of Bohmian mechanics and in doing so deal it a fatal conceptual blow. The authors of that paper concluded that a particle following the laws of Bohmian mechanics would end up taking a trajectory that was so unphysical—even by the warped standards of quantum theory—that they described it as “surreal.”

Nearly a quarter-century later, a group of scientists has carried out an experiment in a Toronto laboratory that aims to test this idea. And if their results, first reported earlier this year, hold up to scrutiny, the Bohmian view of quantum mechanics—less fuzzy but in some ways more strange than the traditional view—may be poised for a comeback.



 

https://www.youtube.com/watch?v=JIGI-eXK0tg

[Wilikon]

That may sound like a throwback to classical mechanics, but there’s a crucial difference. Classical mechanics is purely “local”—stuff can affect other stuff only if it is adjacent to it (or via the influence of some kind of field, like an electric field, which can send impulses no faster than the speed of light). Quantum mechanics, in contrast, is inherently nonlocal. The best-known example of a nonlocal effect—one that Einstein himself considered, back in the 1930s—is when a pair of particles are connected in such a way that a measurement of one particle appears to affect the state of another, distant particle. The idea was ridiculed by Einstein as “spooky action at a distance.” But hundreds of experiments, beginning in the 1980s, have confirmed that this spooky action is a very real characteristic of our universe.

In the Bohmian view, nonlocality is even more conspicuous. The trajectory of any one particle depends on what all the other particles described by the same wave function are doing. And, critically, the wave function has no geographic limits; it might, in principle, span the entire universe. Which means that the universe is weirdly interdependent, even across vast stretches of space. The wave function “combines—or binds—distant particles into a single irreducible reality,” as Sheldon Goldstein, a mathematician and physicist at Rutgers University, has written.


One.

 

[Trading]

The article is worth reading. It's based on Mahler, Rozema, Fisher, Vermeyden, Resch, Wiseman, Steinberg - Experimental nonlocal and surreal Bohmian trajectories, http://advances.sciencemag.org/content/2/2/e1501466.full .

To the lazy, here is a summary on lay terms (it isn't my field):

Quantum mechanics causes serious problems. It's not just the question of particles we can't find until we look at them (as the article says), but also the problem of particles that purportedly can be at different places at the same time.

Well, contrary to quantum theory that is fully indeterministic, classic physics on gravity is fully deterministic.

But gravity also must work on the sub-atomic level (they are still searching for the so-called gravitons, particles that are the vehicles of gravity on sub-atomic level), since when, for instance, a star attracts a planet, that attraction must work on all the sub-atomic particles of the planet also.

So, how can quantum mechanics be right when gravity, which has also to work (they don't know how) on sub-atomic level, is fully deterministic?

If all the sub-atomic particles are undetermined and can have bizarre effects/movements, how came we never see bizarre events on the supra-atomic level?

Well, the article writes about an old theory, the Broglie–Bohm theory, which says quantum mechanics is wrong. Sub-atomic particles can be also determined, if we have information about the initial state of the system and applied the accepted equation/wave function.

Problems of the Broglie–Bohm theory were highlighted on an 1992 paper (known as ESSW), saying it would also force to conclude that sub-atomic particles could have surreal moves, since electrons or photons would appear as well to cross on two different places at the same time, like more or less quantum mechanics says.

But the article summarized mentions the above quoted 2016 article saying that this 1992 paper is wrong, that Broglie–Bohm mechanics is deterministic and that doesn't force to accept surreal movements.

That the conclusion on the surreal moves was based on the still bizarre entangled effect (particles connected, even at very far distances, seemed to know at all times where the other was and what was happening to it: see, for instance http://www.wired.com/2016/05/simple-yes-simple-guide-quantum-entanglement/) and that the surreal movement of the first particle was figured out only based on what the other particle said about the movement of the first particle.

Well, contrary to what has been said, it seems that the information each particle knows about the other isn't trustworthy at long distances.

As the distance between the particles grows, one particle starts giving wrong information about the other, creating the impression that the other particle crossed on two different places at the same time.

If truth, this paper, and the experiment on which it is based, also seems to helps solving the problem of how particles so far away could be informed about each other without communicate at speeds faster than light.

If distance makes them give wrong information, perhaps they can't communicate faster than light.

[BADecker]

This is precisely why modern QM is of a probabilistic nature. Something that works and is accurate might be figured out by QM. But if it isn't tested in ways other than QM, it will never be known to be accurate.

[BADecker]

This is precisely why modern QM is of a probabilistic nature. Something that works and is accurate might be figured out by QM. But if it isn't tested in ways other than QM, it will never be known to be accurate.

Perhaps we are looking in the wrong place or in the wrong way. Maybe we should be looking for something that combines the two forms of QM, rather than choosing which QM is more correct.