Sep 16, 2016 07:08 PM
Can retrocausality solve the puzzle of action-at-a-distance?
https://aeon.co/essays/can-retrocausalit...a-distance
EXCERPTS: [...] Over the past forty years, a lot of ingenuity has gone into designing experiments to test the quantum predictions on which Bell’s result depends. Quantum mechanics has passed them all with flying colours. Just last year, three new experiments claimed to close almost all the remaining loopholes. ‘The most rigorous test of quantum theory ever carried out has confirmed that the “spooky action-at-a-distance” that [Einstein] famously hated… is an inherent part of the quantum world,’ as Nature put it.
Newton once remarked that if he’d seen further than his predecessors, it was because he stood on the shoulders of giants. For the would-be Newtons of the present century, replicating that feat has become newly challenging. It is not just that you need to be a genius to scale such heights. With Newton, Einstein and Schrödinger huddled on one side, and Bell on the other, the shoulders of the giants now seem seriously out of line.
The surprising news is that there’s a simple and elegant solution to the problem – an option that Bell himself missed, apparently, because he confused it for something else. With Bell’s authority behind it, the confusion persists to this day, and the solution goes almost unnoticed. Yet if it works, it explains Bell’s correlations without Schrödinger’s ‘magic’ and it gets our giants back in line. Quantum mechanics no longer seems in tension with special relativity, and Bell can agree with Newton, Einstein and Schrödinger that there is no action at a distance.
[...] With superdeterminism filed for posterity where it belongs – under ‘Even giants make mistakes’ – it is easy to read Bell’s Theorem as an argument for retrocausality. The argument shows that quantum mechanics implies that the alternative to retrocausality is action-at-a-distance. But ‘that would be magic’, as Schrödinger put it, and it conflicts with special relativity. So retrocausality it should be.
At this point, some readers may feel that, while action-at-a-distance is peculiar, it’s not half as odd as the present affecting the past. Retrocausality suggests the kind of paradoxes familiar from time-travel stories. If we could affect the past, couldn’t we signal to our ancestors in some way that would prevent our own existence? Luckily for the Paris option, it turns out that the kind of subtle retrocausality needed to explain Bell’s correlations doesn’t have to have such consequences. In simple cases, we can see that it couldn’t be used to signal, for the same reason that entanglement itself can’t be used to signal. But first, let’s consider a couple of other objections that critics raise at this point.
Physicists sometimes object that if retrocausality can’t be used to signal then it doesn’t have any experimental consequences. We physicists are interested in testable hypotheses, everything else is mere philosophy, they proclaim (using ‘philosophy’ in its pejorative sense!). But retrocausality offers an explanation of the results of all the standard experimental tests of the Bell correlations. If it works, it is confirmed by these experiments just as much as action-at-a-distance is confirmed. Experiments alone won’t distinguish between the two proposals, but this is no more a reason for ignoring retrocausality than it is for ignoring action-at-a-distance. The choice between the two needs to be made on other grounds – eg, on the basis that retrocausality is easier to reconcile with special relativity.
Either way, the result will be that our naive picture of time needs to be revised in the light of a new understanding of physics
Some readers may raise a more global objection to retrocausality. Ordinarily, we think that the past is fixed while the future is open, or partly so. Doesn’t our freedom to affect the future depend on this openness? How could we affect what was already fixed? These are deep philosophical waters, but we don’t have to paddle out very far to see that we have some options. We can say that, according to the retrocausal proposal, quantum theory shows that the division between what is fixed and what is open doesn’t line up neatly with the distinction between past and future. Some of the past turns out to be open, too, in whatever sense the future is open.
To understand what sense that is, we’d need to swim out a lot further. Is the openness ‘out there in the world’, or is it a matter of our own viewpoint as agents, making up our minds how to act? Fortunately, we don’t really need an answer: whatever works for the future will work for the past, too. Either way, the result will be that our naive picture of time needs to be revised in the light of a new understanding of physics – a surprising conclusion, perhaps, but hardly a revolutionary one, more than a century after special relativity wrought its own changes on our understanding of space and time....
Consciousness Is Made of Atoms, Too
http://m.nautil.us/blog/consciousness-is...-atoms-too
EXCERPTS: In his first lecture on physics to freshmen and sophomores at the California Institute of Technology, in 1961-62, Richard Feynman said:
"If, in some cataclysm, all of scientific knowledge were to be destroyed, and only one sentence passed on to the next generations of creatures, what statement would contain the most information in the fewest words? I believe it is the atomic hypothesis (or the atomic fact, or whatever you wish to call it) that all things are made of atoms—little particles that move around in perpetual motion, attracting each other when they are a little distance apart, but repelling upon being squeezed into one another. In that one sentence, you will see, there is an enormous amount of information about the world, if just a little imagination and thinking are applied."
[...] Sensations are the building blocks of consciousness. They must first be combined into perceptions and converted into objects in the environment. [...] the capacity to shape, edit, and organize this neural content, present or remembered, into a picture, experience, or awareness of the “world.” [...]
In 1934, the Estonian biologist Jakob von Uexküll published a monograph titled, "A Stroll Through the Worlds of Animals and Men" [...] in which he attempted to show that every animal creates a “world” (he called it its umwelt) from stimuli in the environment to which it responds. Even an animal such as the common wood tick, with which he begins his essay, creates such a world. [...] These three stimuli alone create an umwelt for the tick, “impoverished” as it may be. [...] Those portions, converted into digital form, are the sensations that constitute its tiny world.
There is nothing “mental” or “physical” in this account of sensations. That distinction makes sense only much further down the line in the evolution of neural systems and requires the development of memory and neural plasticity along with a far richer sensory world than the wood tick’s....
https://aeon.co/essays/can-retrocausalit...a-distance
EXCERPTS: [...] Over the past forty years, a lot of ingenuity has gone into designing experiments to test the quantum predictions on which Bell’s result depends. Quantum mechanics has passed them all with flying colours. Just last year, three new experiments claimed to close almost all the remaining loopholes. ‘The most rigorous test of quantum theory ever carried out has confirmed that the “spooky action-at-a-distance” that [Einstein] famously hated… is an inherent part of the quantum world,’ as Nature put it.
Newton once remarked that if he’d seen further than his predecessors, it was because he stood on the shoulders of giants. For the would-be Newtons of the present century, replicating that feat has become newly challenging. It is not just that you need to be a genius to scale such heights. With Newton, Einstein and Schrödinger huddled on one side, and Bell on the other, the shoulders of the giants now seem seriously out of line.
The surprising news is that there’s a simple and elegant solution to the problem – an option that Bell himself missed, apparently, because he confused it for something else. With Bell’s authority behind it, the confusion persists to this day, and the solution goes almost unnoticed. Yet if it works, it explains Bell’s correlations without Schrödinger’s ‘magic’ and it gets our giants back in line. Quantum mechanics no longer seems in tension with special relativity, and Bell can agree with Newton, Einstein and Schrödinger that there is no action at a distance.
[...] With superdeterminism filed for posterity where it belongs – under ‘Even giants make mistakes’ – it is easy to read Bell’s Theorem as an argument for retrocausality. The argument shows that quantum mechanics implies that the alternative to retrocausality is action-at-a-distance. But ‘that would be magic’, as Schrödinger put it, and it conflicts with special relativity. So retrocausality it should be.
At this point, some readers may feel that, while action-at-a-distance is peculiar, it’s not half as odd as the present affecting the past. Retrocausality suggests the kind of paradoxes familiar from time-travel stories. If we could affect the past, couldn’t we signal to our ancestors in some way that would prevent our own existence? Luckily for the Paris option, it turns out that the kind of subtle retrocausality needed to explain Bell’s correlations doesn’t have to have such consequences. In simple cases, we can see that it couldn’t be used to signal, for the same reason that entanglement itself can’t be used to signal. But first, let’s consider a couple of other objections that critics raise at this point.
Physicists sometimes object that if retrocausality can’t be used to signal then it doesn’t have any experimental consequences. We physicists are interested in testable hypotheses, everything else is mere philosophy, they proclaim (using ‘philosophy’ in its pejorative sense!). But retrocausality offers an explanation of the results of all the standard experimental tests of the Bell correlations. If it works, it is confirmed by these experiments just as much as action-at-a-distance is confirmed. Experiments alone won’t distinguish between the two proposals, but this is no more a reason for ignoring retrocausality than it is for ignoring action-at-a-distance. The choice between the two needs to be made on other grounds – eg, on the basis that retrocausality is easier to reconcile with special relativity.
Either way, the result will be that our naive picture of time needs to be revised in the light of a new understanding of physics
Some readers may raise a more global objection to retrocausality. Ordinarily, we think that the past is fixed while the future is open, or partly so. Doesn’t our freedom to affect the future depend on this openness? How could we affect what was already fixed? These are deep philosophical waters, but we don’t have to paddle out very far to see that we have some options. We can say that, according to the retrocausal proposal, quantum theory shows that the division between what is fixed and what is open doesn’t line up neatly with the distinction between past and future. Some of the past turns out to be open, too, in whatever sense the future is open.
To understand what sense that is, we’d need to swim out a lot further. Is the openness ‘out there in the world’, or is it a matter of our own viewpoint as agents, making up our minds how to act? Fortunately, we don’t really need an answer: whatever works for the future will work for the past, too. Either way, the result will be that our naive picture of time needs to be revised in the light of a new understanding of physics – a surprising conclusion, perhaps, but hardly a revolutionary one, more than a century after special relativity wrought its own changes on our understanding of space and time....
Consciousness Is Made of Atoms, Too
http://m.nautil.us/blog/consciousness-is...-atoms-too
EXCERPTS: In his first lecture on physics to freshmen and sophomores at the California Institute of Technology, in 1961-62, Richard Feynman said:
"If, in some cataclysm, all of scientific knowledge were to be destroyed, and only one sentence passed on to the next generations of creatures, what statement would contain the most information in the fewest words? I believe it is the atomic hypothesis (or the atomic fact, or whatever you wish to call it) that all things are made of atoms—little particles that move around in perpetual motion, attracting each other when they are a little distance apart, but repelling upon being squeezed into one another. In that one sentence, you will see, there is an enormous amount of information about the world, if just a little imagination and thinking are applied."
[...] Sensations are the building blocks of consciousness. They must first be combined into perceptions and converted into objects in the environment. [...] the capacity to shape, edit, and organize this neural content, present or remembered, into a picture, experience, or awareness of the “world.” [...]
In 1934, the Estonian biologist Jakob von Uexküll published a monograph titled, "A Stroll Through the Worlds of Animals and Men" [...] in which he attempted to show that every animal creates a “world” (he called it its umwelt) from stimuli in the environment to which it responds. Even an animal such as the common wood tick, with which he begins his essay, creates such a world. [...] These three stimuli alone create an umwelt for the tick, “impoverished” as it may be. [...] Those portions, converted into digital form, are the sensations that constitute its tiny world.
There is nothing “mental” or “physical” in this account of sensations. That distinction makes sense only much further down the line in the evolution of neural systems and requires the development of memory and neural plasticity along with a far richer sensory world than the wood tick’s....
