https://blogs.scientificamerican.com/obs...-illusion/

EXCERPT (Lee Smolin): Many of the great advances in science are marked by the discovery that an aspect of nature we thought was fundamental is actually an illusion, due to the coarseness of our sensory perceptions. Thus, air and water appear to us to be continuous fluids, but we discover on deeper experiment that they are made of atoms. The Earth appears to us motionless, but a deeper understanding teaches us that it moves relative to the sun and the galaxy.

One persistent illusion is that physical objects only interact with other objects they are close to. This is called the principle of locality. [...] This can be explained by positing that the bodies do not interact directly, but only through the mediation of a field, such as an electromagnetic field, which propagates from one body to the other.

Locality is an aspect of an even more compelling illusion: that we exist within an absolute space, with respect to which we mark our positions as we move “through” it. [...] Newton assured us that absolute space is seen by God, making your location relative to it an aspect of the divinity of the world. ... Leibniz broke the mystification by declaring that all that exists is relative positions and motions. He proposed as a matter of principle that any acceptable science of motion must be formulated in terms of relative motions alone. And this, after two centuries of waiting, is what Einstein delivered to us in his general theory of relativity. In this glorious construction, space is subsumed into spacetime, which is explicable as a dynamically evolving network of relationships.

And what defines those relationships? Nothing but causality. The elements of space-time are events [...] and each of these is caused by events in their past. Each event will also become a cause of events in the future. Most of the information in the geometry of spacetime is actually a coding of the relations of causality that relate the events. ... And the basic principles of relativity theory insist that causes can only propagate through space at a finite speed, which cannot exceed the speed of light. We call this the principle of relativistic causality.

This principle would seem to be so natural that it must be true. But not so fast. Of all the strange aspects of quantum physics so far discovered, the strangest of all has to be the shocking discovery that the principle of relativistic causality is violated by quantum phenomena. Roughly speaking, if two particles interact and then separate, flying far apart from each other, they nevertheless may continue to share properties of a strange kind [...] We say the two particles are “entangled.” ... an experimenter can ... affect the properties of one of the particles, directly and immediately, by choosing to measure some particular corresponding property of the other. It matters not at all that it would require a signal much faster than light to effect directly such an influence. This has been shown in many experiments carried out since the 1970s ... the results show that entangled pairs violate that concept of locality.

In its present form, quantum mechanics only predicts statistical averages for the outcomes of many kinds of experiments, including these. [...] But many physicists ... aspire to discover an improved version of quantum theory. This would go deeper and replace the present statistical theory with a more complete theory, which would provide a complete and exact description of what goes on in every individual quantum process. For such a theory to work, it would have to be based on influences traveling arbitrarily faster than light, thus destroying the principle of relativistic causality as well as our intuitive notions of local influence.

Is such a more complete understanding of quantum physics possible? [...] I believe it is not only possible but an inevitable next step in the progress of physics. I believe that the completion of quantum mechanics will be a major part of the resolution of another deep problem—that of unifying our understandings of gravity, spacetime and the quantum, to produce a quantum theory of gravity. ... the violations of locality forced on us by quantum gravity are precisely what are needed to explain the nonlocality brought on by quantum entanglement.

[...] There is some theoretical evidence that this project of making a quantum theory of gravity will require space and spacetime to become discrete and built out of finite atoms of geometry. In the same sense that a liquid is just a description of the collective motions of myriads of atoms, space and spacetime will turn out to be just a way of talking about the collective properties of the large number of atomic events. Their constant coming in and out of being, causing the next ones as they recede into the past, make up the continual construction of the world—also known to us as the flow of time.

[...] Initially there is no space—just a network of individual elementary events, together with the relations expressing which of these were the direct causes of which other events. The notion of the flow of events collectively giving rise to a smooth description in terms of the geometry of a spacetime must emerge—and the most important aspect of this is locality. The notion of distance must emerge, and in such a way that those events that are close to each other are, on average, correspondingly more likely to have influenced each other. Getting this right is the holy grail of quantum gravity theorists... (MORE - details)

EXCERPT (Lee Smolin): Many of the great advances in science are marked by the discovery that an aspect of nature we thought was fundamental is actually an illusion, due to the coarseness of our sensory perceptions. Thus, air and water appear to us to be continuous fluids, but we discover on deeper experiment that they are made of atoms. The Earth appears to us motionless, but a deeper understanding teaches us that it moves relative to the sun and the galaxy.

One persistent illusion is that physical objects only interact with other objects they are close to. This is called the principle of locality. [...] This can be explained by positing that the bodies do not interact directly, but only through the mediation of a field, such as an electromagnetic field, which propagates from one body to the other.

Locality is an aspect of an even more compelling illusion: that we exist within an absolute space, with respect to which we mark our positions as we move “through” it. [...] Newton assured us that absolute space is seen by God, making your location relative to it an aspect of the divinity of the world. ... Leibniz broke the mystification by declaring that all that exists is relative positions and motions. He proposed as a matter of principle that any acceptable science of motion must be formulated in terms of relative motions alone. And this, after two centuries of waiting, is what Einstein delivered to us in his general theory of relativity. In this glorious construction, space is subsumed into spacetime, which is explicable as a dynamically evolving network of relationships.

And what defines those relationships? Nothing but causality. The elements of space-time are events [...] and each of these is caused by events in their past. Each event will also become a cause of events in the future. Most of the information in the geometry of spacetime is actually a coding of the relations of causality that relate the events. ... And the basic principles of relativity theory insist that causes can only propagate through space at a finite speed, which cannot exceed the speed of light. We call this the principle of relativistic causality.

This principle would seem to be so natural that it must be true. But not so fast. Of all the strange aspects of quantum physics so far discovered, the strangest of all has to be the shocking discovery that the principle of relativistic causality is violated by quantum phenomena. Roughly speaking, if two particles interact and then separate, flying far apart from each other, they nevertheless may continue to share properties of a strange kind [...] We say the two particles are “entangled.” ... an experimenter can ... affect the properties of one of the particles, directly and immediately, by choosing to measure some particular corresponding property of the other. It matters not at all that it would require a signal much faster than light to effect directly such an influence. This has been shown in many experiments carried out since the 1970s ... the results show that entangled pairs violate that concept of locality.

In its present form, quantum mechanics only predicts statistical averages for the outcomes of many kinds of experiments, including these. [...] But many physicists ... aspire to discover an improved version of quantum theory. This would go deeper and replace the present statistical theory with a more complete theory, which would provide a complete and exact description of what goes on in every individual quantum process. For such a theory to work, it would have to be based on influences traveling arbitrarily faster than light, thus destroying the principle of relativistic causality as well as our intuitive notions of local influence.

Is such a more complete understanding of quantum physics possible? [...] I believe it is not only possible but an inevitable next step in the progress of physics. I believe that the completion of quantum mechanics will be a major part of the resolution of another deep problem—that of unifying our understandings of gravity, spacetime and the quantum, to produce a quantum theory of gravity. ... the violations of locality forced on us by quantum gravity are precisely what are needed to explain the nonlocality brought on by quantum entanglement.

[...] There is some theoretical evidence that this project of making a quantum theory of gravity will require space and spacetime to become discrete and built out of finite atoms of geometry. In the same sense that a liquid is just a description of the collective motions of myriads of atoms, space and spacetime will turn out to be just a way of talking about the collective properties of the large number of atomic events. Their constant coming in and out of being, causing the next ones as they recede into the past, make up the continual construction of the world—also known to us as the flow of time.

[...] Initially there is no space—just a network of individual elementary events, together with the relations expressing which of these were the direct causes of which other events. The notion of the flow of events collectively giving rise to a smooth description in terms of the geometry of a spacetime must emerge—and the most important aspect of this is locality. The notion of distance must emerge, and in such a way that those events that are close to each other are, on average, correspondingly more likely to have influenced each other. Getting this right is the holy grail of quantum gravity theorists... (MORE - details)