Nov 10, 2015 10:33 PM
A New Way of Thinking About Spacetime That Turns Everything Inside Out
http://gizmodo.com/a-new-way-of-thinking...1741498475
EXCERPT: One of the weirdest aspects of quantum mechanics is entanglement, because two entangled particles affecting each other across vast distances seems to violate a fundamental principle of physics called locality: things that happen at a particular point in space can only influence the points closest to it. But what if locality — and space itself — is not so fundamental after all?
[...] Jenann Ismael and others question the assumption, made by nearly every physicist and philosopher from Democritus onward, that space is the deepest level of physical reality. Just as the script of a play describes what actors do on a stage, but presupposes the stage, the laws of physics have traditionally taken the existence of space as a given. Today we know that the universe has more to it than things situated within space. Nonlocal phenomena leap out of space; they have no place in its confines. They hint at a level of reality deeper than space, where the concept of distance ceases to apply, where things that appear to lie far apart are actually nearby, or perhaps are the same thing manifested in more than one place, like multiple images of a single shard of kaleidoscopic glass.
When we think in terms of such a level, the connections between subatomic particles across a lab bench, between the inside and the outside of a black hole, and between opposite sides of the universe don’t seem so spooky anymore. Michael Heller [...] says: “If you agree that the fundamental level of physics is not local, everything is natural, because these two particles which are far apart from each other explore the same fundamental nonlocal level. For them, time and space don’t matter.” Only when you try to visualize these phenomena in terms of space — which is forgivable, because it’s hard for us to think in any other way — do they defy comprehension.
The idea of a deeper level seems natural because, after all, it is what physicists have always sought. Whenever they can’t fathom some aspect of our world, they assume they must not yet have gotten to the bottom of it all.
[...] “Spacetime can’t be fundamental,” says the theorist Nima Arkani-Hamed. “It has to come out of something more basic.”
This thinking completely inverts physics. Nonlocality is no longer the mystery; it’s the way things really are, and locality becomes the puzzle. When we can no longer take space for granted, we have to explain what it is and how it arises, either on its own or in union with time.
Clearly, constructing space isn’t going to be as straightforward as melding molecules into a fluid. What could its building blocks possibly be? Normally we assume that building blocks must be smaller than the things you build out of them. A friend of mine and his daughter once erected a detailed model of the Eiffel Tower out of popsicle sticks; they hardly needed to explain that the sticks were smaller than the tower.
When it comes to space, though, there can be no “smaller,” because size itself is a spatial concept. The building blocks cannot presume space if they are to explain it. They must have neither size nor location; they are everywhere, spanning the entire universe, and nowhere, impossible to point to. What would it mean for things not to have positions? Where would they be? “When we talk about emergent space-time, it must come out of some framework that is very far from what we’re familiar with,” Arkani-Hamed says.
Within Western philosophy, the realm beyond space has traditionally been considered a realm beyond physics — the plane of God’s existence in Christian theology. In the early eighteenth century, Gottfried Leibniz’s “monads” — which he imagined to be the primitive elements of the universe — existed, like God, outside space and time. His theory was a step toward emergent space-time, but it was still metaphysical, with only a vague connection to the world of concrete things. If physicists are to succeed in explaining space as emergent, they must claim the concept of spacelessness as their own.
Einstein foresaw these difficulties. “Perhaps... we must also give up, by principle, the space-time continuum,” he wrote. “It is not unimaginable that human ingenuity will some day find methods which will make it possible to proceed along such a path. At the present time, however, such a program looks like an attempt to breathe in empty space.”
John Wheeler, the renowned gravity theorist, speculated that space-time is built out of “pregeometry,” but admitted that this was nothing more than “an idea for an idea.” Even someone as irrepressible as Arkani-Hamed has had his doubts: “These problems are very hard. They’re outside our usual language for talking about them....”
http://gizmodo.com/a-new-way-of-thinking...1741498475
EXCERPT: One of the weirdest aspects of quantum mechanics is entanglement, because two entangled particles affecting each other across vast distances seems to violate a fundamental principle of physics called locality: things that happen at a particular point in space can only influence the points closest to it. But what if locality — and space itself — is not so fundamental after all?
[...] Jenann Ismael and others question the assumption, made by nearly every physicist and philosopher from Democritus onward, that space is the deepest level of physical reality. Just as the script of a play describes what actors do on a stage, but presupposes the stage, the laws of physics have traditionally taken the existence of space as a given. Today we know that the universe has more to it than things situated within space. Nonlocal phenomena leap out of space; they have no place in its confines. They hint at a level of reality deeper than space, where the concept of distance ceases to apply, where things that appear to lie far apart are actually nearby, or perhaps are the same thing manifested in more than one place, like multiple images of a single shard of kaleidoscopic glass.
When we think in terms of such a level, the connections between subatomic particles across a lab bench, between the inside and the outside of a black hole, and between opposite sides of the universe don’t seem so spooky anymore. Michael Heller [...] says: “If you agree that the fundamental level of physics is not local, everything is natural, because these two particles which are far apart from each other explore the same fundamental nonlocal level. For them, time and space don’t matter.” Only when you try to visualize these phenomena in terms of space — which is forgivable, because it’s hard for us to think in any other way — do they defy comprehension.
The idea of a deeper level seems natural because, after all, it is what physicists have always sought. Whenever they can’t fathom some aspect of our world, they assume they must not yet have gotten to the bottom of it all.
[...] “Spacetime can’t be fundamental,” says the theorist Nima Arkani-Hamed. “It has to come out of something more basic.”
This thinking completely inverts physics. Nonlocality is no longer the mystery; it’s the way things really are, and locality becomes the puzzle. When we can no longer take space for granted, we have to explain what it is and how it arises, either on its own or in union with time.
Clearly, constructing space isn’t going to be as straightforward as melding molecules into a fluid. What could its building blocks possibly be? Normally we assume that building blocks must be smaller than the things you build out of them. A friend of mine and his daughter once erected a detailed model of the Eiffel Tower out of popsicle sticks; they hardly needed to explain that the sticks were smaller than the tower.
When it comes to space, though, there can be no “smaller,” because size itself is a spatial concept. The building blocks cannot presume space if they are to explain it. They must have neither size nor location; they are everywhere, spanning the entire universe, and nowhere, impossible to point to. What would it mean for things not to have positions? Where would they be? “When we talk about emergent space-time, it must come out of some framework that is very far from what we’re familiar with,” Arkani-Hamed says.
Within Western philosophy, the realm beyond space has traditionally been considered a realm beyond physics — the plane of God’s existence in Christian theology. In the early eighteenth century, Gottfried Leibniz’s “monads” — which he imagined to be the primitive elements of the universe — existed, like God, outside space and time. His theory was a step toward emergent space-time, but it was still metaphysical, with only a vague connection to the world of concrete things. If physicists are to succeed in explaining space as emergent, they must claim the concept of spacelessness as their own.
Einstein foresaw these difficulties. “Perhaps... we must also give up, by principle, the space-time continuum,” he wrote. “It is not unimaginable that human ingenuity will some day find methods which will make it possible to proceed along such a path. At the present time, however, such a program looks like an attempt to breathe in empty space.”
John Wheeler, the renowned gravity theorist, speculated that space-time is built out of “pregeometry,” but admitted that this was nothing more than “an idea for an idea.” Even someone as irrepressible as Arkani-Hamed has had his doubts: “These problems are very hard. They’re outside our usual language for talking about them....”
