One of the strangest aspects of quantum mechanics is entanglement, since two entangled particles influence each other across vast distances, which at first glance violates the fundamental physical principle of locality: what happens at a certain point in space can only affect points nearby. But what if locality - and space itself - isn't all that fundamental, after all? George Masser explores the possible consequences of this in his new book Spooky Action At a Distance. (Albert Einstein called quantum entanglement "eerie action at a distance").
When philosopher Jennan Ismael was ten years old, her father, an Iraqi-born professor at the University of Calgary, bought a large wooden cabinet at auction. After rummaging through it, she stumbled upon an old kaleidoscope and was delighted. She experimented with it for hours and figured out how it worked. “I didn’t tell my sister that I found him because I was afraid she would take it,” she recalls.
When you peer into the kaleidoscope and turn the pipe, the multicolored figures begin to bloom, twirl and unite in a seemingly completely inexplicable and unpredictable way, as if they were having an eerie effect on each other from a distance. But the more you admire them, the more you notice patterns in their movement. The shapes at opposite ends of your visual field change in unison, and this symmetry allows you to understand what is really happening: these shapes are not physical objects, but images of objects - shards of glass that rotate inside a mirror tube.
“There is one piece of glass that appears redundantly in different parts of the space,” Ismael says. “If you focus on the overall encompassing space, the physical description of a three-dimensional kaleidoscope would be a fairly straightforward causal story. There is a piece of glass, it is reflected in the mirrors, and so on. Seen in reality, the kaleidoscope is no longer a mystery, although it still surprises.
Decades later, preparing for a talk on quantum physics, Ismael remembered the kaleidoscope and bought a brand new shiny copper tube in a velvet case. He became, as it dawned on her, a metaphor for nonlocality in physics. Perhaps particles in entanglement experiments or galaxies in distant galactic limits behave strangely, since they are projections - secondary creations, in a sense - existing in a completely different region of objects.
“In the case of the kaleidoscope, we know what we have to do: we have to see the whole system; we have to see how the image of space is created, says Ismael. - How to build an analogue of this for quantum effects? To do this, you need to see the cosmos that we know - everyday space, in which we measure events located in different parts of the cosmos - as an inseparable structure. Perhaps when we look at the two parts, we see the same event. We interact with the same element of reality in different parts of space."
Together with others, she questions the assumption, followed by almost every physicist and philosopher since Democritus, that space is the deepest level of physical reality. Just as the script for a play describes the actions of the actors on stage, but precedes the stage, the laws of physics traditionally take the existence of space for granted. We know today that the universe is more than just things in space. The phenomenon of nonlocality leaps over space; there is no place where it is limited. It manifests itself at the level of reality deeper than space, where the concept of distance no longer matters, where distant things seem to be nearby, as if the same thing appears in more than one place, like numerous images of one piece of glass in a kaleidoscope.
When we think about terms at this level, the connections between subatomic particles on a laboratory bench, inside and outside a black hole, and between opposite parts of the universe no longer seem so creepy. Michael Heller, physicist, philosopher and theologian of the Pontifical Academy of Theology in Krakow, Poland, says: “If you agree that physics is nonlocal at a fundamental level, then it’s quite natural, since two particles that are far from each other reside on one fundamental non-local level. For them, space and time do not matter. It is only when you try to visualize these phenomena from a space perspective - which is forgivable since we are used to thinking that way - that they confuse our understanding.
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The idea of a deep level seems natural because, after all, physicists have always strived for it. Whenever they could not understand certain aspects of our world, they assumed that they had not yet got to the bottom of it all. They zoomed in and saw the building blocks. That liquid water can boil or freeze is somewhat mysterious. But these transformations make sense if we represent the liquid, gaseous and solid state not as elementary substances, but as different forms of one fundamental substance.
Aristotle considered different states of water to be different incarnations of the so-called primordial matter, and atomists - sagaciously - thought that atoms are rearranged into more rigid or free structures. En masse, these building blocks of matter acquire properties that individually lack. Likewise, space can be made up of parts that are not spatial in themselves. These parts can also be disassembled and reassembled into nonspatial structures, such as those hinting at black holes and the Big Bang.
“Spacetime cannot be fundamental,” says theorist Nima Arkani-Hamed. "It should be made of something simpler."
This thinking completely turns physics around. Nonlocality is no longer a mystery; it is reality, and locality becomes the real mystery. When we can no longer take space for granted, we have to explain what it is and from what it arises, independently or in the process of uniting with time.
Obviously, building space won't be as easy as fusing molecules into a liquid. What could be its building blocks? We usually say that the building blocks should be smaller than the things that make up them. If you assemble a detailed Eiffel Tower from toothpicks, you will not have to explain that toothpicks are smaller than the tower.
But when it comes to space, there is no “less”, because size itself is a spatial concept. Building blocks cannot precede space if it has to explain them. They should have neither size nor space; they must be everywhere, throughout the universe and nowhere at the same time, so that they cannot be poked. What does the lack of position mean for a thing? Where will she be? “When we talk about the outflowing space-time, it must flow out of some framework, from which we are very far,” says Arkani-Hamed.
In Western philosophy, the kingdom outside of space has traditionally been considered the kingdom outside of physics - the place of God's presence in Christian theology. In the early 18th century, Gottfried Leibniz's "monads" -which he represented as primitive elements of the universe - existed, like God, outside of space and time. His theory was a step towards the emerging space-time, but remained in the field of metaphysics, being loosely connected with the world of concrete things. If physicists succeed in explaining emerging space, they will have to develop their own concept of the absence of space.
Einstein foresaw these difficulties. “Perhaps… we should, in principle, abandon the space-time continuum,” he wrote. - It is quite possible to imagine that human ingenuity will one day find methods that will make this path possible. At present, however, such a program looks like an attempt to breathe in empty space."
John Wheeler, a renowned theorist of gravity, suggested that spacetime was built from "pregeometry" but admitted that it was just "idea for idea's sake." Even Arkani-Hamed shares his doubts: “These problems are very complex. It is impossible to discuss them in the language we are used to”.
What drives Arkani-Hamed and his colleagues to go on is finding the kind of ways that Einstein described - ways to describe physics in the absence of space, breathing in a vacuum. He explains these attempts in terms of history: “For over 2,000 years people have been asking questions about the deep nature of space and time, but they were premature. We've finally arrived in an era where you can ask these questions and hope to get some meaningful answers."
Based on materials from Gizmodo
Ilya Khel