?Where do time and space originate
To say that space and time arise from the boundary surface of space is to cast the question into another region and nothing more
Translation Introduction
Spacetime is a term that came out of Albert Einstein's theory of relativity, and it means the fabric of space in which space and time are interwoven into a single web. To put it roughly, it's like a huge stretched rubber fishing net. When you put something heavy on it, it bends because of its weight. The theory of relativity shows that this does happen. Both space and time are distorted by the presence of mass in them. The more massive a star is, for example, the closer you get to it, the slower time will be for you.
After Einstein, scientists have been keen to explore the basic structure of spacetime itself, how it came into being and what it is made of in the first place. In this short article from New Scientist, Mike Brooks presents some of the theories that attempt to understand the fundamental structure of this universe.
Translation text
We tend to think of spacetime as the fundamental structure of the universe. But whether that’s true, or whether spacetime emerges from something deeper, is a question that keeps physicists up at night. “It’s not just a philosophical question you discuss over a beer,” says Marika Taylor of the University of Birmingham in the UK. “It’s actually something that goes into the mathematics that people do in this area.”
To understand this, a good place to start is with quantum mechanics, which describes the behavior of subatomic particles. One of the fundamental principles of this theory is that the connections between particles can transcend our usual notions of space and time. This happens through a phenomenon called quantum entanglement, where particles can influence each other’s properties even when they are half the universe apart!
To put it roughly, it's like a huge stretched rubber fishing net, which, when you put something heavy on it, bends under the weight
Cosmologists now accept that entanglement is intimately linked to the emergence of space itself. If we know the degree of entanglement between two quantum particles, we can work out the distance between them. So if you do the math for a lattice of many particles, you start to form a geometry from which what we call “space” can emerge. Perhaps space emerges from quantum entanglement.
Furthermore, advances in string theory, a candidate for the “theory of everything,” say that what happens inside space can be described entirely by the data on the outside of that space, or more precisely, the “boundaries of that space,” a phenomenon known as “holographic duality.” Combine that with quantum entanglement, and you can understand the spatial structure of the universe, which has distances between objects and a geometry of space.
Spyridon Michalakis, a mathematical physicist at the California Institute of Technology, has worked with Sean Carroll of Johns Hopkins University in Maryland and Charles Kao of Virginia Tech to build an intriguing explanation for the origins of spacetime.
As they have found, the entanglement between particles at the boundaries of spacetime creates a certain “distance,” and entanglement distances translate into “geodesics” (the paths that particles follow as they move through the universe). This geodesic builds a geometry of spacetime, similar to the curved geometry that Albert Einstein’s general theory of relativity says underlies gravity.
“Entanglement turns into curvature, and this curvature can be thought of as the geometry of space,” Michalakis says.
But this does not answer the fundamental question. To say that space and time arise from the boundary surface of space is to throw the question into another area, Taylor says: “We have not explained why space exists in a deep sense.”
Constructivist theory seeks an information-based view of the origins of space
Different question
The answer may be something entirely different. That’s certainly what Chiara Marletto of the University of Oxford thinks. She works with her Oxford colleague David Deutsch and others on “constructivist theory,” which aims to express the laws of physics differently based on the possible transformations of the physical system, as well as to combine all the available data into quanta of information.
Because the universe seems to act as a kind of information processor (like a computer processor), constructivism seeks an information-based view of the origins of space. “We would like to say that time is not fundamental to this universe at all, and spacetime is not fundamental either,” says Marletto. Such ideas are still being worked out, however.
A deeper understanding of spacetime will come from studying cosmic phenomena, like black holes and the singularities at the center of them all, Taylor says. “The whole idea of spacetime collapses down there, and understanding how it collapses is closely tied to the question of how it came about in the first place,” she says. “We know that things are going crazy down there. Once we understand that, we can flip the picture and see how the three spatial dimensions actually appear.”
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