The Nature of Space and Time

The Nature of Space and Time.


In the 1970s, physicists Stephen Hawking and Jacob Bekenstein noted a link between the surface area of black holes and their microscopic quantum structure, which determines their entropy. This marked the first realization that a connection existed between Einstein’s theory of general relativity and quantum mechanics. Less than three decades later, theoretical physicist Juan Maldacena observed another link between gravity and the quantum world. That connection led to the creation of a model that proposes that spacetime can be created or destroyed by changing the amount of entanglement between different surface regions of an object. In other words, this implies that spacetime itself, at least as it is defined in models, is a product of the entanglement between objects.

To further explore this line of thinking, ChunJun Cao and Sean Carroll of the California Institute of Technology (CalTech) set out to see if they could derive the dynamical properties of gravity (as familiar from general relativity) using the framework in which spacetime arises out of quantum entanglement. Their research was recently published in arXiv. Using an abstract mathematical concept called Hilbert space, Cao and Carroll were able to find similarities between the equations that govern quantum entanglement and Einstein’s equations of general relativity. This supports the idea that spacetime and gravity do emerge from entanglement. Carroll told Futurism the next step in the research is to determine the accuracy of the assumptions they made for this study. “One of the most obvious ones is to check whether the symmetries of relativity are recovered in this framework, in particular, the idea that the laws of physics don’t depend on how fast you are moving through space,” he said.

A Theory of Everything




Credit: Kristin Houser for Futurism, 6 January 2018.