Cosmic Paradox Reveals the Awful Consequence of an Observer-Free Universe

According to a recent article from Quanta Magazine, researchers working at the frontier of quantum physics have uncovered a “puzzling conundrum.” 

When one applies the powerful tools of quantum gravity to an entire universe—not just black holes—a glaring paradox appears: in certain “observer-free” models of a closed cosmos, the universe seems to admit only a single possible quantum state. This conclusion, first raised by Juan Maldacena, Carl P. Feinberg Professor in the School of Natural Sciences, and several collaborators in the School—including Member Ahmed Almheiri; Raghu Mahajan, Member (2019–20) and Visitor (2017–19); and Ying Zhao, Member (2018–21)—challenges one of physics’s deepest ideals: the hope of an objective, observer-independent description of the universe. 

The story began nearly three decades ago, when Maldacena demonstrated that complex calculations in string theory could be dramatically simplified using concepts from particle physics through a “holographic” correspondence. These methods are useful for problems involving black holes. But when Maldacena applied the same framework to a closed universe, it produced the unnerving result described above.

“Physicists have good reason to trust the calculation, which builds on fundamental physical ideas. The math implies a universe with only one state; our universe is clearly not like that.” 

“So what’s going on?” A team of theorists, including Zhao, has developed a possible solution: they reframed the problem by treating the observer as a kind of boundary. Their work, published in early 2025, shows that once a classical observer is placed inside a closed universe, “all the complexity of the world returns.”

“If the idea holds up,” the article states, “using the subjective nature of the observer as a way to account for the complexity of the universe would represent a paradigm shift in physics. Physicists typically seek a view from nowhere, a stand-alone description of nature. They want to know how the world works, and how observers like us emerge as parts of the world. But as physicists come to understand closed universes in terms of private boundaries around private observers, this view from nowhere seems less and less viable. Perhaps views from somewhere are all that we can ever have.”

Read more at Quanta Magazine.