Most popular science books start the universe with a single, explosive Big Bang. A new study argues something quieter but no less dramatic: the early cosmos may have been deep inside a gigantic black hole that first crumpled in on itself and then rebounded.

“The Big Bang is often described as the explosive birth of the universe – a singular moment when space, time and matter sprang into existence,” lead researcher Enrique Gaztanaga of the study published in Physical Review D wrote in The Conversation. “But what if this was not the beginning at all? What if our universe emerged from something else – something more familiar and radical at the same time?

How a Crunch Becomes a Cosmos

Imagine an immense, nearly uniform ball of gas and dust falling inward under its own weight. Long before it can vanish to an infinitely dense point, quantum pressure pushes back, forcing the material to stop and then bounce outward.

“Our calculations suggest the Big Bang was not the start of everything, but rather the outcome of a gravitational crunch or collapse that formed a very massive black hole – followed by a bounce inside it,” Gaztanaga said.

All of this action unfolds behind the object’s event horizon — the invisible boundary that defines any black hole. From the outside, nothing looks unusual. Inside, space stretches at breakneck speed, creating a brand-new universe.

Cosmologists usually invoke an unknown “inflaton” field to make the infant universe expand and add “dark energy” to explain why that expansion is speeding up today. The new model ties both episodes to the same quantum push.

“Today’s standard cosmological model, based on the Big Bang and cosmic inflation (the idea that the early universe rapidly blew up in size), has been remarkably successful in explaining the structure and evolution of the universe,” Gaztanaga said. “But it comes at a price: it leaves some of the most fundamental questions unanswered. For one, the Big Bang model begins with a singularity – a point of infinite density where the laws of physics break down. This is not just a technical glitch; it’s a deep theoretical problem that suggests we don’t really understand the beginning at all.”

Flipping the Script on Previous Assumptions

The team’s new universal models, such as this, are frequent. However, this research team believes that the model’s strength lies in its testability. 

“The smoking gun for our bouncing scenario is the presence of both a small spatial curvature and a small [cosmological constant] term,” the team writes in the study. “While the latter has already been measured with high precision, the former remains a testable prediction for upcoming cosmological surveys.”

Moreover, the new model predicts that space is not flat, but has a slight positive curvature to it.

Because the rebound starts from a cloud with real size, not an abstract point, the authors say space should be almost flat but not perfectly so. Their equations “predict a small but non-zero closed spatial curvature,” small enough to hide from earlier telescopes but large enough for new projects such as the ESA’s Euclid satellite or the Dark Energy Spectroscopic Instrument to detect.

If they are proven true, it would have a profound impact, to say the least.

“This model does more than fix technical problems with standard cosmology,” Gaztanaga said. “It could also shed new light on other deep mysteries in our understanding of the early universe – such as the origin of supermassive black holes, the nature of dark matter, or the hierarchical formation and evolution of galaxies.”

Future computer simulations will test whether the rebound still works when lumps, spins, and all the other messiness of real matter are added. For now, the study offers a fresh, easy-to-state possibility: the universe may not have exploded out of nothing at all. It might have sprung back from a cosmic crunch, hidden inside a black-hole womb.