Dying star could give birth to a new universe

Two physicists at Goethe University in Frankfurt have proposed a mathematical solution in which the collapse of a massive star at the end of its life does not have to end in a singularity, but may instead seed the growth of a small universe hidden inside the star itself. The study is signed by Daniel Jampolski and Luciano Rezzolla, and the result was published in the peer-reviewed journal Physical Review D and picked up in wider science reporting on June 14, 2026.

The standard picture of a massive star’s collapse ends in a black hole. When a star of sufficient mass exhausts its fuel, gravity overcomes pressure and matter caves in until general relativity predicts a singularity, a point of infinite density where known physics breaks down. For decades that singularity has been read as a sign that Einstein’s theory is incomplete and that, at extreme scales, a description uniting gravity and quantum physics is still missing.

The new solution offers a different outcome. Instead of all the matter compressing into a single point, the authors describe a configuration in which a region forms inside the star and begins to expand, echoing the earliest moments after the Big Bang. In that scenario dark energy, the same component thought to accelerate the expansion of our own universe, plays a central role: it pushes the space inside the star outward and so prevents the collapse from ending in infinite density.

What exactly does the new model describe?

The result belongs to theoretical physics, which means it is a mathematical solution to the equations rather than an observation of a specific object in the sky. The authors consider an exotic object known as a gravastar, a hypothetical alternative to a black hole that has neither a classical event horizon nor an interior singularity. In their setup an outside observer still sees something that closely resembles a black hole, while the interior is fundamentally different because it contains expanding space.

It is important to stress what the paper does not claim. It does not prove that our universe actually sits inside another star, nor that every black hole hides a new cosmos. The point is that the equations permit such a solution, which is a mathematical result, not a confirmed fact about nature. The idea that a collapse might give rise to new space has appeared before in cosmology, but every such construction must pass consistency checks and, ideally, offer something that could be measured.

Can a theory like this even be tested?

That is where the main limitation lies. Because the proposed universe sits behind something that looks from the outside like a horizon, observing its interior directly is not possible the way we observe stars or galaxies. The next step for physicists would be to examine whether gravastars and similar objects leave any measurable trace, for instance in the gravitational waves produced by mergers of compact objects, or in the way they bend light around themselves.

For now the paper should be read as a proposal, one of several possible solutions to the equations describing the most extreme phases of stellar life. Its value lies in showing that the outcome of collapse may not be as clear-cut as the standard picture suggests, and that the boundary between the end of one star and the start of something new may not be as sharp as it seems. What do you think: could our universe be the interior of a long-collapsed star?