Our Universe may be perfectly nested inside a black hole that is part of a larger Universe, like a cosmic Russian doll. In turn, all of the black holes discovered so far in our Universe—from microscopic to supermassive—could be ultimate portals to alternate realities.
According to a mind-bending new theory, a black hole is actually a wormhole—a tunnel between Universes. According to the theory, the matter attracted by the black hole does not collapse into a single point as predicted, but rather gushes out a “white hole” at the other end of the black one.
Nikodem Poplawski of Indiana University presents new mathematical models of the spiraling motion of matter falling into a black hole in a paper published in the journal Physics Letters B. His equations indicate that such wormholes are viable alternatives to the “space-time singularities” predicted by Albert Einstein to exist at the centers of black holes.
According to Einstein’s equations
for general relativity, singularities form when matter in a given region becomes too dense, as it would at the ultra-dense heart of a black hole.
Singularities, according to Einstein’s theory, take up no space, are infinitely dense, and are infinitely hot—a concept supported by numerous lines of indirect evidence but still so far-fetched that many scientists find it difficult to accept. They might not have to if Poplawski is correct.
The matter that black holes absorb and appear to destroy is actually expelled and becomes the building blocks for galaxies, stars, and planets in another reality, according to the new equations.
According to Poplawski
, the concept of black holes as wormholes could explain certain mysteries in modern cosmology. According to the big bang theory, the universe began as a singularity. However, scientists do not have a convincing explanation for how such a singularity could have formed in the first place.
If our universe was birthed by a white hole instead of a singularity, Poplawski said, “it would solve this problem of black hole singularities and also the big bang singularity.” Wormholes might also explain gamma ray bursts, the second most powerful explosions in the universe after the big bang. Gamma ray bursts occur at the fringes of the known universe. They appear to be associated with supernovae, or star explosions, in faraway galaxies, but their exact sources are a mystery.
that the bursts are matter discharges from other universes. The matter, he claims, may be escaping into our universe via supermassive black holes—wormholes—at the centers of those galaxies, though how this is possible is unclear.
“It’s a crazy idea, but who knows?” he says. Poplawski’s theory can be tested in at least one way: some of our universe’s black holes rotate, and if our universe was born inside a similarly rotating black hole, our universe should have inherited the parent object’s rotation. Poplawski believes that if future experiments show that our universe appears to rotate in a specific direction, it will be indirect evidence supporting his wormhole theory.
According to physicists
, the wormhole theory may also help explain why certain features of our Universe deviate from what theory predicts.
According to the standard physics model, the curvature of the universe should have increased over time after the big bang, so that now—13.7 billion years later—we appear to be sitting on the surface of a closed, spherical universe. However, observations show that the universe appears to be flat in all directions. Furthermore, data on light from the very early universe show that everything was a fairly uniform temperature just after the big bang.
That would imply that the most distant objects we see on opposite horizons of the universe were once close enough to interact and reach equilibrium, much like molecules of gas in a sealed chamber.
Again, observations do not match predictions because the objects that are the furthest apart in the known universe are so far apart that the time it would take to travel between them at the speed of light would be longer than the age of the universe.
According to inflation
, shortly after the universe was created, it experienced a rapid growth spurt during which space itself expanded at faster-than-light speeds. In a fraction of a second, the universe expanded from the size of an atom to astronomical proportions. The universe therefore appears flat, because the sphere we’re sitting on is extremely large from our viewpoint—just as the sphere of Earth seems flat to someone standing in a field. Inflation also explains how objects so far away from each other might have once been close enough to interact.
But, even if inflation is real, astronomers have always struggled to explain what caused it. This is where the new wormhole theory comes into play. Some theories of inflation, according to Poplawski, claim that the event was caused by “exotic matter,” a hypothetical substance that differs from normal matter in part because it is repelled rather than attracted by gravity. According to Poplawski’s equations, such exotic matter could have been created when some of the first massive stars collapsed and became wormholes.
“There may be some relationship between the exotic matter that forms wormholes and the exotic matter that triggered inflation,” he said.
The new model
isn’t the first to propose that other universes exist inside black holes. Damien Easson, a theoretical physicist at Arizona State University, has made the speculation in previous studies.
“What is new here is an actual wormhole solution in general relativity that acts as the passage from the exterior black hole to the new interior universe.In our paper, we just speculated that such a solution could exist, but Poplawski has found an actual solution,” said Easson, referring to Poplawski’s equations (who was not involved in the new study). Nevertheless, the idea is still very speculative, Easson said in an email.
“Is the idea possible? Yes. Is the scenario likely? I have no idea. But it is certainly an interesting possibility. Future work in quantum gravity—the study of gravity at the subatomic level—could refine the equations and potentially support or disprove Poplawski’s theory”, Easson said.
Overall, the wormhole theory is interesting
, but not a breakthrough in explaining the origins of our universe, said Andreas Albrecht, a physicist at the University of California, Davis, who was also not involved in the new study. By saying our universe was created by a gush of matter from a parent universe, the theory simply shifts the original creation event into an alternate reality. In other words, it doesn’t explain how the parent universe came to be or why it has the properties it has—properties our universe presumably inherited.
“There’re really some pressing problems we’re trying to solve, and it’s not clear that any of this is offering a way forward with that,” he said.
Still, Albrecht doesn’t find the idea of universe-bridging wormholes any stranger than the idea of black hole singularities, and he cautions against dismissing the new theory just because it sounds a little out there.
“Everything people ask in this business is pretty weird,” he said. “You can’t say the less weird [idea] is going to win, because that’s not the way it’s been, by any means.”
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