Mrkim Report This Comment
Date: September 02, 2011 11:28AM
for National Geographic News
Published April 9, 2010
Like part of a cosmic Russian doll, our universe may be nested inside a black
hole that is itself part of a larger universe.
In turn, all the black holes found so far in our universe—from the microscopic
to the supermassive—may be doorways into alternate realities.
According to a mind-bending new theory, a black hole is actually a tunnel
between universes—a type of wormhole. The matter the black hole attracts
doesn't collapse into a single point, as has been predicted, but rather gushes
out a "white hole" at the other end of the black one, the theory
(Related: "New Proof Unknown 'Structures' Tug at Our Universe."
In a recent paper published in the journal Physics Letters B, Indiana University
physicist Nikodem Poplawski presents new mathematical models of the spiraling
motion of matter falling into a black hole. His equations suggest such wormholes
are viable alternatives to the "space-time singularities" that Albert
Einstein predicted to be at the centers of black holes.
According to Einstein's equations for general relativity, singularities are
created whenever matter in a given region gets too dense, as would happen at the
ultradense heart of a black hole.
Einstein's theory suggests singularities take up no space, are infinitely dense,
and are infinitely hot—a concept supported by numerous lines of indirect
evidence but still so outlandish that many scientists find it hard to
If Poplawski is correct, they may no longer have to.
According to the new equations, the matter black holes absorb and seemingly
destroy is actually expelled and becomes the building blocks for galaxies,
stars, and planets in another reality.
(Related: "Dark Energy's Demise? New Theory Doesn't Use the Force."
Wormholes Solve Big Bang Mystery?
The notion of black holes as wormholes could explain certain mysteries in modern
cosmology, Poplawski said.
For example, the big bang theory says the universe started as a singularity. But
scientists have no satisfying explanation for how such a singularity might 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. (Related: "Gamma-Ray Burst Caused Mass
Poplawski proposes that the bursts may be discharges of matter from alternate
universes. The matter, he says, might be escaping into our universe through
supermassive black holes—wormholes—at the hearts of those galaxies, though
it's not clear how that would be possible.
"It's kind of a crazy idea, but who knows?" he said. (Related:
"Are Wormholes Tunnels for Time Travel?"
There is at least one way to test Poplawski's theory: Some of our universe's
black holes rotate, and if our universe was born inside a similarly revolving
black hole, then our universe should have inherited the parent object's
If future experiments reveal that our universe appears to rotate in a preferred
direction, it would be indirect evidence supporting his wormhole theory,
Wormholes Are "Exotic Matter" Makers?
The wormhole theory may also help explain why certain features of our universe
deviate from what theory predicts, according to physicists.
Based on the standard model of physics, after the big bang the curvature of the
universe should have increased over time so that now—13.7 billion years
later—we should seem to be sitting on the surface of a closed, spherical
But observations show the universe appears flat in all directions.
What's more, data on light from the very early universe show that everything
just after the big bang was a fairly uniform temperature.
That would mean that the farthest objects we see on opposite horizons of the
universe were once close enough to interact and come to equilibrium, like
molecules of gas in a sealed chamber.
Again, observations don't match predictions, because the objects farthest from
each other in the known universe are so far apart that the time it would take to
travel between them at the speed of light exceeds the age of the universe.
To explain the discrepancies, astronomers devised the concept of inflation.
Inflation states that shortly after the universe was created, it experienced a
rapid growth spurt during which space itself expanded at faster-than-light
speeds. The expansion stretched the universe from a size smaller than an atom to
astronomical proportions in a fraction of a second.
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—assuming inflation is real—astronomers have always been at pains to
explain what caused it. That's where the new wormhole theory comes in.
According to Poplawski, some theories of inflation say the event was caused by
"exotic matter," a theoretical substance that differs from normal
matter, in part because it is repelled rather than attracted by gravity.
Based on his equations, Poplawski thinks such exotic matter might 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.
(Related: "Before the Big Bang: Light Shed on 'Previous Universe.'"
Wormhole Equations an "Actual Solution"
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," said Easson, who was not involved in the new study.
"In our paper, we just speculated that such a solution could exist, but
Poplawski has found an actual solution," said Easson, referring to
(Related: "Universe 20 Million Years Older Than Thought."
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.
Wormhole Theory No Breakthrough
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
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
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."