“Our own Universe may be the interior of a black hole existing in another universe.” In a remarkable paper about the nature of space and the origin of time, Nikodem Poplawski, a physicist at Indiana University, suggests that a small change to the theory of gravity implies that our universe inherited its arrow of time from the black hole in which it was born.
Poplawski proposes that the universe in which the Earth exists may be located within the wormhole of a black hole which itself exists in an even larger universe. A universe could exist 'inside every black hole,' claims scientist
Using an adaptation of Einstein's general theory of relativity, Poplawski analysed the theoretical motion of particles entering a black hole. He concluded that it was possible for a whole new universe to exist inside every black hole, which could mean that our own universe could be inside a black hole as well.
Explaining his theory in the journal Physics Letters B, he said he used the Einstein-Cartan-Kibble-Sciama (ECKS) theory of gravity, in his analysis to account for the angular momentum of particles in a black hole. Doing this it made it possible to calculate a quality of space-time called torsion, a property believed to repel gravity.
He says instead of matter reaching infinite density in a black hole called "singularities" in Einstein's theory of relativity - the behaviour of the space-time acts more like a spring being compressed with matter rebounding and expanding continuously.
Dr Poplawski explains that this "bounce-back" effect is caused by the torsion of space-time having a repulsive force against the gargantuan strength of gravity in a black hole.
Dr Poplawski also claims that this recoiling effect could be what has led to our expanding universe that we observe today and could explain why our universe is flat, homogeneous and isotropic without needing cosmic inflation.
It is hard to see how we could test whether or not Dr Poplawski's theory is correct; the force of gravity in black holes is such that nothing can escape, so no information about what is going on inside one can ever reach us.
However, according to Dr Poplawski, if we were living in a spinning black hole then the spin would transfer to the space-time inside, meaning the universe would have a preferred direction - something we would be able to measure. Such a preferred direction could be related to the observed imbalance of matter and anti-matter in the universe and could explain the oscillation of neutrinos.
Poplawski says that the idea that black holes are the cosmic mothers of new universes is a natural consequence of a simple new assumption about the nature of spacetime. Poplawski points out that the standard derivation of general relativity takes no account of the intrinsic momentum of spin half particles. However there is another version of the theory, called the Einstein-Cartan-Kibble-Sciama theory of gravity, which does.
This theory predicts that particles with half integer spin should interact, generating a tiny repulsive force called torsion. In ordinary circumstances, torsion is too small to have any effect. But when densities become much higher than those in nuclear matter, it becomes significant. In particular, says Poplawski, torsion prevents the formation of singularities inside a black hole.
Astrophysicists have long known that our universe is so big that it could not have reached its current size given the rate of expansion we see now. Instead, they believe it grew by many orders of magnitude in a fraction of a second after the Big Bang, the period known as known as inflation.
Poplawski's approach immediately solves the inflation problem, saying that torsion caused this rapid inflation, which means the universe as we see it today can be explained by a single theory of gravity without any additional assumptions about inflation.
Another important corollary of Poplawski's approach is that it makes it possible for universes to be born inside the event horizons of certain kinds of black hole where torsion prevents the formation of a singularity but allows energy density to build up, which leads to the creation of particles on a massive scale via pair production followed by the expansion of the new universe.
"Such an expansion is not visible for observers outside the black hole, for whom the horizon's formation and all subsequent processes occur after infinite time," says Poplawski. For this reason, he emphasizes, the new universe is a separate branch of space time and evolves accordingly.
Poplawski's theory also suggests an solution lto why time seems to flow in one direction but not in the other, even though the laws of physics are time symmetric.
Poplawski says the origin of the arrow of time comes from the asymmetry of the flow of matter into the black hole from the mother universe. "The arrow of cosmic time of a universe inside a black hole would then be fixed by the time-asymmetric collapse of matter through the event horizon," he says.
Translated, this means that our universe inherited its arrow of time from its source. "Daughter universes," he says, "may inherit other properties from their mothers," implying that it may be possible to detect these properties, providing an experimental falsifiable proof of his idea.
Casey Kazan via Ref: arxiv.org/abs/1007.0587: Cosmology With Torsion - An Alternative To Cosmic Inflation