THE Big Bang theory is the widest known and most broadly accepted scientific explanation of the origins of our universe.
It emerged in the 1920s when astronomer Edwin Hubble discovered that almost all galaxies were racing away from each other at ever increasing velocities. The universe was in a state of inflation.
Wind back that clock 13.82 billion years and they all start at the same point.
The Big Bang.
But, like all science, it’s an idea open to challenge — if there’s new evidence, or at least if the mathematical argument adds up.
And that appears to have happened.
“I believe the Big Bang never happened,” says Brazilian physicist. Juliano César Silva Neves.
The idea isn’t new.
But Neves has added weight to this alternative explanation of our universe’s observed behaviour through applying an old mathematical trick to black holes.
Black holes are weird beasts.
They represent the point at which much of our math breaks down: infinity.
Nor, on the surface, do black holes appear to have anything in common with the rest of the universe.
The known universe is expanding. It’s filled with wispy tendrils of galaxies. But dial back time, all its matter contracts to a single point beyond which nothing can bee seen.
A black hole is an incredibly dense lump of imploded star. This contracts to a point of such intense gravity not even light can escape. But there is no way to see beyond its event horizon.
“There are two kinds of singularity in the Universe,” says Neves.
“One is the alleged cosmological singularity, or Big Bang. The other hides behind the event horizon of a black hole.”
Both represent the point at which known physics collapse.
With all that mass and energy concentrated in an infinitely small space ... nothing adds up.
So what if singularities don’t exist in the first place?
“There are no singularities in so-called regular black holes,” says Neves.
It’s a powerful assertion. One that goes against much established thought.
But we have not yet been able to directly observe black holes. And we will likely never know what’s going on behind an event horizon.
Which means alternative arguments may apply.
And the annoying mathematical roadblock of infinity may have a bypass.
“The inspiration for the bouncing Universe came from a mathematical trick to avoid the formation of singularities in black holes,” he said.
The idea was formulated in 1968 by US physicist James Bardeen.
He found an alternative explanation for the general relativity equations used to describe black holes.
“What defines a black hole isn’t a singularity but an event horizon,” Neves argues. “Outside the event horizon of a regular black hole, there are no major changes, but inside it, the changes are deep-seated. There’s a different space-time that avoids the formation of a singularity.”
It would still be super dense. But it just would not be constant.
The black holes’ density depends on how far from its centre you are, he says.
This means mass — the stuff the universe is made of — still acts as though it has a physical volume, even though it is still squeezed into a singularity-like space.
Neeves says Bardeen’s argument can be applied to the other known type of singularity — the one that produced the Big Bang.
“In order to measure the rate at which the Universe is expanding with the standard cosmology, the model in which there’s a Big Bang, a mathematical function is used that depends only on cosmological time,” Neves says.
But he argues scale also plays a part. And once this is incorporated in the equations, the Big Bang evaporates.
It eliminates the need for the infintessimally small quantum universe to burst out into physical space 13.82 billion years ago.
THE BIG BOUNCE
Neves’ argument proposes a universe without singularities would produce an eternal cycle of expansion and contraction.
The universe races outwards until it reaches a tipping point. The space between the widely dispersed mass acts as a rubber band, reversing its motion.
This contraction would continue, with galaxies moving ever faster and ever closer towards a common point.
They then merge in a Big Crunch, which produces a rebound ...
Once again, it’s not a new idea.
The application of Bardeen’s mathematical argument gives it extra credibility.
But can the idea be tested?
“In modern science, a theory is worthless if cannot be verified, however beautiful and inspiring it may be,” Neves admits.
He says each contraction and expansion event may not eliminate all evidence of the previous state of the universe.
“Who knows, there may be remains of black holes in the ongoing expansion that date from the prior contraction phase and passed intact through the bottleneck of the bounce,” Neves told Agência FAPESP.
Identifying these would clinch the argument and kill-off the Big Bang theory once and for all.
“What traces? The candidates include remnants of black holes from a previous phase of universal contraction that may have survived the bounce,” Neves says.