Feeds

WTF is … the multiverse?

BICEP2's flex, inflation and ... quantum physics

Choosing a cloud hosting partner with confidence

Along with the general excitement surrounding the announcement that astrophysicists may have found a way to confirm the “cosmic inflation” model of the early universe came a keen sub-debate: does this result imply we live in just one universe of a so-called “multiverse”.

The Register doesn't have the requisite competency in physics to judge the veracity of multiverse theories, but we did have a conversation with ANU astrophysicist Dr Brad Tucker. We attempted to rack Dr Tucker's brains to try to answer two questions: can cosmic inflation imply a multiverse, and if so, why?

In asking the question, and in answering it, both El Reg and Tucker respectively acknowledge that there's still deep scepticism about multiverse models – but it's probably easier to watch the science unfold if you understand why multiverse models have been put forward in the first place.

What the BICEP2 experiment discovered is a polarisation – primordial B-mode polarisation – that it believes demonstrates the existence of an inflationary period in the universe. This inflation was predicted and explored by luminaries such as Alan Guth and Andrei Linde back in the 1980s.

If the BICEP2 results are correct – remembering that they're still to go through peer review – they would constitute the best observational evidence so far to support the inflationary model.

The reason BICEP2 implies inflation is that the polarisation is present fairly uniformly across the whole of the cosmic background radiation. In other words: whatever caused the polarisation represents sufficient energy to make the mathematics of cosmic inflation stack up.

And it was a tweet of a comment by Linde – that “If inflation is there, then the multiverse is there” – that captured The Register's interest.

Inflation and particle physics

As Dr Tucker explained, in the “generic inflation” model, in order to create enough energy and space for our universe to undergo that inflationary period, “you imply an infinite amount of energy and space.”

Even though our universe is big, “an infinite amount” of energy and space leaves a lot left over to be explained.

Hence the multiverse hypothesis: it balances the scales. The inflationary period, followed by a gravitational collapse into the universe we can observe, gives us the 13.8 billion years of universe history we can observe – leaving the excess energy and space beyond the reach of we inside the bubble.

“To get inflation, you have to have a vast amount of vacuum energy,” Dr Tucker explained.

He explained that the vastness of astrophysics intersects with the tiny world of particle physics – because it's in the quantum world that vacuum energy was posited and, via our observations of quantum noise, is measured.

Here's a vastly over-simplified thought experiment: if you took a cubic metre of dead vacuum and watched it for long enough, with sufficient sensitivity, you would eventually see pairs of particles and anti-particles (same mass, opposite charge) spontaneously pop into existence and annihilate each other, leaving behind a brief flash of energy.

As has been discussed before in El Reg, this has been observed. But there's nowhere near enough vacuum energy to account for cosmic inflation – at least, not in the universe we can see and measure.

Between the vacuum energy we know about and the amount needed to drive inflation throughout the early universe, Dr Tucker says, "the scales are off by a hundred orders of magnitude".

A cynical view of the multiverse might be that it's simply a way to balance the books of the universe, to give it enough vacuum energy to drive the cosmic inflation that the BICEP2 has just demonstrated.

“If inflation exists, the vacuum energy is contained on a larger scale than in our 'own' universe,” Dr Tucker explained.

Does this, however, imply that there's more than one bubble? Isn't it enough to postulate that beyond the bounds of the universe we can observe, there's nothing but that larger-scale structure in which there's nothing but the missing energy?

About that, “there's a lot of debate,” Tucker said.

“What's exciting is that we're just taking the first footsteps. Does this result imply that the excess energy can be found somewhere, or does it just tell us we still don't quite understand inflation?” ®

Secure remote control for conventional and virtual desktops

More from The Register

next story
GRAV WAVE DRAMA: 'Big Bang echo' may have been grit on the scanner – boffins
Exit Planet Dust on faster-than-light expansion of universe
Mine Bitcoins with PENCIL and PAPER
Forget Sudoku, crunch SHA-256 algos
SpaceX Dragon cargo truck flies 3D printer to ISS: Clawdown in 3, 2...
Craft berths at space station with supplies, experiments, toys
'This BITE MARK is a SMOKING GUN': Boffins probe ancient assault
Tooth embedded in thigh bone may tell who pulled the trigger
DOLPHINS SMELL MAGNETS – did we hear that right, boffins?
Xavier's School for Gifted Magnetotaceans
Big dinosaur wowed females with its ENORMOUS HOOTER
That's right, Doris, I've got biggest snout in the prehistoric world
Japanese volcano eruption reportedly leaves 31 people presumed dead
Hopes fade of finding survivors on Mount Ontake
That glass of water you just drank? It was OLDER than the SUN
One MEELLION years older. Some of it anyway
Canberra drone team dances a samba in Outback Challenge
CSIRO's 'missing bushwalker' found and watered
prev story

Whitepapers

Forging a new future with identity relationship management
Learn about ForgeRock's next generation IRM platform and how it is designed to empower CEOS's and enterprises to engage with consumers.
Storage capacity and performance optimization at Mizuno USA
Mizuno USA turn to Tegile storage technology to solve both their SAN and backup issues.
The next step in data security
With recent increased privacy concerns and computers becoming more powerful, the chance of hackers being able to crack smaller-sized RSA keys increases.
Security for virtualized datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.
A strategic approach to identity relationship management
ForgeRock commissioned Forrester to evaluate companies’ IAM practices and requirements when it comes to customer-facing scenarios versus employee-facing ones.