Are we living in a multiverse? Researchers claim our universe could be just 'one bubble in a frothy sea of bubbles'

Series of experiments could shed new light on the 'multiverse'



Theory claims ours is just one universe among many

Researchers hope it will be a proof of principle and show the multiverse can be tested



The universe could be a bubble amongst a 'frothy sea' of other bubble universes, scientists have claimed.



They hope a new series of experiments could shed new light on the 'multiverse', which says ours is just one universe among many.

Researchers hope it will be a proof of principle and show the multiverse theory can be tested.

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Are we living in a bubble? Canadian researchers say they have created the first experiment that can test the so called 'multiverse' theory that our universe is one of many

WHAT IS THE MULTIVERSE THEORY? The term ‘multiverse’ was invented in December 1960, by Andy Nimmo, then vice chairman of the British Interplanetary Society.

It is based on the theory of eternal inflation, which suggests that shortly after the Big Bang that formed the universe, space-time expanded at different rates in different places.

According to eternal inflation theory, this gave rise to bubble universes that may function with their own separate laws of physics.

The idea of other universes out there may seem strange, but scientists say it can help solve some problems of fundamental physics.

For instance, the long-standing mystery of why nature appears to be fine-tuned for the emergence of life can be explained by the picture of a multiverse.

Some scientists argue that intelligent observers exist only in those rare areas in which the conditions happen to be just right for life to evolve.

The rest of the multiverse remains barren, but no one is there to notice it.



Researchers at the Perimeter Institute for Theoretical Physics in Canada say the theory of multiple universes stems from the idea of there being a vacuum in the beginning of time.



'The vacuum simmered with energy (variously called dark energy, vacuum energy, the inflation field, or the Higgs field).



'Like water in a pot, this high energy began to evaporate – bubbles formed,' they explain.

Each bubble contained another vacuum, whose energy was lower, but still not nothing.



This energy drove the bubbles to expand.



Inevitably, some bubbles bumped into each other. It’s possible some produced secondary bubbles.



Each of these bubbles was a universe.



'In this picture, our universe is one bubble in a frothy sea of bubble universes,' the team say.

The theory arises from the idea of cosmic inflation, that the universe expanded very far very fast after the Big Bang.



While this is the most widely accepted theory of universe formation, it has never been proved - something the researchers believe they could change.



'We’re trying to find out what the testable predictions of this picture would be, and then going out and looking for them,' said Perimeter Associate Faculty member Matthew Johnson

The researchers have been considering the rare cases in which our bubble universe might collide with another bubble universe.



'We simulate the whole universe,' he said.

'We start with a multiverse that has two bubbles in it, we collide the bubbles on a computer to figure out what happens, and then we stick a virtual observer in various places and ask what that observer would see from there.

'Simulating the universe is easy,' he claims.

'We’re simulating things only on the largest scales,' he says.



'All I need is gravity and the stuff that makes these bubbles up.



'We’re now at the point where if you have a favourite model of the multiverse, I can stick it on a computer and tell you what you should see.'

Johnson says the program has already reached the point where it can rule out certain models of the multiverse.

Cosmologists studying a map of the universe from data gathered by the Planck spacecraft concluded that it shows anomalies that can only have been caused by the gravitational pull of other universes - but the results have now been called into question



'We’re now able to say that some models predict something that we should be able to see, and since we don’t in fact see it, we can rule those models out.'

For instance, collisions of one bubble universe with another would leave what Johnson calls 'a disk on the sky' – a circular bruise in the cosmic microwave background.



That the search for such a disk has so far come up empty makes certain collision-filled models less likely.

It’s the first time, the team writes in their paper, that anyone has produced a direct quantitative set of predictions for the observable signatures of bubble collisions.















