What if There was No Big Bang?

Cosmology  

Most of us understand the Big Bang as the concept that our entire universe came from a single point, what astrophysicists call a 'Singularity.' A new model however suggests that we might not need a singularity to have a Big Bang.

T
he question of cosmology of how do you get something from nothing has confounded philosophers for millennia. The question's accepted answer for the better part of recent history (outside of religious conceptions) has been the Big Bang.

The University of Lethbridge's Saurya Das and Ahmed Farag Ali – who was a PhD student at the U of L before taking a faculty position at Benha University in Egypt, recently put forth a mathematical model that assumes the Big Bang never happened and the universe has simply been eternal.

The paper explaining the model was recently published in the journal Physics Letters B, has received a lot of attention in the cosmology community for convincingly contradicting the conventional wisdom that the universe originated from a Singularity about 13.8 billion years ago.

While it explains a lot of what we have so far observed about the universe, the Big Bang theory and the Singularity in particular, leads to some conclusions which are very difficult to model and explain.

"The Singularity [in cosmology] is basically where all theories and all physics breaks down, so nobody really likes that,” Das said.

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The best current theories can only explain what happens immediately after the Big Bang, not during or before it. Even the idea of “before” the Big Bang is itself a conundrum, as the Singularity is thought to be the origin of space and time.

"We need more confirmations and more careful study of our model, for sure. We have to understand the mathematics better and whatever predictions it makes has to be tested with observations."

The new model developed by Das and Ali gets around that problem, as it simply states there was no singularity and the universe’s existence has been in a more or less steady state of existence.

Physicists have long believed that a quantum version of gravity would include a hypothetical particle, called the graviton, which generates the force of gravity. In their new model, Ali and Das propose that such gravitons could form this quantum fluid.

The new model moves away from the “expanding universe” theory. It also gets away from the matter of the universe’s previous infinite size and density, which the paper calls the “smallness problem,” by relying on a “cosmological constant” term that puts the universe at a finite size.

Speaking to Nature Middle East last month, Ali said the theory helped unify quantum mechanics and general relativity: "Our theory serves to complement Einstein’s general relativity, which is very successful at describing physics over large distances…But physicists know that to describe short distances, quantum mechanics must be accommodated."

Das said he’s been encouraged to see such interest in the model but cautioned there’s still plenty more work do to.

“We need more confirmations and more careful study of our model, for sure,” he said. “We have to understand the mathematics better and whatever predictions it makes has to be tested with observations.”

The new model also takes dark matter into account. So far, dark matter has only been perceptible through its gravitational effect on visible matter such as stars. When Das and a colleague set the mass of the graviton in the model to a small level, they could make the density of their fluid match the universe’s observed density of dark matter, while also providing the right value for dark energy’s push.

“This is the first time that anyone has shown that these two major problems in cosmology can be solved simultaneously by the quantum Raychaudhuri equation,” says Ali.

“We feel a deep sense of satisfaction that this model may resolve some of the most important cosmological issues in one stroke,” adds Das.

If his work turns out to fundamentally alter our understanding of where everything comes from, Das also suggests it would be far from the final answer.

“Of course, it brings new problems, new questions, like: What was the universe before what we think is the Big Bang?” he said. “That’s great, because a lot of us would be interested in investigating those things further and hopefully getting answers to them, in due course.”


SOURCE  Metro News

By 33rd Square

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