Was the universe and the world we live in created with a Big Bang 13.7 billion years back, or has it been enlarging and contracting for an eternity? A new newspaper, motivated by different explanations of the physics of black holes, investigates the latter potential, also rejecting a core tenant of the Big Bang hypothesis.
The universal source story called the Big Bang postulates that, 13.7 billion years ago, our world emerged from a singularity — a point of infinite density and gravity — and that before this occasion, space and time didn’t exist (which means the Big Bang happened at no place without moment).
For one, the world is still expanding in every direction. The further away an object is, the quicker it appears to move away from an audience, indicating that space itself is expanding (rather than objects simply moving through space at a steady speed).
Another essential item of evidence is the cosmic microwave background (CMB), which is thought to be heat left over from this fantastic cosmological event. It may be observed in each direction and contains no single origin point. Scientists think the CMB started dispersing throughout the world about 380,000 years after the Big Bang, when atoms began to form and the universe became clear, as stated by the European Space Agency.
However, there’s no direct proof of the first singularity (collecting information from this very first moment of growth is impossible with present methods). In the new paper, Brazilian physicist Juliano Cesar Silva Neves argues that the original singularity may not have existed.
He explained that “there are lots of observations in cosmology that support the theory that the world went through a period of accelerated expansion, but that there’s no direct evidence that this growth started with a singularity”.
In a paper published on Aug. 29 in the journal General Relativity and Gravitation, Silva Neves, a researcher at the Mathematics, Statistics & Scientific Computation Institute (IMECC-UNICAMP) of the University of Campinas, in Brazil, suggests an alternate cosmological model that does away with the requirement of the original singularity. His model includes a concept called bouncing cosmology.
The concept first appeared at least 40 years ago and it claimed that the world is expanding, but without the assumption that the world came to being when that growth started and the universe was infinitely tiny. Instead, it proposes that the world is forever undergoing a cycle of regeneration and growth. These alternating phases smoothly follow each other like the phases of the tide.
Silva Neves unites this concept with other concepts of the physics of black holes. Like the original singularity from which the universe emerged, black holes are thought to have a point of infinite density within their center. But while a stage of “infinite” mass can exist easily in theory, scientists have always struggled with how such a thing could exist in reality.
In a 1968 paper, physicist James Bardeen suggested a concept of this so-called regular black hole — that is a black hole with no singularity at the middle. Such a thing is mathematically feasible if its mass isn’t constant, but instead depends upon the distance to its centre.
Silva Neves said his “cosmological model was constructed from research in ordinary black holes,” and avoids the need for a singularity in both black holes and also the beginning of universal expansion. He notes however, that this remains purely hypothetical.
“There is no empirical proof for bouncing cosmologies today,” he explained. “But there’s no evidence for its first singularity too.”
Silva Neves said that if indeed the universe is infinite, it may be possible to find that which he calls “vestiges of the preceding stages” — remnants and leftovers of the previous cosmic contraction and expansion periods.
“Black holes’ gravitational waves from the previous phase may be present now,” he said.
According to astrophysicist Gonzalo Olmo in the University of Valencia, in Spain, Silva Neves’ model is mathematically viable.
“To implement this black hole tip in a cosmological model implies moving from a homogeneous universe where most of spatial points have identical properties into inhomogeneous models,” Olmo told Space.com.
“Observations of the cosmic microwave background signify a high level of homogeneity in the early universe and it’s uncertain how this inhomogeneous model could yield a homogeneous universe like the one we see.”
That, however, does not indicate another bouncing cosmology model couldn’t get it right later on, Olmo explained.