It is currently Tue Nov 20, 2018 12:04 pm


No Big Bang?

  • Author
  • Message
Offline
User avatar

Wade Hampton III

  • Posts: 1608
  • Joined: Fri Oct 18, 2013 10:40 pm
  • Location: Pontiac, SC

No Big Bang?

PostTue Sep 11, 2018 3:56 am

February 9, 2015 by Lisa Zyga, Phys.org ...

This is an artist's concept of the metric expansion of space, where space (including
hypothetical non-observable portions of the universe) is represented at each time by
the circular sections. Note on the left the dramatic expansion (not to scale) occurring
in the inflationary epoch, and at the center the expansion acceleration. The scheme is
decorated with WMAP images on the left and with the representation of stars at the
appropriate level of development.
57428
57428.JPG
57428.JPG (48.38 KiB) Viewed 215 times

The universe may have existed forever, according to a new model that applies quantum
correction terms to complement (Jew) Einstein's theory of general relativity. The model may
also account for dark matter and dark energy, resolving multiple problems at once. The
widely accepted age of the universe, as estimated by general relativity, is 13.8 billion
years. In the beginning, everything in existence is thought to have occupied a single
infinitely dense point, or singularity. Only after this point began to expand in a "Big
Bang" did the universe officially begin.

Although the Big Bang singularity arises directly and unavoidably from the mathematics
of general relativity, some scientists see it as problematic because the math can explain
only what happened immediately after—not at or before—the singularity. "The Big Bang
singularity is the most serious problem of general relativity because the laws of physics
appear to break down there," Ahmed Farag Ali at Benha University and the Zewail City
of Science and Technology, both in Egypt, told Phys.org.
57427
57427.JPG
57427.JPG (37.19 KiB) Viewed 215 times

li and coauthor Saurya Das at the University of Lethbridge in Alberta, Canada, have
shown in a paper published in Physics Letters B that the Big Bang singularity can be
resolved by their new model in which the universe has no beginning and no end.

Old ideas revisited?

The physicists emphasize that their quantum correction terms are not applied ad hoc
in an attempt to specifically eliminate the Big Bang singularity. Their work is based
on ideas by the theoretical physicist David Bohm, who is also known for his contributions
to the philosophy of physics. Starting in the 1950s, Bohm explored replacing classical
geodesics (the shortest path between two points on a curved surface) with quantum
trajectories. In their paper, Ali and Das applied these Bohmian trajectories to an
equation developed in the 1950s by physicist Amal Kumar Raychaudhuri at Presidency
University in Kolkata, India. Raychaudhuri was also Das's teacher when he was an
undergraduate student of that institution in the '90s. Using the quantum-corrected
Raychaudhuri equation, Ali and Das derived quantum-corrected Friedmann equations,
which describe the expansion and evolution of universe (including the Big Bang)
within the context of general relativity. Although it's not a true theory of quantum
gravity, the model does contain elements from both quantum theory and general relativity.
Ali and Das also expect their results to hold even if and when a full theory of quantum
gravity is formulated.

No singularities nor dark stuff!

In addition to not predicting a Big Bang singularity, the new model does not predict
a "big crunch" singularity, either. In general relativity, one possible fate of the
universe is that it starts to shrink until it collapses in on itself in a big crunch
and becomes an infinitely dense point once again. Ali and Das explain in their paper
that their model avoids singularities because of a key difference between classical
geodesics and Bohmian trajectories. Classical geodesics eventually cross each other,
and the points at which they converge are singularities. In contrast, Bohmian
trajectories never cross each other, so singularities do not appear in the equations.
In cosmological terms, the scientists explain that the quantum corrections can be
thought of as a cosmological constant term (without the need for dark energy) and a
radiation term. These terms keep the universe at a finite size, and therefore give
it an infinite age. The terms also make predictions that agree closely with current
observations of the cosmological constant and density of the universe.

New gravity particle!

In physical terms, the model describes the universe as being filled with a quantum
fluid. The scientists propose that this fluid might be composed of gravitons —
hypothetical massless particles that mediate the force of gravity. If they exist,
gravitons are thought to play a key role in a theory of quantum gravity. In a
related paper, Das and another collaborator, Rajat Bhaduri of McMaster University,
Canada, have lent further credence to this model. They show that gravitons can form
a Bose - Einstein condensate (named after [the Jew] Einstein and another Indian
physicist, Satyendranath Bose) at temperatures that were present in the universe
at all epochs. Motivated by the model's potential to resolve the Big Bang singularity
and account for dark matter and dark energy, the physicists plan to analyze their
model more rigorously in the future. Their future work includes redoing their study
while taking into account small inhomogeneous and anisotropic perturbations, but they
do not expect small perturbations to significantly affect the results. "It is satisfying
to note that such straightforward corrections can potentially resolve so many issues
at once," Das said.
*

Return to Science & Technology

Who is online

Users browsing this forum: No registered users and 0 guests

cron