Researchers Look Beyond the Birth of the Universe
May 12, 2006
The figure represents our expanding universe as the right branch of the arc. Our time now is located at the 1.8 grid mark on the right side of the drawing. According to Ashtekar's team's calculations, when looking backward throughout the history of the universe, 'time' does not go to the point of the Big Bang but bounces to the left branch of the drawing, which describes a contracting universe. Singh explains, "The state of the universe depicted by its wavefunction is shown in space (\mu) and time(\phi). The big bang singularity lies where space vanishes (goes to zero). Our expanding phase of the universe is shown by the right branch which, when reversed backward in time, bounces near the Big Bang to a contracting phase (left branch) and never reaches the Big Bang."
According to Einstein’s general theory of relativity, the Big Bang represents The Beginning, the grand event at which not only matter but space-time itself was born. While classical theories offer no clues about existence before that moment, a research team at Penn State has used quantum gravitational calculations to find threads that lead to an earlier time.
“General relativity can be used to describe the universe back to a point at which matter becomes so dense that its equations don’t hold up,” says Abhay Ashtekar, Holder of the Eberly Family Chair in Physics and Director of the Institute for Gravitational Physics and Geometry at Penn State. “Beyond that point, we needed to apply quantum tools that were not available to Einstein.” By combining quantum physics with general relativity, Ashtekar and two of his post-doctoral researchers, Tomasz Pawlowski and Parmpreet Singh, were able to develop a model that traces through the Big Bang to a shrinking universe that exhibits physics similar to ours.
In research reported in the current issue of Physical Review Letters, the team shows that, prior to the Big Bang, there was a contracting universe with space-time geometry that otherwise is similar to that of our current expanding universe. As gravitational forces pulled this previous universe inward, it reached a point at which the quantum properties of space-time cause gravity to become repulsive, rather than attractive.
“Using quantum modifications of Einstein’s cosmological equations, we have shown that in place of a classical Big Bang there is in fact a quantum Bounce,” says Ashtekar. “We were so surprised by the finding that there is another classical, pre-Big Bang universe that we repeated the simulations with different parameter values over several months, but we found that the Big Bounce scenario is robust.”
While the general idea of another universe existing prior to the Big Bang has been proposed before, this is the first mathematical description that systematically establishes its existence and deduces properties of space-time geometry in that universe.
The research team used loop quantum gravity, a leading approach to the problem of the unification of general relativity with quantum physics, which also was pioneered at the Penn State Institute of Gravitational Physics and Geometry. In this theory, space-time geometry itself has a discrete 'atomic' structure and the familiar continuum is only an approximation. The fabric of space is literally woven by one-dimensional quantum threads. Near the Big-Bang, this fabric is violently torn and the quantum nature of geometry becomes important. It makes gravity strongly repulsive, giving rise to the Big Bounce.
"Our initial work assumes a homogenous model of our universe," says Ashtekar. "However, it has given us confidence in the underlying ideas of loop quantum gravity. We will continue to refine the model to better portray the universe as we know it and to better understand the features of quantum gravity."
Source: Penn State
-
Electrons in concert: A simple probe for collective motion in ultracold plasmas
Feb 06, 2012 |
4.2 / 5 (5) |
0
-
Physics team finds new constraints on how lumpy space-time can be
Jan 11, 2012 |
4.8 / 5 (14) |
13
-
Stephen Hawking celebrates 70th birthday
Jan 08, 2012 |
not rated yet |
0
-
'Unwell' Stephen Hawking misses 70th birthday event
Jan 08, 2012 |
5 / 5 (2) |
1
-
Physicists propose test for loop quantum gravity
Jan 03, 2012 |
4.3 / 5 (34) |
106
-
Engineers build first sub-10-nm carbon nanotube transistor
Feb 01, 2012 |
4.9 / 5 (29) |
30
-
Something old, something new: Evolution and the structural divergence of duplicate genes
Jan 31, 2012 |
4.6 / 5 (7) |
1
-
The hidden nanoworld of ice crystals: Revealing the dynamic behavior of quasi-liquid layers
Jan 30, 2012 |
5 / 5 (3) |
1
-
Stock market network reveals investor clustering
Jan 27, 2012 |
3.9 / 5 (23) |
8
-
Of microchemistry and molecules: Electronic microfluidic device synthesizes biocompatible probes
Jan 26, 2012 |
5 / 5 (1) |
0
-
How to magnetize a concrete wall?
1 hour ago
-
Physics behind Nerf Guns
1 hour ago
-
Upward speed of an object in water
2 hours ago
-
flipping quarks
2 hours ago
-
partial derivation question
2 hours ago
-
How to magnetize water using super magnet?
3 hours ago
- More from Physics Forums - General Physics
More news stories
Physicists build highly efficient 'no-waste' laser
A team of University of California, San Diego researchers has built the smallest room-temperature nanolaser to date, as well as an even more startling device: a highly efficient, "thresholdless" laser that ...
10 hours ago |
5 / 5 (14) |
3
|
Transparent iron? For the first time, an experiment shows that atomic nuclei can become transparent
At the high-brilliance synchrotron light source PETRA III, a team of DESY scientists headed by Dr. Ralf Röhlsberger has succeeded in making atomic nuclei transparent with the help of X-ray light. At the ...
10 hours ago |
5 / 5 (6) |
1
|
Quantum physicist explains $100K offer for proof scaled-up quantum computing is impossible
(PhysOrg.com) -- MIT researcher Scott Aaronson has certainly riled the physics community with his offer this past Friday, of $100,000 to anyone who can prove that scaled-up quantum computing is impossible. ...
Unusual 'collapsing' iron superconductor sets record for its class
(PhysOrg.com) -- A team from the National Institute of Standards and Technology and the University of Maryland has found an iron-based superconductor that operates at the highest known temperature for a material ...
14 hours ago |
4.3 / 5 (3) |
2
|
Flipping a light switch in the cell: Quantum dots used for targeted neural activation
By harnessing quantum dotstiny light-emitting semiconductor particles a few billionths of a meter acrossresearchers at the University of Washington (UW) have developed a new and vastly more targeted ...
12 hours ago |
5 / 5 (3) |
0
|
Astronomy team discovers nearby dwarf galaxy
(PhysOrg.com) -- A team led by UCLA research astronomer Michael Rich has used a unique telescope to discover a previously unknown companion to the nearby galaxy NGC 4449, which is some 12.5 million light years ...
Amasia: As next supercontinent forms, Arctic Ocean, Caribbean will vanish first
(PhysOrg.com) -- Geologists at Yale University have proposed a new theory to describe the formation of supercontinents, the epic process by which Earths major continental blocks combine into a single ...
Why are there so few fish in the Earth's oceans?
(PhysOrg.com) -- A Stony Brook University researcher has found that, contrary to popular belief, there are not plenty of fish in the sea.
Study shows how DNA finds its match
It's been more than 50 years since James Watson and Francis Crick showed that DNA is a double helix of two strands that complement each other. But how does a short piece of DNA find its match, out of the millions ...
Scientists strengthen memory by stimulating key site in brain
Ever gone to the movies and forgotten where you parked the car? New UCLA research may one day help you improve your memory.
Most stretchable spider silk reported
The egg sac silk of the cocoon stalk of the cave spider Meta menardi is the most stretchable egg sac silk yet tested, according to a study published Feb. 8 in the open access journal PLoS ONE.