Big Bang Cosmology
Quantua Magazine published a story on June 6 about recent developments in Big Bang cosmology.
I am just amazed at that bundle of confusion.
Following are excepts with my comments. Perhaps some will find this entertaining.
"Asking what came before the Big Bang is meaningless"
in other words we have a theory but we won't explain it.
"The trouble with Stephen and Jim's approach is it was ambiguous," Turok said — "deeply ambiguous."
"We discovered that it just failed miserably," Turok said.
The Penrose-Hawking "singularity theorems" meant there was no way for space-time to begin smoothly, undramatically at a point.
Likewise, Hartle and Hawking expressed the wave function of the universe — which describes its likely states — as the sum of all possible ways that it might have smoothly expanded from a point.
It appears cosmologists are now using a probability scheme.
Their model will start with all likely states and then they will somehow figure out how the current universe randomly arose out of this possible mix.
If I were a video game programmer this is a useful initial approach when seeking to present the player with unpredictable challenges. This is not the correct approach for a science to develop a testable theory.
In their view, the only sensible contour is one that scans through real values (as opposed to imaginary values, which involve the square roots of negative numbers) for a variable called "lapse."
I am glad someone is looking for a sensible contour for their 'minisuperspace.'
They are working on a better model, with charm.
For the past year, Turok and colleagues have been developing a new cosmological model that has much in common with the no-boundary proposal. But instead of one shuttlecock, it envisions two, arranged cork to cork in a sort of hourglass figure with time flowing in both directions. While the model is not yet developed enough to make predictions, its charm lies in the way its lobes realize CPT symmetry, a seemingly fundamental mirror in nature that simultaneously reflects matter and antimatter, left and right, and forward and backward in time. One disadvantage is that the universe's mirror-image lobes meet at a singularity, a pinch in space-time that requires the unknown quantum theory of gravity to understand. Boyle, Finn and Turok take a stab at the singularity, but such an attempt is inherently speculative.
I am not encouraged with this approach, with antimatter in opposing directions and time moving in both directions, with mirror-image lobes. Taking a stab at it implies no confidence.
All of this sounds like just mathematical modelling (apparently benefiting from gaming theory) without ever getting to the physics that actually drives the motions in the universe.
I expect EUT can bring sanity to cosmology but it must replace quite a mess.
link to article
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