On 12/22/2018 12:04 PM, Philip Thrift wrote:
https://www.eurekalert.org/pub_releases/2018-12/lsu-be122018.php
Theoretical physicists developed a theory called loop quantum gravity
in the 1990s that marries the laws of microscopic physics, or quantum
mechanics, with gravity, which explains the dynamics of space and
time. Ashtekar, Olmedos and Singh's new equations describe black holes
in loop quantum gravity and showed that black hole singularity does
not exist.
"In Einstein's theory, space-time is a fabric that can be divided as
small as we want. This is essentially the cause of the singularity
where the gravitational field becomes infinite. In loop quantum
gravity, the fabric of space-time has a *tile-like structure*, which
cannot be divided beyond the smallest tile. My colleagues and I have
shown that this is the case inside black holes and therefore there is
no singularity," Singh said.
"These tile-like units of geometry--called 'quantum excitations'--
which resolve the singularity problem are orders of magnitude smaller
than we can detect with today's technology, but we have precise
mathematical equations that predict their behavior," said Ashtekar,
who is one of the founding fathers of loop quantum gravity.
But is this consistent with https://arxiv.org/abs/1109.5191v2 which
showed spacetime to be smooth down to 1/525 of the Planck length?
Brent
"At LSU, we have been developing state-of-the-art computational
techniques to extract physical consequences of these physical
equations using supercomputers, bringing us closer to reliably test
quantum gravity," Singh said.
Einstein's theory fails not only at the center of the black holes but
also to explain how the universe was created from the Big Bang
singularity. Therefore, a decade ago, Ashtekar, Singh and
collaborators began to extend physics beyond the Big Bang and make new
predictions using loop quantum gravity. Using the mathematical
equations and computational techniques of loop quantum gravity, they
showed that the Big Bang is replaced by the "Big Bounce."
[ a short lecture on LQG: https://www.youtube.com/watch?v=QMpkFde3euA ]
- pt
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