
Quantum Gravity’s Time Problem - dnetesn
http://abstractions.nautil.us/article/71/quantum-gravitys-time-problem
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woodandsteel
I have a question. In string theory, what is the nature of time? Is it
universal and absolute, like QM, or dynamic like relativity, or yet something
else?

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marcosdumay
Normal QM is what you get when you do quantization of Newtonian Mechanics,
that's why it has an absolute time.

If you quantize General Relativity instead, you'll get a variant of QM with
relative times. But it's much more complex, and useless for most daily
applications¹, so people don't use it often.

1 - X-ray measurements and nuclear physics are two important exceptions.

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contravariant
Did you mean special relativity? Or is there some limited way in which you can
quantize general relativity?

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marcosdumay
Yep, I meant special relativity.

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kurthr
TL;DR _“I think we now understand that space-time really is just a geometrical
representation of the entanglement structure of these underlying quantum
systems,”_ said Mark Van Raamsdonk

I'm a bit disappointed since this article really doesn't get to much new or
much substance. The emergent time/gravity idea is interesting, but this is a
rehash of other recently discussed results in theoretical universes much
different from ours, that are believed by a small group of physicists to be
relevant... but haven't been shown to be.

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walrus1066
The problem with all these quantum gravity theories is they cannot be proven,
or falsified, by experiment.

Not the theorists fault, we'd need an LHC the circumference of the galaxy, or
build a black hole in a lab, to test quantum gravity. But it means we will
never know if the theory in question is actually how nature works.

~~~
JumpCrisscross
> _we will never know_

We as in our lifetimes? Or we as in our species?

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danbruc
I am not aware of any mechanism that definitively places experiments testing
theories of quantum gravity outside of our reach. We may not be able to probe
Planck scale effects in the laboratory for a very long time or possibly even
never, but it seems to depend a lot on the specific theory one wants to test
where and at which scales deviations from current theories occur. I don't see
any reasons why deviations could not occur only an order of magnitude beyond
our current experimental limits and therefore be experimentally accessible in
a lifetime. And even if experiments in the laboratory were currently
impossible, there is always the possibility that we can gather indirect
evidence by observing distant galaxies, black holes, the cosmic microwave
background or something along that line.

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walrus1066
The Planck energy is where we can be 100% certain to observe quantum gravity.
There are 16 orders of magnitude between the LHC collision energies and the
Planck scale. That's a humongous energy range in which to look for new
physics. You could build a collider that's 10x more powerful than the LHC, but
it'd be a stab in the dark, as the new physics may occur at 100x the LHC
energy, or much much more.

To date there is no indirect evidence (e.g. Particle decay rates that deviate
from the standard model predictions) that points to quantum gravity effects
occuring below the Planck scale.

This indirect evidence is required to make a case for building a super
expensive particle collider. For example, the LHC was built because we knew
through indirect evidence, that it would either find the higgs boson, or new
physics if the higgs wasn't found.

Without indirect evidence your experiment is a stab in the dark, which is
fine, but for particle physics an insanely expensive stab in the dark.

Regarding astronomical evidence, it can give hints on quantum phenomena, but
can't shed much light on their cause. For instance, we know dark matter exists
via astronomy, but it can't tell us what the stuff actually is, we need
laboratory evidence for that, I.e. Produce it in a collider, measure its mass,
spin, other quantum properties, and how it interacts with other particles.

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emblem21
Greetings.

The worldsheet is time-symmetric, otherwise, if you pulled a single point of
the worldsheet, the point would remain, and no elastic resistance would occur.
If we presume that elastic resistance occurs, then we assume any pulled point
will restore to elastic equilibrium with the aggregate elastic potential of
the entire worldsheet, and thus, time symmetry IS the zero aggregate elastic
equilibrium of a worldsheet.

We are not talking about zero UNIFORM elastic equilibrium, in which each point
is at zero elasticity between all other points in a worldsheet. We are talking
about zero aggergate elastic equilibrium between all other points in a
worldsheet, thus, we are presuming the elastic resistance between all points
on a worldsheet is always in flux, but eventually trends towards zero.

Eventually, this natural jiggling of the elasticity of points forms elastic
folding within the worldsheet itself. Most of these folds revert back to zero
aggregate elasticity, but sometimes, these structures hold because while they
have odd topography, they achieve elastic equilibrium with the rest of the
worldsheet because of their odd topography. This is because of the
distribution of tension within the topology. Because it is at elastic
equilibrium, the topology remains. Eventually, more topologies appear and
eventually, some even interlock with each other like worldsheet velcro.

If the elastic equilibrium of these topological structures is pulled beyond
its internal tension balance, each of these "tension contracts" will be pulled
apart in favor of the dominant tension. Despite these topologies being made of
time symmetric worldsheets, the topologies themselves are time asymmetric and
cannot be made again by simply reserving the elasticity as the worldsheet
still remains at zero aggregate elasticity, and thus, preserves its time
symmetry AS A WHOLE. This is how arrows of time can arise from time symmetric
universes.

From here, these tension contracts combine with each other, forming either a
velcro binding or a tension binding, where one topology correctly scales the
flow of tension to its neighbors, increasing its tensile strength, and thus,
extending its influence upon the rest of the worldsheet. This, I believe, is
the foundation behind Higgs fields.

The key take away is that every particle in the entire universe is nothing
more than complicated folds of a two-dimensional conformal field theory
coupled to symmetric time. Nothing rests on the worldsheet or exists beyond
it. All energy and matter is made up of a complex combination of elastic
equilibrium. Gravity, then, is the resolution of elastic equilibrium between
two tension contracts. To prove this, we simply have to envision a blackhole
as being anchored upon the universe at the very edge of the event horizon
because that is where the rest of the worldsheet has achieved elastic
equilibrium with the blackhole.

This is why negative energy does not appear in the wild. EVERYTHING is already
made up of "negative" energy.

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SolarNet
Time cube is leaking...

[http://timecube.2enp.com/](http://timecube.2enp.com/)

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kelseydh
Wow, this is fascinating. It is totally incoherent, yet interspersed with
brief moments of consistent clarity.

