#JuanMaldacena - Does #Information Create the #Cosmos?

https://www.youtube.com/watch?v=dprKOGA57_I&ab_channel=CloserToTruth

#Philosophy #PhilosophyOfScience #Science #PhilosophyOfCosmology #Cosmology #QM #QuantumMechanics #Physics #QuantumPhysics #Superposition #WaveFunction #Entanglement #Universe #Gravity #QuantumGravity #Relativity #GR #GeneralRelativity #Holography #HolographicPrinciple #CloserToTruth #RobertKuhn

#JuanMaldacena Public #Lecture: The #Meaning of #Spacetime

"What is spacetime, exactly? And how does it impact our understanding of important phenomena in our #Universe?"

https://www.youtube.com/watch?v=DODp-ajPuU8&ab_channel=PerimeterInstituteforTheoreticalPhysics

#Science #Physics #Philosophy #PhilosophyOfScience #Cosmology #PhilosophyOfCosmology #Space #Time #GR #GeneralRelativity #QM #QuantumMechanics #QuantumFieldTheory #QuantumGravity #LoopQuantumGravity #BlackHoles #Entanglement #PerimiterInstitute

Referenced link: https://phys.org/news/2023-06-quantum-gravity-holography-cosmological.html
Discuss on https://discu.eu/q/https://phys.org/news/2023-06-quantum-gravity-holography-cosmological.html

Originally posted by Phys.org / @physorg_com: http://nitter.platypush.tech/physorg_com/status/1671878904330719235#m

Could #quantumgravity models arising from holography explain cosmological acceleration? @physrevlett https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.130.221601 https://phys.org/news/2023-06-quantum-gravity-holography-cosmological.html

Unveiling #quantumgravity: New results from #IceCube and #Fermi #data - In a #study published in #NatureAstronomy, a team of #researchers from the University of Naples "Federico II," the University of Wroclaw, and the University of Bergen examined a quantum-gravity model of #particlepropagation in which the #speed of #ultrarelativisticparticles decreases with rising #energy.

https://phys.org/news/2023-06-unveiling-quantum-gravity-results-icecube.html

Nominations sought for the position of director at the @mpi_grav in Potsdam in one of the following areas: quantum gravity, theoretical cosmology in the era of big data, early universe astrophysics & cosmology.

ℹ️ https://aei.mpg.de/opening-for-a-director

#QuantumGravity #Cosmology #Astrophysics

When I have time I try to follow the development of phsyics and the elusive problem(s) of quantum gravity. Leonard Susskind in particular is always a tremendous pleasure to listen to. In this speech https://www.youtube.com/watch?v=-OkwGDKoY0o he argues for deep parallels between the growth of complexity in qubit systems and Newton's equations of gravity (and also EPR = ER). Also here: https://arxiv.org/pdf/1802.01198.pdf

This is great fun, but it's hard as an outsider to assess. Anyone care to weigh in? #quantumgravity

#RenateLoll has helped pioneer a radically new approach to #quantumgravity. She assumes that the fabric of #spacetime is a blend of all possible fabrics, and she has developed the #computationaltools needed to calculate the far-reaching implications of that assumption.

https://www.quantamagazine.org/renate-loll-blends-universes-to-unlock-quantum-gravity-20230525/

Nominations sought for the position of director at the @mpi_grav in Potsdam in one of the following areas: quantum gravity, theoretical cosmology in the era of big data, early universe astrophysics & cosmology.

ℹ️ https://aei.mpg.de/opening-for-a-director

#QuantumGravity #Cosmology #Astrophysics

A hunch: in much the same way that we imagine virtual particle pairs being created and annihilated in QFT, I bet that voxels of spacetime are being created and annihilated. Mass shifts the balance from creation to annihilation, and positive geometric curvature results from each existing voxel having fewer connected neighbors than expected. Likewise, dark energy shifts the balance toward creation, which should produce local negative curvature in places with low density.

It also just clicked for me viscerally that gravity wells are places with less than zero potential energy. I think this might imply that spacetime voxels borrow potential energy when they spring into existence. If they're quantized, then it would immediately explain energy-time uncertainty because regions with higher energy would spontaneously create more voxels, allowing more precise measurements.

If we take as given that field energies are "stuck" to their voxels, simple conservation demands that a deleted voxel must somehow divest itself of not just its own energy but the energy of all fields within it. By locality it can only do so by sending it to voxels to which it is connected; the higher energy those neighbors are, the less likely they are to accept more, and so there is a degeneracy pressure forcing spacetime to exist in regions with high energy. Conversely, in gravity wells the ambient energy level would be negative, and so a voxel would have no trouble giving away energy to its neighbors in order to zero itself out and cease to exist.

If this hunch is right, the question becomes: what do the voxel creation and annihilation interactions look like?

(NB: throughout this post I'm assuming that thinking about spacetime as a graph of voxels is a better approach than trying to deal with continuous fields. Even if you think spacetime is continuous, discrete models and continuous models are dual to one another for the purpose of approximation.)

#physics #QuantumGravity

Nominations sought for the position of director at the @mpi_grav in Potsdam in one of the following areas: quantum gravity, theoretical cosmology in the era of big data, early universe astrophysics & cosmology.

ℹ️ https://aei.mpg.de/opening-for-a-director

#QuantumGravity #Cosmology #Astrophysics

Fascinating how scientists think… the ‘thought problems’ they sometimes employ to develop benchmarks for new theories. Like this new #physics paper in the #quantummechanics and #quantumgravity space: “Black holes resolve paradoxes by destroying quantum states” #science #scientificCommunity https://www.sciencenews.org/article/black-hole-paradoxes-quantum-states

Nominations sought for the position of director at the @mpi_grav in Potsdam in one of the following areas: quantum gravity, theoretical cosmology in the era of big data, early universe astrophysics & cosmology.

ℹ️ https://aei.mpg.de/opening-for-a-director

#QuantumGravity #Cosmology #Astrophysics

Nominations sought for the position of director at the @mpi_grav in Potsdam in one of the following areas: quantum gravity, theoretical cosmology in the era of big data, early universe astrophysics & cosmology.

ℹ️ https://aei.mpg.de/opening-for-a-director

#QuantumGravity #Cosmology #Astrophysics

Nominations sought for the position of director at the @mpi_grav in Potsdam in one of the following areas: quantum gravity, theoretical cosmology in the era of big data, early universe astrophysics & cosmology.

ℹ️ https://aei.mpg.de/opening-for-a-director

#QuantumGravity #Cosmology #Astrophysics

Nominations sought for the position of director at the @mpi_grav in Potsdam in one of the following areas: quantum gravity, theoretical cosmology in the era of big data, early universe astrophysics & cosmology.

ℹ️ https://aei.mpg.de/opening-for-a-director

#QuantumGravity #Cosmology #Astrophysics

Nominations sought for the position of director at the @mpi_grav in Potsdam in one of the following areas: quantum gravity, theoretical cosmology in the era of big data, early universe astrophysics & cosmology.

ℹ️ https://www.aei.mpg.de/opening-for-a-director

#QuantumGravity #Cosmology #Astrophysics

#PaulSteinhardt - Time to Take the ‘#BigBang’ out of the #BigBangTheory?

https://www.youtube.com/watch?v=S7-HNi2ne44&ab_channel=SimonsFoundation

#Science #Physics #Astrophysics #Cosmology #PhilosophyOfCosmology #Inflation #CMB #QM #QuantumMechanics #Entropy #QuantumGravity #SimonsFoundation #Lecture

Huh. I've been stewing on Up And Atom's video on the Landauer limit: https://youtu.be/XY-mbr-aAZE . If you don't know, Landauer's result connects Shannon's information entropy to Boltzmann's thermodynamic entropy by describing the minimum waste heat required to erase one bit of information i.e. cut the state space in half.

And a while later, Google's creepy Android newsfeed algorithm recommended to me this article about some researchers who claim that absolute zero is reachable in finite time, using finite energy, if you take quantum physics into account, i.e. a violation of the Third Law: https://thedebrief.org/quantum-version-of-the-third-law-of-thermodynamics-says-absolute-zero-is-theoretically-possible/ .

However, this claim is more reasonable than it seems, because the feat is only possible if you can perform infinitely complex manipulations. Complexity is just a synonym for information, so this means that you have infinite knowledge of the quantum state of the system being cooled, which is something you can only know the exact history of all particles since the last time they were each individually at 0 K.

It occurred to me that, since Landauer's equation connects energy to information/entropy, it's entirely possible that energy and information are the same thing, in almost exactly the same way that energy and mass. The weird difference is the dependency on absolute temperature. Temperature is just kinetic energy per volume, basically, so this implies that the more bits you pack into a given quantum system of fixed volume, the more energy it costs to erase one bit i.e. cool the system. That feels like it ties in very directly with the Bekenstein bound / black hole entropy, and the relationship with temperature as an "energy density" feels analogous to gravitational potential energy, i.e. bits get more expensive to remove as they fall into the gravity well because they are attracted to each other.

And, getting *very* far out on a limb: since the heat death of the universe is the process over which the expanding universe cools to 0 K over infinite time, the heat death is actually the *start* of time, is it not? Someone else's time, if not ours. After all, zero temperature means zero information entropy per volume. So I wonder if we actually have a twin universe for which our Big Bang is their heat death and vice versa, and that's what the AdS/CFT and dS/dS stuff is about. Perhaps our gravity could be dual to their thermodynamics, and their gravity to our thermodynamics, via some duality compatible with our respective geometries. Hell, since attraction looks like repulsion when you reverse the flow of time, maybe the thermodynamic information content of their universe (attractive) is dual to dark energy (repulsive) in ours?

#physics #QuantumPhysics #QuantumGravity #entropy #InformationEntropy #ItFromBit

#DonLincoln, #Fermilab - Is #Gravity A Force?

https://www.youtube.com/watch?v=ZHxoM9lvzVA&ab_channel=Fermilab

#Philosophy #PhilosophyOfScience #Physics #Newton #Einstein #Minkowski #GR #GeneralRelativity #QuantumGravity #EntropicGravity

Unrelated to my other #physics post earlier today, I've also been thinking pretty hard about #QuantumGravity lately, and in particular about having classical spacetime arise from a polytope tiling of an underlying geometric space, which naturally leads to a directed acyclic graph along which information entropy can flow. Here's a Google doc with my current musings, which at the moment are limited to the case of a 1+1 Minkowski spacetime arising from a computational DAG over classical bits:

https://docs.google.com/document/d/1eil22rmD1MyiZ-YBzc0D6r0X_CfuOLCfPG4MszNlUTU/edit?usp=sharing

Extending this to GR will require figuring out possible rules under which the number of polytopes per spacelike slice can vary.