r/quantum

How to approach learning quantum mechanics?

I've gotten into it as a hobby/interest without much of a background, and my goal is to solve a problem. I've been reading Sakurai and watching videos as well, but i was wondering if just finding out all the meanings of the seemingly complicated symbols (like Ψ² ∝ just means probability distribution of finding a particle at a certain point, this just means that etc.) and breaking those symbols down into something more digestible is a decent approach to learning how to solve a problem.

reddit.com
u/ImpressiveRelease948 — 18 hours ago

Built a quantum software optimization layer and validated it on real IBM Quantum hardware (up to 152 qubits)

Hi everyone,

Over the past several months, I've been building Quantum Knife OS, a proprietary software layer designed to improve execution quality on today's noisy quantum hardware.

This week I completed another round of validation on real IBM Quantum hardware (IBM Fez, IBM Kingston, and IBM Marrakesh).

Some results from the latest validation:

  • Executed successfully on real IBM Quantum hardware
  • Tested on benchmark scales up to 152 qubits
  • Up to 8.14× higher measured correlation than the baseline implementation on the 98-qubit benchmark
  • Approximately 12× higher measured correlation at 16 qubits
  • Strong retained correlation across the evaluated benchmark suite
  • Achieved entirely through software, without modifying the underlying quantum hardware

The motivation behind this project is simple.

Today's quantum computers are limited by hardware noise, topology constraints, and execution quality. Rather than designing new hardware, I'm exploring how much improvement can be achieved through a software optimization layer.

To protect my intellectual property, I'm not publishing the proprietary mathematics, optimization algorithms, or implementation details at this stage. However, I am sharing:

  • IBM Quantum hardware validation reports
  • IBM execution screenshots
  • Raw IBM job data
  • Benchmark comparisons
  • Performance summaries

I'm interested in technical feedback on the validation methodology, benchmarking approach, and presentation of the results.

If anyone here works in quantum computing, quantum software, or quantum compiler optimization, I'd genuinely appreciate your thoughts and discussion.

This is the first public milestone of the project, and there's still a lot more work ahead.

Thanks for reading.

https://preview.redd.it/pyga6wn7h8bh1.png?width=1915&format=png&auto=webp&s=bfc5f0e77c6e0e264355da1abec1b7d129438bd4

https://preview.redd.it/ghvz3wn7h8bh1.png?width=1918&format=png&auto=webp&s=65597f34aaa1370893eb7569f91e64d8e32dcc86

reddit.com
u/Past_Tangerine_847 — 1 day ago

Is this an absurd idea?

Do you think it's possible that dark matter is unobserved "matter" that has not collapsed into physical existence due to being observed? In the double slit experiment for example, if you fire a single electron at a time at the slits, you eventually see an interference pattern develop on the screen, one observation at a time. But if you never observed the location of the electron, would it remain an unobserved wave? So I guess I'm just wondering if dark matter is just the uncollapsed portion of the universe.

Maybe not, because we are observing a well defined gravitational influence.

reddit.com
u/No_Broccoli_5850 — 1 day ago
▲ 37 r/quantum

Scientists create quantum sound device that could transform communications

I just saw this incredible breakdown on ScienceDaily and wanted to share a quick, bite-sized summary of what's going on. Essentially, researchers from McGill and Princeton have built a tiny quantum device that forces high-speed electrons through an ultra-thin crystal actually just a few atoms wide down near absolute zero. When the electrons get pushed to "supersonic" speeds meaning they travel faster than the speed of sound inside that specific material they start behaving collectively and shoot out highly predictable, controllable bursts of phonons.

sciencedaily.com
u/Existing_Tomorrow687 — 3 days ago

Club photographer with a novice quantum question.

I am a club photographer and I often use a technique called dragging the shutter where I use light in two ways. I use a slow shutter speed (giving the camera a lot of time to capture whatever ambient light is available) to capture motion or momentum and a flash to “freeze” the action. The result are tact sharp images that also show motion blur. It got me thinking about how we try to observe electrons. I understand that with light it knocks electrons out of there path due to the observer effect but is there a way to record the motion of an electron at the same time as being able to “see” clearly where it is? Apologies if this doesn’t make sense of if I’m not using the right nomenclature.

reddit.com
u/blahblah4507 — 3 days ago
▲ 3 r/quantum+1 crossposts

Nic Carter says the only way Bitcoin gets a quantum upgrade is if large holders force it through. Thoughts?

Watching this interview where he argues that Bitcoin's governance is so stuck that no meaningful protocol change can happen through normal consensus. His take is that the only realistic path forward is a group of big institutions and token holders just throwing their economic weight around and making it happen.

He also mentions that Bitcoin has no way to swap out its cryptography if the math ever breaks (because of a quantum computer), whereas basically every other cryptographic system (TLS, SSH, etc.) is designed to be upgradeable.

Thoughts?

Context: https://youtu.be/3ByUtLGSAqM?si=MS3wvEoIwzIaLAgF

u/NoUnderstanding6021 — 5 days ago
▲ 0 r/quantum+2 crossposts

If ER=EPR is accurate, then wouldn’t than mean the quantum vacuum and spacetime are the same thing?

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u/Zerilos1 — 4 days ago

How would you safely reduce the size of ML-DSA-87 public keys and signatures in a blockchain?

I'm currently experimenting with a blockchain that uses ML-DSA-87 as its default signature scheme instead of ECDSA.

One of the biggest trade-offs is transaction size.

A single transaction includes an ML-DSA-87 public key and signature, making each transaction several KiB larger than a traditional ECDSA-based blockchain.

I don't want to weaken security, and I'd prefer to avoid protocol changes that add significant complexity (such as maintaining a public key registry in the blockchain state).

So I'm curious:

- Are there any safe ways to reduce the effective size of ML-DSA-87 public keys or signatures?

- Are there any compression techniques that preserve security?

- Is transport-level compression (e.g. P2P message compression) generally preferred over compressing the cryptographic objects themselves?

- If you were designing a post-quantum blockchain today, how would you handle this trade-off?

From what I've read, ML-DSA signatures are already highly structured, so I suspect there isn't much room for lossless compression without changing the scheme itself.

I'd love to hear how others would approach this problem.

reddit.com
u/Ok_Alfalfa_7767 — 4 days ago

Career advice for Physics PhD Student

Hi everyone. I am a Physics PhD researcher specializing in computational modeling of semiconductor nanostructures — quantum dots, nanoplatelets, and low-dimensional confined systems.
My work involves constructing and solving multiband k·p Hamiltonians to model electronic and excitonic states in nanoscale semiconductors, combining theoretical derivation with numerical implementation — finite element methods (COMSOL), Python, and HPC-based calculations.

While I still have 2 years until I defend my thesis, I keep thinking about my future. Do I want to stay in academia or move to industry. And tbh most of the time the answer is industry. However, when I surf throgh linkedin/glassdor I can't find a job relevant to my skills. Ofc I am ready to add up more skills, and learn new things in order to become a rare, good specialist. But I need to know where to head? if that is quantum computing or TCAD semiconductor modeling or maybe smth that I didn't even notice is very close to my specialisation and highly in demand.

P.S. I am in Europe, and would like to continue in any EU country unless some good opportunity arises in US.

reddit.com
u/earthurovich — 3 days ago
▲ 128 r/quantum+26 crossposts

Says in India, Art Deco is architecture of the common man (as compared to displays of power in America) vs. neo-Gothic/neo-Classical structures

Also says that the rise of gated communities, the lack of integration with Navi Mumbai is hurting Mumbai's growth. Explains why it's impossible for India to create it's own national architectural style

Thoughts?

u/Odd_Wolverine_4037 — 8 days ago
▲ 18 r/quantum+1 crossposts

Quantum mechanics on a lattice in roblox, with emergent physics.

Injected atom mode, to view every possible element (excluding isotopes), and quantum configuration (up to n=1-30). Simulation-wise, right now only Hydrogen-1-3 (Protium, Deuterium, and Tritium) and Helium-1-4. I don't know why, but for some reason the observer system manages to detect He-1 and He-2 without a bond (molecular bonding not added), even though they don't physically exist by themselves in our universe.

all quantum fields are implemented, and scalar fields are validated with observed kinks and domain walls.

Quantum mechanics: ~15–25% implemented as field/validation/visual/identity foundations

Electromagnetism: ~3–8% implemented, mostly charge-like signatures and tiny scalar coupling validation

Nuclear/atomic identity: ~10–20% implemented as observer/evidence/catalog systems, but not full nuclear physics yet

Cosmology/field evolution: ~15–25% implemented as sandbox cosmology/expansion diagnostics, not full GR

Gravity: ~0–3% implemented physically

Chemistry/materials: ~0–2% implemented physically

Thermodynamics/stat mech: ~5–10% implemented as diagnostics/derived state, not full particle thermodynamics

140k lines of code: Roblox Studio lags now (using vs code to code rn), but simulation runs smoothly. Does anybody know how to make nice UI? UI in roblox is so horrible to make and importing from figma messes it up always?

u/Enough_Eye_5140 — 5 days ago

Superposition Explanation Help

Hello! I am new to quantum mechanics and stuff, and I am just starting to learn about superposition. I am a bit confused about it and would like some clarification on this: is superposition saying that a system does exist in multiple states simultaneously (like with 100% certainty), or that it has a probability of existing in multiple states simultaneously? For example, does a coin exist in a state of being both heads and tails (both 100%), or exist in a state of having a 40% probability of being heads and a 60% probability of being tails?

Along with this, I am confused about how the results of the double-slit experiment prove superposition.

Would really like some clarification on this if anyone can help!

reddit.com
u/Useful_Cake_5901 — 6 days ago
▲ 0 r/quantum+1 crossposts

Where is my place? Quantum theory postdoc wants to ride on AI wave

hey folks, I am a quantum theorist currently doing a postdoc.

TLDR: I'm currently automating a big part of my research workflow, so I’m wondering how someone with domain science like me could be useful in AI-driven research.

The thing is this, I'm not really looking for generic advice in "academia vs industry". More like: I want to continue what I do know, but at larger scale, how does someone with my profile actually get into big tech or AI labs, and where would I even start?

Broadly speaking I'm working on quantum materials, many-body physics, quantum optics, that kind of stuff. I am interested in novel quantum materials and physical systems that could matter for quantum sensing, semiconductors, energy, information storage, etc. and in my group we are also collaborating heavily with experimental groups. I also took a couple of lectures on deep learning, so I am not totally clueless there, but my main thing is still quantum theory. The reason I am asking is that more and more of my daily work I can automate by agents, and honestly I love it; I used to spend lots of time carefully writing cluster jobs, setting up saving, caching, array jobs, parameter scans, all the annoying details you need so the whole thing does not break after running for 3 days. I used to code quite a lot in C and C++, plus some Python for plotting. Now I can do a lot of this with AI and it is often better, faster, and less error prone than what I wrote myself. Of course, you need to configure your harness and put lots of saveguards, tests, physical consistency checks etc, but it works. Not perfectly, obviously, but the direction is pretty clear. So while the progress has been rather slow the last decades in my field (my impression), I think this could explode now, and the route from basic research to applications could accelerate to a great extend.

So I am wondering if there is a real niche here? Something like an AI babysitter for scientific research, but not "train another model" (I know I have 0 chance to enter this job market and I have 0 ambition). More like someone who knows the quantum theory, knows what equations are actually realistic to do, knows how to formulate the models and sanity check the outputs, and then uses agent systems to scale the boring parts. Literature, numerics, parameter scans, code, simulations, maybe even parts of theory exploration. Do big tech companies or AI labs or companies that I don't know about actually hire people for this kind of thing? Domain scientists who are not pure ML engineers, but can move AI driven scientific research in physics, materials, quantum, scientific computing, etc?

Honestly I always thought I would stay on the standard academic path with some Postdoc positions, papers, then PI position, group, grants, the whole thing. And I do love academia. But in fact I also do not want to miss out on the moment where the actually impactful parts of scientific research moves somewhere else, because they have the compute and the ressources.

reddit.com
u/vsilv — 5 days ago
▲ 21 r/quantum+1 crossposts

Inside a Quantum Computer: Every Major Component Explained

Quantum computers look like something straight out of science fiction—but every wire, shield, and chamber has a critical purpose. This detailed infographic breaks down the anatomy of a modern superconducting quantum computer, from the dilution refrigerator that cools it close to absolute zero to the quantum processor chip where qubits perform calculations impossible for classical computers.

Discover how microwave control lines, readout resonators, thermal shields, vacuum chambers, and amplifiers work together to keep qubits stable long enough to solve some of the world's most complex problems. Whether you're a science enthusiast, student, or simply curious about the future of computing, this visual guide makes one of the most advanced machines ever built easier to understand.

u/firechatin — 7 days ago
▲ 2 r/quantum+2 crossposts

Which is it really, though? Is Quantum the weird one, really?

Quantum computing isn’t weird. Classical computing is weird because it forces the universe into a tiny, rigid, binary box — and then calls everything outside that box “weird.” I saw another post here about classical computing distraught and in tears at the idea that quantum computing is weird, but I disagree with the idea. Because if the fact is that our universe exists because of quantum computing, then "classical" computing is the one that's weird, because it's either the defect, the starting point, or some cheap imitation that we built to understand the universe. I'm not getting any valuable answer from any AI, so someone give me something good.

reddit.com
u/Max-Ghoul — 6 days ago

UG student quantum industry outlook

Hello all, I’m a third year physics student wondering about careers in quantum technology. For reference I am from Ireland, my current uni offers Msc in Quantum Science and Technology and I’m aware of plenty startups and established companies around Ireland in the quantum computing field. I love physics and I’m seriously motivated to stay in physics for my career.

Basically I’m wondering how to proceed? Is it a good idea to go all in on quantum computing / technologies? I am much more interested in hardware / science over computer science. What should I be trying to do during my bachelors to firstly prepare myself for the work and secondly to maximise employability? Is a phd a better route than the masters? Is maybe trying to go straight into industry (if I can make myself attractive enough to employers) viable? Should I stay in Ireland or are there better prospects further afield?

Any advice would be greatly appreciated thank you

reddit.com
u/Quick_Ship7134 — 7 days ago
▲ 0 r/quantum+1 crossposts

Information-First Quantum Gravity and Emergent Spacetime (2022–2026)

## Executive Summary

Recent years have seen rapid progress in *emergent spacetime* approaches that treat information or entanglement as fundamental. Key frameworks include **holography/AdS–CFT** (and its quantum-error-correction interpretation), **tensor-network models** of space, **loop/spin-foam quantizations**, **causal set/dynamical triangulation** discretizations, **SYK-like and computational (“Ruliad”) models**, **entropic/information-theoretic gravity**, and **relational/observer-centric quantum frameworks**. Major 2022–2026 results include explicit constructions of emergent de Sitter (dS) geometry from entanglement in non-Hermitian tensor networks, derivations of time as an emergent quantum variable via system–environment entanglement, and a first-principles Loop-QG study of black-hole evaporation showing a non-singular bounce to a white hole. On the observational side, cosmological and gravitational-wave probes have been proposed: e.g. Weyl-invariant quantum-gravity models predict a blue-tilted tensor spectrum (testable by LiteBIRD/DECIGO), and novel phases in early-universe models suggest primordial non-Gaussianities and Lorentz violations. Tabletop tests (entanglement of masses via gravity) are also under intense study. However, these approaches differ dramatically in ontology (e.g. boundary qubits vs. spin-network nodes vs. “computations” vs. observers). Criticisms remain: for instance, Aziz & Howl (2025) show that even *classical* gravity (when matter is treated as a quantum field) can produce entanglement, complicating claims that observing entangled masses would definitively imply quantized gravity. We summarize the major programs, highlight key 2022–2026 papers (with authors, claims, methods, equations and links), compare ontologies, list experimental/observational tests, and outline open challenges. Finally, we assess the prospects for an overarching “information-first” framework: such a unification must make *distinct, falsifiable predictions* (e.g. specific entanglement/complexity signatures or deviations from smooth spacetime) to be viable. A prioritized reading list and suggested next steps conclude the report.

## Research Programs & Approaches

- **Holography (AdS/CFT and Generalizations):** Proposed by Maldacena (1998), AdS/CFT duality posits a boundary CFT (Hilbert space of qubits) whose entanglement encodes a higher-dimensional bulk spacetime and gravity. Notable developments include Ryu–Takayanagi entanglement–area formula and its covariant extensions, and the realization that AdS/CFT acts as a quantum error-correcting code (holographic QECC). Recently this program has been pushed beyond pure AdS: for example, Chou & Chang (2026) construct a *cMERA tensor-network* that yields emergent **de Sitter** space from a boundary non-Hermitian fermion system. Other holographic ideas include **ER=EPR** (wormholes ⇔ entanglement), **bit threads**, and celestial holography (flat-space amplitudes on the celestial sphere). A very recent arXiv (2025) connects *celestial holography* to dS/CFT, mapping cosmological correlators to CFT operators on the celestial sphere. Holography’s ontology: fundamental CFT quantum states and their entanglement patterns give rise to emergent geometry.

- **Tensor Networks and Entanglement = Geometry:** Here one discretizes space by networks of tensors or qubits (MERA, PEPS, etc.), such that the network connectivity and entanglement define a geometry. Advances include non-unitary tensor networks for cosmology, and the use of *quantum information measures* (entanglement entropy, mutual information, complexity) to reconstruct spatial geometry. For example, Cao *et al.* and Pollack *et al.* (2017–2023) showed how *“magic”* (non-Clifford resources in QECC) can encode dynamical bulk geometry and gravity in holographic codes. These models generally posit quantum bits (tensor degrees) as ontological atoms; geometry is a secondary description of their entanglement network.

- **Quantum Error Correction (QEC) & Holographic Codes:** Building on holography, researchers have identified that the bulk-boundary map is a quantum error-correcting code. Recent work embeds *bulk gravitational dynamics* into QECC language: e.g. introducing `T`-gate “magic” as a source of interaction in toy holographic circuits. This program’s ontology centers on logical/physical qubits and code subspaces; spacetime and gravity emerge from how logical information is protected and recovered.

- **Loop Quantum Gravity (LQG) and Spin Networks/Foams:** A non-perturbative, background-independent approach quantizing geometry itself. Space is built from spin-network graphs (nodes/links labeled by SU(2) spins) with discrete area and volume spectra, and spacetime histories are spin foams (2-complexes). Recent progress: Belfaqih *et al.* (2025) study **black-hole evaporation** in a “covariant effective” LQG model, coupling matter to a non-singular quantum geometry. They recover thermal Hawking radiation (to leading order) and find, *via backreaction*, that black holes likely transition into white holes rather than remnants. LQG’s ontology: fundamental `atoms-of-space` (spin-network quanta) and the relations among them (graph connectivity) are primary; smooth spacetime is emergent in a continuum limit.

- **Causal Set and Discrete Spacetime:** Proposes spacetime as fundamentally a discrete partially-ordered set of events (with a causal relation). Key results include constructing dynamics via “sequential growth” and investigating Lorentz-invariant phenomenology (e.g. modified dispersion). Recent years have emphasized connecting causal sets to quantum fields and cosmology, but direct empirical predictions remain scarce. Ontology: elementary spacetime events and their order (information flow).

- **SYK/Random Matrix/Chaos Models and “Wormholes”:** The Sachdev-Ye-Kitaev (SYK) model (0+1D chaotic fermions) is dual to AdS$_2$ gravity in the IR. Recent work extends SYK to higher dimensions and connects it to traversable wormholes and quantum teleportation protocols. Wolfram-style models also aim for emergent spacetime: **Wolfram Physics Project** introduces the *Ruliad*, the space of all possible computation histories. Wolfram (2026) describes the Ruliad as “the ultimate foundational construct” whose patterns (as seen by embedded observers) give rise to physics. In this view, computation rules and patterns are fundamental; spacetime, fields, and even consciousness emerge as coarse-grained phenomena.

- **Information-thermodynamic and Entropic Gravity:** Inspired by Jacobson (1995) and Verlinde (2011), these approaches derive (or reinterpret) gravity as an entropic or thermodynamic force arising from microscopic degrees of freedom. Recent work by Othman (2025) reviews this paradigm, emphasizing that “spacetime geometry and gravitational phenomena arise from underlying quantum information structures”. Verlinde’s original entropic force model remains controversial: critics have pointed to experiments (e.g. neutron interferometry) that conflict with a simple entropic-gravity prediction, and Othman’s review acknowledges ongoing debates. Ontology here: fundamental are microscopic “bits” or horizon microstates; gravity emerges as an emergent statistical force on these information degrees.

- **Relational/Observer-Centric Quantum Gravity:** These approaches (Page–Wootters, Rovelli’s Relational QM, QBism, etc.) treat time, measurement and observers as fundamental. For instance, Gemsheim & Rost (2023) derive the usual time-dependent Schrödinger evolution for a subsystem starting from a time-independent global state of system+environment, bolstering the Page–Wootters relational time idea. Other recent work formulates quantum reference frames and relational observables in quantum gravity. Ontology: primary are quantum events or observations relative to observers; “time” and “classical spacetime” arise from correlations among subsystems, not as fundamental entities.

## Key Papers (2022–2026)

- **“Emergent de Sitter Space and Non-Unitary Tensor Networks”** – *Chou & Chang (2026)*. Using a non-Hermitian critical fermion chain and continuous MERA ansatz, they explicitly construct an emergent 4D de Sitter geometry from boundary entanglement. They show geodesics in the network behave like extremal surfaces (Ryu–Takayanagi) and recover dS-like horizons and proper time from bond counting. This is the first bottom-up tensor-network realization of dS holography, providing a concrete **dS/cMERA correspondence**. Key results include matching entanglement growth to de Sitter expansion, with equations relating network RG “depth” to cosmic time. *Link:* arXiv 2606.17983.

- **“Emergent spacetime from spatial energy potentiality: a new framework for early universe cosmology”** – *Chishtie (2025)*. Proposes that both **time and gravity emerge** via a quantum phase transition of a fundamentally 3D spatial universe into 4D spacetime. The Big Bang is interpreted as this phase transition. Using quantum-field-loop calculations, Chishtie shows how what were previously mere parameters become physical time, and describes a smooth dimensional “bounce” replacing the singularity. This model yields testable predictions: specific CMB non-Gaussianity patterns, stochastic gravitational-wave backgrounds, slight Lorentz-violation effects, and modifications to Big Bang nucleosynthesis. Notably, it claims to naturally resolve the Hubble tension (7% discrepancy) without inflation. *Link:* arXiv 2306.07485.

- **“The emergence of time from quantum interaction with the environment”** – *Gemsheim & Rost (2023)*. In a concise 5-page paper, they extend the Page–Wootters formalism by **including interaction** between system and clock/environment. Starting from a global energy eigenstate of (system+environment+interaction), they show that the reduced system obeys the standard time-dependent Schrödinger equation. This provides a missing piece: time-evolution emerges naturally even when system and clock interact fully. The result bridges previous treatments (which often assumed no coupling or semiclassical clocks) and demonstrates how relational time arises in *fully quantum* models. *Link:* arXiv 2309.05159.

- **“Capturing the Page Curve and Entanglement Dynamics of Black Holes in Quantum Computers”** – *Chowdhury *et al*. (2024)*. Implements a toy model of black-hole evaporation (the “qubit transport model”) on IBM superconducting quantum processors to study Hawking radiation entropy. Using random-unitary circuits to scramble “black-hole qubits” and two different protocols (swap test and randomized measurements), they measure the Rényi entropies of the emitted “Hawking” qubits. They successfully reproduce the rising-and-falling Page curve of entanglement entropy through the black-hole lifetime, demonstrating that current quantum hardware (with error mitigation) can probe black-hole information dynamics. Key results: (1) Both protocols estimate entropies accurately in simulation; (2) On real devices, randomized measurements were more noise-robust; (3) Even noisy hardware can simulate complex entanglement dynamics. This is a milestone in *quantum simulation of quantum gravity* effects. *Link:* arXiv 2412.15180.

- **“Classical theories of gravity produce entanglement”** – *Aziz & Howl (2025, Nature)*. Investigates the proposed tabletop entanglement test of quantum gravity (the “BEC experiment”): if two masses become quantum-entangled via gravity, one usually infers gravity must be quantum. Aziz & Howl challenge this. They show that if one properly treats matter as a quantum **field** interacting with a *classical* gravitational field, even *local* classical gravity can mediate quantum information transfer (entanglement). In other words, classical gravity can act as a “quantum channel” under QFT, so observing entanglement does **not** unambiguously prove gravity is quantized. They derive how the scaling of entanglement differs between classical and quantum cases, giving guidance on what experiments would truly distinguish them. This result imposes strict conditions: only if *all* classical channels are ruled out (e.g. by observing violation of certain locality/causality constraints) can one claim to have seen “quantum gravity.” *Link:* Nature 646, 813 (2025).

- **“Testing quantum gravity with primordial gravitational waves”** – *Calcagni & Modesto (2024, JHEP)*. Constructs a UV-complete, Weyl-invariant quantum gravity model and computes its cosmological perturbations. They find that spontaneous breaking of Weyl symmetry yields near-scale-invariant scalar and tensor spectra. Crucially, the tensor tilt is *blue* ($n_t=1-n_s>0$), and the tensor-to-scalar ratio $r\approx0.01$ for Planck-scale cutoff. These values are potentially observable by upcoming missions (LiteBIRD, BICEP Array). They also derive a strict lower bound on the new physics scale ($\Lambda_* >8.5\times10^{10}$ GeV) from current bounds $r<0.036$. Thus, their model predicts a **testable signature**: a small but nonzero $r$ and a positive tensor tilt. *Link:* arXiv 2206.07066 (JHEP 12 (2024) 024).

- **“Celestial Holography meets dS/CFT”** – *Furugori *et al*. (2025, JHEP)*. Builds a bridge between *celestial CFT* (a proposed holographic dual for asymptotically flat space) and *de Sitter/CFT* holography. By analytic continuation and Weyl rescaling, they map $(D+2)$-dimensional QFTs in Minkowski space to $(D+1)$-dimensional theories on the sphere (the celestial sphere). This allows *dS$_{D+1}$ operators* in the Bunch–Davies vacuum to be represented by operators on the celestial $S^D$. The framework provides a systematic way to compute cosmological (dS) correlators using celestial techniques. Ontologically, this suggests our universe’s de Sitter space may be encoded on a conformal boundary in a way akin to scattering amplitudes. *Link:* arXiv 2507.17558 (accepted by JHEP).

- **“What Ultimately Is There? Metaphysics and the Ruliad”** – *Wolfram (2026, blog post)*. A speculative but far-reaching essay by Stephen Wolfram on the *Ruliad*, the “limit of all possible computations.” He argues that the true ontology is a vast hypergraph (the Ruliad) whose multiway evolution embodies every possible rule application. Observers (like us) perceive a tiny corner of the Ruliad; familiar physics (space, time, continuity, particles) emerge from the combinatorial patterns that such observers can experience. Wolfram emphasizes that space itself is discrete (“a very large number of discrete…atoms of space”) whose relations form hypergraphs. The essay is visionary rather than formal, but it concretely asserts an information-first ontology: **computations and their relations** are fundamental. *Link:* writings.stephenwolfram.com (Feb 2026).

## Ontologies and Explanatory Scope

These theories differ sharply in what they take as *fundamental*:

| Approach | Fundamental Ontology | Comments | Key References |

|-----------------|------------------------------------|-------------------------------------------------------------------------------------|--------------------------------|

| **Holography/AdS-CFT** | Boundary quantum fields/qubits (CFT state) | Bulk spacetime and gravity emerge from boundary entanglement; duality often assumes fixed asymptotics. | Maldacena 1998; Ryu–Takayanagi; holographic QECC. |

| **Tensor Networks** | Qubits/tensors and their entanglement network | Geometry arises from entanglement structure; network geometry corresponds to spacetime slices. | Cao *et al.* 2020; Chou & Chang 2026. |

| **Quantum Error Correction** | Encoded logical qubits / quantum codes | Logical information protected across a network; emergent locality from code structure. | Pastawski *et al.* 2015; Harlow *et al.* 2016. |

| **Loop QG / Spin Foams** | Spin-network nodes/links (“atoms of space”) | Space is a discrete graph of spins; evolution via spin foams. No background metric. | Rovelli–Smolin (1990s); Belfaqih *et al.* 2025. |

| **Causal Sets** | Discrete spacetime events + causal order | Spacetime = set of points with partial order; continuum emerges at large scales (no metric distance a priori). | Sorkin et al.; continuum limits etc. |

| **Computational (Ruliad/SYK)** | Computations, rules, or random matrices | Ruliad: ultimate rule-space; SYK: large-$N$ chaotic fermions. Observers/computation basis. | Wolfram 2026; Kitaev–SY 2015; Ye–Sachdev–Kitaev. |

| **Entropic/Info Gravity** | Microstates or information bits (entropy) | Space emerges from statistical/entropic behavior of hidden degrees. Often analogies to thermodynamics. | Verlinde 2011; Jacobson 1995; Othman 2025. |

| **Relational/Observer** | Observers, clocks, and correlations | Events and observations are primary; spacetime is a bookkeeping of relations (e.g. Page–Wootters, Rovelli-RQM). | Page–Wootters 1983; Gemsheim–Rost 2023; Rovelli 2021. |

Thus e.g. holography sees *boundary fields* as real, with spacetime emergent, whereas LQG treats *quantum geometry* (spin labels) as real and matter fields as secondary. Wolfram’s Ruliad posits pure computation, with *everything* (fields, space, etc.) as emergent from patterns in that computation. Some approaches (entropic gravity, relational quantum mechanics) even question the fundamental status of spacetime itself. The explanatory scope varies: holography unites gravity with QFT in AdS; LQG applies to 3+1D without background but struggles with de Sitter; causal sets aim for discreteness plus Lorentz invariance; information-based views claim to encompass all known physics as effective descriptions of underlying information processing.

## Empirical/Observational Tests

Efforts to connect these ideas with data include:

- **Cosmology (CMB, Large-Scale Structure):** Models of emergent spacetime often predict distinctive imprints in the early universe. For example, Chishtie’s spatial-phase-transition model forecasts *non-Gaussianities* in the CMB and a stochastic gravitational-wave background from the 3D→4D transition. Calcagni & Modesto’s Weyl-invariant gravity predicts a small tensor-to-scalar ratio ($r\approx0.01$) and a *blue* tensor tilt, potentially measurable by next-generation CMB polarization missions (LiteBIRD, BICEP Array). Similarly, any deviations from scale invariance or parity violations in primordial perturbations could signal holographic or entropic gravity effects.

- **Gravitational Waves:** New proposals aim to test quantum gravity via gravitational waves. Calcagni & Modesto show a *blue-tilted* gravitational-wave spectrum (in contrast to standard inflationary models), which future detectors (DECIGO, Einstein Telescope) could detect as high-frequency backgrounds. Others have suggested searching for echoes or anomalies in LIGO/Virgo black-hole merger signals that might hint at Planck-scale structure (e.g. due to LQG “Planck stars”). So far no clear anomalies have been seen, placing constraints on exotic effects.

- **Black Hole Observations:** Predictions from these theories can also be tested by astrophysical black holes. Belfaqih *et al.* (2025) imply that black holes should transition to white holes on finite timescales due to quantum geometry; if true, primordial black holes might produce observable bursts. The Event Horizon Telescope (EHT) and LIGO/Virgo might also constrain deviations from classical GR (e.g. Lorentz-violating dispersion, echo signals). Tests of the Hawking information paradox (like measurements of black-hole entropy or the Page curve) remain largely theoretical, but analogue systems (e.g. fluid or optical black-hole analogues) have provided indirect support for unitary evaporation.

- **Laboratory Tabletop Experiments:** Quantum-information proposals have spurred lab tests. The famous Bose–Marletto–Vedral (BMV) protocol suggests entangling two microspheres via gravity; an observation of entanglement would imply a quantum-mediated gravitational interaction. However, Aziz & Howl (2025) show that even *classical* gravity (plus QFT) can entangle two masses. This means that detecting entanglement alone is not a conclusive signature of quantum gravity. Nonetheless, careful variation of setups could test their predictions (e.g. scaling of entanglement with distance and mass). Other proposals include bouncing neutrons, precision atomic interferometry, and spin-entanglement schemes to probe Planck-scale decoherence or gravitational-induced phase shifts.

- **Quantum Simulators:** As illustrated by Chowdhury *et al.* (2024), quantum computers and simulators can **emulate** aspects of black-hole information dynamics. Such simulations don’t test nature directly, but they validate theoretical models (e.g. Page curve behavior in specific models) and may one day use analog systems (Bose condensates, superconducting circuits) to simulate emergent geometry or causal horizons.

In summary, while direct evidence for quantum gravity remains elusive, several concrete tests have been proposed. The **current empirical status** is that no deviations from GR or the Standard Model have been confirmed at accessible scales, but parameter space is narrowing. Upcoming experiments in cosmology and quantum information could provide critical clues.

## Open Problems & Criticisms

- **Extension to Realistic Spacetimes:** Most holographic models require AdS boundary conditions, whereas our universe is (approximately) de Sitter. Building a fully consistent dS/CFT or flat-space holography remains unresolved. Tensor-network and error-correction models are often built on regular lattices or simple codes, making it hard to incorporate dynamics, non-conformal matter, or realistic cosmology. LQG and causal sets face difficulties recovering smooth low-energy spacetime and incorporating the Standard Model.

- **Measurement and Classical Limit:** The transition from quantum spacetime to the classical world is unclear in many approaches. Observer-based approaches grapple with the quantum measurement problem. For instance, relational time formalisms must still explain why clocks show one outcome, not a superposition.

- **Lack of Unique Predictions:** A common criticism is that many “information-based” models lack distinctive, testable predictions. Entropic gravity has been challenged: e.g. Kobakhidze (2011) argued that neutron interference experiments disprove simple entropic-force claims. More recently, the above nature paper shows even entanglement tests can admit classical-gravity explanations, undermining a touted test. Likewise, Wolfram’s Ruliad has faced skepticism for being so general (“everything at once”) that specific physical predictions are hard to extract.

- **Internal Consistency:** Some frameworks still have unresolved consistency issues. For example, non-Hermitian or non-unitary models (like Chou–Chang’s fermion chain) may require new interpretation of quantum mechanics. Many proposed “emergent gravity” scenarios presuppose unknown micro-degrees-of-freedom; making these precise and self-consistent is a challenge. Furthermore, combining approaches (e.g. embedding LQG structures into string theory) has proven nontrivial.

- **Quantum vs Classical Ambiguity:** The Aziz–Howl result exemplifies a conceptual issue: what exactly counts as “quantum gravity”? If classical gravity coupled to quantum fields can mimic quantum features, separating genuinely quantum-spacetime effects from effective, semiclassical ones is subtle.

In short, while the information-first perspective is intellectually rich, it faces hurdles of rigor and testability. Critics often demand concrete observables (e.g. specific Lorentz violations, discrete spectra, or topology changes) tied to new parameters, rather than only re-interpretations of known physics.

## Towards a Unified Information-First Framework

Is it possible to unify these diverse approaches into a coherent “It-from-Qubit” (or “It-from-Bit”) metaphysics? In principle, many schemes share core ideas: that *relations*, *entanglement*, or *computation* underlie spacetime. For example, both tensor networks and holographic QECC cast gravity as emergent from quantum information processing. The Ruliad conceptually contains all possible such constructions. A synthesis might posit a single underlying **Hilbert space or combinatorial structure** from which different limits (AdS/CFT-like codes, spin networks, causal sets, etc.) emerge as subtheories.

However, for such a unification to be scientific, it must yield *falsifiable* predictions not achievable by existing theories. Some candidate signatures of an ultimate information-first theory could be:

- **Discrete or Quantized Geometry:** Definitive evidence of minimum length/area, e.g. a universal Planck-scale spacing detectable in high-precision interferometry or gamma-ray burst time-of-flight studies.

- **Information-based Deviations:** Unusual correlations (“nonlocal” entanglement patterns) across cosmological distances that cannot be explained by standard inflationary fluctuations. For instance, a specific non-Gaussianity template directly linked to initial entanglement structure.

- **Observer-Dependent Effects:** If time and space arise from entanglement, manipulating quantum clocks might reveal relativity-without-coordinate effects (as in Page–Wootters tests). One might predict violations of the conventional uncertainty relations when two observers use quantum clocks in relative motion.

- **Quantum Channel Signatures in Gravity:** Building on Aziz–Howl, one could predict how a **pure quantum channel (graviton exchange)** differs from a classical channel at a detailed level (e.g. different scaling laws for entanglement entropy or decoherence). Observation of that specific scaling could confirm a quantized spacetime effect.

- **Complexity/Volume Laws:** Holographic complexity conjectures (CV/CA proposals) suggest spacetime interior volumes grow with quantum complexity. A strong prediction would be an observable linkage between black-hole interiors (e.g. quasinormal mode spectra) and boundary computational complexity – though testing this is far beyond current reach.

Concretely, any unified model would need to predict *anomaly signatures* in near-future data. For example, the Weyl-invariant model’s blue tensor spectrum is a template for what to look for. Similarly, LQG bounces might produce astrophysical signals (gamma-ray bursts or cosmic rays from white-hole remnants). Tabletop, it might predict a definite crossover distance below which Newtonian gravity fails due to quantum entanglement structure.

In sum, while reconciling all approaches into one information-first framework is an ambitious goal, the path forward is clear: identify the minimal set of new entities (bits, computations, causal relations) and derive unique experimental consequences. Only a theory that can be potentially falsified (e.g. by particular GW signatures, or by violation of LOCC locality assumptions) can ultimately be validated.

## Prioritized Reading List (Select References)

  1. **J. Maldacena (1998)**, *The large N limit of superconformal field theories and supergravity* (hep-th/9711200) – Original AdS/CFT proposal.

  2. **M. Van Raamsdonk (2010)**, *Building up spacetime with quantum entanglement* (Gen. Rel. Grav. 42 (2010) 2323) – Argues that quantum entanglement “glues” spacetime together.

  3. **S. Gemsheim & J. M. Rost (2023)**, *Emergence of time from quantum interaction with the environment* (Phys. Rev. Lett. 131, 140202) – Demonstrates time-evolution emerging from a timeless global state (relational time).

  4. **I. H. Belfaqih *et al.* (2025)**, *Hawking evaporation and the fate of black holes in loop quantum gravity* (arXiv:2504.11998) – Effective LQG model giving non-singular black holes and predicting a black-to-white-hole transition.

  5. **J. Aziz & R. Howl (2025)**, *Classical theories of gravity produce entanglement* (Nature 646, 813–817) – Shows classical gravity+QFT can entangle matter, impacting experimental tests of quantum gravity.

  6. **H. Furugori *et al.* (2025)**, *Celestial Holography meets dS/CFT* (JHEP) – Bridges celestial sphere amplitudes with de Sitter holography, linking flat-space and cosmological holographic duals.

  7. **S. Wolfram (2026)**, *What Ultimately Is There? Metaphysics and the Ruliad* (blog essay) – Elaborates the computational-universe paradigm where space, time, and physics emerge from a hypergraph of all computations.

*(Additional foundational refs: E. Verlinde (2011) “On the Origin of Gravity” (entropic gravity), M. Srednicki (1993) “Entropy and area”, R. Sorkin et al. on causal sets, Page & Wootters (1983) on relational time.)*

## Future Directions and Experiments

Based on the above, we recommend pursuing:

  1. **Refined Gravity-Entanglement Experiments:** Design tabletop tests that can distinguish quantum vs classical gravitational channels. Incorporate the QFT-induced entanglement mechanisms of Aziz–Howl. For instance, use different materials or geometries to test their predicted scaling laws for entanglement with distance.

  2. **Quantum Simulations of Spacetime Codes:** Build on Chowdhury *et al.*’s work by implementing more elaborate quantum circuits that simulate holographic codes or spin-network evolution. This could include simulating bulk dynamics (e.g. shockwaves, wormhole formation) on near-term quantum hardware.

  3. **Tensor-Network Cosmology:** Develop non-unitary MERA or novel tensor-network ansätze for realistic FRW/dS spaces, extending Chou & Chang. Compare their entanglement/geometric predictions with CMB data (e.g. looking for signatures of a discrete network in the two-point function).

  4. **Quantum Clocks and Relational Time Tests:** Experimentally realize a Page–Wootters clock-system with controllable interaction (as in Gemsheim–Rost) to test if evolution matches conventional Schrödinger dynamics. Entangle a “clock” qubit with a system and verify if conditional states reproduce ordinary time behavior.

  5. **Astrophysical Search for Black-Hole Bounces:** Analyze gamma-ray, neutrino or cosmic-ray data for transient events that could be white-hole bounces predicted by LQG. Develop simulations of such signals to guide observational efforts.

Each of these directions connects theory to observation or experiment, providing critical tests of the information-first paradigm.

**Tables and Figures:** Below we summarize and compare approaches. For example, a mermaid diagram of historical milestones is shown, and a schematic bar-chart (of research emphases) indicates the relative focus on each approach in recent literature.

```mermaid

timeline

title Selected Milestones (1998–2026)

1998 : AdS/CFT duality proposed (Maldacena)

2006 : Ryu–Takayanagi entanglement=area

2013 : ER=EPR conjecture; Quantum codes in AdS/CFT

2015 : “It from Qubit” workshops (Caltech/PI)

2023 : Rost & Gemsheim – Emergent time from interactions

2024 : Calcagni–Modesto – Blue-tilt GW predictions

2025 : Belfaqih *et al.* – LQG black-hole bounce

2026 : Chou–Chang – dS from tensor networks

```

```mermaid

graph LR

Holography --> Tensor_Networks

Holography --> QEC_Codes

Tensor_Networks --> Emergent_Geometry

QEC_Codes --> Emergent_Dynamics

LQG --> Discrete_Spacetime

CausalSet --> Discrete_Spacetime

Ruliad --> Computation

Ruliad --> Emergent_Time

Observer --> Relational_Time

```

| **Approach** | **Fundamental Entities** | **Key Predictions** | **Current Status** | **Refs** |

|-------------------|----------------------------------|------------------------------------------------------------|----------------------------------|-----------------------------------------------|

| Holography/AdS-CFT | Boundary quantum fields (qubits) | Entanglement=area, Page curve, complexity=volume/etc. | Well-established in AdS; dS flat extensions ongoing | Maldacena 1998, RT formula, Chou & Chang 2026 |

| Tensor Networks | Qubits/tensors, entanglement links | Emergent geometry from entanglement; multiscale renormalization | Active (MERA/cMERA, PEPS, etc.) | Cao *et al.* 2020, Chou & Chang 2026 |

| QEC/Holographic Codes | Logical qubits in error-correcting code | Bulk locality from code; resilience of information | Demonstrated in toy models | Pastawski *et al.* 2015, Harlow 2016 |

| Loop QG/Spin Foams | Spin-network nodes/links (“atoms of space”) | Discrete area/volume; black-hole singularity resolution | Mature formalism; continuum limit debated | Rovelli–Smolin (1990s), Belfaqih *et al.* 2025 |

| Causal Sets | Discrete spacetime events (partial order) | Lorentz-invariant discreteness; phenomenology of dispersion | Ongoing; few unique predictions | Sorkin et al., research (e.g. continuum approximation) |

| Computational (Ruliad/SYK) | All computations or random matrices | Complex emergent laws; maximal symmetry (Ruliad) | Speculative/early-stage | Wolfram 2026, Kitaev 2015 (SYK) |

| Entropic/Info Gravity | Microscopic “bits”/degrees of freedom | Dark-energy as entropic pressure; modified gravity laws | Controversial; indirect tests only | Verlinde 2011, Othman 2025 |

| Relational/Observer | Quantum events/relations/observers | Time from entanglement; relational observables | Active in foundations | Page–Wootters 1983, Gemsheim–Rost 2023 |

**Figure:** Schematics of how quantum information and spacetime are linked in various approaches (not to scale).

In conclusion, the **prospect of an information-first metaphysics** depends on isolating unique empirical predictions. We have identified several promising targets above (timely GW spectra, lab entanglement signatures, quantum-clock phenomena, etc.). Achieving a unified theory will require rigorously formulating how “information” or “computation” gives rise to *all* observed physics, and then using the above tests to confirm or refute it.

**Suggested Research Directions:** Based on the above analysis, we recommend pursuing tabletop gravitational entanglement experiments that include the quantum-field effects identified by Aziz–Howl, further developing tensor-network models for realistic cosmology, and leveraging quantum computers to simulate more elaborate emergent-gravity models. Engaging both theorists and experimentalists, as in the 2025 Aspen conference on QG observables, will be crucial to advance this interdisciplinary field.

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u/ChaosWeaver007 — 7 days ago