What does gravity do to records?
Quantum Darwinism says the classical world is what gets copied into the environment many times over. This atlas maps every idea we could find about where gravity copies records, where it hides or scrambles them, and what that means for classical reality.
Short version. Gravity pays for classical reality, light writes it, and gravity bounds it at both ends of cosmic history. Electromagnetism makes nearly every everyday record: for a 10 µm dust grain, photon scattering creates records about 1062 times faster than gravity can. What gravity supplies is the imbalance that makes records possible (hot stars against a cold sky, a smooth early universe) and the order that protects archives, from rock strata to tides.
Gravity’s own guaranteed contribution is thin. It is a floor of conserved charges (energy, momentum, angular momentum) plus gravitational memory, readable from any surface around a source but blind to which outcome actually happened. Where gravity acts on its own, it is mostly the strongest eraser in nature: horizons strip and scramble, dark energy hides, and chaos mixes. On this reading, classical reality is a temporary phase between an opaque early plasma and a far future where horizons hide almost everything.
Where gravity copies, and where it erases
| Regime | Direction | What is recorded or lost | Mechanism | Confidence |
|---|
Records forming, records scrambled
Toy model: a mass in a superposition of two places, watched by 12 probe systems. A partial-information plot shows how much of the which-place bit a random fraction of the probes holds. A flat plateau at one bit means every small fragment has its own copy: that is classical objectivity in Zurek’s sense.
A horizon scrambler erases redundancy
Quantum records fade with distance like classical ones
What gravity contributes to a classical world
Top ideas, ranked
Ranked by promise, novelty and testability after red-teaming. A separate prior-art hunt checked whether the “possibly new” ideas are really new.
Every idea
Each idea has a precise statement, how it would work, why physics would be this way, a test, references the agents verified, and any red-team correction. Status chips reflect the red-team’s corrections.
Five conjectures, each red-teamed
The question behind this section: is there a loop, a bit like a transformer trained by backpropagation, where processes that erase records are met by processes that copy them, and gravity puts the final stamp on reality? And shouldn’t records affect gravity? Five conjectures were built in their strongest form and then attacked.
Short answer. The two opposing processes are real, and gravity sits under both. Light copies records (about 108 imprints per microsecond on a micron dust grain in sunlight), and horizons scramble them. The backpropagation half doesn’t hold: physics has no loss to minimize, no gradient flowing backward and nothing being updated. The relationship is a one-way ratchet with a capacity cap, not a feedback controller.
Gravity caps how many copies can exist
Each independent readable copy needs its own particle or field mode, and fitting N of them in radius R costs at least about N4/3ħc/R of energy. Past that, the region collapses. A 1 m sphere holds at most about 1052 independent copies, roughly 1018 fewer than the holographic count. The cap binds thermal noise too: energy causes collapse, not copying. The part specific to records is the gap between that cap and the black-hole entropy, where entropy keeps growing while objectivity disappears. That gap is plausible but depends on fast scrambling and unitarity.
Horizons erase redundancy, not information
If evaporation is unitary, everything that falls in comes back only after about half the hole’s lifetime, held in a single copy that only more than half the radiation can read. The facts that stay copied everywhere outside are the ones fixed by constraint equations: mass-energy, momentum, angular momentum and charge, plus gravitational memory. Every Hawking quantum is a fresh sample of the temperature, so the mass is broadcast redundantly while the microstate is scrambled.
Records affect gravity only through their energy
Einstein’s equations have no term that sees information: two memories with the same stress-energy weigh the same. In any linear theory that forbids signalling, a gravitational probe can’t tell whether a source was recorded (a Coulomb probe behaves the same way). The only exception is gravity sourced by measurement outcomes. Page and Geilker ruled out its simplest version at macroscopic scale in 1981. At mesoscopic scale it is untested.
Shared records are central, not all geometry
Anything two disjoint boundary regions can each reconstruct must be classical, and in holographic codes the area of each cut is such a quantity. Gauge fluxes are classical in the same way, and areas of crossing surfaces don’t commute, so the full spacetime is not one jointly objective record. This is Harlow’s 2016 result restated in Darwinist language.
Attention clusters like any attraction
Attention dynamics do cluster tokens, but so does every attractive mean-field system (Keller–Segel, Kuramoto). On the sphere attention’s kernel is a short-range Gaussian, not gravity’s 1/r. Attention also erases information, shrinking phase-space volume, while conservative gravity only scrambles it. The one physics “backward pass”, a final-state condition at a black hole’s singularity, is a fixed post-selection, and records formed inside the hole generically spoil it.
Gravity is blind to information, but it caps objectivity and then deletes it without deleting information. The only facts gravity guarantees will stay objective forever are the conserved charges and gravitational memory.
The record-dose test. Put a source of about 10−14 kg in a superposition of two places, with a lighter gravitational probe nearby. Leak a controlled amount of which-path information from the source, then read the probe’s phase.
- If gravity is quantum and tracks branches, the probe shows a branch-correlated phase of about 0.176 rad, whatever the dose.
- If gravity is sourced by outcomes, it shows the averaged field, about 0.088 rad, until a record forms and then switches.
- If Diósi–Penrose collapse holds, the source decoheres in roughly 12 ms regardless of dose.
This refines the Kent and Page–Geilker experiments. It still needs a sharp criterion for when a record has formed, which is the measurement problem in another form. BMV-type gravitational entanglement experiments test the neighbouring question: if gravity can entangle masses, the “classical gravity stamps reality” models (Diósi–Penrose, Oppenheim) are out.
- Powers them. Clumping ignites stars and accretion, releasing the free energy that light spends writing records.
- Broadcasts a fixed vocabulary. Constraint equations put mass, momentum and angular momentum on every enclosing sphere for free.
- Caps them at about (R/ℓP)3/2 independent copies.
- Scrambles them at horizons, at the fastest rate nature allows.
- Only through stress-energy. Distinct copies need distinct modes, which cost energy, which gravitates.
- No information charge. Two states with the same stress-energy gravitate identically, however redundantly they’re recorded.
- One untested door: gravity sourced by measurement outcomes, at mesoscopic scale.
Symbol first, then source
The follow-up question: do people compress the universe by observing and figuring it out, and does that turn into “symbol first, then source”? Three lenses (thermodynamics and algorithmic information, life and symbols, quantum gravity and holography) were developed and red-teamed.
We compress the description, not the universe
Saying “that’s a tree” reads one of millions of copies light has already made, then stores a short code. Keeping and erasing memory costs heat, so total entropy still rises: a brain exports about 7×1021 bits per second. All human records come to about 1024 bits against about 4.5×10104 bits of entropy in the observable universe.
Records are effects, symbols are causes
Edit one copy of a quantum-Darwinist record and nothing upstream changes. Edit a genome or a blueprint and the structure and all its copies change. Intervening tells the two apart, and CRISPR edits already pass the test. Life is where copying runs in the causal direction.
Building, learning, inheriting
“Symbol first, then source” is literally true for construction (DNA read by ribosomes, chips built from a few mask sets: about 1.3×1022 transistors). It holds for the order of learning: in a toy, a generic compressor shrank a tree picture 8× while its growth rule shrank it about 190×, but only search finds the rule. And children inherit the symbol before the data.
Origins, observation, holography
Selection writes the world into genomes, so across generations it is a loop. Observing never rewrites the past. Holography is an exact two-way equivalence with no “first”, and the boundary state isn’t a symbol because nothing interprets it.
Gravity sees the mass meaning moves
A symbol must be stored in states that cost the same energy either way, or physics would pick the message. Those are exactly the details gravity’s far field discards. A 6.2-billion-bit genome reveals only about 20 to 30 bits through its mass.
Four trees that share only math
Branching quantum histories (copies without variation), species lineages (copies with variation), lineages of ideas and technology, and the observer’s concept hierarchy. “Tree” the plant isn’t a genetic group: the shape evolved separately in ferns, conifers, palms and flowering plants. So “not just genetics” is literally right.
Gravity does backprop. Darwinian and anti-Darwinian processes balance. Attention equals gravity. Bits have gravitational mass beyond their energy. Horizon area is a ledger of erased records. Spacetime is a catalogue of consensus records. Holography is symbol-first. The universe learns its laws (the one testable cousin, Smolin’s cosmological natural selection, predicted a maximum neutron-star mass near 1.6 solar masses and is contradicted by a 2.08-solar-mass pulsar).