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Evidence record

How big can something be and still be quantum?

Every sentence on the exploration belongs to at least one claim below. Each says what kind of statement it is, what it rests on, what the evidence does not establish, and how far it was checked. Nothing here is a score, and none of it is a verdict on a belief or a theory.

Last checked 24 September 2026.

  • Source checked: 35
  • Presented as open: 4
  • A judgement, not a fact: 3
  • Partly checked: 4

If something here is wrong, misquoted, out of date or unfair, write to support@unknownoceans.com and give the claim number, which does not change.

What the question takes for granted

An experimental question with a theoretical one behind it: how far quantum superposition has been shown to reach, and whether anything beyond the practical difficulty of isolating large objects stops it. The page reports the record and the two candidate answers without choosing between them.

  • Large objects are not seen in superpositions of position in ordinary conditions

    Established

    Every source on the page starts from it. What is contested is why.

  • There is one measure of how big a quantum object is

    Contested

    The heaviest objects in superposition were displaced by far less than the lighter ones, so a record in mass and a record in separation are different records. The 2026 paper uses a combined measure, macroscopicity, to compare them. The page says so.

  • Quantum mechanics holds at every scale

    Open

    Standard quantum mechanics sets no upper limit on size; collapse models say it fails above some mass. Experiments have narrowed the collapse models without deciding the question.

How the question is labelled

Claim: Where the strangeness stops

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: How big

Kind
Framing. Signposting. It asserts nothing a source could check.

The question

Claim: Clusters of more than seven thousand atoms have been put in two places at once.

Kind
Experimental result. What an experiment or trial found, under its own conditions. A result in animals, cells or a simulation is not a result in people.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Probing quantum mechanics with nanoparticle matter-wave interferometryabstract; Discussion

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Physical systems · Experiment

    The source reads: We specifically demonstrate quantum interference of sodium nanoparticles, which can each contain more than 7,000 atoms at masses greater than 170,000 Da. ... a nanometer-sized piece of metal being ‘here and there’ in the same quantum state with a 133 nm separation between the two locations

What this does not establish

"Two places" means a delocalized centre of mass in a grating interferometer, 133 nanometres across; the clusters were not seen in two places. One laboratory, not yet repeated elsewhere.

Later work looked for

Crossref, 2020 on, "nanoparticle matter-wave interferometry" and "matter-wave interference massive molecules": the 2026 sodium-cluster result supersedes the 2019 record; page updated.

Corrected

24 September 2026. Previously: “Molecules of two thousand atoms have been sent through two slits at once.” Superseded: a 2026 experiment (Pedalino and others, Nature) interfered sodium clusters of more than 7,000 atoms. The 2019 molecules also went through a grating interferometer rather than two slits.

Claim 3 · checked 24 September 2026 · AI-assisted audit

Claim: Nobody has found the size at which that stops working.

Kind
Open question. Something the page says is not known.
Review
Presented as open. The page says this is unresolved, and the review found that it is.

Claim 4 · checked 24 September 2026 · AI-assisted audit

Claim: Interference experiments have been pushed from electrons to metal clusters of thousands of atoms without encountering a boundary.

Kind
Experimental result. What an experiment or trial found, under its own conditions. A result in animals, cells or a simulation is not a result in people.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Models of wave-function collapse, underlying theories, and experimental testssection I.B.6, Experimental Tests

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field

    The source reads: Over eighty years have passed since the classic experiment by Davisson and Germer in 1927 where interference was demonstrated with electrons.

  • Supports

    Probing quantum mechanics with nanoparticle matter-wave interferometryabstract; Discussion

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Physical systems · Experiment

    The source reads: Here we present an experimental platform that extends matter-wave interference to large metal clusters, a qualitatively new material class for quantum experiments. ... which can each contain more than 7,000 atoms ... reveals no breakdown of the quantum superposition principle related to mass or size alone.

Later work looked for

Crossref, 2020 on, "nanoparticle matter-wave interferometry": the 2026 metal-cluster experiment is the newest record found; page updated.

Corrected

24 September 2026. Previously: “Interference experiments have been pushed from electrons to large molecules without encountering a boundary.” Updated to the 2026 record (Pedalino and others, Nature).

Claim 5 · checked 24 September 2026 · AI-assisted audit

Claim: Whether the limit is merely technical, or whether something physically destroys superpositions above some mass, is a question being decided by pushing further.

Kind
Open question. Something the page says is not known.
Review
Presented as open. The page says this is unresolved, and the review found that it is.

"Pushing further" includes experiments that never make a superposition: the 2022 review finds non-interferometric tests the most effective against collapse models.

  • Supports

    Present status and future challenges of non-interferometric tests of collapse modelsabstract; closing section

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field

    The source reads: Whether the principle applies also to macroscopic systems or, instead, there is a progressive breakdown when moving to larger scales, is a fundamental and still open question. ... And only experiments can tell.

Claim 6 · checked 24 September 2026 · AI-assisted audit

Claim: A single particle sent through two slits interferes with itself.

Kind
What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Decoherence, the measurement problem, and interpretations of quantum mechanicssection II.B.1

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field

    The source reads: in a setup where electrons pass individually (one at a time) through a double slit. As is well known, this experiment clearly shows that, within the standard quantum-mechanical formalism, the electron must not be described by either one of the wave functions describing the passage through a particular slit

Later work looked for

How the textbook experiment works; not a finding later work revises.

Claim 7 · checked 24 September 2026 · AI-assisted audit

Claim: A cat does not.

Kind
What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review
Source checked. The cited passage was read, and it says this.

The cat is Schrödinger’s, standing for any everyday object.

  • Supports

    Models of wave-function collapse, underlying theories, and experimental testsabstract

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field

    The source reads: the principle of linear superposition, a central tenet of the theory, apparently contradicts a commonplace observation: macroscopic objects are never found in a linear superposition of position states.

Later work looked for

Crossref, 2020 on, "macroscopic quantum superposition": the 2023 and 2026 experiments extend superposition to heavier objects under isolation, which the page reports; nothing shows an everyday object in superposition.

Claim 8 · checked 24 September 2026 · AI-assisted audit

Claim: The interesting thing is that nobody has found where the first stops being true,

Kind
Open question. Something the page says is not known.
Review
Presented as open. The page says this is unresolved, and the review found that it is.

  • Supports

    Probing quantum mechanics with nanoparticle matter-wave interferometryDiscussion

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Physical systems · Experiment

    The source reads: Observing matter-wave interference of the most massive objects to date reveals no breakdown of the quantum superposition principle related to mass or size alone.

Claim 9 · checked 24 September 2026 · AI-assisted audit

Claim: and the two candidate reasons are completely different.

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

The two reasons are decoherence, which works inside ordinary quantum mechanics, and a physical collapse, which changes it. The page sets them out in its two halves.

Claim 10 · checked 24 September 2026 · AI-assisted audit

How far it has been pushed

Claim: How far it has been pushed

Kind
Framing. Signposting. It asserts nothing a source could check.

The record keeps moving

Claim: The record keeps moving

Kind
Historical claim. A statement about the past that historical evidence can test.
Review
Source checked. The cited passage was read, and it says this.

Claim 12 · checked 24 September 2026 · AI-assisted audit

Claim: Interference has been demonstrated with electrons, with neutrons, with atoms, with fullerenes,

Kind
Historical claim. A statement about the past that historical evidence can test.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Models of wave-function collapse, underlying theories, and experimental testssection on molecule interferometry

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026

    The source reads: matter-wave interferometry of electrons ... neutrons (Rauch and Werner, 2000), atoms (Cronin et al., 2009) and molecules (Hornberger et al., 2011) has a long and successful history ... In 1999, matter-wave interferometry with large neutral molecules was first demonstrated with the C60 fullerene in Vienna

Claim 13 · checked 24 September 2026 · AI-assisted audit

Claim: by 2019 with tailored molecules of up to two thousand atoms,

Kind
Experimental result. What an experiment or trial found, under its own conditions. A result in animals, cells or a simulation is not a result in people.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

  • Supports

    Quantum superposition of molecules beyond 25 kDaabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Physical systems · Experiment

    The source reads: we report interference of a molecular library of functionalized oligoporphyrins ... with masses beyond 25,000 Da and consisting of up to 2,000 atoms, by far the heaviest objects shown to exhibit matter-wave interference to date

  • Supports

    Probing quantum mechanics with nanoparticle matter-wave interferometryExperiment

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026

    The source reads: as well as organic and tailored macromolecules

What this does not establish

The 2019 paper was read only as its abstract; the full text is paywalled. Its mass and atom count are the abstract’s.

Later work looked for

Crossref, 2020 on, "matter-wave interference massive molecules": superseded as the record by the 2026 sodium-cluster experiment, which the page now reports next to it.

Claim 14 · checked 24 September 2026 · AI-assisted audit

Claim: and by 2026 with sodium clusters of more than seven thousand atoms and masses above 170,000 atomic units.

Kind
Experimental result. What an experiment or trial found, under its own conditions. A result in animals, cells or a simulation is not a result in people.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Probing quantum mechanics with nanoparticle matter-wave interferometryabstract

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Physical systems · Experiment

    The source reads: We specifically demonstrate quantum interference of sodium nanoparticles, which can each contain more than 7,000 atoms at masses greater than 170,000 Da.

What this does not establish

The clusters ranged from 5,000 to 10,000 atoms; the interference that distinguished quantum from classical behaviour was measured around 172,000. Heavier clusters gave fringes too, but there the paper cannot tell quantum from classical.

Later work looked for

Crossref, 2020 on, "nanoparticle matter-wave interferometry sodium clusters": this is the newest record found; nothing later changes it.

Corrected

24 September 2026. Previously: “Interference has been demonstrated with electrons, with neutrons, with atoms, with fullerenes, and by 2019 with tailored molecules of up to two thousand atoms and a mass beyond 25,000 atomic units.” The 2019 record was superseded in 2026 (Pedalino and others, Nature 649).

Claim 15 · checked 24 September 2026 · AI-assisted audit

Claim: Each step needs slower particles, colder sources and better isolation from gas and radiation.

Kind
Experimental result. What an experiment or trial found, under its own conditions. A result in animals, cells or a simulation is not a result in people.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Probing quantum mechanics with nanoparticle matter-wave interferometryExperiment; Interference scans

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Physical systems · Experiment

    The source reads: Matter-wave interference at high masses requires both the preparation of low particle velocities and the ability to handle short de Broglie wavelengths. ... we achieve this by combining a cryogenic metal cluster source ... the scattering of gas particles and thermal radiation can reduce the predicted contrast

Later work looked for

Describes how the method works; not a finding later work revises.

Corrected

24 September 2026. Previously: “Each step requires colder sources, longer flight times, better isolation from gas and radiation.” The source names low velocities, a cryogenic source and scattering by gas and thermal radiation; longer flight times are what collapse models would punish, not a requirement it states.

Claim 16 · checked 24 September 2026 · AI-assisted audit

Claim: The experiments get much harder as the mass grows,

Kind
What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review
Source checked. The cited passage was read, and it says this.

Later work looked for

Crossref, 2022 on, "nanoparticle matter-wave interferometry": the 2026 paper still names slower beams and better detection as the obstacles; nothing changes it.

Corrected

24 September 2026. Previously: “The difficulty grows steeply with mass,” Worded to what the review says; it gives no rate.

Claim 17 · checked 24 September 2026 · AI-assisted audit

Claim: and no step has revealed a limit imposed by nature rather than by the apparatus.

Kind
Experimental result. What an experiment or trial found, under its own conditions. A result in animals, cells or a simulation is not a result in people.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Probing quantum mechanics with nanoparticle matter-wave interferometryDiscussion

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Physical systems · Experiment

    The source reads: Observing matter-wave interference of the most massive objects to date reveals no breakdown of the quantum superposition principle related to mass or size alone.

  • Context

    Quantum superposition of molecules beyond 25 kDaabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Physical systems · Experiment

    The source reads: Our results show excellent agreement with quantum theory and cannot be explained classically.

Later work looked for

Crossref, 2020 on, "matter-wave interference" and "collapse model bounds": no reported breakdown of superposition found.

Claim 18 · checked 24 September 2026 · AI-assisted audit

Claim: Heavier things have been put in superposition over far smaller distances.

Kind
Experimental result. What an experiment or trial found, under its own conditions. A result in animals, cells or a simulation is not a result in people.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Probing quantum mechanics with nanoparticle matter-wave interferometryMain, opening; Discussion

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Physical systems · Experiment

    The source reads: Recently, the vibration mode of a bulk acoustic resonator was prepared in a quantum superposition state, with an effective mass of 16 μg ... with a 133 nm separation between the two locations

  • Supports

    Schrödinger cat states of a 16-microgram mechanical oscillatorabstract; main text, page 10

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Physical systems · Experiment

    The source reads: Here we demonstrate the preparation of a mechanical resonator with an effective mass of 16.2 micrograms in ... delocalized over a distance of 2.1 · 10⁻¹⁸ m

    Notation restored: Exponents restored as the arXiv PDF (2211.00449v1) sets them, checked from the glyph positions with pdftotext -bbox, 2026-09-24. The text as extracted reads: Here we demonstrate the preparation of a mechanical resonator with an effective mass of 16.2 micrograms in ... delocalized over a distance of 2.1 · 10−18 m

Later work looked for

Crossref, 2020 on, "macroscopic quantum superposition" and "Schrödinger cat states mechanical oscillator": nothing later found that changes it.

Corrected

24 September 2026. Previously: “” The page presented molecule interference as the whole record. The 2026 paper itself places it beside a 16-microgram mechanical superposition, which a reader asking "how big" needs.

Claim 19 · checked 24 September 2026 · AI-assisted audit

Claim: In 2023 a vibration of a crystal, with an effective mass of sixteen micrograms or some 10¹⁷ atoms, was put in two states at once, spread over about two billionths of a nanometre.

Kind
Experimental result. What an experiment or trial found, under its own conditions. A result in animals, cells or a simulation is not a result in people.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Schrödinger cat states of a 16-microgram mechanical oscillatormain text, page 10

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Physical systems · Experiment

    The source reads: Since we are not considering a center-of-mass mode, there is some freedom in choosing ... effective mass of M^(rms)_eff = 16.2 µg, corresponding to ∼ 10¹⁷ atoms, delocalized over a distance of 2.1 · 10⁻¹⁸ m

    Notation restored: Exponents restored as the arXiv PDF (2211.00449v1) sets them, checked from the glyph positions with pdftotext -bbox, 2026-09-24. The text as extracted reads: Since we are not considering a center-of-mass mode, there is some freedom in choosing ... effective mass ofM (rms) eff = 16.2µg, corresponding to∼ 1017 atoms, delocalized over a distance of 2.1 · 10−18 m

What this does not establish

The superposition is of a vibration, not of the crystal moving as a whole, and the effective mass depends on how the vibration is counted, as the paper says.

Later work looked for

Crossref, 2023 on, "Schrödinger cat states mechanical oscillator": nothing found that changes it.

Corrected

24 September 2026. Previously: “” Added with claim 19; figures from Bild and others, Science 380 (2023).

Claim 20 · checked 24 September 2026 · AI-assisted audit

Claim: Which object holds the record depends on whether size means mass or the distance between the two possibilities.

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

Follows from claims 15 and 20. The 2026 paper compares such experiments with a combined measure, macroscopicity, and by that measure its clusters rank above all earlier experiments.

  • Context

    Probing quantum mechanics with nanoparticle matter-wave interferometryDiscussion

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026

    The source reads: This value quantifies to what extent a given quantum experiment probes the validity of quantum mechanics and how well it can exclude minimal modifications of the Schrödinger equation

Corrected

24 September 2026. Previously: “” Added with claims 19 and 20.

Claim 21 · checked 24 September 2026 · AI-assisted audit

Claim: What has been put through two paths at once

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: 1927

Kind
Historical claim. A statement about the past that historical evidence can test.
Review
Source checked. The cited passage was read, and it says this.

Claim 23 · checked 24 September 2026 · AI-assisted audit

Claim: Electrons

Kind
Historical claim. A statement about the past that historical evidence can test.
Review
Source checked. The cited passage was read, and it says this.

Claim 24 · checked 24 September 2026 · AI-assisted audit

Claim: Diffraction from a crystal, the first demonstration that matter interferes.

Kind
Historical claim. A statement about the past that historical evidence can test.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Models of wave-function collapse, underlying theories, and experimental testssection on molecule interferometry

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026

    The source reads: Experiments with matter waves exist since 1927 when Davissson and Germer diffracted a beam of electrons. It was the first proof of de Broglie’s hypothesis on particle-wave duality. ... While bulk and surface crystals are well-adapted to diffract electrons and neutrons

What this does not establish

The review calls Davisson and Germer the first proof and says crystals diffract electrons; it does not name their nickel crystal.

Claim 25 · checked 24 September 2026 · AI-assisted audit

Claim: 1999

Kind
Historical claim. A statement about the past that historical evidence can test.
Review
Source checked. The cited passage was read, and it says this.

Claim 26 · checked 24 September 2026 · AI-assisted audit

Claim: Fullerenes

Kind
Historical claim. A statement about the past that historical evidence can test.
Review
Source checked. The cited passage was read, and it says this.

Claim 27 · checked 24 September 2026 · AI-assisted audit

Claim: Sixty carbon atoms, the first large molecule shown to interfere.

Kind
Historical claim. A statement about the past that historical evidence can test.
Review
Source checked. The cited passage was read, and it says this.

Corrected

24 September 2026. Previously: “Sixty carbon atoms, the first object with internal structure and many degrees of freedom.” Atoms and diatomic molecules, which have internal structure, had interfered before; the review records the fullerene as the first large molecule.

Claim 28 · checked 24 September 2026 · AI-assisted audit

Claim: 2019

Kind
Historical claim. A statement about the past that historical evidence can test.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

  • Supports

    Quantum superposition of molecules beyond 25 kDaabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026

    The source reads: we report interference of a molecular library of functionalized oligoporphyrins ... with masses beyond 25,000 Da

What this does not establish

The 2019 paper was read only as its abstract.

Claim 29 · checked 24 September 2026 · AI-assisted audit

Claim: 25,000 atomic units

Kind
Experimental result. What an experiment or trial found, under its own conditions. A result in animals, cells or a simulation is not a result in people.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

  • Supports

    Quantum superposition of molecules beyond 25 kDaabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Physical systems · Experiment

    The source reads: we report interference of a molecular library of functionalized oligoporphyrins ... with masses beyond 25,000 Da

What this does not establish

The 2019 paper was read only as its abstract. "Beyond 25,000" is its wording.

Later work looked for

Crossref, 2020 on: superseded as the record in 2026 (claim 33).

Claim 30 · checked 24 September 2026 · AI-assisted audit

Claim: Functionalized molecules of up to two thousand atoms.

Kind
Experimental result. What an experiment or trial found, under its own conditions. A result in animals, cells or a simulation is not a result in people.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

  • Supports

    Quantum superposition of molecules beyond 25 kDaabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Physical systems · Experiment

    The source reads: we report interference of a molecular library of functionalized oligoporphyrins ... with masses beyond 25,000 Da and consisting of up to 2,000 atoms

What this does not establish

The 2019 paper was read only as its abstract.

Later work looked for

Crossref, 2020 on: superseded as the record in 2026 (claim 34).

Corrected

24 September 2026. Previously: “Molecules of up to two thousand atoms, built specifically to survive the experiment.” The abstract says the molecules were functionalized; it does not say why, and "built to survive the experiment" was not something read.

Claim 31 · checked 24 September 2026 · AI-assisted audit

Claim: 2026

Kind
Historical claim. A statement about the past that historical evidence can test.
Review
Source checked. The cited passage was read, and it says this.

Corrected

24 September 2026. Previously: “” New entry for the 2026 record; published 21 January 2026 per Crossref.

Claim 32 · checked 24 September 2026 · AI-assisted audit

Claim: 170,000 atomic units

Kind
Experimental result. What an experiment or trial found, under its own conditions. A result in animals, cells or a simulation is not a result in people.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Probing quantum mechanics with nanoparticle matter-wave interferometryabstract

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Physical systems · Experiment

    The source reads: We specifically demonstrate quantum interference of sodium nanoparticles, which can each contain more than 7,000 atoms at masses greater than 170,000 Da.

Later work looked for

Crossref, 2026 on, "nanoparticle matter-wave interferometry": nothing later found.

Corrected

24 September 2026. Previously: “” New entry for the 2026 record.

Claim 33 · checked 24 September 2026 · AI-assisted audit

Claim: Sodium clusters of more than seven thousand atoms, each in two places 133 nanometres apart.

Kind
Experimental result. What an experiment or trial found, under its own conditions. A result in animals, cells or a simulation is not a result in people.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Probing quantum mechanics with nanoparticle matter-wave interferometryabstract; Discussion

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Physical systems · Experiment

    The source reads: which can each contain more than 7,000 atoms ... a nanometer-sized piece of metal being ‘here and there’ in the same quantum state with a 133 nm separation between the two locations

Later work looked for

Crossref, 2026 on, "nanoparticle matter-wave interferometry": nothing later found.

Corrected

24 September 2026. Previously: “” New entry for the 2026 record.

Claim 34 · checked 24 September 2026 · AI-assisted audit

Why large objects look classical anyway

Claim: Why large objects look classical anyway

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: Any object interacting with its surroundings, through stray gas, thermal radiation or light, leaks information about its position into the environment, and interference becomes unobservable almost immediately.

Kind
What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Decoherence, the measurement problem, and interpretations of quantum mechanicssection III.E.2

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field

    The source reads: photons and air molecules are shown to continuously “measure” the spatial structure of dust particles, leading to rapid decoherence into an apparent (improper) mixture of wave packets that are sharply peaked in position space

  • Supports

    Decoherence, the measurement problem, and interpretations of quantum mechanicssection III.D.2

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field

    The source reads: Even microscopic systems such as large molecules are rapidly decohered by the interaction with thermal radiation on a time scale that is much shorter than any practical observation could resolve

What this does not establish

"Almost immediately" holds for objects in ordinary surroundings. In a vacuum, well shielded, molecules and clusters keep interfering long enough to be measured, which is what the experiments above do.

Later work looked for

Crossref, 2020 on, "decoherence timescale macroscopic": nothing found that revises the account; the 2026 paper names gas and thermal radiation as the decoherence it had to control.

Claim 36 · checked 24 September 2026 · AI-assisted audit

Claim: This is decoherence.

Kind
About a word. What a word in the original language means, or how it is translated.
Review
Source checked. The cited passage was read, and it says this.

Corrected

24 September 2026. Previously: “This is decoherence, it is quantitative, and it explains why the boundary looks like a boundary in ordinary conditions.” The sentence was split so the qualification in claim 38 could be added.

Claim 37 · checked 24 September 2026 · AI-assisted audit

Claim: It is quantitative, and it explains why the boundary looks like a boundary in ordinary conditions, though not, on its own, why a measurement has a single outcome.

Kind
What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review
Source checked. The cited passage was read, and it says this.

Later work looked for

Crossref, 2020 on, "decoherence measurement problem": the division between the two is still how the literature read describes it; nothing changes it.

Corrected

24 September 2026. Previously: “it is quantitative, and it explains why the boundary looks like a boundary in ordinary conditions.” Both reviews say decoherence accounts for the loss of observable interference but does not by itself solve the measurement problem; the page now says so.

Claim 38 · checked 24 September 2026 · AI-assisted audit

Claim: Decoherence works inside ordinary quantum mechanics, which sets no upper limit on size.

Kind
What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review
Source checked. The cited passage was read, and it says this.

Later work looked for

How the theory is built; not a finding later work revises.

Corrected

24 September 2026. Previously: “It predicts that with sufficient isolation the effect should persist at any mass.” The prediction is quantum mechanics’, not decoherence’s; decoherence only explains why it is hidden. Reworded to say where it comes from.

Claim 39 · checked 24 September 2026 · AI-assisted audit

Claim: On that theory, a well enough isolated object of any mass should still interfere.

Kind
What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
Review
Source checked. The cited passage was read, and it says this.

What this does not establish

A prediction, tested by interference only up to about 170,000 atomic units. Collapse models predict otherwise.

Claim 40 · checked 24 September 2026 · AI-assisted audit

What might stop it

Claim: What might stop it

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: Every attempt to find the boundary has found only the limits of the apparatus.

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

The page’s summary of claims 18 and 47: no experiment has found a breakdown of superposition, and each record was set where the equipment ran out.

Claim 42 · checked 24 September 2026 · AI-assisted audit

Whether something else also intervenes

Claim: Whether something else also intervenes

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: A class of models adds a physical process that destroys superpositions spontaneously, at a rate increasing with mass, so that a large object could not be in two places even in perfect isolation.

Kind
What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
Review
Source checked. The cited passage was read, and it says this.

What this does not establish

What the models say, not what has been observed. No experiment has seen such a process.

Claim 44 · checked 24 September 2026 · AI-assisted audit

Claim: These models were invented to solve the measurement problem and they make predictions, which is what distinguishes them from interpretations.

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Source checked. The cited passage was read, and it says this.

The contrast with interpretations is the review authors’ own framing, who work on collapse models.

Claim 45 · checked 24 September 2026 · AI-assisted audit

Claim: Experiments with massive objects, and searches for the faint heating and radiation such a process would cause, are steadily excluding their parameters.

Kind
What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Present status and future challenges of non-interferometric tests of collapse modelsabstract; section 1

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field

    The source reads: We provide an overview of such experiments, including cold atoms, optomechanical systems, X-rays detection, bulk heating as well as comparisons with cosmological observations. ... we have recently witnessed an increasing effort in placing strong experimental bounds on the value of their parameters.

  • Supports

    Underground test of gravity-related wave function collapseabstract

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Physical systems · Experiment

    The source reads: Our result sets a lower bound on the effective size of the mass density of nuclei, which is about three orders of magnitude larger than previous bounds.

Later work looked for

Crossref, 2021 on, "continuous spontaneous localization bounds" and "Diósi-Penrose model test": further bounds and model variants, no reported evidence for collapse; nothing changes it.

Corrected

24 September 2026. Previously: “Experiments with massive objects and searches for the tiny heating such a process would cause are steadily excluding their parameters.” The strongest bounds the review reports come from searches for spontaneous radiation, not only heating.

Claim 46 · checked 24 September 2026 · AI-assisted audit

Claim: So far the exclusions have gone against the models rather than for them,

Kind
What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Present status and future challenges of non-interferometric tests of collapse modelssection 2; closing section

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field

    The source reads: The lack of observation of such hints provides a bound on the collapse parameters ... The unprobed part of the parameter space has been greatly reduced, pushing the limits of quantum theory further.

Later work looked for

Crossref, 2021 on, "collapse models experimental test": no positive detection found.

Claim 47 · checked 24 September 2026 · AI-assisted audit

Claim: and the question is open.

Kind
Open question. Something the page says is not known.
Review
Presented as open. The page says this is unresolved, and the review found that it is.

Claim 48 · checked 24 September 2026 · AI-assisted audit

Whether gravity is where it stops

Claim: Whether gravity is where it stops

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: One proposal, from Lajos Diósi and Roger Penrose, is that gravity itself is responsible.

Kind
Hypothesis. A proposed explanation, not an established one.
Review
Source checked. The cited passage was read, and it says this.

Other readings

The 2013 review also covers an earlier gravity proposal by Károlyházy, and a non-gravitational origin for collapse (trace dynamics).

Corrected

24 September 2026. Previously: “One proposal is that gravity itself is responsible,” Attributed to the physicists who proposed it.

Claim 50 · checked 24 September 2026 · AI-assisted audit

Claim: A mass in two places curves spacetime in two different ways, and Penrose argues that quantum theory and general relativity cannot both be satisfied by such a superposition, so it decays, faster for larger masses.

Kind
An argument. An argument a named thinker makes. That it is made is checked; whether it succeeds is argued.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Underground test of gravity-related wave function collapseabstract; main text

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Argument

    The source reads: Roger Penrose proposed that a spatial quantum superposition collapses as a back-reaction from spacetime, which is curved in different ways by each branch of the superposition. ... the more massive the system in the superposition, the larger the difference in the two space-times and the faster the wave-function collapse.

  • Supports

    Models of wave-function collapse, underlying theories, and experimental testssection III.3, The model of Penrose

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field

    The source reads: There is thus a conflict between the demands of quantum theory and of general relativity.

What this does not establish

An argument, not a result. Whether it succeeds is exactly what the tests below ask.

Corrected

24 September 2026. Previously: “because a superposition of masses is a superposition of spacetimes and general relativity has no way to describe one.” Stated as fact on the page; it is Penrose’s argument, a conflict between the two theories as the review puts it, and is now attributed to him.

Claim 51 · checked 24 September 2026 · AI-assisted audit

Claim: The simplest version, with no adjustable parameter, has already failed a test that needed no interference: the collapse should make matter emit faint radiation, and a germanium detector under the Gran Sasso mountain in Italy saw too little of it.

Kind
Experimental result. What an experiment or trial found, under its own conditions. A result in animals, cells or a simulation is not a result in people.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Underground test of gravity-related wave function collapseabstract; main text

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Physical systems · Experiment

    The source reads: resulting, if charged, in the emission of radiation. ... the radiation emission rate, which is faint but detectable. ... This rules out the natural parameter-free version of the ... there was no need to create a spatial superposition

  • Supports

    Underground test of gravity-related wave function collapsemain text

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Physical systems · Experiment

    The source reads: by measuring the spontaneous radiation emission rate from a Germanium crystal ... The experiment was carried out in the low background environment of the Gran Sasso underground National Laboratory (LNGS) of INFN.

  • Supports

    Present status and future challenges of non-interferometric tests of collapse modelssection 2.4

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field

    The source reads: It also ruled out the parameter-free version of the DP model relating R0 to the width of the wave function, as suggested by Penrose.

What this does not establish

One experiment, by a team that includes Diósi and whose authors wrote the 2022 review. It tests the Diósi-Penrose model as written with a mass density, and the radiation it predicts depends on that form.

Later work looked for

Crossref, 2021 on, "Diósi-Penrose model test" and "gravity-related collapse radiation": later papers extend the model and propose tests; none found that reverses the result.

Corrected

24 September 2026. Previously: “Testing that requires interference with masses large enough for their own gravity to matter, which is many orders of magnitude beyond the current record and is a stated goal of several laboratories.” Out of date and wrong in its first clause: testing the gravity proposal does not require interference, and a 2021 underground experiment (Donadi and others, Nature Physics 17) ruled out its parameter-free version. The "stated goal of several laboratories" was not carried by any source read.

Claim 52 · checked 24 September 2026 · AI-assisted audit

Claim: Versions with an adjustable scale survive.

Kind
What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review
Source checked. The cited passage was read, and it says this.

Later work looked for

Crossref, 2021 on, "Diósi-Penrose model": still treated with a free parameter in later work; nothing changes it.

Claim 53 · checked 24 September 2026 · AI-assisted audit

Claim: Testing them by interference would need, on one estimate, masses around a billion atomic units, thousands of times the current record.

Kind
What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Models of wave-function collapse, underlying theories, and experimental testssection III.3

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field

    The source reads: For the experimentally interesting a = 0.5 µm this gives m to be about 10⁹ amu.

    Notation restored: Exponent restored as the arXiv PDF (1204.4325v3) sets it, checked from the glyph positions with pdftotext -bbox, 2026-09-24. The text as extracted reads: For the experimentally interesting a = 0.5 µm this gives m to be about 10 9 amu.

  • Supports

    Probing quantum mechanics with nanoparticle matter-wave interferometryabstract

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Physical systems · Experiment

    The source reads: more than 7,000 atoms at masses greater than 170,000 Da

What this does not establish

The estimate is for a superposition half a micrometre wide and assumes the gravity models’ scale; a different width moves it. "Thousands of times" is 10⁹ against 1.7 × 10⁵, about 6,000.

Claim 54 · checked 24 September 2026 · AI-assisted audit

What was read