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Evidence record

Can two things be connected across any distance?

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: 38
  • A judgement, not a fact: 8

If something here is wrong, misquoted, out of date or unfair, write to support@unknownoceans.com and give the claim number, which does not change.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

A physics question with an experimental answer to one part of it: Bell tests rule out local explanations in which answers are carried in advance, given stated assumptions, and leave open what the correlations mean.

  • Whether distant things are connected can be tested by experiment

    Established

    Bell turned the assumption of locality into an inequality, and the 2015 experiments tested it with the main loopholes closed.

  • The experimenters’ choices of what to measure are independent of what the particles carry

    Contested

    Every Bell test assumes it. Experiments can bound it but a Bell inequality cannot test it, and the Stanford Encyclopedia reports that rejecting it (superdeterminism) has gained some support in recent years.

  • "Connected" means something passes between the particles

    Open

    No usable signal passes. Whether anything undetectable does depends on the interpretation, which is unsettled.

How the question is labelled

Claim: Two particles, one answer

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

Claim: Entanglement

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

The question

Claim: The inequality that settles it was written down in 1964, took fifty years to test without a loophole, and rules out an entire class of explanations.

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

    On the Einstein Podolsky Rosen paradoxCrossref record; section I

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

    The source reads: In this note that idea will be formulated mathematically and shown to be incompatible with the statistical predictions of quantum mechanics.

  • Supports

    Bell’s Theoremsection 4

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

    The source reads: A first proposal to test a Bell inequality was made by Clauser, Horne, Shimony, and Holt (1969)

  • Supports

    Bell’s Theoremsection 5.3

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

    The source reads: In 2015 three papers appeared claiming a conclusive test of Bell inequalities.

  • Supports

    Loophole-free Bell inequality violation using electron spins separated by 1.3 kilometresabstract

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

    The source reads: Here we report on a Bell experiment that is free of any such additional assumption and thus directly tests the principles underlying Bell’s inequality.

What this does not establish

Bell’s paper of November 1964 derived the inequality; the first proposal for an experiment to test it was Clauser, Horne, Shimony and Holt’s in 1969. "Without a loophole" is the experimenters’ own term and covers the detection and locality loopholes: the Delft team says no experiment can exclude every conceivable local realist theory.

Corrected

24 September 2026. Previously: “The experiment that settles it was designed in 1964, took fifty years to perform without a loophole, and rules out an entire class of explanations.” Bell’s 1964 paper derived the inequality and did not design an experiment; the first proposed test was Clauser, Horne, Shimony and Holt’s in 1969, which the page itself says further down.

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

Claim: Measurements on entangled particles are correlated more strongly than any theory in which each particle carried its answer with it could produce.

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.

What this does not establish

What is ruled out also assumes the measurement choices are independent of what the particles carry and that each result is final once recorded; the page spells these out under "What it rules out, exactly".

Later work looked for

Crossref and the Stanford Encyclopedia (revised January 2024), 2016 on, "loophole-free Bell test": loophole-free violations have since been reported with atoms (Rosenfeld and others 2017) and superconducting circuits (Storz and others, Nature 2023); nothing that changes it.

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

Claim: In 2015 the experiment was finally done with the detection and locality loopholes closed at once, and the correlations held.

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

    Loophole-free Bell inequality violation using electron spins separated by 1.3 kilometresdiscussion

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

    The source reads: Our experiment realizes the first Bell test that simultaneously addresses both the detection loophole and the locality loophole.

  • Supports

    Bell’s Theoremsection 5.3

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

    The source reads: In 2015 three papers appeared claiming a conclusive test of Bell inequalities.

Later work looked for

Crossref and the Stanford Encyclopedia (revised January 2024), 2016 on, "loophole-free Bell test": loophole-free violations have since been reported with atoms (Rosenfeld and others 2017) and superconducting circuits (Storz and others, Nature 2023); nothing that changes it.

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

Claim: Prepare two particles together and separate them.

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

Claim: Measure one and you learn something about the other immediately, however far apart they are.

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

    On the Einstein Podolsky Rosen paradoxsection II

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

    The source reads: If measurement of the component sigma1 . a, where a is some unit vector, yields the value +1 then, according to quantum mechanics, measurement of sigma2 . a must yield the value -1 and vice versa.

    Vector notation spelled out in the transcription.

  • Supports

    Bell’s Theoremsection 2

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

    The source reads: If experiments are done with the axes of the two devices aligned, the results are guaranteed to be opposite

What this does not establish

This is what quantum mechanics predicts for a pair like the singlet. Experiments have tested it at distances up to kilometres, not at any distance whatever, and what you learn is a correlation, not a message.

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

Claim: The obvious explanation is that they agreed in advance, the way two gloves in two boxes are already left and right.

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 own analogy for the reasoning Bell attributes to Einstein, Podolsky and Rosen: predictable at a distance, therefore predetermined.

  • Context

    On the Einstein Podolsky Rosen paradoxsection II

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

    The source reads: Since we can predict in advance the result of measuring any chosen component of sigma2, by previously measuring the same component of sigma1, it follows that the result of any such measurement must actually be predetermined.

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

Claim: In 1964 John Bell showed that this explanation makes a numerical prediction, and that quantum mechanics predicts something different.

Kind
A proved result. A mathematical theorem, as its proof or a reference work states it. What it says about the world depends on how well the mathematics fits.
Review
Source checked. The cited passage was read, and it says this.

The "numerical prediction" is a bound, an inequality, rather than a single number.

  • Supports

    On the Einstein Podolsky Rosen paradoxsection I

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

    The source reads: In this note that idea will be formulated mathematically and shown to be incompatible with the statistical predictions of quantum mechanics.

  • Supports

    Loophole-free Bell inequality violation using electron spins separated by 1.3 kilometresabstract

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

    The source reads: Bell showed that in any local realist theory the correlations between distant measurements satisfy an inequality and, moreover, that this inequality can be violated according to quantum theory.

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

The experiment

Claim: The experiment

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

What Bell proved

Claim: What Bell proved

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

Claim: If each particle carries a definite answer to every possible measurement, arranged in advance, neither answer depends on what is chosen at the far end, and the choices are independent of the answers, then the correlations between distant measurements must satisfy an inequality.

Kind
A proved result. A mathematical theorem, as its proof or a reference work states it. What it says about the world depends on how well the mathematics fits.
Review
Source checked. The cited passage was read, and it says this.

The first condition is Bell’s 1964 form; later versions of the theorem drop the requirement that answers be fixed in advance.

  • Supports

    On the Einstein Podolsky Rosen paradoxsection II

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

    The source reads: it follows that the result of any such measurement must actually be predetermined. ... The vital assumption [2] is that the result B for particle 2 does not depend on the setting a, of the magnet for particle 1, nor A on b.

  • Supports

    Bell’s Theoremsection 3.2.2

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

    The source reads: Bell’s original analyses (1964, 1971) tacitly assumed that the complete state

  • Supports

    Bell’s Theoremsection 3.2.2

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

    The source reads: has variously been called the Free Will assumption, the Freedom of Choice Assumption, the No-conspiracies Assumption

  • Supports

    Bell’s Theoremopening summary

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

    The source reads: Bell’s theorem shows that no theory that satisfies the conditions imposed can reproduce the probabilistic predictions of quantum mechanics under all circumstances.

Corrected

24 September 2026. Previously: “If each particle carries a definite answer to every possible measurement, arranged in advance, and neither answer depends on what is chosen at the far end, then the correlations between distant measurements must satisfy an inequality.” The theorem also needs the settings to be independent of what the particles carry, which Bell assumed tacitly and the Stanford Encyclopedia lists as the measurement independence assumption. The page names it two sections later; stating the theorem without it overstated what follows from the first two conditions alone.

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

Claim: It is a constraint on that whole class of theories,

Kind
A proved result. A mathematical theorem, as its proof or a reference work states it. What it says about the world depends on how well the mathematics fits.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Bell’s Theoremsection 2

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

    The source reads: This shows that no theory satisfying the factorizability condition can reproduce the statistical predictions of quantum mechanics in all situations.

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

Claim: and getting to it is arithmetic.

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.

For the CHSH form the derivation is a few lines of bounding sums of plus and minus ones; Bell’s own 1964 proof uses integrals, which Bell himself called "quite simple".

  • Context

    On the Einstein Podolsky Rosen paradoxsection III

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

    The source reads: The proof of the main result is quite simple.

  • Context

    Bell’s Theoremsection 2, equations 9 to 12

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

    The source reads: We now prove the first part of the theorem, namely, that the CHSH inequality follows from the factorizability condition (F).

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

Claim: Bell did take one thing from quantum mechanics: that two measurements along the same axis always disagree.

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

    On the Einstein Podolsky Rosen paradoxsection IV

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

    The source reads: It can reach -1 at a = b only if [equation (13): A(a, lambda) = -B(a, lambda)] except at a set of points lambda of zero probability.

  • Supports

    Bell’s Theoremsection 1

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

    The source reads: The original derivation (1964) relied on a set-up involving perfect anticorrelation of the results of spin experiments on pairs of spin-1/2 particles prepared in the singlet state.

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

Claim: The form the first loophole-free test used, written five years later by Clauser, Horne, Shimony and Holt, takes nothing from it at all.

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.

"Takes nothing from it" means the inequality does not assume the perfect anticorrelation; quantum mechanics still supplies the prediction that violates it.

  • Supports

    Bell’s Theoremsection 1

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

    The source reads: Clauser, Horne, Shimony and Holt (1969) derived an inequality, the CHSH inequality, that does not require this assumption.

  • Supports

    Bell’s Theoremsection 5.3

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

    The source reads: The first (Hensen et al., 2015) achieved a violation of the CHSH inequality via an event-ready scheme.

  • Supports

    Loophole-free Bell inequality violation using electron spins separated by 1.3 kilometresmain text, opening

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

    The source reads: We consider a Bell test in the form proposed by Clauser, Horne, Shimony and Holt (CHSH)

Corrected

24 September 2026. Previously: “The form the experiments use, written five years later by Clauser, Horne, Shimony and Holt, takes nothing from it at all.” Only the Delft experiment tested the CHSH inequality. Both 2015 photon experiments tested the Clauser-Horne inequality in Eberhard’s form (Giustina, Shalm, and the Stanford Encyclopedia section 5.3).

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

Claim: Quantum mechanics predicts correlations that exceed the bound.

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, for suitable entangled states and measurement settings; for others quantum mechanics stays inside the bound. That the world follows the prediction is the experiments’ result, below.

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

Claim: The disagreement is not philosophical. It is a number that can be measured.

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 reading of claims 13 and 17: the two sides predict different values of one measurable quantity.

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

The paper it comes from

Claim: The paper it comes from

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

Claim: Bell's 1964 paper is six pages long and was published in a journal that no longer exists.

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

    On the Einstein Podolsky Rosen paradoxCrossref record; reprint footer

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

    The source reads: Originally published in Physics, 1, 195-200 (1964).

    Crossref lists 85 works in Physics Physique Fizika, all dated 1964 to 1968.

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

Claim: It was written as a response to an argument by Einstein, Podolsky and Rosen that quantum mechanics must be incomplete.

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

    On the Einstein Podolsky Rosen paradoxsection I, first sentence

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

    The source reads: THE paradox of Einstein, Podolsky and Rosen [1] was advanced as an argument that quantum mechanics could not be a complete theory but should be supplemented by additional variables.

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

Claim: Their argument assumed that distant measurements cannot influence each other and concluded that the particles must carry hidden properties.

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

    On the Einstein Podolsky Rosen paradoxsection II

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

    The source reads: Now we make the hypothesis [2], and it seems one at least worth considering, that if the two measurements are made at places remote from one another the orientation of one magnet does not influence the result obtained with the other.

  • Supports

    On the Einstein Podolsky Rosen paradoxsection II

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

    The source reads: it follows that the result of any such measurement must actually be predetermined.

What this does not establish

Checked against Bell’s account of the argument, in Bohm’s version with spins, not against the 1935 paper itself, which argued for incompleteness from position and momentum.

Claim 22 · checked 24 September 2026 · AI-assisted audit

Claim: Bell took that assumption seriously enough to derive its consequence, and found that it is measurable.

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

    On the Einstein Podolsky Rosen paradoxsection I

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

    The source reads: It is the requirement of locality, or more precisely that the result of a measurement on one system be unaffected by operations on a distant system with which it has interacted in the past, that creates the essential difficulty.

  • Supports

    On the Einstein Podolsky Rosen paradoxsection VI

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

    The source reads: experiments of the type proposed by Bohm and Aharonov [6], in which the settings are changed during the flight of the particles, are crucial.

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

Claim: That is the move worth noticing: an objection that had been treated as philosophy for thirty years was turned into an inequality with a number on each side.

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 reading. Thirty years is rounded: Einstein, Podolsky and Rosen published in 1935, Bell in 1964.

  • Context

    Bell’s Theoremsection 8

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

    The source reads: The fact that a conjunction of theses of the sort usually regarded as metaphysical has consequences that can be subjected to experimental test has led Shimony to speak of the enterprise of experimental testing for violations of Bell inequalities as “experimental metaphysics”

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

The loopholes, and closing them

Claim: The loopholes, and closing them

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

Claim: Early experiments violated the inequality but left two ways out.

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.

Two main ones, as the Delft team puts it. Others (memory, coincidence timing, freedom of choice) are named in the 2015 papers.

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

Claim: The detection loophole: if only a fraction of particles are detected, the sample might be unrepresentative.

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.

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

Claim: The locality loophole: if the two stations are close enough, a signal at light speed could coordinate them.

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.

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

Claim: A 2015 experiment used electron spins in diamond, 1.3 kilometres apart on a university campus, with detection efficiency high enough and separation large enough to close both 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.

The title’s 1.3 km; the text gives the spins’ separation as 1280 m.

Later work looked for

Crossref and the Stanford Encyclopedia (revised January 2024), 2016 on, "loophole-free Bell test": loophole-free violations have since been reported with atoms (Rosenfeld and others 2017) and superconducting circuits (Storz and others, Nature 2023); nothing that changes it.

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

Claim: The inequality was violated, though not by a wide margin: 2.42 plus or minus 0.20 against a bound of 2, over 245 trials, and a p-value of 0.039 against any local realist model of space-like separated sites.

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

    Loophole-free Bell inequality violation using electron spins separated by 1.3 kilometresabstract

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

    The source reads: We perform 245 trials testing the CHSH-Bell ... find S = 2.42± 0.20

  • Supports

    Loophole-free Bell inequality violation using electron spins separated by 1.3 kilometresabstract

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

    The source reads: A null hypothesis test yields a probability of p = 0.039 that a local-realist model for space-like separated sites produces data with a violation at least as large as observed, even when allowing for memory

  • Supports

    Bell’s Theoremsection 5.3

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

    The source reads: the experiment utilized only a small number, 245, of trials, and thus the statistical significance (2 standard deviations) of the result

What this does not establish

The 0.20 is the standard deviation from the conventional analysis; the 0.039 is from the analysis that allows for memory and imperfect random numbers, and the conventional one gives 0.019.

Later work looked for

Crossref and the Stanford Encyclopedia (revised January 2024), 2016 on, "loophole-free Bell test": loophole-free violations have since been reported with atoms (Rosenfeld and others 2017) and superconducting circuits (Storz and others, Nature 2023); nothing that changes it.

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

Claim: Two photon experiments closed the same two loopholes later the same year, testing a related inequality with far stronger statistics: the Vienna team reported eleven and a half standard deviations.

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.

Delft was published on 21 October 2015, both photon papers on 16 December 2015 (Crossref). The NIST-led team reported a smallest adjusted p-value of 2.3 × 10⁻⁷.

  • Supports

    Significant-loophole-free test of Bell’s theorem with entangled photonsabstract

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

    The source reads: corresponding to an 11.5 standard deviation effect

  • Supports

    Significant-loophole-free test of Bell’s theorem with entangled photonsmain text

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

    The source reads: We employed a CH-Eberhard (CH-E) type inequality

  • Supports

    Significant-loophole-free test of Bell’s theorem with entangled photonsaffiliations

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

    The source reads: Austrian Academy of Sciences, Boltzmanngasse 3, Vienna 1090, Austria

  • Supports

    Strong loophole-free test of local realismabstract

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

    The source reads: our smallest adjusted p-value is 2.3 × 10⁻⁷

    Notation restored: Superscript exponent restored from the abstract on arxiv.org/abs/1511.03189, which gives the value as 2.3 × 10^-7 in its LaTeX, read 2026-09-24. The text as extracted reads: our smallest adjusted p-value is 2.3× 10−7

  • Supports

    Strong loophole-free test of local realismmain text

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

    The source reads: Our Bell test uses a version of the Clauser-Horne inequality

  • Supports

    Bell’s Theoremsection 5.3

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

    The source reads: In both of these experiments a violation of the CH inequality was obtained, at a high degree of statistical significance. ... Besides the detection and communication loophole, these two experiments address also the following issues

  • Supports

    Bell’s Theoremsection 5.3, on Hensen and colleagues

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

    The source reads: In 2015 three papers appeared claiming a conclusive test of Bell inequalities. ... the statistical significance (2 standard deviations) of the result

Later work looked for

Crossref and the Stanford Encyclopedia (revised January 2024), 2016 on, "loophole-free Bell test": loophole-free violations have since been reported with atoms (Rosenfeld and others 2017) and superconducting circuits (Storz and others, Nature 2023); nothing that changes it.

Corrected

24 September 2026. Previously: “Two photon experiments reported the same violation two months later, one of them at eleven and a half standard deviations.” Not the same violation: both photon experiments tested the Clauser-Horne inequality in Eberhard’s form, not CHSH. The 11.5 figure is attributed to the team that reports it.

24 September 2026. Previously: “Two photon experiments closed the same two loopholes two months later, testing a related inequality with far stronger statistics: the Vienna team reported eleven and a half standard deviations.” The interval of two months rested on publication dates that none of the texts read carries. The reference work places all three papers in 2015 with the Delft one first, which is what the sentence now says.

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

Claim: What the 2015 experiment had to do at once

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

Claim: Detect nearly everything

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

Claim: Report an outcome for essentially every trial, so no argument remains that the detected subset was special.

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.

Every heralded trial yields +1 or -1: a count is +1 and no count is -1, so none is discarded.

Later work looked for

Crossref and the Stanford Encyclopedia (revised January 2024), 2016 on, "loophole-free Bell test": loophole-free violations have since been reported with atoms (Rosenfeld and others 2017) and superconducting circuits (Storz and others, Nature 2023); nothing that changes it.

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

Claim: Separate far enough

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

Claim: 1.3 kilometres, so that no influence travelling at the speed of light could reach the other station before its measurement was complete.

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.

Later work looked for

Crossref and the Stanford Encyclopedia (revised January 2024), 2016 on, "loophole-free Bell test": loophole-free violations have since been reported with atoms (Rosenfeld and others 2017) and superconducting circuits (Storz and others, Nature 2023); nothing that changes it.

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

Claim: Choose settings unpredictably

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

Claim: Fast random choices of what to measure, space-like separated from the event that announced a pair, so nothing at the source could have known them.

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.

What this does not establish

"Could have known" means no signal at light speed could have carried them; a common cause further in the past is the separate question the page takes up in claims 44 to 48.

Later work looked for

Crossref and the Stanford Encyclopedia (revised January 2024), 2016 on, "loophole-free Bell test": loophole-free violations have since been reported with atoms (Rosenfeld and others 2017) and superconducting circuits (Storz and others, Nature 2023); nothing that changes it.

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

What it settles

Claim: What it settles

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

What it rules out, exactly

Claim: What it rules out, exactly

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

Claim: It rules out every theory in which the outcome of each measurement is fixed in advance by properties carried locally, in which the experimenters’ choices are independent of those properties, and in which a result is final once recorded.

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.

What this does not establish

At the statistical strength the three experiments report: for Delft alone, p = 0.039.

Later work looked for

Crossref and the Stanford Encyclopedia (revised January 2024), 2016 on, "loophole-free Bell test": loophole-free violations have since been reported with atoms (Rosenfeld and others 2017) and superconducting circuits (Storz and others, Nature 2023); nothing that changes it.

Claim 41 · checked 24 September 2026 · AI-assisted audit

Claim: It does not show that information travels faster than light.

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

    Bell’s Theoremsection 8.2

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

    The source reads: quantum correlations cannot be exploited to send signals superluminally

Later work looked for

The Stanford Encyclopedia entry was substantively revised in January 2024; nothing read that changes it.

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

Claim: The correlations cannot be used to send a message: each side alone sees random results, and the correlation only appears when the two records are brought together and compared, which happens no faster than light allows.

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.

"Random" is exact for the singlet state, where each side’s two results are equally likely whatever either side measures.

  • Supports

    Bell’s Theoremsection 8.2

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

    The source reads: quantum correlations cannot be exploited to send signals superluminally

  • Supports

    Bell’s Theoremsection 2

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

    The source reads: regardless of the direction of the axes of the devices, for each side of the experiment the two possible results have the same probability, one-half.

  • Context

    Significant-loophole-free test of Bell’s theorem with entangled photonsmain text

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

    The source reads: Combining their data at the end of the experiment, they estimate the probabilities that appear in the inequality.

Later work looked for

The Stanford Encyclopedia entry was substantively revised in January 2024; nothing read that changes it.

Claim 43 · checked 24 September 2026 · AI-assisted audit

Claim: It also leaves open theories that keep definite properties by abandoning locality outright, and theories that deny the independence of the settings, a position with some recent advocates that no Bell test can refute outright.

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 Stanford Encyclopedia names ’t Hooft, Hossenfelder, Palmer and Hance among the advocates of rejecting setting independence (superdeterminism), and lists retrocausality as the other way to reject it.

  • Supports

    Bell’s Theoremsection 8.1.3

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

    The source reads: This is the position that is involved in acceptance of the de Broglie-Bohm theory or any similar theory.

  • Supports

    Bell’s Theoremsection 8.1.2

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

    The source reads: has gained some support in recent years.

  • Supports

    Bell’s Theoremsection 5.3

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

    The source reads: (except in the presence of superdeterminism or other hypotheses that, by definition, do not allow a test through Bell inequalities)

Corrected

24 September 2026. Previously: “It also leaves open theories that keep definite properties by abandoning locality outright, and theories that deny the independence of the settings, which is a position with few adherents and no refutation.” "Few adherents" had no source; the Stanford Encyclopedia says the position has gained some support in recent years and names its advocates. "No refutation" is narrowed to what the encyclopedia says: such hypotheses cannot, by definition, be tested by a Bell inequality, though experiments can bound them, as the next sentences say.

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

Claim: The 2015 experiment bounds that second one rather than leaving it alone.

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.

Later work looked for

Crossref and the Stanford Encyclopedia (revised January 2024), 2016 on, "loophole-free Bell test": loophole-free violations have since been reported with atoms (Rosenfeld and others 2017) and superconducting circuits (Storz and others, Nature 2023); nothing that changes it.

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

Claim: The violation survives a much shorter readout, which excludes any model in which the settings came into being less than 690 nanoseconds before they were recorded.

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

    Loophole-free Bell inequality violation using electron spins separated by 1.3 kilometresdiscussion

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

    The source reads: our experiment already excludes all models that predict that the random inputs are determined a maximum of 690 ns before we record them, because the inequality is still violated for a much shorter spin readout

Later work looked for

Crossref and the Stanford Encyclopedia, 2016 on, "freedom-of-choice loophole" and "cosmic Bell test": the bound has since been pushed back to 7.8 billion years with quasar light (Rauch and others 2018), with fair sampling assumed; page updated in claim 48.

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

Claim: A conspiracy has to be older than that.

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 claim 46: a model that fixes the settings in advance has to fix them earlier than the bound.

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

Claim: Later tests that took their settings from the light of distant quasars pushed the bound back to at least 7.8 billion years, though they had to assume fair sampling to do 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

    Cosmic Bell test using random measurement settings from high-redshift quasarsabstract

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

    The source reads: measurement settings were determined based on real-time measurements of the wavelength of photons from high-redshift quasars, whose light was emitted billions of years ago

  • Supports

    Cosmic Bell test using random measurement settings from high-redshift quasarsabstract

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

    The source reads: This experiment pushes back to at least ∼7.8 Gyr ago the most recent time by which any local-realist influences could have exploited the “freedom-of-choice” loophole to engineer the observed Bell violation

  • Supports

    Cosmic Bell test using random measurement settings from high-redshift quasarsconclusions

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

    The source reads: For each Cosmic Bell test reported here, we assume fair sampling and close the locality loophole.

  • Supports

    Bell’s Theoremsection 8.1.2

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

    The source reads: other tests have employed measurements on photons from Milky Way stars (Handsteiner et al. 2017) and from distant quasars (Rauch et al. 2018).

What this does not establish

The quasar tests leave the detection loophole open, so they bound setting-dependence in a different experiment from the one that closed both loopholes. The authors also assume the quasar light was not altered or previewed on its way.

Later work looked for

Crossref, 2018 on, "cosmic Bell test": nothing later that pushes the bound further was found.

Corrected

24 September 2026. Previously: “” Currency: the 690 ns bound is the 2015 figure. Later tests pushed it back by some sixteen orders of magnitude, with the detection loophole open, and the page now says so with the source.

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

Claim: What entanglement is not

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

Claim: It lets you send messages instantly.

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

Claim: Each side alone sees noise.

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

    Bell’s Theoremsection 2

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

    The source reads: regardless of the direction of the axes of the devices, for each side of the experiment the two possible results have the same probability, one-half.

Later work looked for

The Stanford Encyclopedia entry was substantively revised in January 2024; nothing read that changes it.

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

Claim: The correlation appears only when the records are compared, which takes an ordinary signal.

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

    Bell’s Theoremsection 8.2

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

    The source reads: quantum correlations cannot be exploited to send signals superluminally

Later work looked for

The Stanford Encyclopedia entry was substantively revised in January 2024; nothing read that changes it.

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

Claim: Measuring one particle visibly changes the other.

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

Corrected

24 September 2026. Previously: “Measuring one particle changes the other.” Whether measuring one particle changes the other is interpretation-dependent: on the de Broglie-Bohm theory the setting at one side affects the other (Stanford Encyclopedia, section 3.1.2), and the page itself says there is no consensus on the picture. What is a misconception is a detectable change.

Claim: Nothing detectable happens at the far end.

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

    Bell’s Theoremsection 8.2

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

    The source reads: quantum correlations cannot be exploited to send signals superluminally

Later work looked for

The Stanford Encyclopedia entry was substantively revised in January 2024; nothing read that changes it.

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

Claim: Whether anything undetectable does depends on the interpretation.

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.

  • Supports

    Bell’s Theoremsection 3.1.2

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

    The source reads: an example of a theory of this sort is the de Broglie-Bohm theory, which violates PI but does not permit superluminal signalling.

  • Supports

    Bell’s Theoremsection 8

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

    The source reads: Some prima facie plausible options are excluded, leaving a number of options open.

Corrected

24 September 2026. Previously: “” Added with the narrowed misconception in claim 53, so the answer does not take a side the page elsewhere says is open.

Claim 55 · checked 24 September 2026 · AI-assisted audit

Claim: What is ruled out is the story in which both answers were fixed locally in advance.

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.

What this does not establish

Given setting independence and final outcomes, as claim 41 says.

Later work looked for

Crossref and the Stanford Encyclopedia (revised January 2024), 2016 on, "loophole-free Bell test": loophole-free violations have since been reported with atoms (Rosenfeld and others 2017) and superconducting circuits (Storz and others, Nature 2023); nothing that changes it.

Claim 56 · checked 24 September 2026 · AI-assisted audit

Claim: It is an oddity at the edge of physics.

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

Corrected

24 September 2026. Previously: “It is an unexplained oddity at the edge of physics.” The page’s last section says what entanglement describes has no consensus, so calling "unexplained" a misconception contradicted it. The answer addresses "at the edge".

Claim: It is routine.

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 violation has been measured in photons, electron spins, atoms and superconducting circuits.

  • Context

    Bell’s Theoremsection 5.3

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

    The source reads: More recently, loophole-free experiments were realized with atoms (Rosenfeld et al., 2017) and superconductors (Storz et al. 2023) too.

Claim 58 · checked 24 September 2026 · AI-assisted audit

Claim: The same violation these experiments measured is what device-independent cryptography and certified randomness are built on.

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

    Bell’s Theoremsection 7

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

    The source reads: Bell’s theorem has played a direct role in the development of device independent quantum cryptography.

  • Supports

    Bell’s Theoremsection 7

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

    The source reads: to build a random-number generator that can produce output that is unpredictable to any adversary that is limited only by general physical principles

  • Supports

    Loophole-free Bell inequality violation using electron spins separated by 1.3 kilometresmain text

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

    The source reads: a loophole-free Bell test is a critical component for device-independent quantum security protocols

Later work looked for

Crossref, 2016 on, "device-independent quantum key distribution": experimental key distribution certified by Bell’s theorem was reported in 2022 (Nature 607); nothing that changes it.

Claim 59 · checked 24 September 2026 · AI-assisted audit

What is left over

Claim: What is left over

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

Claim: A philosophical argument turned into an inequality, and then into a measurement.

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.

A summary of claims 21 to 31.

  • Context

    Bell’s Theoremsection 8

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

    The source reads: The fact that a conjunction of theses of the sort usually regarded as metaphysical has consequences that can be subjected to experimental test has led Shimony to speak of the enterprise of experimental testing for violations of Bell inequalities as “experimental metaphysics”

Claim 65 · checked 24 September 2026 · AI-assisted audit

What the world is like instead

Claim: What the world is like instead

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

Claim: What the equations predict is not in dispute, and the experiments agree with it.

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

    Bell’s Theoremsection 5.3

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

    The source reads: leaves really no space for doubts about their conclusiveness

  • Supports

    Bell’s Theoremsection 8

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

    The source reads: If one accepts that the experimental evidence gives us strong reason to believe that Bell inequality-violating correlations are features of physical reality, then one or more of these assumptions must be given up.

Later work looked for

The Stanford Encyclopedia entry was substantively revised in January 2024; nothing read that changes it.

Corrected

24 September 2026. Previously: “Everyone agrees on what the equations predict and on what the experiments show.” "Everyone agrees" was stronger than any source; the Stanford Encyclopedia supports the narrower statement that the predictions are standard and the 2015 tests leave no real doubt.

Claim 62 · checked 24 September 2026 · AI-assisted audit

Claim: What they describe is the part that has no consensus, and the choices are set out in the question about 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.

  • Supports

    Bell’s Theoremsection 8

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

    The source reads: As may be expected, the conclusions of experimental metaphysics are not unambiguous. Some prima facie plausible options are excluded, leaving a number of options open. In this section these are briefly outlined, with no attempt made to adjudicate between them.

  • Qualifies

    A snapshot of foundational attitudes toward quantum mechanicsabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Observational study: associations, not causes

    The source reads: the foundations of quantum mechanics themselves remain hotly debated in the scientific community, and no consensus on essential questions has been reached

    A poll of 33 conference participants; read as abstract only.

Claim 63 · checked 24 September 2026 · AI-assisted audit

Claim: That is an unusual situation for a mature science: complete agreement on the numbers and none on the picture.

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 own judgement on claims 62 and 63.

Claim 64 · checked 24 September 2026 · AI-assisted audit

What was read