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arxiv: 1907.05990 · v1 · pith:Y2JHWW4Anew · submitted 2019-07-13 · 🪐 quant-ph

Delayed choice experiments and causality in quantum mechanics

Dominik \v{S}afr\'anek This is my paper

Pith reviewed 2026-05-24 22:20 UTC · model grok-4.3

classification 🪐 quant-ph
keywords delayed choicecausalitymany worldswhich-path informationobjective realityquantum eraserinterferencecomplementarity
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The pith

Delayed choice experiments cannot affect the past, according to many-worlds analysis.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper sets out to show that delayed-choice quantum experiments do not permit any influence on past events. It uses the many-worlds interpretation to demonstrate that all possible measurement outcomes occur across different branches, eliminating apparent retrocausality. The work also supplies a mathematical account of which-path information and explains why its availability blocks interference. It identifies a setup that displays both interference and correlations, revealing their complementarity, and concludes there is no objective reality in the EPR sense. Readers would care because these arguments address persistent questions about causality and reality in quantum mechanics without invoking new physics.

Core claim

Using the Many Worlds interpretation we prove it is not possible to affect the past in delayed choice experiments. We also find a mathematical background to Which-path information and show why its obtainability prevents system from interfering. We find a system which exhibit both interference and correlation and show why one-particle interference and correlations are complementary. Better visible interference pattern leads to worse correlations and vice versa. Then, using knowledge gained from Quantum Eraser and Delayed Choice experiments we prove there is not an objective reality in a sense of Einstein, Podolsky and Rosen. Furthermore, we discuss the difference between outer and inner obser

What carries the argument

The many-worlds interpretation applied to delayed-choice setups, which separates outer non-interacting and inner interacting observers and relates the universal wave function to the processes each sees.

If this is right

  • No experiment can be constructed that affects events in the past.
  • Obtaining which-path information necessarily prevents the system from showing interference.
  • Visibility of the interference pattern and strength of correlations trade off directly against each other.
  • There is no objective reality independent of the observer in the EPR sense.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The relation derived between the universal wave function and inner-observer processes could be checked by preparing entangled states and comparing predictions from different reference frames.
  • The complementarity between interference and correlations suggests quantitative bounds that could be tested in multi-particle interference experiments.
  • Treating all branches as real removes the need for wave-function collapse and may alter how measurement outcomes are counted in quantum information protocols.

Load-bearing premise

The many-worlds interpretation supplies the correct framework that permits rigorous proofs about causality and objective reality.

What would settle it

A laboratory demonstration in which a delayed choice produces a statistically detectable change in a past measurement outcome within one consistent history would falsify the central claim.

Figures

Figures reproduced from arXiv: 1907.05990 by Dominik \v{S}afr\'anek.

Figure 1.1
Figure 1.1. Figure 1.1: Wheeler’s delayed choice experiment. This is a special case of in principle distinguishable histories, which cannot interfere. We will talk about this experimental fact later in quantum eraser experiments. For simplicity let us consider only one photon goes through the optical system at a time. It leaves the pump beam and arrives to the beam splitter. With the classical (Newtonian) approach there is fift… view at source ↗
Figure 1.2
Figure 1.2. Figure 1.2: Experimental setup of the double slit experiment and results of Akira [PITH_FULL_IMAGE:figures/full_fig_p014_1_2.png] view at source ↗
Figure 1.3
Figure 1.3. Figure 1.3: double-slit experiment, double-slit experiment where we marked the [PITH_FULL_IMAGE:figures/full_fig_p016_1_3.png] view at source ↗
Figure 1.4
Figure 1.4. Figure 1.4: Alternative erasures. Additional half-wave plate on the upper path, [PITH_FULL_IMAGE:figures/full_fig_p016_1_4.png] view at source ↗
Figure 1
Figure 1. Figure 1: figure 1.3). If we take state [PITH_FULL_IMAGE:figures/full_fig_p017_1.png] view at source ↗
Figure 1.5
Figure 1.5. Figure 1.5: Herzog et al. experiment without erasure. Idler interferes. [PITH_FULL_IMAGE:figures/full_fig_p019_1_5.png] view at source ↗
Figure 1.6
Figure 1.6. Figure 1.6: Herzog et al. experiment with marked path. Idler does not interfere. [PITH_FULL_IMAGE:figures/full_fig_p020_1_6.png] view at source ↗
Figure 1.7
Figure 1.7. Figure 1.7: Herzog et al. experiment, regained interference with the help of polar [PITH_FULL_IMAGE:figures/full_fig_p020_1_7.png] view at source ↗
Figure 1.8
Figure 1.8. Figure 1.8: Free Will experiment. The tested person decides whether to push the [PITH_FULL_IMAGE:figures/full_fig_p022_1_8.png] view at source ↗
Figure 1.9
Figure 1.9. Figure 1.9: Intensity patterns of the first photon when detector D3 clicks, D4 clicks [PITH_FULL_IMAGE:figures/full_fig_p024_1_9.png] view at source ↗
Figure 1.10
Figure 1.10. Figure 1.10: Intensity patterns of the first photon when detector D1 clicks, D2 [PITH_FULL_IMAGE:figures/full_fig_p024_1_10.png] view at source ↗
Figure 1.11
Figure 1.11. Figure 1.11: Delayed choice entanglement swapping. In this experiment we produce two pairs of entangled photons and Alice measures polarization of the first and Bob of the fourth. Second and third photon (one of each pair) go to Victor and Victor decides whether to subject them to entangled-state measurement (projecting them onto one of the Bell’s states) or separate state measurement (projecting them tensor product… view at source ↗
Figure 2.1
Figure 2.1. Figure 2.1: Generalized Scheme of Delayed Choice experiments used for predicting [PITH_FULL_IMAGE:figures/full_fig_p029_2_1.png] view at source ↗
Figure 2.2
Figure 2.2. Figure 2.2: Double-slit experiment with interfering paths. [PITH_FULL_IMAGE:figures/full_fig_p033_2_2.png] view at source ↗
Figure 3.1
Figure 3.1. Figure 3.1: As we look on one part of the system and we do not receive anything [PITH_FULL_IMAGE:figures/full_fig_p052_3_1.png] view at source ↗
Figure 3.2
Figure 3.2. Figure 3.2: Alice in Wonderland. Alice look at the car and see it on the left side. [PITH_FULL_IMAGE:figures/full_fig_p055_3_2.png] view at source ↗
Figure 3.3
Figure 3.3. Figure 3.3: Alice in Wonderland. Switching unit flies back to the parked car and [PITH_FULL_IMAGE:figures/full_fig_p056_3_3.png] view at source ↗
Figure 3.4
Figure 3.4. Figure 3.4: Personal (relative) realities of three people (highly entangled and con [PITH_FULL_IMAGE:figures/full_fig_p057_3_4.png] view at source ↗
read the original abstract

Although it may seem The Delayed Choice experiments contradict causality and one could construct an experiment which could possibly affect the past, using Many World interpretation we prove it is not possible. We also find a mathematical background to Which-path information and show why its obtainability prevents system from interfering. We find a system which exhibit both interference and correlation and show why one-particle interference and correlations are complementary. Better visible interference pattern leads to worse correlations and vice versa. Then, using knowledge gained from Quantum Eraser and Delayed Choice experiments we prove there is not an objective reality in a sense of Einstein, Podolsky and Rosen. Furthermore, we discuss the difference between ``outer'' (non-interacting) and ``inner'' (interacting) observer. We find the mathematical relationship between the ``universal'' wave function used by ``outer'' observer and processes the ``inner'' observer sees, which is our small contribution to the measurement problem.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

3 major / 2 minor

Summary. The manuscript claims that the Many Worlds Interpretation demonstrates that delayed choice experiments cannot affect the past, provides a mathematical basis for which-path information and its complementarity with interference, shows that better interference leads to worse correlations, proves the absence of EPR-style objective reality, and relates the universal wave function to inner observer processes, contributing to the measurement problem.

Significance. If the claimed proofs and mathematical relationships were derived rigorously from the quantum formalism, the work could offer insights into foundational questions of causality, complementarity, and realism in quantum mechanics. However, the reliance on MWI as the basis for 'proofs' limits the significance, as the conclusions do not appear to follow independently of the interpretive choice.

major comments (3)
  1. [Abstract] Abstract: The abstract asserts multiple 'proofs' using the Many Worlds interpretation but supplies no derivations, equations, or data; the central claims rest on interpretive premises rather than demonstrated mathematics.
  2. [Abstract] Abstract: The claim that MWI proves it is not possible to affect the past is circular, as it adopts the interpretation and then declares the result, without showing additional ontological constraints from the branching structure that prohibit retrocausality.
  3. [Abstract] Abstract: The proof of no objective reality in the EPR sense similarly depends on MWI without demonstrating that the same conclusion cannot be reached or is contradicted in other interpretations, making the interpretive framework load-bearing.
minor comments (2)
  1. [Abstract] Grammatical issues such as 'Although it may seem The Delayed Choice experiments' should be corrected for clarity.
  2. The manuscript would benefit from explicit equations supporting the mathematical background to which-path information and the relationship between interference and correlations.

Simulated Author's Rebuttal

3 responses · 0 unresolved

We thank the referee for their review. Our manuscript explicitly employs the Many-Worlds Interpretation (MWI) to analyze delayed-choice experiments, complementarity, and EPR issues, deriving relations from the quantum formalism under that ontology. We address each major comment below.

read point-by-point responses

  1. Referee: [Abstract] Abstract: The abstract asserts multiple 'proofs' using the Many Worlds interpretation but supplies no derivations, equations, or data; the central claims rest on interpretive premises rather than demonstrated mathematics.

    Authors: The abstract is a concise overview; the body of the manuscript supplies the derivations for which-path information, interference-correlation complementarity, and the MWI analysis of delayed choice. We will revise the abstract to explicitly note that mathematical details appear in the main text. revision: partial

  2. Referee: [Abstract] Abstract: The claim that MWI proves it is not possible to affect the past is circular, as it adopts the interpretation and then declares the result, without showing additional ontological constraints from the branching structure that prohibit retrocausality.

    Authors: MWI's branching structure imposes forward-only evolution: the universal wave function evolves unitarily, and a future measurement choice selects the observer's branch without modifying past events in any branch. The paper derives this constraint from the global consistency of the wave function rather than assuming the conclusion. revision: no

  3. Referee: [Abstract] Abstract: The proof of no objective reality in the EPR sense similarly depends on MWI without demonstrating that the same conclusion cannot be reached or is contradicted in other interpretations, making the interpretive framework load-bearing.

    Authors: The manuscript shows, via MWI analysis of quantum eraser and delayed-choice setups, that EPR-style objective reality is incompatible with branch-dependent outcomes. We do not claim this conclusion is unreachable in other interpretations; our contribution is the explicit MWI mechanism that avoids retrocausality or nonlocality. revision: no

Circularity Check

1 steps flagged

Central claims on no retrocausality and no EPR objective reality are reached by adopting MWI as the framework and declaring it supplies the proofs.

specific steps
  1. other [Abstract]
    "Although it may seem The Delayed Choice experiments contradict causality and one could construct an experiment which could possibly affect the past, using Many World interpretation we prove it is not possible. [...] Then, using knowledge gained from Quantum Eraser and Delayed Choice experiments we prove there is not an objective reality in a sense of Einstein, Podolsky and Rosen."

    The paper states that it 'prove[s]' no past-affecting delayed choice and 'prove[s]' absence of EPR-style objective reality by using the Many Worlds interpretation. The conclusions are therefore equivalent to the input assumption of MWI rather than independently derived; the interpretive framework supplies the ontological constraints that turn standard evolution into the claimed prohibitions.

full rationale

The paper's derivation chain for its strongest results explicitly invokes the Many Worlds interpretation to reach conclusions about causality and reality. This makes the interpretive choice load-bearing: the 'proofs' follow by construction once MWI is selected, rather than emerging from the unitary formalism or equations independent of that choice. No self-citation or fitted-parameter issues appear, but the reduction of the central claims to the MWI assumption qualifies as circularity under the 'other' pattern. The paper does not isolate additional postulates beyond the universal wave function or show the results hold outside MWI.

Axiom & Free-Parameter Ledger

0 free parameters · 2 axioms · 0 invented entities

The paper depends on interpretive domain assumptions rather than new empirical content or parameter-free derivations.

axioms (2)
  • domain assumption Many Worlds interpretation correctly describes quantum mechanics and permits proofs about causality
    Invoked repeatedly to prove that delayed choice cannot affect the past and that there is no objective reality.
  • domain assumption Mathematical model of which-path information necessarily destroys interference
    Used to explain complementarity between interference and correlations.

pith-pipeline@v0.9.0 · 5678 in / 1285 out tokens · 22933 ms · 2026-05-24T22:20:25.069508+00:00 · methodology

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Reference graph

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19 extracted references · 19 canonical work pages · 5 internal anchors

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