Answer · confidence: partial
Has any company or lab claimed past messages work, and do quantum tests agree?
Research question: As of October 2026, have any companies, researchers, or public projects launched services or experiments that claim to deliver messages to the past or receive replies from the future, and what have recent quantum retrocausality or delayed-choice experiments reported about whether such signaling is p
The verified facts do not report any company, researcher, or public project that launched a service to send messages to the past or receive replies from the future, so that part of the question goes unanswered 712. Recent analyses report that delayed-choice results can be explained with textbook quantum mechanics, without information from the future 245. A 2019 experiment reported nonclassicality based on a dimension witness rather than retrocausal explanations 8, and one article notes that the retrocausality experiment itself has never actually been carried out 9. The newest fact, a June 4, 2026 paper, states that its framework does not propose that the future sends signals to the past, about four months before October 2026 17.
Checked 2026-10-21. Only documented and supported facts are used.
Dig deeper on this questionSources
[1] documented
A 2015 analysis by Wood and Spekkens argues that quantum correlations can satisfy no-signalling in a causal model only through fine-tuning of the model's parameters.
"concluding that the no-signalling requirement of the quantum correlations can only be achieved in the causal modelling framework by fine-tuning the parameters in the model."Quantum causal models, faithfulness and retrocausality
[2] supported
The paper argues that the outcomes of Wheeler's delayed-choice experiment and the delayed quantum eraser can be explained entirely with textbook quantum mechanics, without needing information from the future.
"At no point in the argument, information from the future is needed to explain what happens next."Delayed choice experiments: An analysis in forward time
[3] supported
The author argues that a violation of faithfulness does not necessarily rule out retrocausal explanations of EPRB correlations, although it constrains them.
"does not necessarily rule out retrocausal explanations of the EPRB correlations, although it certainly constrains such explanations"Quantum causal models, faithfulness and retrocausality
[4] supported
The authors report that a modified experiment with the steps reordered to avoid the delayed choice gives exactly the same final quantum state, so the two scenarios are operationally equivalent.
"for both experiments, we show, in a strictly mathematical way, that a modified version in which the time-ordering of the steps is changed to avoid the delayed choice leads to exactly the same final state."Delayed choice experiments: An analysis in forward time
[5] supported
In the delayed quantum eraser, the data of the signal photon stays unchanged throughout, so the apparent retro-causality arises only from retroactive selection of signal data based on the idler photon's actions, as Hossenfelder argued.
"the data of the first, signal particle remains necessarily unchanged during the whole experiment"Delayed choice experiments: An analysis in forward time
[6] supported
Peacock and Hepburn argued that most existing no-signalling proofs are somewhat tautological because they assume an explicitly local interaction Hamiltonian.
"Peacock and Hepburn have argued that most existing no-signalling proofs are to an extent tautological"Noncausal Superluminal Nonlocal Signalling
[7] supported
The Spanish Wikipedia article states that, although some theories have been proposed as forms of retrocausality, there are no proven scientific observations supporting it.
"Aunque algunas teorías se han propuesto como formas de retrocausalidad, no existen observaciones científicas probadas al respecto."Retrocausalidad
[8] supported
The authors report an experimental proof of the nonclassicality of a delayed choice experiment, based on violating a dimension witness inequality rather than on retrocausal explanations.
"Here, we take a different route and under a natural assumption about the dimensionality of the system under examination, we present an experimental proof of the nonclassicality of a delayed choice experiment based on the violation of a dimension witness inequality."Device-independent test of a delayed choice experiment (2019)
[9] supported
According to the article, the retrocausality experiment has never actually been carried out, because many physicists believe its hypotheses could violate certain principles of quantum mechanics.
"Sin embargo, el experimento en sí mismo nunca ha sido efectuado, debido a que muchos físicos creen que sus hipótesis podrían violar ciertos principios de la mecánica cuántica ."John Cramer
[10] supported
Wheeler argued that a delayed choice of polarization analyzer setting gives us an unavoidable influence on what we can say about the past.
"There is an inescapable sense in which we, in the here and now, by a delayed setting of our analyzer of"Why delayed choice experiments do Not imply retrocausality (2015)
[11] supported
Cramer created and published the Transactional Interpretation of Quantum Mechanics (TIQM), the theoretical framework behind his retrocausal ideas, in July 1986.
"También ha creado y publicado el periódico The Transactional Interpretation of Quantum Mechanics (TIQM) en julio de 1986."John Cramer
[12] supported
Feinberg's reinterpretation principle is cited as judging it impossible to build a tachyon detector that could receive information of the kind needed to send messages to the past.
"De modo específico, el principio de reinterpretación de Feinberg juzga imposible la construcción de un detector de taquiones capaz de recibir información de ese tipo."Retrocausalidad
[13] supported
The 'separation fallacy' assumes the particle was already in an eigenstate at the entrance of the apparatus, when in fact the superposition only reduces to an eigenstate once a measurement occurs.
"the superposition evolves until some distinction is made that constitutes a measurement, and only then is the state"Why delayed choice experiments do Not imply retrocausality (2015)
[14] supported
Claims by parapsychologist Helmut Schmidt that retrocausal psychokinesis could manipulate radioactivity were openly refuted by the international scientific community, though marginal sources still support them.
"Estas afirmaciones han sido refutadas abiertamente por la comunidad científica internacional"Retrocausalidad
[15] supported
Shimony described the quantum causal connection as generically different from classical causation, because it cannot be unequivocally analysed into a cause and an effect.
"The wiser course is to say that quantum mechanics presents us with a kind of causal connection which is"Why delayed choice experiments do Not imply retrocausality (2015)
[16] supported
In May 2022, professional physicists held a conference titled 'Superdeterminism and Retrocausality' in Bonn, although the article notes retrocausal models are generally not accepted in mainstream physics.
"Sin embargo, en mayo de 2022, físicos profesionales celebraron una conferencia llamada «Superdeterminism and Retrocausality»."Retrocausalidad
[17] supported
The author states that the LGC framework does not propose that the future sends signals to the past.
"LGC does not propose that the future sends signals to the past."Delayed-Choice Quantum Eraser Revisited Through the Law of Geometric Consistency (LGC): Information, History, and Physical Reality (2026)
[18] supported
The document reports that delayed-choice experiments showed interference is not a property of a quantum system's past trajectory, but depends on the availability of path information at the final measurement stage.
"These paradigms demonstrated that interference is not a property of the past trajectory of a quantum system but rather depends critically on the predictable availability of path information at the stage of final measurement"Interference is Controlled by Prediction (2025)