Thinking Backwards about Time

In: Timing & Time Perception
Daniel P. Sheehan Department of Physics, University of San Diego, San Diego, CA 92110, USA

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The concept of time in physics and its connection to consciousness are becoming increasingly problematic. A missing ingredient to both could be retrocausation — the temporal inverse of everyday causation — in which the future influences the past. Apparent evidence for it is in the phenomenon of precognition. Thus far, psychology and physics have assiduously avoided incorporating precognition into their paradigms, even though experimental evidence for it is substantial. Among many noteworthy studies, the Graff–Cyrus experiment is explicated here as an outstanding example of the phenomenon. It is hoped that consciousness, retrocausation, and precognition can be accommodated within the current paradigm of physics, helping bridge the gap to psychology.

This essay is a brief reflection on two articles concerning the nature of physical and psychological time (Gruber et al., 2022, Buonomano and Rovelli, 2021). It is not comprehensive and does not address what is included in these papers; rather, it considers what is conspicuously absent from them.

The myriad of current theories concerning the nature of time are both exhilarating and exasperating; there is no end to them and no consensus concerning their veridicality has been reached. Like the many interpretations of quantum theory, each can account for the world in which we live, but few (or none) provide unambiguous tests by which their primacy can be established. Instead, their adoption seems to be largely a matter of personal aesthetics.

As ably suggested in both articles, the concept of time in physics and its connection to consciousness are becoming increasingly problematic. I believe both will be central to a major paradigm shift sometime this century, perhaps in the coming decade or two. Unfortunately, both papers conspicuously avoid a key phenomenon that sheds critical light upon their natures, one that has been hiding in plain sight for millennia, one that has had strong experimental support for decades: precognition. In its varied forms (e.g., presentiment, premonition, and remote viewing), precognition indicates backward-in-time (retrocausal) influences upon consciousness.

Retrocausation is the temporal inverse of everyday causation. Whereas in causation the past influences the future, in retrocausation the future influences the past. (Personally, I prefer correlation over causation, but here the latter is used for convenience.) Precognition refers to awareness of future events that are beyond normal sensing or computational grasp; a leading explanation for it involves retrocausation.

As a physical concept, retrocausation — and perhaps by extension, precognition — cannot be rejected out of hand. The fundamental laws of nature are invariant under time reversal; specifically, they exhibit CPT symmetry (charge conjugation, parity inversion, and time reversal). As such, they should have time-forward and time-reverse solutions, in which case they can describe physical phenomena unfolding in either (or both) temporal direction(s). For instance, consider a boulder rolling down a hill. It is at the middle of the hill presently (now). Is it rolling at the middle of the hill now because it was at the top of the hill earlier (in the past), or is it rolling there now because it will be at the bottom of the hill later (in the future)? The answer is: yes. In purely mechanical terms it is acceptable to describe the present as being caused by past conditions or being retrocaused by future ones — or by both!

Although at first glance retrocausation seems an awkward move, its benefits outweigh its cost. First, it honors the conceptual and mathematical formalism of physics, admitting that the past and future have equal physical — though not necessarily equally visible — holds on the present. Second, some interpretations of quantum theory, notably Two-State Vector Formalism (TSVF) and the Transactional Interpretation (TI) both explicitly invoke time-reversed signaling with great success. (TSVF, for instance, is ideal for dealing with weak and interaction-free measurements, and TI confers real ontological status to the wavefunction as well as an easy derivation of the Born rule.) Third, by invoking retrocausal signals, all the mind-bending paradoxes of quantum theory — like the EPR, Einstein’s bubble, Wheeler delayed choice, quantum eraser — are gracefully resolved (Cramer, 2016). More exotic possibilities for time’s direction have been proposed, for example, circular arrows, as might arise in oscillating cosmologies (Cocke, 1967; Schmidt, 1966).

While retrocausation has theoretical benefits, it becomes more complicated in the macroscopic world. For the most part, in our everyday experience time runs forward, not backward. That macroscopic phenomena in Nature (and our personal lives) seem to develop only in this forward direction is usually ascribed to the second law of thermodynamics, a statistical law stating that entropy (the multiplicity of microstates available to a system) tends to increase. Many challenges to this law have arisen over the last 25–30 years (Čápek and Sheehan, 2005).) It should be remembered that the second law is statistical in character and does not necessarily apply to individual fundamental processes, for instance, between individual quantum wavefunctions, even macroscopic ones.

Thus far, psychology and physics have assiduously avoided incorporating precognition into their paradigms. For instance, it is entirely absent among the nine layers of time in (Buonomano and Rovelli, 2021), and it receives only passing mention in Gruber et al. (2022), despite experimental evidence for it being plentiful (Sheehan, 2006, 2011, 2017). Why has it been so conspicuously dismissed? I believe there are multiple intersecting reasons, among which are: (i) some claims of precognition have been fraudulent or mistaken; (ii) experiments involve human subjects; (iii) evidence is often statistical in nature; and especially, (iv) it is believed that precognition does not comport well with the current scientific paradigm. Reasons (ii) and (iii) are currently unavoidable — though this might change — but neither disqualifies the evidence. Reason (i) has been overcome by carefully designed experiments, and reason (iv) is a red herring because modern physics does not preclude it.

The suppression of precognition is disappointing but not especially surprising. As Kuhn emphasizes, in The Structure of Scientific Revolutions, a community is loath to abandon its current paradigm until a replacement is available. In the case of precognition, no rigorous physical explanation has been discovered, though hypotheses have been advanced (Mindfield, 2018).

Science is replete with — and, in fact, depends upon — phenomena whose explanations are incomplete; they constitute the cutting edge of any field. Advance is driven by anomaly. Consider, for instance, high-temperature superconductivity, dark matter, dark energy, massive neutrinos, the tiny cosmological constant, the low initial entropy of the universe, the contested status of the second law of thermodynamics (Čápek and Sheehan, 2005). All are supported by considerable experimental evidence, but none has a generally accepted theoretical explanation. Precognition falls squarely in this company and, thus, should receive comparable attention, especially because it apparently connects two of the most compelling explicanda sought by science: time and consciousness.

The current experimental evidence for precognition is significant. Among many noteworthy experiments, here is summarized the so-called Graff–Cyrus experiment (Graff and Cyrus, 2017). Its goal is to describe photographs that appear on page A6 of the Around the World section in the Reading Eagle newspaper (Pennsylvania) 2–3 days before they are published — and well before the photos are taken. The protocol is as follows (assuming Tuesday to be the target photo’s publication date):

  1. 1.On the previous Saturday/Sunday, a remote viewer attempts to mentally access the Tuesday target photograph (in conscious or dream state). (At this point, the international event has not occurred yet and the photo has not been taken.)
  2. 2.The Viewer provides sketches, words and concepts about the target photograph.
  3. 3.The Viewer emails the session results to the Tasker by Monday, 9:00 AM EDT.
  4. 4.The event occurs on Monday and a photo of it is taken. [The Associated Press (AP) delivers more than 3,000 photos daily from journalists around the world, recording all types of global events. Any of these could be the target photo.]
  5. 5.The Reading Eagle chooses a single photograph Monday evening and publishes it Tuesday morning on page A6.
  6. 6.The Viewer receives feedback (the target photo) after the newspaper is published.
  7. 7.The Viewer may seek additional information after receiving the initial feedback in order to amplify the session results.

A total of 33 sessions were conducted between February and mid-April, 2016. Independent evaluators ranked data from 21 of the 33 sessions (64%) as having medium to high degrees of correlations with the target newspaper photographs. The results were statistically significant.

Precognitive results such as these are not easily described within the standard paradigm of physics without appealing to some form of retrocausation. For the Graff–Cyrus experiment, one explanation advanced is that the Viewer on Tuesday retrocausally connects with her Saturday self (Sheehan and Cyrus, 2018). Both are within each other’s light cones, in fact, along the same world-line, thus are relativistically local. Their correlation does not require energy transfer because both ends of the communication channel are biochemically driven such that they might be activated by stimulation only. Too little is currently known about neurophysics to say much more, but with high confidence it can be said that classical physics (subject to the second law) is inadequate to explain these results.

Two possibilities seem to me most probable. My materialist side hopes that consciousness, retrocausation, and precognition can be accommodated within the current paradigm of physics, possibly with the help of quantum theory. Some experimental evidence, however, indicates that standard materialism is insufficient, in which case some type of dualist and idealist mechanism might be operating. Regardless, the phenomenon of precognition strongly indicates that our current conceptions of time and consciousness are incomplete. It is time that we take time seriously enough to include all relevant phenomena, including precognition.


The author thanks P.S. Cyrus and the two referees for helpful suggestions.


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