The Double Slit Experiment – Correlation between Mind and Matter?

There is no mystery in the “double slit experiment.” There is no “observer effect” in reality. Particle trajectories can be calculated with Bohmian theory.

Revised March 13, 2018; November 15, 2019;  November 25, 2022


1. The failure of the materialistic approach in explaining consciousness is becoming ever more apparent; see Refs. 1 and 2 below.

  • The materialistic approach, of course, is to explain mental phenomena to arise in the brain, which is composed of inert matter.

2. Many scientists/philosophers are hoping that quantum mechanics can come to the rescue (Ref. 3,4).

  • They say that even though deterministic Newtonian mechanics cannot explain consciousness, quantum mechanics can (because quantum mechanics does not have such an apparent deterministic nature.)
Quantum Mechanics to the Rescue?

3. Quantum mechanics (QM) is different from other branches of physics, where one can get an intuitive idea of what is taking place.

  • What we currently do with QM can be called a “black box” approach. When we apply the correct equations, we get the right results. Einstein did not like this at all. Yet, to his frustration, all his predictions of the inadequacy of QM did not materialize, AND the predictions of QM have been correct to amazing accuracy.

4. Those experiments, the results of which can only be explained by QM, appear to be non-deterministic.

  • This has compelled some scientists to investigate whether there is a connection between QM and the mind, which IS non-deterministic. Two experiments, in particular, have been at the forefront of these discussions. The “double-slit experiment” and the “Schrödinger’s cat experiment.”

5. This essay challenges the two central assumptions on this postulated relationship between QM and the mind.

  1. Even if QM and the mind are non-deterministic in their own rights, there is no particular reason to believe there is an apparent connection between them.
  2. There is nothing really “non-deterministic” about QM other than the indeterminacy depicted by the Heisenberg uncertainty principle. That is just the accuracy of a given measurement.
Quantum Mechanics Is Not Intrinsically Psychophysical

6. Let us look into (i) first. Henry Stapp is a leading physicist who argues that quantum theory will ultimately explain consciousness. In his book, “Mindful Universe” he says (p.2), “… quantum theory itself is intrinsically psychophysical as designed by its founders, and as used in actual scientific practice, it is ultimately a theory about the structure of our experience that is erected upon a radical mathematical generalization of the laws of classical physics”.

  • My primary point is that quantum theory is NOT psychophysical; there is no way to accommodate “subjectivity” in QM. Where is the “mind connection” in the theory of QM?
  • Others work on theories that try to explain consciousness as arising from quantum effects in the brain; see, for example, “Conversations on Consciousness” by Susan Blackmore (2006). No one has clarified how these theories make the connection between “psyche” and “physical” in “psychophysical.”
The “Observer Effect” in QM

7. Let us review one experiment that has become the main demonstration for the “observer effect” in QM, the “double-slit experiment.” Here is a short video by Dr Quantum to illustrate the “paradox” of the double-slit experiment:

8. The two main points of this experiment are:

  1. the particles behave like waves when both slits are open, and
  2. this “wave nature” goes away when the particle’s path is “observed” or monitored.
Bohmian theory of Quantum Mechanics

9. There is a version of QM called the Bohmian theory or the Pilot Wave theory developed by the late David Bohm. It uses Schrodinger’s equation to track the propagation of a “pilot wave.” That theory is explicitly nonlocal, i.e., quantum entanglement is built-in.

  • With this theory, each wave equation solution describes a DETERMINISTIC path for the particle, and the statistical average agrees with the experiments and the results of the standard QM calculations.
  • The actual trajectories have been harder to measure not because of a “mind effect” but because observation can disturb the particle trajectory itself. Recent experiments have been conducted to “weakly” measure a system without appreciably disturbing the trajectories. Those experimental results are consistent with the predictions of the Bohmian theory (Ref. 5).

Thus the role played by Bohmian mechanics in these “QM experiments” is just like the role statistical mechanics played in thermodynamics.

  • Here is a very short video showing INDIVIDUAL trajectories for a double-slit experiment calculated using the Bohmian theory. There is nothing “mysterious.” Each particle has a definite trajectory. There is no “observer effect.”

  • When it is attempted to observe an individual particle’s path, the system’s coherence or the pilot wave is disturbed, and the interference pattern goes away. Thus there is no “observer effect” in the sense of bringing “subjectivity” in.
“Schrödinger’s Cat” Thought Experiment

10. Another famous experiment that is the subject of much discussion is the “Schrödinger’s cat” thought experiment. This experiment, suggested by Schrödinger back in 1935, involves a cat in a closed chamber.

  • A radioactive sample in the chamber, if it undergoes decay within a given period, triggers the release of a hammer that breaks a vial of a toxic gas that kills the cat. If a conscious observation is required to collapse the wave function, the cat’s fate is unknown until the box is opened. Unfortunately, both the consciousness-based and consciousness-free interpretations of quantum measurement are indistinguishable for the observer outside the box.
  • In 2006,  an actual experiment was conducted to simulate this experiment. It was reported that “…measurement alone, rather than conscious observation of measurement, is sufficient”; see Ref. 6.
No Real “Observer Effect”

11. Thus, there is no “observer effect” in the double-slit experiments or the Schrödinger cat experiment.

  • In the double-slit experiment, an “observer” could disturb the system’s coherence if the disturbance is strong enough. It does not matter whether the “observer” is human or a mechanical device (in most cases, it is non-human); one ALWAYS gets the same result. This is in contrast to real subjective situations. For example, millions of people make complex subjective decisions in the stock market.
  • So, where does the “objectivity” or “intention” – in the sense of the mind affecting the experimental result – come from? “Intent to monitor” is not a significant subjective decision; just a simple “yes” or “no.”

12. Therefore, it is clear that there was no evidence for “subjectivity” in those experiments even before Bohmian mechanics or Schrödinger’s cat experiment. Those two pieces of evidence make that point undeniable. There is no evidence of the mind affecting the outcomes of those experiments.

The Mind Creates Matter, Not the Other Way Around

13. The Buddha stated that the mind is at the forefront; “Manōpubbangamā Dhammā..” A deeper Abhidhamma analysis is available at “The Origin of Matter – Suddhātthaka.”

  • Even though the mind affects matter and even CREATES matter, science has not advanced enough yet to confirm that.

14. There has to be a paradigm change in science to explain consciousness. Any theory based on matter and attempt to treat mental phenomena as a byproduct will not succeed. The mind is the more fundamental entity and takes precedence over matter.

  • Some philosophers are beginning to sense this reality. Even though he does not appear to know anything about Buddha Dhamma, philosopher Thomas Nagel says the following. “The great advances in the physical and biological sciences were made possible by excluding the mind from the physical world…..But at some point it will be necessary to make a new start on a more comprehensive understanding that includes the mind”. (Ref 1, p.8). Then on p. 15, “…The possibility opens up of a persuasive conception of the natural order very different from materialism – one that makes mind central, rather than a side effect of physical law”.
Consciousness and Quantum Mechanics

March 13, 2018: I have started a new section, “Quantum Mechanics and Dhamma,” where a new interpretation of quantum mechanics is presented, discussing why a connection between quantum theory and consciousness will not be possible.

  1. Thomas Nagel, “Mind and Cosmos” (2012).
  2. Colin McGinn, “All machine and no ghost- McGinn-2012”, New Statesman p. 40, February 20, 2012. (click on the link to open the pdf file)
  3. Henry P. Stapp, “Mindful Universe” (2011).
  4. B. Rosenblum and F. Kuttner, “Quantum Enigma – Physics Encounters Consciousness,” (2006); there are many other recent books.
  5. S. Kocsis et al., “Observing the Average Trajectories of Single Photons in a Two-Slit Interferometer,” Science,  vol. 332, 1170 (2011). (click on the link to open)
  6. R. H. S. Carpenter and A. J. Anderson, “The Death of Schrodinger’s Cat and of Consciousness-based Quantum Wavefunction Collapse,” Annales de la Fondation Louis de Broglie, vol. 31, 45 (2006). (click on the link to open)
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