John Wheeler – The Delayed Choice experiment (105/130)

One of the founding fathers of quantum theory, Max Planck, who is often credited with originating quantum theory – a feat that won him the Physics Nobel Prize in 1918 – once stated: “I regard consciousness as fundamental. I regard matter as derivative from consciousness. We cannot get behind consciousness. Everything that we talk about, everything that we regard as exiting, postulates consciousness.”

Fast forward to today and there are a number of experiments in multiple fields showing that Planck was right. Consciousness is fundamental and it is directly intertwined with what we call physical material matter. You cannot explain consciousness in terms of the existing fundamentals like space, time, mass, and charge. As a result, the logical thing to do is postulate whether consciousness itself is something fundamental to the existence of reality.

A classic experiment used to examine the role of consciousness and its relationship to matter is the quantum double slit experiment. In this experiment, tiny bits of matter (photons, electrons, or any atomic-sized object) are shot toward a screen that has two slits in it. When there is no measuring device placed at the screen, the tiny bits of matter act as a “wave” and creates an “interference” pattern on the other side where a wall is placed to catch the pattern. Because there was no measuring or observation device used to see what slit the matter went through, we cannot know what path it took. When the pattern on the wall is examined to see what path it took, it represents a wave of possibilities, meaning the matter (particle) went through both slits, and one slit, and interfered with itself, which should be physically impossible. Welcome to the wacky world of quantum physics – anything and everything is possible.

The kicker is, when an observation device is set up to observe what slit the particles go through, the particle then only goes through one, thus collapsing the wave pattern and forming a pattern that is representative of the particle only going through one slit. In other words, the behavior of the matter changes when we decide to measure  or observe it, the particles act as they are aware they are being watched. 50 percent of the time the particle will go through one slit, and the other 50 percent of the time it will go through the other and form a two slit pattern, just as if they were balls lobbed through one slit or the other.

Observations not only disturb what has to be measured, they produce it…We compel (the electron) to assume a definite position…We ourselves produce the results of the measurement. (M. Mermin, Boojums All the Way Through: Communicating Science ina Prosaic Age (Cambridge University Press, Cambridge, UK, 1990, referenced by Dr. Dean Radin, From A paper published in the peer-reviewed journal Physics Essays explaining how this experiment has been used multiple times to explore the role of consciousness in shaping the nature of physical reality

If this isn’t already mind-altering enough for you, one physicist, John Archibald Wheeler, pondered what would happen if we don’t interfere with the photons on their way through the slits? What would happen if we didn’t set up a measuring device to observe what slit the matter went through, and instead, what if behind the back wall there were detectors? One detector is focused on each slit, and just before the particle lands on the screen after it has passed through the slit device, the detectors are pulled away. When no one could detect which slit the photon had gone through, there was a wave pattern, but when the detectors were in place, there was no wave pattern. Similar to observing the particles before they went through the slit. No observation produced an interference pattern, and observation formed a one line, one slit pattern.

If they collapse to a state of particles from a wave at the moment of detection, after they have gone past the slit device, this means that even though they went through the slit unobserved and should produce a wave (interference) pattern, the very act of observing, still, instantly transforms them into particles and collapses the wave function.

This begs the question, how could these detectors interfere with something that had already happened? It would mean that what happened in the present changed the past. The very act of detecting the particles after they go through the slit determines how they went through the slit, either as a wave or as particles. How is this possible?

Like the quantum double slit experiment, the delayed choice/quantum eraser has been demonstrated and repeated multiple times. For example, physicists at the Australian National University (ANU) have conducted John Wheeler’s delayed-choice thought experiment, and the findings were recently published in the journal Nature Physics.

In 2007 (Science 315, 966, 2007), scientists in France shot photons into an apparatus and showed that their actions could retroactively change something that had already happened.

“If we attempt to attribute an objective meaning to the quantum state of a single system, curious paradoxes appear: quantum effects mimic not only instantaneous action-at-a-distance, but also, as seen here, influence of future actions on past events, even after these events have been irrevocably recorded.” (source)