On the other hand, from an idealistic point of view, all that "weirdness" disappears. I tried to show this in two short essays that Bernardo generously published in his blog (here and here), but I kept finding inconsistencies in my formulations of a consciousness-based interpretation of quantum mechanics.
Finally, I've found a new interpretation that seems to me internally consistent. Not only that: It provides new predictions about the behaviour of quantum systems. In other words, it can be tested experimentally. It sounds too good to be true, I know. I don't really expect this experiment to work. But I think it would be worth trying. And I don't think anything similar has ever been done.
If the results of the experiment were contrary to my predictions, it wouldn't disprove idealism; only my particular version of it (which is quite different from Bernardo's).
In writing the essay, I have deliberately avoided the word "idealism", and reduced all mentions of consciousness to a bare minimum. I was trying to make this new interpreation of QM as appealing to physicists (and physicalists) as possible.
I would greatly appreciate any comments, suggestions and criticisms.
Here is the essay, with footnotes and all (it is rather long, but I've seen longer posts on this forum, so I hope it's okay):
The Observing Universe
A new answer to the old riddles of quantum mechanics
Roughly a century after the discovery of quantum mechanics, the most successful theory in the history of science, physicists have not yet reached a consensus about its meaning. What does quantum mechanics tell us about the nature of reality? All attempts to find an uncontroversial answer have failed so far.
In this short essay, I argue that the reason for this failure is that quantum theory is incomplete. There is a fundamental property of the universe that physicists have overlooked. This property, once recognized and incorporated into physical theory, would provide a straightforward solution to all the riddles of quantum mechanics.
This hidden property of the physical universe can best be designated by a very familiar name: observation. In this view, observation isn’t something that human scientists or other conscious agents do. Observation is a fundamental property of the universe. Nature is constantly observing itself.
Does this imply that Nature is conscious? Well, yes. But we don’t need to assume that Nature has thoughts, or emotions, or volition, like we humans do. It is important to distinguish between consciousness and its contents. Consciousness is not our thoughts, or our emotions, or our sensations. Consciousness is what enables us to discriminate those thoughts, emotions and sensations. Consciousness is what enables us to discriminate all the contents of our experience.1
Discrimination is the primary property of consciousness. It is a fundamental property of reality itself. It is implicit in all scientific theories, but most scientists don’t realize it because they take it for granted. Without discrimination, for example, subatomic particles would have no recognizable properties. Nature would be a featureless chaos.
There must be something fundamental in Nature that can discriminate between positive and negative electric charge, for example. Or between “spin up” and “spin down”. Or between different quantities of mass, volume, momentum, etc. Without this basic discrimination, the behaviour of the physical universe would be unpredictable.
Observation and measurement
In traditional physics, the terms “observation” and “measurement” are often used interchangeably. Here we must make a clear distinction between the two.
Observation is performed by Nature, the one and only observer. Measurement is carried out by living organisms (e.g. human scientists). In this sense, we can say for example that a tree “measures” the amount of electromagnetic energy coming from the sun during a given time period, or that a bee “measures” the frequency of light reflected from a flower petal. Measurement is local. Observation is nonlocal.
Instead of talking of multiple observers (there is only one), we have to talk therefore of multiple measurers. The sum of the physical bodies of all the measurers (living organisms) existing in the universe constitute Nature’s measurement apparatus.
Only through these multiple measurers can Nature observe the physical universe. In other words, without living organisms there would be no physical world. There is nothing (nothing physical) outside observation. The physical world is the observed world. Observation is creation. By measuring the physical world, all living organisms are co-creating it.
There is only one law in observation: the law of entanglement. Entanglement is the most fundamental law of physics.
Entanglement is the fundamental law that accounts for the consistency and stability of the physical world. Without entanglement, the measurements carried out by the infinity of measurers would be inconsistent. The physical world would break down. Entanglement is the only reason all living organisms (that we know of) do measure the same physical world.
In order to move forward, physicists need to abandon the old notion of a world made of objects (or “building blocks”) ruled by mechanical laws of cause and effect. There are no objects independent of observation. There is only observation. There is no cause and effect. There is only entanglement.
Observation is not governed by causation, but by entanglement. Entanglement is the fundamental law that enables Nature to observe all physical events simultaneously, encompassing all points in space-time at once.
In order for Nature to be able to observe a physical system, that physical system has to be entangled with the physical body of a living organism. In the context of scientific research, setting up experiments is nothing but creating chains of entanglement between the physical systems under scrutiny and the physical bodies of the experimenters. The same applies to practical applications of physical science: building a machine is building a complex chain of entanglement.
Entanglement is not some mysterious link between distant objects. There are no objects. There is only observation and measurement. What gets entangled are the probabilities of measurement. When we say that particle A is entangled with particle B, what we are saying is that the probabilities of measuring particle A in certain states (location x, say, or spin “up”) are entangled (correlated) with the probabilities of measuring particle B in corresponding states (location y, or spin “down”). In other words, the wave function of particle A is entangled with the wave function of particle B.
To truly understand the implications of quantum mechanics, we need to abandon classical thinking. The classical mechanistic view of the world is no longer possible.
Let’s imagine, for example, a Geiger counter with a LED light that flashes red whenever it detects a radioactive particle. According to classical thinking, the LED light will emit photons of a certain frequency. Those photons will travel through space and enter my eyes, where they will cause certain reactions on the photoreceptors in my retina, etc. This mechanistic explanation is very useful for practical purposes, but it is only an approximation. Thinking of photons as tiny billiard balls travelling through space and colliding with things leaves us with an inaccurate mental image of physical reality.
We need to abandon all mechanistic notions of causation. The correlation between the state of the Geiger counter and the state of the photoreceptors in my eyes is due to entanglement. The same applies to the correlation between the state of the Geiger counter’s detector and its LED light, between the state of the detector and of the radioactive particles it may detect, etc.
The particularity of human measurers
There is no fundamental difference in the way humans measure the physical world, as compared to other living organisms. But there is a particularity that has only developed in recent history, with the rise of Western science: the application of mathematics. Modern science has seen the deployment of increasingly accurate and sophisticated mathematical equations to gauge the results of the amazingly precise measurements possible today.
This mathematical sophistication in scientific experiments has led most scientist to believe that the physical universe is ruled by mathematical laws. This is an illusion. The physical universe is only ruled by entanglement. It is entanglement that makes the results of scientific experiments conform to the mathematical equations employed by scientists in their measurements.
From this perspective, it becomes obvious that concepts like electric charge, spin, mass, etc., are not fundamental. These are concepts created by human scientists in their endeavour to refine their measurements through mathematical equations. The fundamental properties of physical reality are pairs of opposites like attraction/repulsion, light/dark, warm/cold, and so on. These are the type of qualities that can be measured by the simplest living organisms, even by single cells.
In other words, biology is more fundamental than physics. And psychology is more fundamental than biology. In this view, psychology is the most fundamental of all sciences.
This doesn’t mean that there were no stars, no galaxies, no planets before the appearance of the first living organisms. It is important to understand that space-time is the result of observation and measurement. Living organisms, including humans, constantly measure space-time. And as they do, they create it. As we measure the physical universe, we do measure the past as well as the present. The evolution of the physical universe from the Big Bang to the formation of galaxies and stars and planets and the first appearance of life is the result of the measurements carried out by living organisms existing on Earth. There was a time before life appeared on Earth, but there never was a time that hasn’t been measured by us.
There is no contradiction in saying that the Big Bang is the creation of living organisms. In fact, it’s perfectly accurate to say that all living organisms are constantly measuring the Big Bang, and that in some fundamental way that is all they are doing. Of course, no other known living beings have reached the measuring sophistication and precision of human scientists. But at the heart of all measurements there is a singularity, a pure mystery that can’t be completely reached by any measurement or scientific theory: that’s what scientists call the Big Bang.
A long-standing debate among physicists is this: are atoms and quarks and gluons real? Do they exist objectively? Or are they only mathematical abstractions, theoretical concepts scientists use to describe their measurements? In the view I’m proposing here, atoms and subatomic particles are definitely real and objective, since they have been measured by scientists, and therefore have been observed by Nature. But it’s important to realize that, even if from our present perspective the physical universe has always been made up of quarks, atoms and so on, this wasn’t true a few centuries ago. Western science could have evolved in a different way, with different mathematical theories determining a different kind of measurements, and the results would have been something completely different.
(From this perspective —as a science-fictiony aside—, it doesn’t make sense to assume that hypothetical advanced civilizations existing on distant planets would reach exactly the same scientific theories that humans have. Since we have never interacted with them, our physical bodies are not entangled with theirs. Their measurements would inevitably produce uncorrelated results. In other words, these hypothetical aliens would not exist in the same physical reality than we do. If we’d meet them, they would appear to us rather like fairy-like creatures or immaterial spirits, coming from “another dimension”. Which is actually what seems to happen in many alleged “alien encounters”. That said, it is more probable that these supposed aliens, if they do exist, would have originated on Earth itself, and not on some distant planet. They could be the result of a divergence happening in the evolution of life, or even in the early evolution of humanity, a disentanglement between two or more separate lineages. But all this is pure speculation, of course.)
Like Einstein pointed out in a famous discussion with Heisenberg, our scientific theories decide what can be observed. This means that we are not necessarily stuck with quarks and gluons and electrons. A new scientific theory may arise that will transcend and make obsolete all notion of subatomic particles and fundamental forces, effectively erasing them from our measurements.
Observation and entanglement
Let’s take a closer look at how observation works. To do this, we can use the famous Schrödinger’s cat thought experiment as an illustration.
We all know the scenario: we have a cat inside a closed box, together with some radioactive substance, a Geiger counter and some lethal mechanism that will be triggered if the counter detects the decay of a radioactive atom. According to some traditional interpretations, the cat remains in a superposition of states (dead-alive) until we open the box.
In the view I’m presenting here, the cat is never in a superposition of states. It is either alive, or dead. It is always in a definite state. The simple reason is that the cat, and the Geiger counter, and the radioactive substance, are being constantly observed by Nature, the one and only observer.
Nature is not only the observer, but also the observed. Nature not only discriminates and registers the result of any observation, it also decides what that result will be. That decision may be purely random and blind, or governed by some mysterious will or intelligent purpose: whatever the case, that question is irrelevant for the present discussion.
Quantum physics shows us a fundamentally indeterministic picture of the world. But the result of any observation, although not absolutely determined, is never completely free: it has to lie within the possibilities described by the laws of physics. More precisely, it is constrained by the probabilities described by Schrödinger’s wave function.
The wave function describes the (evolution in time of the) probabilities of measurement. For example, the wave function of a single photon describes the probabilities of detecting it in any given location in space-time. But this description only makes sense from the perspective of particular measurers (in this case, human scientists using some measuring device capable of detecting single photons). From the perspective of Nature, there are no probabilities of measurement. There is only actuality. Or, if you like, the probabilities of measurement are always either 1 or 0.
Does this mean that Nature knows the exact location of every single photon, say, at any given point in time? Not at all. Nature can’t observe photons or electrons or even atoms directly. Nature can only observe the sensory system of living organisms. This means that Nature can only observe photons or elementary particles when they become entangled with the sensory system of living organisms. Without this entanglement, observation isn’t possible.
In other words: it is the entanglement with the physical sensory system of living organisms (measurers) that causes the collapse of the wave function.
We can illustrate this with a simple double-slit experiment: Individual photons are shot through a plate pierced by two parallel slits and detected on a screen behind it. An interference pattern appears on the screen, showing that each photon seems to be passing through both slits at once. However, if we change the experimental configuration (by introducing an additional detector) so that we can detect through which slit each photon passes, the interference pattern disappears.
In the first configuration, there is no entanglement between the location of each single photon as it passes through the double-slit plate and the physical body of the experimenter. In other words, there is no correlation between the probabilities of the photon passing through one slit or the other and the probabilities of observing the experimenter’s sensory system in one state or other. However, in the second configuration we introduce a new entanglement, a correlation between the path of the electron and the probability of observing the experimenter’s sensory system in certain states. It is not necessary for the experimenter to look at the additional detector providing the “which-path information”. The entanglement caused by the introduction of that detector is enough to destroy the interference pattern.
In other words: in the first configuration of the experiment (without “which-path” detection) Nature can’t observe the path of each photon as they shoot through the double-slit plate. In the second configuration, Nature can observe that path. In the first configuration, there are no actual photons (until they reach the screen), but only waves of probabilities. In the second configuration we find actual, objective photons passing through one slit or the other.
Coming back to Schrödinger’s cat, it is irrelevant when (and if) the human experimenter opens the box. The act of measurement doesn’t bring any change to the physical system. It is the entanglement introduced by the Geiger counter that causes the collapse of the wave function. The Geiger counter introduces a correlation between the probabilities of atom decay occurring in the radioactive substance and the probabilities of observing the experimenter’s sensory system in certain states (seeing a dead cat or a living cat, say).
What happens if we remove from the box the Geiger counter?
The answer is simple: nothing happens. By removing the Geiger counter, we removed the entanglement between the probabilities of finding subatomic particles in certain states and the probabilities of observing the physical body (sensory system) of the human experimenter in corresponding states. Therefore, there is no observation. The radioactive substance remains in a superposition of possible states.
Peeping into a closed box (God does not play dice)
We’ve said that, due to entanglement, Nature is constantly observing the whole system inside the box (radioactive substance, Geiger counter and cat). How does this happen?
To simplify the thought experiment, let’s replace the living cat with a small porcelain cat. The mechanism connected to the Geiger counter will trigger a hammer that will smash the porcelain cat to pieces.
Nature can’t observe directly what happens inside the closed box. But Nature is constantly observing the living body of the human experimenter. When the human experimenter sets up the experiment, her physical body (more precisely, her sensory system) becomes entangled with the radioactive substance the moment she introduces the Geiger counter. From the perspective of Nature, this entanglement causes the collapse of the wave function of the radioactive substance.
From the local perspective of the human experimenter, the experiment has only begun. From the nonlocal perspective of Nature, it is already done.
Let’s break it down bit by bit. The human experimenter puts the radioactive substance, the Geiger counter and the hammer-triggering mechanism inside the box. She makes sure that the Geiger counter and the mechanism work properly. Then she puts the porcelain cat into the box. She closes the box.
The human experimenter has no way to know when and if the atom decay will happen. If the wave function of the radioactive substance predicts a 0.5 (50%) probability of an atom decay taking place within an hour, the experimenter only knows that there is a 50-50 chance of finding an intact or smashed cat when she opens the box after an hour.
But Nature doesn’t need to wait for the human experimenter to open the box. From the perspective of Nature, it is completely irrelevant if the human experimenter opens the box or not. Being fundamentally nonlocal, Nature knows the probabilities of measurement at any given point in space-time.
Contrary to superdeterministic interpretations, the view we are presenting here (which could be called the “observational interpretation of quantum mechanics”) ascribes total freedom to living organisms (including human experimenters) to carry out their measurements in any way they choose.
Let’s say the experimenter gets impatient and decides to open the box sooner, instead of waiting an hour. It doesn’t matter. Nature is always ready to provide a consistent answer, a consistent result to the act of measurement. The moment the experiment is set up (and completed), Nature knows exactly when and if the atom decay will take place.
As an example, let’s say that the atom decay happens at minute 37. If the human experimenter opens the box before minute 37, the probability of finding a smashed cat is 0. If she opens the box after minute 37, the probability is 1. If she doesn’t open the box at all, nothing changes: the probability is still 0 until minute 37, and 1 afterwards.
In other words: Nature not only can observe the actual state of the sensory system (or measurement system) of living organisms. It can also observe the potential state that measurement system would be in in any given configuration, at any point in space-time. In the case of our thought experiment, by directly observing the sensory system of the human experimenter, Nature can indirectly observe the state of the atoms in the radioactive substance.
I believe this is actually what Einstein meant with his famous phrase “God does not play dice”. He wasn’t concerned about determinism, but about preserving the concept of an objective physical reality independent of human measurements.
According to early formulations of quantum mechanics by Bohr, Heisenberg and others, there is no physical reality prior to the act of measurement. Physical systems remain in indeterminate states of superpositions until measurements are carried out. This is like saying that, every time we perform a measurement, Nature has to improvise (play dice) and come up with an off-the-cuff result. To Einstein this seemed absurd. He was, of course, right.
Observation and objective reality
The new interpretation of quantum mechanics we are offering here (the “observational interpretation”) provides a new solution to the century-old riddle of quantum mechanics, as illustrated by the long debate between Einstein and Bohr. According to this view, both were partially right: physical reality is determined by the measurement apparatus, and doesn’t exist outside observation (Bohr); but physical reality is objective, independent of any local act of measurement (Einstein).
It is inevitable to wonder what the two great masters would have thought of this new approach. In any case, the notion of observation as a nonlocal property of Nature itself introduces a novel perspective that transcends traditional dichotomies, thus providing a new possibility of finally understanding what quantum mechanics is saying about the ultimate nature of physical reality.
We now can at last answer Einstein’s famous question about the moon: The moon is always there, because it is being observed all the time (by Nature itself), even when no one is looking at it!
The experiment (The undetectable detector)
This new interpretation of quantum mechanics may appear compelling to some, preposterous to others. The good news is that, since in some special cases it makes different predictions than other interpretations, it can be tested experimentally.
This could be done with a relatively simple double-slit type experiment. I propose here a variation of a well-known experiment published in Physical review, March 2002, by S. P. Walborn, M. O. Terra Cunha, S. Padua and C. H. Monken2.
An argon ion pump laser is set up to emit single photons. Each photon passes through a special nonlinear crystal called beta-barium borate (BBO), where it is converted to two entangled, longer wavelength photons. The two entangled photons go off in two different directions, p and s.
The s photons (those which go down path s) travel through a double-slit to detector Ds. The p photons travel directly to detector Dp. Detector Dp is configured to measure the polarization of each registered photon. Detector Ds is configured to measure both the polarization and the location of each photon.
With this set-up we should observe an interference pattern on detector Ds. In other words, each s photon somehow “goes through both slits at once”.
(Source: Wikipedia)
A quarter wave plate (QWP) is now put in front of each slit. This device is a special crystal that changes linearly polarized light into circularly polarized light. The two wave plates are set so that given a photon with a particular linear polarization (x/y), one wave plate will change it to right circular polarization while the other will change it to left circular polarization.3
Because p and s photons form entangled pairs, by measuring the linear polarization of each p photon, we can know the polarization of the corresponding s photon before it reaches the quarter wave plates. With this configuration, it is possible to figure out which slit the s photon went through, without disturbing the s photon in any way.
(Source: Wikipedia)
It is not necessary to actually measure the polarization of p and figure out what slit s passed through. Once the quarter wave plates are introduced, the mere possibility of making that measurement is enough to make the interference pattern disappear.4
According to the observational interpretation, the explanation for this “weird” effect is that, by introducing the quarter wave plates, we are creating an entanglement between the probabilities of an s photon passing through slit 1 or slit 2 and the probabilities of observing the physical bodies of the human experimenters (their sensory systems) in certain corresponding states. (By setting up the experiment in this way we are “forcing” Nature to observe the path each photon is taking through the double-slit. Each experiment is a question that we ask Nature. Nature is forced to provide the answer. If we pay attention to the answer or not is irrelevant.)
To test the validity of this interpretation, let’s replace detector Dp with an “undetectable detector” (UDp): a device that is configured to measure the polarization of each photon, exactly like the original detector Dp, but with a crucial difference: detector UDp is designed to show the results of its measurements in a display undetectable by the human sensory system. For example, by using ultraviolet light on a white screen (I leave it to experimental physicists to figure out the technical details).
With this new configuration, the “which-path information” would still be there. It just would be invisible to the human experimenters, undetectable by the human sensory system. The entanglement between the sensory system of the experimenters and the path taken by the photons would be broken.
According to the observational interpretation, with detector UDp in place the interference pattern would appear again on detector Ds. All other interpretations (as far as I can tell) would make a different prediction: the result should be the same as with detector Dp in place (no interference pattern).5
If the result of this experiment agreed with the observational interpretation, it would open up a whole new field of scientific exploration: that of the central role played by the sensory system of living organisms in the generation of physical reality.
Footnotes:
1 Following A. H. Almaas, I’m making a distinction between consciousness and awareness. Consciousness is defined as awareness plus discrimination. Consciousness requires awareness, but it is possible to have awareness without consciousness (without discrimination). This undiscriminated awareness can be experienced in deep meditative states. It is unnecessary to go into more details for the purpose of this short essay. For further clarification, see A. H. Almaas (2004). The Inner Journey Home. Shambhala.
2 Walborn, S. P.; et al. (2002). "Double-Slit Quantum Eraser". Phys. Rev. A. 65.
3 Specifically, the first wave plate (QWP1), placed before slit 1, will change an x polarized photon (that is, a photon linearly polarized along the x axis) to a left circularly polarized photon (L), while the second wave plate (QWP2), placed before slit 2, will change it to a right circularly polarized photon (R). With a y polarized photon, the reverse will happen: QWP1 will change it to R, while QWP2 will change it to L.
4 Walborn et al. explain this with the formula |Ψi = 1/√2(|ψ1(r)〉|M1〉+|ψ2(r)〉|M2〉), where |Mj〉 is the state of the which-path marker corresponding to the possibility of passage through the path j and |M1〉 is orthogonal to |M2〉. The only interpretation they provide is “The which-path marker’s presence alone is sufficient to make the two terms on the right-hand side of equation (2) orthogonal and thus there will be no cross terms in |〈r|Ψ〉|². Therefore, it is enough that the which-path information is available to destroy interference.” (Walborn, S. P.; et al. (2002). "Double-Slit Quantum Eraser". Phys. Rev. A. 65 (1-2).) One could ask the question: available to whom? And why should the “availability of information” change the behaviour of a physical system?
5 I’m not familiar with interpretations based on “availability of information”. It may well be that, according to some information-based interpretations, the replacement of detector Dp with the “undetectable detector” UDp would effectively destroy the information available to the experimenters, thus bringing back the interference pattern. I have no idea why, in these hypothetical interpretations, the information available to human experimenters should play such a crucial role in the behaviour of physical systems.
