Has realism been refuted in quantum mechanics?

The definition of realism, based on the article [1] linked to me by the person who asked the question:

Realism, in philosophy, the viewpoint which accords to things which are known or perceived an existence or nature which is independent of whether anyone is thinking about or perceiving them.

So, my answer is: No, but I think I know the common misconception that would lead you to think that.

Basically, this question is asking if quantum mechanics states that our sensation, perception, and cognition determine the state of the universe. No, it does not.

You most likely have heard something similar to the phrase “electrons are everywhere until we observe them, at which point they are in a fixed position”, and thus concluding that our perception changes the state of the universe. That’s not really how it works.

Instead, think of this in terms of a function that describes the probability that the electron may be in some position. This is known as a wave function. If we’re trying to determine the position of a particle in a quantum system of 1 dimension, the wave function is defined as a complex-valued probability amplitude together with a dimension (say, x) as a function of time. We can find the probability density that the particle as at a certain position, p, by multiplying the wave function by its complex conjugate, and evaluating at p. The key is that this is entirely independent of our perception; rather, the thing to note is that when we observe the position of a particle in a quantum mechanical system, we are fixing time to a certain value, and thus we can evaluate the wave function at that particular instant in time, and thus producing an output that is only spatial coordinates, which indicate the position of the particle. This is known as a collapse of the wave function.

The collapse of the wave function occurs whenever we fix time. It is merely the case that human observation necessarily fixes time, and the fixing of time collapses the wave function, but our observation is not what collapses it.

tl;dr No, realism is not refuted by quantum mechanics. Human perception doesn’t magically make a quantum particle stay in a fixed place; rather, fixing the time dimension of a quantum mechanical system “collapses the wave function” of the system, and admits an output which is strictly spatial, which corresponds to the position of the particle.

[1] realism | philosophy

Realism generally is not refuted by quantum mechanics because some kinds of realism are compatible with quantum mechanics, while others are not. Whether a given kind of realism is compatible or not depends on what other assumptions are made.

One kind of realism is the existence of hidden variables, i.e., the dynamical variables such as position of an electron. Saying these are real means that they always have definite values, independent of measurement. Now, Bell’s theorem shows that local hidden variables are not compatible with quantum mechanics. So, if you want this kind of realism (e.g., the de Broglie-Bohm interpretation), you have no choice but to admit that they are nonlocal, but in a way that is completely hidden from us. (Actually, there is another logical choice, which is called super-determinism, but that flies in the face of science itself, so it is not a reasonable option.)

Another kind of realism is the existence of the universal wave function, which is a key feature of the many worlds interpretation. The universal wave function is the state of the whole universe, that includes within it many branches (called “worlds”) that are, for all practical purposes, completely isolated from each other. There is locality, but no hidden variables. More generally, it lacks what is called counterfactual definiteness: because all experimental outcomes are actual, there is no single definite result. There is only an appearance of a unique outcome of an experiment from the limited perspective of a particular branch. Because all the branches are isolated from each other, all the other worlds from this one are completely hidden and inaccessible.

These are the two main types of realism that are compatible with quantum mechanics. Both kinds of realism are, to say the least, quite bizarre. Either everything is nonlocally connected in some mysterious and hidden way, or there are an infinite number or parallel worlds, all hidden from this one.

Bottom line: no matter how you slice it, there is no common-sense realism that is compatible with quantum mechanics.

Sadly it doesnt say anything about our macroscopic reality. We don’t even know whether localism or realism is false, only that they cant both be true in the quantum world.

If realism was wrong, we wouldnt be able to assume that quantum stuff has defined properties when not observed. It would be the dream turned nightmare for positivists. Only observed stuff is real, but as soon as the measurement is done, the state is already (not even unknown but) not existing again. We can’t say where an electron is, we can only say we measured it somewhere some time ago.

If localism was wrong, stuff could interact with other stuff over distance, without any mediator, just like that. A metaphorical image would be telepathy or psychokinesis (not saying those would be possible, metaphor is just for imagining action at a distance). In the times of internet this doesnt even feel too crazy, but it is as soon as we imagine it. Some planet somewhere in the universe could interact with our planet, without the use of any force field (gravitational, electromagnetic etc), instantaneously. If you add in special relativity this becomes even more weird behavior as in SR there is no idea of “same-time-ness” for two distant objects. How can they then interact instantaneously, so action and reaction at the same time?

But does one of them being wrong prove anything about the nature of consciousness? I fear we are not able to say anything about that, even though people (me included) try that over and over again. Some people feel there must be a connection between consciousness and those weird quantum behaviors, but no one was able to bring up a good theory of such a connection yet.

We sadly have no real idea about consciousness at all, other than the neuroscientific dream of understanding it objectively as an emergent property of complex neuronal systems (i myself doubt this will ever get anywhere).

But without a theory of consciousness, how would we able to bring it into connection with QM? We can’t. And that’s where we stand, boggled by not understood quantum behavior and not understood subjectivity of our experience.

There was a time when the newspapers said that only twelve men understood the theory of relativity. I do not believe there ever was such a time. There might have been a time when only one man did, because he was the only guy who caught on, before he wrote his paper. But after people read the paper a lot of people understood the theory of relativity in some way or other, certainly more than twelve. On the other hand, I think I can safely say that nobody understands quantum mechanics.

-Richard Feynman

Whether or not that quote is accurate, I'll attempt to explain quantum mechanics to the best of my ability. Before attempting to learn anything about quantum mechanics, though, you should understand where the quantum realm lies and why it is separate from the classical realm. The best comparison, I think, is that of the Earth. If you look around and attempt to measure several meters across the ground, from your perspective, the Earth is flat. If you go into space and look at the Earth from there, though, you will be able to see that the Earth is most definitely round, you just happen to live in the flat Earth realm which is the limiting case of the round Earth realm. In a similar manner, classical mechanics is what you observe in the limiting case of low speed and large size; at very fast speeds, the effects of relativity start becoming noticeable and at very small sizes, the effects of quantum mechanics start becoming noticeable. In physics, quantum mechanics refers to a few basic postulates governing the quantum world and the consequences of these postulates; since this answer is intended for a general audience, I will focus on a few of the effects resulting from these postulates rather than the postulates themselves which I don't think will be substantially interesting or enlightening for non-physicists.

So what are these effects? One of the most important is wave-particle duality. According to wave-particle duality, every particle is a wave and every wave is a particle. What this means is that particles possess wave-like properties (they have phase, they have a frequency, and they can interfere with other particles) and waves possess particle-like properties (photons, the particles associated with electromagnetic waves, for example, can be absorbed and emitted discretely just like particles). At large sizes, the wavelength of an object will be negligible relative to the size of the object, just as the curvature of the Earth becomes negligible as you zoom on really close to it. Another important feature of quantum mechanics is the uncertainty principle which states that the product of the uncertainty of a particle's position and momentum must be greater than a certain value, in other words, the position and momentum of a particle cannot both be precisely known. This has to do with the probabilistic nature of quantum mechanics. When you measure a particle's momentum or position, there are multiple values that you might measure with different probabilities. After many measurements, you will arrive at a distribution averaged around what you would expect to measure classically with some standard deviation. Per the uncertainty principle, the smaller the standard deviation in position is (i.e. the higher the chance that you will measure your particle near the classical value), the greater it will be in momentum and vice versa. At large scales, the magnitude of uncertainty is so small that it won't even come close to the precision of the instrument being used to take the measurements. Interesting to note is that the uncertainty principle is an inherent property of wave-like systems and is not unique to quantum mechanics (see Richard Muller's answer to How does the uncertainty principle relate to Fourier transforms?).

Since any given particle or system of particles is a wave, it can be represented by a wave function. This wave function describes the state of the particle/system and can be used to determine properties of the system such as position and momentum. Of course, in accordance with the uncertainty principle, this wave function won't give you the exact momentum and position of a particle but rather the probability that the position/momentum is within a certain interval. One property of waves not yet mentioned is that they have boundary conditions. If you create a wave on a string that is fastened at both ends, for instance, then the equation for that wave must be zero at both ends of the string. This feature leads to quantization which means that the system can only exist in a discrete (rather than continuous) set of states satisfying the boundary conditions. In the case of the string, the wave can exist in any of an infinite number of discrete states- a state with no nodes, a state with one node, a state with two nodes, etc.

The wave function for a system is found by solving a partial differential equation known as the Schrödinger equation, where H is the Hamiltonian which is an operator representing the system's energy (one of the postulates of quantum mechanics is that variables are replaced by operators). Per request, a more detailed (and math heavy) explanation of the Schrödinger equation is given at the bottom of this answer, but understanding the Schrödinger equation isn't necessary for obtaining a qualitative understanding of quantum mechanics.*

[math]i\hbar \frac{\partial \Psi}{\partial t} = \hat{H}\Psi[/math]

One important consequence of quantum mechanics is the periodic table of elements. When you solve the Schrödinger equation for an electron caught in the electric field produced by a proton, subject to appropriate boundary conditions, you get a wave function whose possible solutions (note that when you solve a partial differential equation, your solution will have arbitrary constants in it leading to multiple possible solutions; this is what leads to quantization) are the s, p, d, etc. atomic orbitals. There are three arbitrary constants in this wave equation which are usually referred to as the quantum numbers. The wave functions each have different energies and symmetries which depend on the quantum numbers which lead to the different properties of atoms depending on which orbitals contain electrons (I haven't mentioned it yet, but the Pauli exclusion principle is another quantum effect which prevents multiple electrons from existing in the same state).

My intention was to list some of the basic features of quantum mechanics (i.e. what happens when things get really small), describe them a little, and then provide an example of their consequences. You asked what it is that causes quantum mechanics, i.e. why things behave the way they do in the quantum realm (as you put it, Stuff happens, but we don't know why). This is a popular question, but the problem with it is that the asker is usually hoping for an explanation of quantum mechanics using classical mechanics. This, of course, is completely backwards- quantum mechanics explains classical mechanics, not the other way around. In a similar manner, if you can accept that the Earth is round, then you can explain the apparent flatness of the Earth in a small area by showing that the curvature can be better approximated by a straight line as you zoom in on it; however, you can't explain the roundness of the Earth based on your worldview that the Earth is flat. Rather than seeking an explanation for quantum mechanics in terms of what you know, you must accept it as a more fundamental description of the world just as you accepted classical mechanics without any explanation before you discovered quantum mechanics (you may not have noticed yourself doing this, since your everyday experience with classical mechanics makes it intuitive, but without quantum mechanics, the classical laws of nature have to be taken as first principles) until a time comes when you discover a description of nature more fundamental than quantum mechanics.

Update: After rereading this answer, I'm still not completely satisfied, so I'd like to add a few closing remarks. In classical mechanics, things are concrete. The classical world is made up of particles. Quantum mechanics, on the other hand, is made up of waves. These waves aren't localized but instead take up all space. It isn't until you look for a particle that it becomes a particle; before that, your particle is nothing more than an infinite collection of probabilities, like a bingo ball in that container that bingo balls spin around in before they get selected. Particles are like children with cell phones. You send them out into the world and let them live their lives and their is some probability that they can be doing anything anywhere at any time (i.e. they are waves). Once you call them to check in on them to see what they are up to, they become concrete (i.e. they are particles). As your child gets older and their life becomes more routine, they become localized and you can be almost certain where they are and what they are doing at any time of day before you call them to check up on them, so as far as you are concerned, they are always concrete particles, even when they aren't, like large particles being approximated by classical mechanics. I hope this was able to add some more clarity to this answer.

*As mentioned, quantum mechanics is based on operators. In classical physics, quantities such as momentum and energy are usually thought of as scalars. Say you have a free classical particle of mass m travelling at a velocity v starting from some initial position a. What is its energy? Well, if you know that E = K + V, then you can simply write [math]E=\frac{1}{2}mv^2[/math]. But what if your particle is quantum? Well, now velocity (or, more commonly stated, momentum) is not well-defined so we can't give a complete description of the state of our system simply by stating its velocity and momentum. We can, however, write a wave equation that describes the state of our system and operate on it to determine its properties. To start with, consider an electromagnetic wave in one dimension (substitutions were made using the de Broglie relations):

[math]\Psi = Ce^{i(kx-\omega t)}=Ce^{\frac{i}{\hbar}(px-Et)}[/math]

Taking the time and space derivatives of this equation and rearranging gives:

[math]E\Psi = i\hbar\frac{\partial\Psi}{\partial t}[/math]
[math]\Rightarrow \hat{E}= i\hbar\frac{\partial}{\partial t}[/math]
[math]p\Psi = -i\hbar\frac{\partial\Psi}{\partial x}[/math]
[math]\Rightarrow \hat{p}= -i\hbar\frac{\partial}{\partial x}[/math]

The hatted versions of energy and momentum are what are known as operators. They aren't scalars but they are quantum mechanically equivalent to the scalars that they represent and in some special circumstances, applying an operator, say the energy operator, to your system will tell you the scalar value of its energy (these are known as the eigenstates of the system). Now, with these operators in hand, the Schrödinger equation will fall into place (note that H, the Hamiltonian operator, is simply the sum of the kinetic and potential energy operators which, of course, ought to represent the system's total energy):

[math]\hat{E}\Psi = i\hbar \frac{\partial}{\partial t}\Psi = (\hat{K}+\hat{V})\Psi = \hat{H}\Psi[/math]

Of course, our previous wave equation was a classical wave. Per the uncertainty principle, we shouldn't be able to obtain our system's energy (or momentum or position) by simply operating on it. I will stop the math here lest this answer get too long and turn into a textbook. To summarize, the reason we can't do this with a quantum system is because that system isn't going to be in an eigenstate of the operator (the eigenstates themselves are the states you would be in if you did happen to know, say, momentum with absolute certainty and position with absolute uncertainty) but rather in some superposition of eigenstates. When you measure the system, it gets projected onto an eigenstate with some probability and the classical value for that operator is simply the expectation value of that operator (i.e. the weighted sum of the eigenvalues).

Scientific realism is compatible with classical physics and other sciences such as biology and geology. In addition, it provides a plausible reason why science works: because its theories describe a real physical world that objectively exists. These, it seems, are the main reasons that scientific realism remains a de facto position for most scientists. But it does have problems.

Quantum theory poses problems for scientific realism, not because of supposed influences of conscious observers on experimental outcomes, but rather because it is not compatible with local realism. For example, the position of an electron does not have a single definite objective value, but is always in a superposition of positions. Even when we measure its position very precisely, there is still a superposition of positions within some small finite region. It is incompatible with quantum theory to say that a single, exact value of position exists objectively (unless one adopts a non-local hidden variables theory - but then the objective reality is extremely strange). Because these limits on definiteness are so small, they can be ignored for all practical purposes in sciences like biology and geology, and properties can be treated as if they had definite values that exist objectively. So, despite this challenge to scientific realism by quantum theory, much of the rest of science need not be concerned with these problems, as a practical matter.

In addition to the problems posed by quantum theory, another problem with scientific realism is that science is forever evolving and our basic theories are never final. In fact, theories are required to be falsifiable and therefore subject to being overturned by new data. Historically, paradigm shifts in physics have fundamentally altered basic concepts of physical reality such as time and space. So, the problem this poses for scientific realism is that the reality described by any given scientific theory may not in fact correspond to the true physical reality that is purported to exist throughout these radical changes in our understanding of it. We may find a better theory in another 100 years that provides a completely different description. So, scientific realism asserts that a physical reality objectively exists, but there is no confidence that our current scientific theory actually provides a correct description of it. Of course, it provides empirically accurate predictions insofar as the theory has been experimentally confirmed, but that is a separate matter from assertions that the theoretical entities hypothesized by the theory have an objective reality.

Some scientists are not aware of these problems with scientific realism, and simply take it for granted. Many scientists, however, are well aware of these limitations to scientific knowledge, and they would not hesitate to admit that scientific knowledge is always provisional and subject to revision, and that science is ultimately about finding theories that make good empirical predictions rather than finding a true description of an objective reality.

Fortunately, scientific realism is not necessary to the essence of science, which can function perfectly well without adding metaphysical assertions to the effect that the entities of its theories describe objectively existing things.

That’s an “excessive” phrase, really, that I think gets used for shock value (click baiting) as much as anything else. But, what it is referring to is that in contrast to classical mechanics, where the state of a system is generally expressed as a collection of observable property values, the state of a quantum system is expressed by a wave function which is not observable, measurable, or anything like that.

Of course we do make measurements on quantum systems, and when we do we get results for those measurements - the particular observable property we measure has a value at that moment of the measurement. However, what happens when we measure is that we force the system to have a quantum state that possesses a specific value for that observable property. Not all quantum states do, and in fact in general an arbitrary quantum state will not have a value for the property of interest. That’s why all we can predict is probabilities - there will be several values that might possibly result from the measurement, and until we do the measurement and look we don’t know which one we’re going to get. Prior to the measurement, a specific well-defined value for the property does not exist.

So, this is what they mean by that phrase. The quantum state of a system always exists, but since we can’t measure it / observe it, it’s questionable what it is telling us about “reality.” What’s “really real” are things we can measure and get actual values for. Until we explicitly measure a property value, though, that property value does not exist in general. Our act of measurement “brings it about” in some sense.

Also, trying to apply these ideas to macroscopic objects is a bad move. You hear people say “the moon doesn’t exist if we aren’t looking at it.” Well, that’s nonsense. Part of the assumptions that go into quantum theory is the notion that the act of measurement has a very significant, dominating affect on the tiny little quantum system under study. That is not the case when you make a measurement on a large object like the moon. We can bounce all the photons we want off of the moon and hardly affect its behavior at all. So when we’re in a situation like that, studying a large object, we should use tried and true classical methods. Classical methods are more informative and should be used anytime we can - we should only resort to quantum methods in cases where the classical methods fail.

Stay safe and well!

Kip

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From a purely neurobiological perspective, the possibility consciousness (whatever exactly that is) possesses quantum properties is truly not so outlandish. Consider that we have hundreds of billions of neurons, each of which synapses or connects with ten of thousand other neurons. That means there are more synapses in the brain (10 to the 14th power) than there are stars in the galaxy. One current mode of thought suggests neurochemical interactions at the synaptic level are responsible for specific memory and information. Our minds are semantic networks of representations - memories, both of information and of specific life episodes. In addition, connections between neurons are insulated with myelin to enhance signal conduction, and the functionality and integrity of that myelin varies regionally and locally - so the signals are likely affected by such integrity. These vast numbers of connections in the brain are differentially myelinated - like having a T1-internet connection versus dial-up (remember dial-up? No? Ask someone older than you). However, lest one think it's all a giant jumbled mess, it's important to consider that these neurons and connections are also organized in functionally different networks. One of the networks has been termed the default mode network, as this is the network in the brain active when one is instructed to simply rest quietly, eyes open, and not think of anything speceific. So, in that default mode, that state of a resting but working mind (meditators excluded), what do you think of when you think of nothing?

What does this all mean? How does it relate to quantum mechanics? Think of it this way: What dictates the likelihood - the statistical probability - that at any given moment something you see, hear, or think of will be associated with, or trigger some other thought, memory, or piece of knowledge or even emotional reaction? The sheer volume of representations in our mind is staggering, and the inter-relations among all of them even more so. In addition, human thought and consciousness share many properties with other physical phenomena described by quantum mechanics (e.g., energy, light) - it's not random, but constrained by numerous different factors (synaptic input, myelination), and thus likely best described by a probability distribution. Just don't try Schrodinger's experiment with my cat (or my head).

To say that quantum theory violates “local realism” is misleading. Violations of Bell’s Inequality indicate a violation of locality, and more specifically that all the causes of an event must lie in or on its past light-cone. Classical physics—at least Maxwellian electrodynamics and General Relativity—is local, and hence cannot violate Bell’s Inequality for experiments done sufficiently far apart. So quantum theory violates locality and classical physics does not. But the essential point is that reality cannot be local in Bell’s sense, as is proven by the experiments showing violations of Bell’s Inequality.

Here is the electromagnetic spectrum:

What you can perceive is in that tiny little bit in the middle, visible light. You cannot detect any of the other wavelengths, even though they can actually kill you. Well, some of them.

That’s a metaphor for reality. You, and the rest of humanity live in a tiny little sliver of reality that we think is all the reality there is.

But it is not. We live in a quantum universe, and it is largely inaccessible to us as far as our perceptions are concerned. But that quantum, incomprehensible, counterintuitive, frankly weird universe is the real universe, and the part we live in is a bit of an illusion.

No, this would not force solipsism on you. Solipsism is really just a belief. You engage in solipsism when you adopt the belief that you are the only “actually conscious” being in existence, and decide that all of the other “apparently conscious” beings around you “aren’t really” - you take the position that they are just automatons that have external behavior that seems conscious while not actually being conscious.

Science doesn’t really offer a way to “know” if an entity is conscious or not. There would be no way for me to prove to you that I’m not just a robot that makes a good act of seeming conscious. Since the two situations can’t be discriminated by science, the difference can’t have any scientific relevance.

Stay safe and well!

Kip

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A (small) number of physicists have proposed that the mind is a quantum-mechanical object. That is, that there are properties of the mind that cannot be explained in purely chemical/classical physical terms.

Note that I said "physicists". No neurologists, psychologists, or anybody who actually works with brain goop for a living says this. Just some physicists. Which tells you very little about consciousness, and a lot about physicists. What it tells you about consciousness is that when you have this:

everything looks like this:

The physicists are joined by some philosophers. In my experience, most of those philosophers lack the grounding in QM to make a meaningful QM theory.

If you want to read more about it, probably the best book on it is Roger Penrose's The Emperor's New Mind:

http://www.amazon.com/Emperors-New-Mind-Concerning-Computers/dp/0198519737

And a lengthy refutation:

http://www.mth.kcl.ac.uk/~llandau/Homepage/Math/penrose.html

Unfortunately, that leaves us with rather a vacuum. Penrose's theory is, to my mind and the mind of a great many others, pure rubbish. But there aren't any complete, productive theories (classical, quantum, or otherwise). It's an open question, and you can't rule out quantum theories. However, there's no particular reason to expect it to be a quantum theory, since so much of the mind is clearly subject to purely classical manipulation. It would be extremely unusual for an object as big as a brain (over a kilogram) to exhibit noticeable quantum behavior, which is generally restricted to subatomic particles ([math]10^{-30} \mathrm {kg}[/math]). Thirty orders of magnitude is a lot.

As Jay Wacker and Andrew Lemke point out, quantum mechanics can scale that far, under the right conditions, and this isn't proof that QM can't be part of the brain. It does, however, make the theory seem (at least to me) less likely.

Quantum mechanics is no more or less “materialistic” than classical physics. It’s just a description of how our world works - a better description than classical physics, but still a description.

“Quantum consciousness” is just … well, quantum woo, basically Just adding the word “quantum” to something doesn’t suddenly make it magical or something.

Just like a car manufacturer calling their electric cars “Quantum” doesn’t magically make the car anything more than an electric car. Even though it’s a nice name.

It undermines Local Realism. This is why some people like Seth Lloyd believe we are living in a computer simulation.

Here is a blurb photo of an atom:

Notice that its just a foggy blurb of a photo! Now if local realism were “real” than an atom should look like something that is more well refined and specific….If the drawings in our textbooks are any indication, they should look like this:

According to Information Theory it would take far more bits of data if the atoms in our universe were as well defined as the latter photo. In fact it would take an infinite amount of data if the universe were perfectly “real”.

Virtual reality computer programmers cannot program anywhere near the amount of data that would approach infinity, and neither can God (aka the programmer who wrote our universe).

But hey, even if we aren’t real, at least our universe has more data built into it than say a universe made out of lego! Could you imagine if “realism” was only defined using lego blocks!???

Quantum mechanics is a theory that was developed in the early 20th century to explain some “anomalies” in physics at the time. In fact, one of these anomalies was something as straight forward as the colour of a hot body. You may have seen a picture of glowing metal heated to hundreds of degrees and higher. That glow evolves in temperature from red-hot to white hot. Thus colour gives a measure of temperature. The problem was that there was no theory that could account for this colour change.

The light emitted from hot objects was known to be electromagnetic radiation as described by Maxwell's equations. Thus the source of the light could be thought of as an oscillating current. Therefore you can use classical antenna theory to model the surface of the emitter. You treat the surface as being composed of antennas of various sizes and orientations, with each size and orientation corresponding to a specific frequency and polarisation of the emitted light. Then to get the spectrum of the emitted radiation, you need to count the number of antennas in a given area (we can call these antennas, harmonic oscillators to get the ball rolling). This approach worked well at the lower frequencies corresponding to infrared radiation, and is known as the Rayleigh-Jeans law. The problem is with higher frequencies, where the law diverged. This was known as the ultraviolet catastrophe.

Max Planck developed a fix for the Rayleigh-Jeans law by imposing an energy threshold below which the constituent antennas would not emit radiation. He then realised that the energy threshold was insufficient, and that for a unique solution, the energy must be emitted in packets. The formula for this is [math]E=hf[/math], where [math]E[/math] is the energy, [math]f[/math] is the frequency of the radiation, and h is a constant… yeah that sounds rather diminutive, but you don't just go introducing a new constant to physics without some consequences. In this case, the consequences are the birth of quantum mechanics. So much so that any physics formula with Planck's constant in it is a quantum formula! That tiny constant changed everything…

However, the work of Planck was only the start of the quantum revolution. Planck's formula was applied to the emitters in the material body. At that point Maxwell's theory of electromagnetism was safe. Then along came Einstein and showed that it wasn't just the emitters that were quantised, but light itself. This was a huge shift, because the classical theory of electromagnetism was almost sacred. In fact, this new understanding spread. This idea of tiny quantised oscillators eventually became the basis for all of modern quantum theory, including quantum field theory and the standard model. This is all linked to the linearity of the theory, essentially the addition of oscillators, or linear decomposition into oscillators. Such oscillators are fundamental solutions to the Schrödinger equation for example. The linearity of the theory is directly related to the Fourier theory of waves in which any arbitrary waveform can be decomposed into a sum of sinusoids. That's why quantum theory is a wave theory, which directly results in the Heisenberg uncertainty principle. So quantum mechanics takes this oscillator decomposition to the ultimate limit, where everything can be represented by harmonic oscillators. The DeBroglie relationship essentially maps matter into the harmonic oscillator domain. In quantum field theory, the oscillators are formally called field modes, and there the decomposition is complete.

The essential heart of the theory are the Planck and DeBroglie relationships, [math]E=hf[/math], and [math]p=h/\lambda[/math], respectively. For classical physics, these equations are true only for waves. For quantum physics, they are true for all objects, including particles. In other words, these relationships are considered universal. That effectively introduces Planck's constant into any quantum formula.

It's almost crazy to think of the implications of this one little constant; Planck's constant: h. Talk about letting the genie out of the bottle…

However… this is not the entire story. We observe particles, or at least particle-like behaviour. In order to incorporate this into the theory, the concept of a measurement was introduced. The idea of a measurement required the identification of measurable quantities. These measurable quantities had to have special properties; specifically measurements must give real-valued results, thus opening a whole can of worms, because the concept of a measurement is not entirely physical. This is known as the measurement problem. It exists to map this strange theory of interacting harmonic oscillators onto measurable properties, and gives rise to the various interpretations of quantum theory.

One might ask what aspect of a measurement is nonphysical? Let’s take this example of a measurement. You place a stick next to a tree and then estimate the height of the tree in terms of the length of the stick. The physical action is just the placement of the stick next to the tree. The measurement is much more than that, as it represents the information gained following that action. The measurement is made by the “person” performing the action. A rock has no knowledge of the measurement. It has no meaning to it. However, at some level, the placement of the stick will have some “meaning”. How do you incorporate that into a physical theory? No one knows…

Ultimately, quantum theory boils down to a theory of interacting harmonic oscillators combined with a measurement postulate. The problem is that the measurement also involves an interaction and no one can explain how the interactions of the harmonic oscillators are somehow different from the interaction of the measurement. If reality is to be understood, this needs to be resolved. However, if we only care about predicting measurement outcomes, then everything works just fine.

Quantum mechanics, at its heart, is simply the recognition that there are no particles and no waves, only something that has properties of both. Sometimes this is called a wave function, but that term typically applies to the wave aspects - not to the particle ones. For this post, let me refer to them as wavicles (combination of wave and particle).

When we see a classical wave, what we are seeing is a large number of wavicles acting together, in such a way that the "wave" aspect of the wavicles dominates our measurements. When we detect a wavicle with a position detector, the energy is absorbed abruptly, the wavicle might even disappear; we then get the impression that we are observing the "particle" nature. A large bunch of wavicles, all tied together by their mutual attraction, can be totally dominated by its particle aspect; that is, for example, what a baseball is.

There is no paradox, unless you somehow think that particles and waves really do exist separately. Then you wonder about this "duality" - it is really a particle or a wave?

But it is really neither.

Once you have this concept (and it was created by Einstein and deBroglie) then you can ask the question: how does this wavicle move? How is it affected by forces? Those were the questions answered by Schrodinger, Heisenberg, Dirac and others, with their quantum mechanical equations. “What about fields, such as the electric, magnetic, and strong force fields?” you would ask. Those were also recognized as being (what I, for lack of a better term in this answer) call wavicles. Yukawa explained the nuclear force as the exchange of a virtual pi meson. Schwinger and Feynman explained the electromagnetic force as the exchange of a virtual photon.

Once you have accepted that the only things that really exist are wavicles, and that they change abruptly when measured - once you accept that the momentum is given by the wavelength and the energy by the frequency, then the Heisenberg uncertainty principle is a mathematical consequence.

Quantum mechanics must violate either locality or realism. It might violate both.

The Copenhagen Interpretation violates locality. That means an action in one place affects something far away instantly. A measurement of the front part of a wavefunction collapses the entire thing immediately, no matter how far away to other end of the wavefunction is. This is spooky action at a distance.

The Many World Interpretation violates realism. There is not just one single definite reality. There are many realities. Many worlds. Particles don't have concrete definite properties. They have self a contradictory properties at the same time.

Scientists don't know which interpretation, if any, is correct. There are other interpretations too. But they all make the same predictions. No experiment can ever tell which is right and which is wrong. Although the interpretations are very different, their observable outcomes are identical.

Philosophical realism, is the belief that reality exists independently of observers

Simplistically, quantum idealists seem to fall into two camps: either everything exists all at once in all possible universes independent of any observer. An idea that can never be proven. Or, everything exists in this universe in a state of superposition that includes all possibilities that are collapsed into an actual event when observed. Some insist that 'observation' includes by any instrument. However, since (on the theory) the instrument is itself a quantum field inseparable from the whole, as indeed every person is, there is no reason why that too should not remain in superposition until observed.

The question then remains observed by whom?

Physicalism or naïve materialism makes unscientific assumptions from the start that reality is physical, as we perceive it to be. What is the framework that forms reality? It could be a dream, it could be an illusion, it could be a virtual environment, or it could indeed be physical.

Mankind perceives things using five senses. Why should we assume that there aren't things that our five senses aren't able to perceive? Why should we assume that there are no non-physical entities or energies that go beyond our perceptions?

Furthermore, our five senses influence how we perceive, but do not actually inform us how things really are. For example, color is not an inherent property of the objects we see. Color is a property of how we are neurologically "wired" to see things. https://www.pantone.com/how-do-we-see-color

Finally, there are scientific limitations. Some people call them gaps in our explanations. They believe that science can solve any problem. Not true. There are physical limits. For example, science tells us that nothing can travel faster than the speed of light. Logically, science will not be able to solve this problem.

Here are a few more problems that necessarily go beyond physical science and the abilities of man to solve.

Physicalism Fails to Explain Life

Why Consciousness is Not the Result of a Physical Process

Please note - There is much to learn about consciousness and the nature of life. This is not an argument that we shouldn't continue to study and learn as much as we can scientifically. We should however use logic to understand how much we don't really know.

Very few physicists—and no really serious present ones I can think of—believe that there is any specific “observer effect” in physics. As John Bell put it, you want a theory that neither requires, nor is embarrassed by, the presence of an observer. The systems we call “observers” and the interactions we call “measurements” are just regular physical system and events governed by the same laws of physics as everything else.

Early on, some physicists suggested otherwise, but already Einstein mocked the idea by asking whether a mouse could be an “observer”. The term is so vague and unsharp that it should not appear in any proposed fundamental physical theory, just as the term “measurement” should not. See Bell’s essay “Against ‘Measurement’”.

No it is not “tenets” and it is not “paradigms”.

You are confused, because you know nothing about it, and show no respect to the people trying to teach you by assuming they are teaching you “tenets” and the “paradigm” is the reality.

In all science all discrepancies can be fudged, to a certain extent. Once again, you show no respect to the scientists who are well aware of every time they have to fudge to get something useable out of the theory. Fudging is a useful technique proved over time. Kepler proved his laws of motion with a fudge.

Hypotheses can’t have errors unless they are defined well enough to be theories. QM is no exception to the rule that the theory is disproved by the single “error” predicted in the model derived from that theory.

I can see that you are very very confused. What “alternative” is there to QM right now? Your smartphone would not work at all unless most of it was useful enough to be proved true to a reasonable standard.

There are no playing fields in science. Science is not a game. Whether fair or unfair in the judgement of the informed consensus, you most certainly are not “informed”.

You show no respect to the scientists by accusing them of dismissing alternatives to QM, when no such alternatives exist, and by accusing them of “fudging” - something all scientists in breakthrough discoveries have to do at first, when they are well aware that peer review and common sense will sooner or later have to resolve any discrepancies.

No respect at all. You know nothing about it. Science is not philosophy and not religion. Standard Model and String Theory - if that is what you mean - are completely compatible with what is commonly agreed - and you make the most childish of mistakes any scientist can make by thinking the “paradigm” has any relevance at all, other than how it is taught to you after it is proved.

What do people mean by “quantum mechanics has proven that objective reality does not exist”?

Well, some may assign this to meaning that various quantities don’t have specific values until measured, in general. This is easily demonstrated by EPR experiments and GHZ experiments. You find that you cannot preassign values ahead of time and still reproduce the data or the predictions of quantum mechanics. In the GHZ experiment, you start with 3 particles with a particular wave function. The 3 particles have spin. We already know that you can’t have simultaneous definite values for 2 or more spin components (the x, y, and z components of the spin) at the same time. The GHZ experiment goes further.

Each particle is received and measured by a different person. They are to randomly choose whether to measure the x or y component. It turns out the certain products of the spin (actually, the [math]\sigma[/math]'s) is always -1, whereas classically, where you can preassign values to the x and y components ahead of time and the product comes out to 1. Well, QM wins of course, and you get -1. But the specific values of the x and y components therefore don’t have definite values until they (one or the other, you can’t measure both!) are measured. (Please see the first reference to clarify this!)

See

the first column of

and the first two pages of

However, in the early days of quantum mechanics, things were more confusing. Einstein is purported to have said,

Nonlocality: “Spooky action at a distance”; has been well understood for over 250 years. In 1758, Boscovich pointed out; echoed by Laplace in 1814, that the state of a physical system at any moment determines the system’s state at any moment in its timespan: past, present, and future. That’s determinism: you can’t get more nonlocal than that. It’s as true of Schrödinger’s linear partial differential equation of 1926 as it is of Newton’s 1687 Laws.

A few people who hadn’t noticed the non-locality that was a well-established tenet of all classical, relativistic, and quantum mechanics from 1687 to the present thought things should depend only on their immediate surroundings. The determinism of all physics shows that the state of a system at any point in its entire timespan of existence: past, present and future, completely determines its present state. Our universe appears to be entirely deterministic and maximally nonlocal. What were they thinking?

Determinism isn’t as good as it looks. You can’t know the entire state at any moment of a system of 10[math]^{23}[/math] or more particles. The best we can do with large systems is apply statistical methods to obtain bulk statistical/thermodynamic information: temperature; entropy; etc.

Determinism shows through in small, necessarily quantum mechanical, systems with say 20 degrees of freedom. Unfortunately, we can’t determine the exact state of a small quantum mechanical system: there is non-commutativity among the required momenta and positions. Nonetheless, a small quantum mechanical system’s state at a given moment can be known well enough to give information about a distant part of the system that couldn’t have been propagated there at ≤c. That’s what Einstein called spooky action at a distance and Schrödinger called entanglement: it’s a direct if counterintuitive consequence of determinism.

As far as we can tell, our universe may entirely be an illusion created by an incorporeal mind. In order to do science, we set that perfectly valid possibility aside and proceed as if anything we may encounter in nature is as real as it appears to be. That’s operational realism.

Thinking you know what’s what.

Especially if you think you really know how your senses and your cognition don’t really render things as things really are, and that by knowing that you can correct for their confounding factors.

I find that a surprising number of people are naive realists. Naive realists talk about objective facts.

AI answer

Common-sense realism, or naive realism, is the view that the world is more or less as it appears to us: objects have properties like color, shape, and size, independent of our perceptions, and these properties exist whether or not we observe them. However, quantum realism and quantum interpretations that suggest a form of panpsychism or cosmopsychism challenge this view by positing a fundamental, interconnected, and potentially conscious nature at the quantum level that influences, if not directly underpins, what we observe at the macroscopic level.

Here’s how common-sense realism could attempt to reconcile or account for these more complex and abstract views:

1. Quantum Realism and the Underlying Structure of Reality

Quantum realism posits that the quantum world is real and primary, forming a foundational reality from which our observable, macroscopic reality emerges. Common-sense realism could adapt by accepting a hierarchical or layered model of reality. In this view:

• Macroscopic Reality: Common-sense realism accurately describes objects and events in our daily experiences.

• Quantum Reality: This underlying layer obeys different principles, such as superposition and entanglement, but manifests at the macroscopic level as stable, seemingly classical objects that common-sense realism describes.

Essentially, common-sense realism could still apply at the macroscopic level, while quantum realism applies at the microscopic level, suggesting that what we perceive as “real” emerges from the quantum substrate, even if it operates under different rules.

2. Interpreting Quantum Panpsychism and Cosmopsychism

Quantum panpsychism and cosmopsychism propose that consciousness (or proto-consciousness) is a fundamental aspect of the universe. This could imply that even at the smallest scales, there is a form of awareness or experience that aggregates into the complex conscious experiences we are familiar with. Common-sense realism could account for these interpretations in several ways:

• Accepting a Dual Aspect of Reality: Common-sense realism might expand to include the notion that objects and particles have both physical properties and proto-conscious aspects. While objects appear as “just objects” to us, they might also contain a latent experiential component that doesn’t affect our everyday experience but forms part of a broader reality.

• Emergent Consciousness from Quantum Interactions: Common-sense realism might adopt an emergentist approach, positing that while consciousness is not apparent in everyday objects, it emerges from complex interactions at the quantum level. This could align with cosmopsychism by suggesting that consciousness arises from interconnected quantum systems, but only becomes relevant at specific scales or under certain conditions.

3. Reframing Perception within a Quantum Context

Common-sense realism assumes that our perceptions closely match reality. However, given quantum mechanics’ findings about observation affecting reality (e.g., wave function collapse), common-sense realism could be reframed to accept that perception itself might play a role in shaping the macroscopic world we experience. In this view:

• Perception as a Filtering Process: Our common-sense perception might “collapse” the complex, probabilistic nature of the quantum world into definitive objects and properties. In this way, common-sense realism remains valid in its domain (macroscopic perception) but recognizes that our perceptions don’t reflect quantum-level complexity directly.

• Reality as Observer-Dependent: Common-sense realism might accept a slight redefinition, allowing that what appears as “common-sense reality” is one aspect of a reality that includes observer-dependent quantum elements. This approach would allow common-sense realism to coexist with quantum mechanics by acknowledging that what appears as stable and independent in our perception depends on deeper, more fluid quantum processes.

4. Addressing Ontology: Reality Layers and Scale

One promising reconciliation is through an ontological framework that suggests reality functions on different levels:

• Macro-Level Independence: At our everyday scale, common-sense realism works because objects behave as though they are independent, self-contained entities.

• Micro-Level Interdependence: At the quantum scale, interconnectedness and wave functions become dominant, which aligns with quantum realism, potentially even suggesting a form of proto-consciousness as in panpsychism. This layered ontology allows for a reality where common-sense realism applies at higher levels, while quantum principles govern the foundational layer.

In this way, common-sense realism could coexist with quantum realism and quantum panpsychism or cosmopsychism by adopting a model where reality behaves differently depending on the level we observe, with “common-sense” properties emerging from a deeper, interconnected quantum foundation.

In Summary

Common-sense realism could account for quantum realism and quantum panpsychism/cosmopsychism by embracing a multilevel reality model. At the macroscopic level, common-sense realism holds, but it’s acknowledged as a “macro” approximation, while quantum realism underpins it, introducing quantum consciousness or interconnectedness at a more foundational level. This layered reality respects the principles of common-sense realism in daily life while allowing room for quantum-based interpretations at a deeper level of existence.the

Naïve realism (also called common-sense realism) is an unconscious cognitive habit operating in each moment of awareness that leads us to assume a certain epistemological position, i.e. an assumption about the validity of certain claims to knowledge. In rare instances it is a consciously held philosophical belief, then it is called direct realism.

The term 'naïve' isn't used in the pejorative sense of "simple minded" or 'stupid', it is instead used in a technical sense of “not having previously been exposed to something” (see Definition). In this case, not previously exposed to philosophical enquiry or scientific evidence regarding the epistemological validity of the knowledge claims that are being made. Thus it is a naturally occurring and unconsciously assumed epistemological position that is not consciously held but rather it is experienced as "simply the way things are".

Specifically, naïve realism leads us to overlook the role of subjective experience in the apprehension of that which is experienced and to unquestioningly assume that the phenomenal content of our subjective experiences are in fact objective external objects. Thus when we see a chair in front of us we simply assume that this is because there is a chair in front of us.

"Naive realism holds that the view of the world that we derive from our senses is to be taken at face value: there are objects out there in the world, and those objects have the properties that they appear to us to have." Theory of Knowledge - naive realism

We do not question the quantum indeterminacy of observables, the operation of our sensory and neurological sub-systems, the subconscious pre-processing of stimuli, the influence of cognitive biases, the perceptual forms that arise in the conscious mind, nor the conceptual categories that we habitually associate with those forms.

Naïve realism is biologically useful because an animal's perceptions of food, danger, mates, etc can be interpreted with sufficient accuracy and quickly responded to, thus this habit is deeply engrained in our minds. However when exploring subtle issues of epistemology, philosophy, metaphysics, physics, etc it can be a significant obstacle to clear, sceptical, rational thought about many topics. This obstacle goes completely unnoticed and when the unconscious beliefs are challenged by certain ideas this results in cognitive dissonance and instinctual aversion to the 'offending' ideas. For many details on this response within the context of science see John Ringland's answer to Do we have a collective paradigm? Else, is it fragmented?

Naïve realism doesn't just apply to what we perceive through out bare senses, but also through augmented senses, such as using a telescope or microscope or particle accelerator or other sophisticated experimental apparatus. By unconsciously ascribing objective reality to phenomenal appearances naïve realism leads us to think of things primarily in terms of their phenomenal appearances and to come to assume that all 'real' things are determined by their phenomenal appearances. This is sometimes called classical objectivism. If something cannot be experienced via its phenomenal appearances then it is considered abstract and is assumed to be unreal. It is this aspect that is challenged by the realist interpretation of quantum mechanics, for example, see John Ringland's answer to What is light made up of, particles or waves?

Throughout history and throughout each of our lives there has been an unconscious accumulation of habits and beliefs arising from unquestioned assumptions about the contents of subjective awareness. Thus the mind conforms to a self-reproducing closed loop of hidden assumptions, which keeps most cultural discourses unwittingly bound within a naïve realist framework.

Note that naïve realism operates at the foundations of empirical science because:

“Empiricists claim that sense experience is the ultimate source of all our concepts and knowledge” (Rationalism vs. Empiricism)

However not all of science is empiricist, most notably quantum mechanics. See John Ringland's answer to Naive Realism: Can it ever be said that Scientific realism takes off from the springboard of commonsense or naive realism?

When naïve realism has been questioned by philosophical enquiry it has been shown to be inconsistent. Furthermore, cognitive science shows it to be unfounded. Finally, quantum mechanics shows it to be utterly false. See The Big Philosophical Questions: Now that naive realism has been disproven by quantum mechanics, how will this impact our collective paradigm?

However due to the unconscious and endemic nature of naïve realism it persists throughout science unabated, which has led some to study the process of cognitive repression within the scientific community. See John Ringland's answer to Despite having evidence that contradicts someone's belief, why can't they come to believe something new? where there is an extended quote regarding this cognitive repression in modern physics.

Naïve realism permeates our perceptions, beliefs, languages, cultural discourses, philosophies and scientific theories. It takes great insight, courage, effort, persistence, clarity, subtlety and caution to coherently and consistently think outside of that closed loop. Even for those who sincerely attempt this it is very easy to unwittingly slip back in to such an engrained habit. It will take some time before the scientific community is able to go beyond naïve realism, see John Ringland's answer to Has science become too dogmatic?

Because naïve realism ignores the role of experience in the apprehension of that which is experienced and assumes objective existence for the objects that are portrayed by experience, this leads to many conceptual difficulties and paradoxes. Especially when we later come to enquire into the nature of experience itself (and consciousness) and we try to understand it in terms of the phenomenal content of experience that we have previously assumed to be objective external objects.

Because quantum mechanics avoids succumbing to naive realism it finds that the role of the observer is central to the theory, whereas in all empirical sciences the observer has no role. For this reason quantum mechanics is favoured by some as a science that can escape the closed loop of naïve realist assumptions and provide pathways towards an understanding of consciousness whereas empirical science cannot. See John Ringland's answer to What is consciousness?

The sentence means that quantum mechanics, the most accurately verified theory of natural sciences and the true logical foundation of physics since 1925, disproves the statement that the world may be described by objective facts such as the right values of observables that all observers should agree upon.

Instead, quantum mechanics is a theory that predicts probabilities of individual results of measurements (equivalently, observations) - using the knowledge extracted from the previous observations - and an observation is always in principle a subjective matter which depends on the choice of the observer and his or her or its logical framework to decide what counts as an observation.

To use quantum mechanics, one needs to pick this observer or his perspective and that choice decides what has been observed by that observer, and quantum mechanics predicts the probabilities of the results that will be observed, in measurements that in principle are made after a decision of that observer. This system therefore depends on the observer or his perspective - equivalently, it is not shared by all observers in the world, it is not objective.

Reality is intrinsically observer-dependent. In some less profound sense, this became true even in relativity when the simultaneity of events started to depend on the observer - his inertial frame. But literally everything of interest depends on the observer in quantum mechanics.

A standard philosophical equivalent of the adjective observer-dependent is subjective. Reality is subjective. Most people have deep emotional or ideological prejudices that prevent them from accepting that the most basic assumption of classical physics - the observer-independent or objective reality - has been proven wrong but it has been proven wrong nevertheless. No amount of loud incorrect comments or demagogic popular books may change the basic facts about the laws of Nature. One may prove this statement rather rigorously - one may prove theorems that any natural enough theory with the assumption of objective reality will make predictions that are in conflict with experiments.