Why We Don't Diffract Around Trees: Quantum Effects In The Macroscopic World.

A common misapprehension of quantum physics, especially by woo-merchants and pseudoscience practitioners is the implication that quantum effects should, or are seen in the macroscopic world around us. As an example, Teresa Tsalaky here explains to us that various quantum effects are the reasons various alternative medicines work beyond placebo, of course, she never explains how they explain these things.

"If you want to understand why ancient healing methods work, look to humankind’s most modern science: quantum physics. Wave-particle duality, the properties of electromagnetic fields, the holographic effect, the impact of the observer—these discoveries can help explain so much. They unlock the secrets of how homeopathy cures, why the holistic approach is so effective, how Reiki and Qigong can heal tissues, what makes iridology an effective diagnostic tool, and why placebos work about thirty percent of the time." (0)

But she's right about one thing, all matter can be described as a wave right? This is as good a place as any to start explaining why the weird and wonderful effects of quantum physics stay restricted to the microscopic realm and do not leak into our macroscopic lives.

Take this scenario.

It's your first day on a new job, eager to impress you leave for work early. Unfortunately, your car won't start, you'll have to travel by bus. You arrive at the bus stop just as your bus is pulling away, You run for the bus, but unfortunately, you run smack bang into a tree. This results in you arriving late. 

Later on during your first day, the boss calls to her office. She wants to know why you were late and why your face is hideously disfigured. You explain about running into the tree.

Your boss looks at you sternly, "You're lying." she says "Don't you know quantum physics? All matter displays wavelike behaviour. You would have just diffracted around that tree. Clear your desk." 

So why don't we demonstrate wave-like behaviour? Why didn't you diffract around that tree? Why throw thrown balls diffract around baseball bats and tennis rackets?

To answer this we need to consider the De Broglie wave and one of the most important elements of quantum physics: Planck's constant.

It was Louis De Broglie (1892-1987) who first suggested that matter, like photons, should demonstrate particle and wave-like behaviour. Electrons, De Broglie suggested should diffract around objects just as light waves and water waves do (1). This wave like nature of matter was first demonstrated experimentally with a stream of electrons by Thompson in the UK and by Davidson-Germer in the US (2) separately and roughly simultaneously. The evidence of the wave-like behaviour of electrons is given by the appearance of an interference pattern at the electron detector screen. Where peaks intersect there are bright peaks or constructive interference, where troughs of the waves intersect there are dark strips where no electrons are detected or destructive interference.  An example of this is seen below, but it's important to note this isn't the Davisson-Germer set up.

The parameters of this matter-wave, also known as the De Brogle wave (the name we'll continue to use) or the probability wave, are given by the relationship:

Where h is Planck's constant and p is the magnitude of the particle's momentum which is in turn, for a particle with mass given by: 

The key to wave like behaviour at the quantum scale lies in the size of Planck's constant in comparison to the particle's momentum. Planck's constant has a value of

which is a decimal point followed by 33 zeroes. As you can see it's an extremely small constant and is found through out quantum physics in this or another form. Diffraction only occurs when the size of the wavelength of the travelling wave or particle is comparable in size to the gap through which it passes or the object around which it's diffracting. Think about FM radio waves which are electromagnetic radiation with a wavelength of roughly 1km, these will diffract around large objects like buildings. Whereas we know from the fact we can't see what is directly behind large buildings that visible light with a wavelength of between 400 -700 nm cannot diffract around these objects.

Now for an electron with a mass of 10^-30 kg travelling at roughly six million meters per second, the De Broglie wavelength is:

Which is roughly about a tenth of a nanometer. This explains why electrons diffract from a sheet of nickel as seen in the Davisson-Germer experiment, the De Broglie wavelength is roughly half the distance between two nickel atoms.





Let's compare this to the De Broglie wavelength of the average human being running for a bus. Let's take the average global body mass of 62 kg and let's say our running speed is 3 m/s when we hit the tree.Which gives us:

As you can see the De Broglie wave-length for a macroscopic object is incredibly small in comparison to that of an atom. To demonstrate this isn't just for a human being, let's look at the reason we don't see a tennis ball diffract around a  tennis racket at Wimbledon. Let's take the mass of the ball to be 0.06 kg and the magnitude of its velocity to be 60 m/s.

So we wouldn't expect a diffraction from a meter or so wide tree simply because of the massive difference in size, and that massive difference in size continues through tennis balls and rackets way down to, as far as we can see thus far particles of roughly 5000 protons, neutrons and electrons (3) with the formula C284.H190.F320.N4.S12. The momentum aspect of the De Broglie equation is simply too large, and Planck's constant too small, for even small slow moving objects for the wave-like behaviour to be demonstrated at macroscopic levels.

So we can see that the tiny value of Planck's constant (h) is the reason we don't see particle-wave duality in the macroscopic world, but it turns out this is the mitigating factor in why we don't see other quantum effects such as the Heisenberg uncertainty principle in classical physics.

That's where we head next.

Sources

(0) http://pathwaystofamilywellness.org/Inspirational/traditional-healing-modern-science.html

(1) https://en.wikipedia.org/wiki/Electron_diffraction

(2) https://en.wikipedia.org/wiki/Davisson%E2%80%93Germer_experiment

(3) https://medium.com/the-physics-arxiv-blog/physicists-smash-record-for-wave-particle-duality-462c39db8e7b

All equations and constants: The Quantum World: Wave Mechanics (Bolton, Lambourne, 2007), Quantum Physics: An Introduction (Manners, 2000) 

A Critical Analysis of "Quantum Parapsychology" By Jacobs and Soderlund. Part 1

As the first post for a new blog examining misunderstanding of quantum physics, I can't think of a better place to start than in a comprehensive review of a book that was recently passed to me. Quantum Parapsychology: How Science is Proving the paranormal by David Jacobs and Sarah Soderlund contains many of the common errors and misunderstandings we've covered before in my numerous quantum woo posts on my Skeptic's Boot blog, in fact looking at the source material here gives me a unique opportunity to bring what we've done thus far together.

This book. It is my anti-particle.

In the first part of the review we'll look at the various introductions, the forewords by the authors themselves and by paranormal investigator Patrick Burns who you may know from *insert name of ghost hunting TV show here*. I normally wouldn't focus on forewords in such a way, but the introductions here give me the distinct impression that what follows will be based on the two major misapprehensions about quantum physics we run into time and time again.

1. That consciousness causes wave-function collapse in the double slit experiment.

2. Particles remain entangled despite interactions with other particles, fields and physical systems.

And as such will tell us much about what we should expect to encounter in the book. Also by tackling them initially, I'm hopefully going to shorten the future reviews.

"Quantum Parapsychology: How Science is proving the paranormal" is written by software engineer David Jacobs and Sarah Soderlund, the latter of whom can be found on Facebook offering psychic newsletters with free divination gifts under the moniker "Paranormal Sarah", she's a psychology student who has also written, "Haunted by the Abyss" which claims to contain her true life experiences with demons and evil spirits. Jacobs offers this as his bio:

One has to wonder if he was such a child prodigy why he ended up in software engineering, a fine career though that is, and not physics? You'll notice what is distinctly absent from Jacobs' bio is any kind of physics qualification. What makes a man like Jacobs believe he's qualified to write a book on quantum physics? An interest as a child? I was very interested in dinosaurs as a child, as was every other kid I met, does this qualify me to write a book on palaeontology?

Of course not.

The problem with reading about quantum physics is what your sources for this reading are. If you're reading the work of Bob Lanza, for example, you're going to be bogged down in the same metaphysical nonsense as Jacobs and Soderlund present here.

The foreword by is by paranormal investigator Patrick Burns, also not a physicist by training. It begins:

What utter rubbish. If there were repeatable, verifiable evidence of the paranormal in any scientist's notebook it would be established science. You can contend it as much as you like. I contend you're wrong.

If you think the consciousness plays a role in quantum mechanics, you very probably haven't "studied" it at all and you are taking the word "observation" way too literally. Just look at the above passage. The act of observation becomes "the mere act of looking upon an object." which you can show is nonsense in short order by considering how absurd it is to "look at" at an electron. You can't look at any quantum object. What you can do is make a measurement of it by firing a stream of photons at it, or by firing it at something else.

Consider why this must change the system or "object" as Burns incorrectly terms it, by comparing it to this macroscopic analogy:

Imagine I tell you I'm about to introduce a baseball to the room you're standing in and I want you to determine one of the ball's observables, position or momentum say. "No problem!" you respond. "Ok, here's your measuring equipment," I say as I hand you a blindfold and a baseball bat. Off you go into the room.

Let's imagine further: you get lucky, and after 100 failed swipes (analogous to 100 photons that fail to be absorbed by the electron in the quantum example) you hit the ball. When you come out of the room I express surprise that you failed to make a measurement with changing the state of the system.

What I hope this shows we should be more aghast if attempting to observe an electron by bombarding it with photons didn't change the system!

Again, correcting Burns definition of "observe" removes the mysticism from the double slit experiment. You could sit a LOOK at that experiment all day, watching the photons forming an interference pattern on the photoreceptive screen. The system's behaviour won't change. You can alternate between staring at the screen or the slit, or the light source or the ceiling. The system won't change, The interference pattern remains.

But when a device is placed at the far side of the slit partition in the above diagram to try and obtain "which way" information, the wave-function collapses and the inference pattern is gone, and the photons arrive as particles. "YOU" have not made a difference. It's the device placed at the slit that has caused the system to change. You can happily leave the experiment running and head to the pub and it will continue to give the same results.

It's not "logic" (always be wary of anyone who says logic but doesn't mention which logical system they are referring to) that states this behaviour shouldn't occur but our intuitive beliefs about how nature behaves. If the paranormal is "experiences that lie outside the range of normal experience...." then we can definitively say quantum physics isn't paranormal given just how often this experiment has been tested over the past hundred years! This is a fact of nature, physicists are over it despite not fully understanding it! Of course, you can't acknowledge that fact if you're selling a book based on quantum mysticism!

FURTHER READING: Confronting Quantum Woo: The Double Slit Experiment.

Predictably, after mangling the double-slit experiment Burns move on to entanglement, again making mistakes we've seen time and time again. In fact, there are so many errors in this one short passage, I've had to highlight them and number them.

(1) Particles do not stay entangled. Entanglement is very delicate when it comes to outward interactions, and an encounter with another particle or even a moderately strong magnetic field can destroy it. (2) When the state of one particle changes the state of the other changes too, meaning that the two particles are no longer described by a wave-function that can't be expressed as separate products. To a physicist that's what entanglement is. (3) This isn't "data" as such because it's non-programmable. That completely random element of entanglement is what prevents it from violating special relativity. (4) Yeah, but how? Also, if this phenomenon is macroscopic it's made up of a large number of particles. To preserve entanglement all these particles must be prevented from interacting with themselves and the environment around them. Bluntly, this isn't possible.

FURTHER READING: Understanding Entanglement

The authors then go on to mangle a quantum experiment we haven't touched upon in Confronting Quantum Woo as of yet, a form of the so-called "quantum eraser experiment". Without going too deep into the experiment, essentially it tells us that adding an extra layer of complexity to a quantum experiment can prevent a wave-function collapse. It's something that definitely deserves further exploration, but would require a lot more space than I can grant it here. Burns has the same interpretation of this experiment as many people do. That this experiment somehow violates causality.

Again, Burns is very tied to the idea of an observer as a human being here, he also ascribes personality to the decision to entangle the photons when what we actually have here is a measurement screen and two beam splitters which may or may not be activated and are set to be completely random. When considering the time difference between measurement and the element which causes the wavefunction to collapse or not, so for the photons to act like a wave or a particle at the screen, we also have to consider the Heisenberg Uncertainty principle. Specifically in this form:

Which tells us the more certain we are about a system's energy, the less certain we can be about the time scales involved. As photons travel at the speed of light is not easy to determine with certainty which events occur first, in fact, if we add in relativistic effects we have to consider things from the reference frame of the travelling photons. Of course, if you ascribe to the wave mechanical description of quantum mechanics when the whole system has to be considered part of the wave-function there isn't really any violation of causality occurring here. Let me again explain this situation to you in classical terms:

Despite our earlier baseball bat experiment, you agree to come back to my lab for a second test. I blindfold you (again) and ask you to select a ball from a bag containing 2 red balls and 2 black balls. Your probability of selecting a red ball is 1/2. After you've selected the ball, I forbid you from looking at it nor do I. When I ask you to select another ball, your probability of selecting a red ball is still 1/2 because you have no prior knowledge of the ball's colour.

We rerun the experiment, you pull the first ball. This time I ask you to check the colour, and indeed it's red. You are then asked to select a second ball. Your chances of selecting a red have changed to 1/3. By doing nothing but obtaining "which colour" information, you have collapsed the wavefunction of the system and created a new one! Imagine if that wave-function was the only information you had about the system, you'd see what you'd done by peaking at the ball as profoundly altering the outcome to the second run.

I won't focus on Burns foreword anymore, other than to point out a fundamental misunderstanding he has about science. Burns states:

These conclusions were made about the order of the solar system and the shape of the Earth before the advent of science. To hold these beliefs as a failing of science is pure unbridled ignorance. The strength of science is it's never sure of itself, it is open to change constantly. This doesn't mean that it should be open to all ideas and theories, just those that are well evidenced.

Perhaps Burns should be less sure of himself.

Now let's look at Jacob's preface as this should lay out his motivation for writing the book and his basic knowledge of science. After elaborating on his child prodigy-like status with regards to physics, he goes on to say:

See the problem with what David has done here? He couldn't fit ghost theory into a framework of physical laws, so he decided those laws must be wrong or some how incomplete. He then set out to find a physical system that he could retro fit to include ghost theory. In 1820, Thomas Jefferson published his version of the Bible, known now as, predictably, the Jefferson Bible. The 84-page document was created when Jefferson took a straight razor to the Bible and removed the parts that did not correspond to scientific understanding. Jacobs has done the same to a physics textbook and has been left with little but a paper doll chain.

Jacobs then addresses the status of "experts" in the paranormal field:

Maybe there are no "paranormal experts" but that isn't the same as saying there are no experts working in the paranormal. Individuals take expertise from other fields and apply it to the paranormal field. You most certainly can be an expert in physics. In fact, later in this preface, Jacobs describes himself as a "quantum physics buff". Let's look at some words that are synonymous with "buff":

Now, you may think this is a little unfair, as the word "fan" is also synonymous with the word "buff". I would argue against this that by producing a book concerning quantum physics, Jacobs is positioning himself as an authority.

Moving to Sarah's preface. Soderlund discusses her experience in quantum physics and states that she does have some formal education in the subject. As a psychology student, she claims to have encountered quantum mechanics in the study of neurolinguistics.

Having not studied neurolinguistics I have no idea how much quantum mechanics is involved, nor can I quantify what "a bit" is. I would personally say that I've only studied "a bit" of quantum mechanics and as part of my physics degree I've spent at least a year and a half studying it! Perhaps, that's because it's only when you've fully engaged with a subject on an academic level do you realise how vast that subject actually is. I spent half a term studying chemistry, I'd never describe myself as having studied "a bit" of chemistry though, and I certainly won't be co-authoring a book on the subject at any time in the near future!

What does "having a mind" for quantum physics mean exactly. I find this statement worrying and insulting in equal measure. No one has a mind for quantum physics, even a superficial grasp of the subject requires a level of mathematical understanding far beyond the intuitive. If you think a person can have a mind for quantum physics you probably haven't studied it.

Soderlund talks at length in her foreword about her formal training in psychology, she talks about how important its applications could be to a paranormal investigation. I agree, but I can't help wondering why she is writing a book about quantum physics and not psychology. I also wonder what she'd think about a book about psychology by two authors with no formal education in the subject. And this is fundamentally the problem with quantum physics, public discourse on the subject is conducted by individuals who aren't qualified. It's then digested by members of the public who takes this misinformation at face value. It's a frustrating situation and it's why so many misapprehensions and misunderstandings about quantum physics continue to exist. For Soderlund to lament the misunderstanding of her field in her foreword, but then to participate in the propagation of misunderstanding of someone else's field is pretty appalling really.

In the next part of this review I'll focus on the actual content of the book, and Jacobs and Soderlund's proposal of a "quantum parapsychology" and go deeper into their understanding of the double-slit experiment.

Understanding Entanglement.

Last time we confronted some quantum woo, we tackled perhaps the most fundamentally misunderstood facet of quantum physics, and it's most exploited. The double slit experiment. In this post, we'll take away the most important point of that post and apply it to another element of the discipline that is almost as misunderstood and as misused- entanglement. Another facet of quantum physics that displays the discipline's deeply non-intuitive nature. As such it is prime fodder for woo-merchants to distort in order to appropriate an air of credibility and legitimacy for nonsense ideas and hypothesises. Just as the misrepresentation of the double slit experiment is used to support ideas of like after death, entanglement is commonly used to support ideas of new-age healing techniques such as distance healing and energy healing and "psychic" abilities and ESP.

As a starting point, let's see what the new age opinion is of entanglement, then we will assess those ideas using the formalism of quantum physics, in the process, we will get an idea of how physicists represent a system of entangled particles and importantly, why entanglement doesn't support ideas of "energy healing" and the like.

Some "woo" definitions of entanglement.

Underground Health Reporter States:

"...all types of particles can become linked and instantaneously influence one another regardless of distance.  When two particles are entangled, they stay that way, and no matter how far apart those two particles get, information passes between them instantaneously.Quantum entanglement explains those times when you were just thinking of your dear sister and your phone rings.  Not only are you not surprised, but you even know what she is calling about.  This happens most often with those you are closest to, because the more QI that’s entangled, the deeper and wider the effect.  In other words, when you think of that person with any emotional charge, the “message” reaches him or her instantaneously."

Pinnacle Healing, who offer "quantum healing workshops" for £180-£229 a pop go further:

"What this means – is simply speaking, that All Are One and that Everything Is Connected because everything has originated from the same source – the Divine – and therefore is bound by commonality, by the truth that we have all been created by the Divine." 

The Paranormal Analyst states:

Is it possible quantum entanglement connect all humans or living beings through sub-atomic particles? Maybe certain people have become attuned to interpreting these signals and have psychic powers.

All those statements highlight the most common misconceptions about entanglement.

1. Entanglement is permanent.

2. All things are entangled. (Many quotes regarding quantum physics with regards to psychic family members such as twins seem to imply that the particles in close family members will be as closely related. Utter nonsense of course. Birth is not a quantum event, nor is sharing a womb!)

3. Entanglement allows for the passage of meaningful information between entangled particles. Information that pertains to more than simply the relevant attributes which are entangled.

The truth is entanglement is extremely delicate. Any measurement causes the collapse of the entangled state and by any measurement, we reapply one of our main takeaways from our examination of the double-slit experiment, measurement is defined in quantum physics as an interaction between two quantum systems or a quantum system and a macroscopic system that causes an irreversible change in those systems.  The example I gave last time was of atomic decay in an isolated region of space- daughter particles are entangled due to the conservation of angular momentum. A measurement occurs when either of these particles collides with a dust particle or other object. Whilst it's conceivable that particles at opposite ends of the universe remain entangled -their mutual journeys must remain uneventful. Any collision or interaction destroys the entanglement. As for the second statement, obviously most particles in your body are not isolated and in accordance with the principles I've laid out above, they aren't going to be entangled. If that isn't detrimental enough, consider that not all particles are entangled only particles which are created in the same process or have some form of entanglement forced upon them (pairs or groups of photons, for example, can have entanglement induced upon them). The third statement requires us to go deeper into the formalism of entanglement.

So we've seen two examples of what new agers mean when say entangled, what do physicists mean?

Entangled States 

A wavefunction or state vector representing the state of two particles is said to represent an entangled state if it cannot be expressed as a product of terms each specifying the state of a single particle. (Quantum Mechanics and its intereptation, Bolton, Macintosh, 2007.)

As I've mentioned before in quantum mechanics the states of particles are described using a wavefunction, often referred to as a DeBroglie wave, a mathematical representation of the various qualities of the system. The wavefunction represents all it is possible to "know" about the state that a particle is in. Entangled particles are simply particles for which it is impossible to describe in isolation. To explore this more fully let's use a quality of particles known as spin. The specifics of spin don't particularly matter here but it's useful to state that spin isn't as many new agers present it, actual movement or rotation of a particle. In fact, it's more useful to describe spin as a magnetic quality. Electrons are particles of 1/2 spin. This means their spin has two possible values, +1/2 which we call spin up, and -1/2 which we predictably call spin down.

We can represent the spin states of a particle using a funky feature of a system known as Dirac notation as a "ket". So, ignoring for simplicity's sake the spatial state of a particle, for a single spin-up electron (which we will denote particle A) sat in isolation in space the wavefunction looks like this:

Pretty simple right? So let's also say we have another electron somewhere in space which is spin down. We'll label it particle B and thus denote its wavefunction:

So far so good. But what if we want to describe a quantum system comprised of these two particles. The system's wavefunction would be: 

Using the rule that particle A always comes first we can simplify this as:

It's clear to see this system isn't entangled. It can be described as a product of the state of particle A multiplied by the state of particle B. Explicitly:

                           

It might be apparent to you that the reason this system isn't entangled because we know the spin states of particle A and B. What if we didn't, but we do know that the particles were created in the same process. We also know that if particle A is spin up, particle B must be spin down. If particle A is spin down, particle B must be spin up. This is a consequence of the Pauli exclusion principle which forbids particles like electrons having the same quantum numbers. Clearly, our wavefunction for the system must represent the two possible states of the system.

What would that look like?

Clearly, this is somewhat more complicated, but using the rules established thus far it should become apparent that the term underlined in red represents the state if particle A is measured spin up. The term underlined in blue represents the state if particle A is measured spin down. This wavefunction can't be described as a product of particle A and particle B wavefunctions, it's not separable. Thus this is truly an entangled state. 

You have also no doubt noticed our entangled wavefunction has picked up an extra complication. Namely C1 and C2. These are the probability amplitudes of the two outcomes. We square these to find the probability of a particular outcome. Their addition ensures the wavefunction is normalised. They are also the key to understanding the collapse of the wavefunction and how the measurement of a particular state destroys entanglement.

The wavefunction above has only two possible outcomes. When the spin of either measurement is made the total wavefunction must collapse to either the red state (A: up, B: down) or the blue state (A: down, B: up), thus the probability of returning one of these states is certain.

We therefore require:

As there's no reason to suspect that either the red state or the blue state is more likely than the other. So we can see:



Giving our full wavefunction:

This wavefunction applies as long is there is uncertainty which state the measurement will yield.

So we can see that if a measurement is taken on particle A and it is found to be spin up:

And our wavefunction becomes:

Which we can see reduces to our original non-collapsed state! Entaglement is destroyed.

So it's clear to see from this mathematically why the measurement of a quantum system causes it wavefuntion to collapse "onto" a particular state. To hold the woo postulates of entanglement to be true we have to believe that all particles were created in the same event. Also, we have to accept that the particles have interacted with not just any other forms of matter but even magnetic fields. What are the chances of a loose electron in your body existing there for a prolonged period without interacting with anything else? And then it's partner existing in your energy healer or psychic twin free from interactions too?

What's important to note here is that you may be tempted here to suppose that the system was in a particular state before measurement and that said interaction simply revealed what state the system was in. This is fundamentally incorrect. Observables (measurable quantities) in quantum physics have no values before measurement, there are no "hidden variables". They have a number of possible values but that is the most we can possibly say. Entanglement has another important consequence, measurement of a particular observable on one particle causes its partner to adopt a value for said quality immediately, no matter how great the separation between the two. These two factors deeply troubled Einstein, arguably the greatest mind of his time, and the inadvertent father of quantum physics. Einstein felt that this non-locality was in direct violation of special relativity.

This leads to the two most famous quotes about quantum physics:

"God does not play dice with the universe."And Einstein's dismissal of entanglement as "spukhafte Fernwirkung" or "spooky action at a distance." We can thank Einstein for introducing the word "spooky" to the lexicon of physics, we can also thank him for the quote which I guarantee will appear in almost every article you ever read that connects quantum physics and any aspect of the paranormal.  In fact, the second of these two quotes is so ubiquitous that it deserves special attention in a separate post.

And for good reason, that's where we head next.

Understanding the Double-Slit Experiment.

Let's continue with our dissection of the alleged quantum/conscious connection by moving further into the Collective Evolution article, an exploration that will lead us straight to Young's double-slit experiment, without question one of the most famous and crucial experiments in the history of physics. In addition to showing that the double slit experiment doesn't suggest that consciousness collapses the wave function of a particle, I'll attempt to go further and show that the double slit experiment suggests considerable evidence that "consciousness hypothesis" offered by quantum-woo proponents must be false. To do this I'll first suggest a hypothesis for consciousness inspired wave-collapse as I couldn't actually find one in Lanza's book. The article linked above, QUANTUM THEORY SHEDS LIGHT ON WHAT HAPPENS WHEN WE DIE: THE AFTERLIFE gives its evidence for Robert Lanza's "theory" that consciousness relates somehow to quantum physics.

"His theory implies that our consciousness does not die with us, but rather moves on, and this suggests that consciousness is not a product of the brain. It is something else entirely, and modern science is only beginning to understand what that might be. This theory is best illustrated by the quantum double slit experiment. It’s is a great example that documents how factors associated with consciousness and our physical material world are connected in some way; that the observer creates the reality."

To consider this relationship an element of science we first need a working hypothesis. The suggestion of a hypothesis offered by Lanza and others in regard to consciousness caused wavefunction collapse can be phrased very informally as:

"Consciousness can exist separately from matter. This consciousness can be shown to have a physical effect in the collapse of the deBroglie wavefunction of a travelling particle. Consciousness is otherwise physically imperceptible. This effect this best shown in Young's double slit experiment." 

This is my interpretation, as I mentioned above Lanza fails to offer an explicit hypothesis in his book and I've struggled to find one elsewhere. Let's call this the QC hypothesis, and return to it in a moment.

I'm sure many of you are familiar with Young's double slit experiment, but I'll give a brief introduction for those that aren't.The double slit experiment was revolutionary as it was our first outright hint that there is more to matter and energy than first suspected, namely that both light and matter on scales far smaller than that of our macroscopic world display both wave and particle characteristics (Actually, a more accurate description would be that both matter and light can be modelled as a wave and a particle. In reality, light is neither). The concept of particle and wave duality was staggering enough for light, but a series of experiments involving electron diffraction showed that matter possessed the same duality of nature. If you want more details about the double slit experiment, the Wikipedia page is actually a pretty decent resource. Rather than wax on about the finer points, I'll use a computer simulation to show the results of the double slit experiment and what this tells us about the nature of matter. Consider below, when reading the phrase collapse of the wavefunction, this refers to an electron switching from a wave-like behaviour to a particle-like behaviour. For example, the appearance of a single dot on a fluorescent screen is particle-like.

We start with a hypothetical apparatus set up as shown below.

Figure 1:
An electron gun fires electrons through two narrow slits onto a fluorescent screen. Where an electron hits the screen a white dot is left behind. We aren't going to concern ourselves too much with the widths of the slits(1nm) or the energy of the electrons(38V).

Figure 2
As the electrons stream through the slits one by one they appear on the screen seemingly randomly. In fact, this underlines how the probabilistic nature of quantum physics can still be reconciled with the deterministic nature of classical physics. We cannot predict with any certainty where the next particle will strike the screen, but we can predict with absolute certainty the overall distribution of a large number of electron hits.

Figure 3
The final distribution shows wide bands of electron hits punctuated with thin black bars showing virtually no elections strikes. These bars don't line up with the blockages in the equipment, and the distribution clearly doesn't resemble what we would get from firing hard projectiles such as bullets through scaled up slits where we would expect a graph of the hits to be two "humps" corresponding to the openings, with some lying between. Compare that to the graph yielded by our electron firing simulation in Figure 4 below.

This fringe pattern is destroyed if we run the experiment again, but this time with one of the slits, slit 1 in the case below, closed. Figure 5 below.

The fringe pattern is known as interference and it can be explained easily using an analogy to water waves. When two waves meet at the point of their maxim amplitude the overall amplitude is increased as in Figure 6 (http://www.phys.uconn.edu) left. The waves are in phase.

When two waves meet with maximum amplitude and minimum amplitude, the waves cancel. Unsurprisingly, this is destructive interference. Figure 7 (http://www.phys.uconn.edu) left. The waves are said to be out of phase.




These patterns are achieved every time this experiment is conducted. Even though the precise build is random and probabilistic, the final distribution is deterministic and fully predictable. Remember this, it's crucial for later when we reassess the consciousness/wavefunction collapse hypothesis. 

These wavefunctions, known as deBroglie waves, are a mathematical interpretation of how a particle propagates through space, they are composed of all the possible positions of the particle at any time and the probability of finding a particle at that particular point. In what follows you'll see why it's necessary to describe the propagation of a particle through space as a wave function. In an attempt to understand these effects in the above experiment, we reopen both slits and turn down the current of the electron gun to allow one electron at a time to hit the screen. Remarkably the fringe pattern returns, albeit slowly, defying the idea that it is the wave function of one electron is interfering with its neighbour. In fact, it's clear that the electron interferes with itself.

Stop laughing at the back!

The consequence of this is we are forced to abandon the classic idea of a particle possessing a single defined trajectory through space. The passage above demonstrates that the particle can be considered passing through each slit, with the contribution of each slit in the wave pattern causing constructive and destructive interference. How does physics explain this? Well.... we can't. We can offer interpretations of this phenomena, such as the Copenhagen interpretation which states that quantum systems don't possess definite properties prior to measurement, only probabilities that reduce to certainties on measurement. There are other interpretations such as many worlds interpretation, but it's the Copenhagen interpretation I'm most comfortable with. There is good experimental evidence to support the idea that quantum qualities become definitive only upon measurement. Einstein argued against this and suggested quantum systems contain hidden variables in his EPR arguments, which were countered by Bell's inequalities and later answered by a modification of the same known as the CHSH inequality. As I don't want to digress too much I won't discuss those further here, but it's well worth a Google search if just to see how even opposition to an idea in science can sometimes strengthen and refine that idea.

So, we're left with an ambiguity, a hole in our carefully crafted quantum science. You may imagine this is where quantum woo merchants begin their machinations, as that's often the tactic of the pseudoscientist, to insert pseudoscience into a gap in conventional understanding. But, It's actually in our attempts to resolve this ambiguity and obtain what we refer to as which way information, that our quantum woo merchants operate.


Figure 8:
In an attempt to resolve the mystery of which slit the electron passes through, we introduce a new element to our experimental setup. We scatter photons off the electrons to see if the electron is in the vicinity of slit 1 or slit 2 and follow their path to the fluorescent screen.

Figure9&10: When we observe the results from this test on our fluorescent screen the interference pattern is gone, replaced by a distribution that is just the sum total of particles passing through the slit. The wavefunction now collapses prior to reaching the screen. It is as if our act of observation itself caused the wavefunction to collapse, and this is most certainly the quantum-woo merchant's interpretation of
this experiment. This brings us to our first misunderstanding supporters have of quantum physics and I can't express how fundamental this is to every conclusion they reach following this.

The Fundamental Error 1: It is not the presence of the conscious observer that collapses the wavefunction, it's the action they perform on the system that causes the wavefunction collapse. 

Let's consider this first in the case of the example given above, electrons fired at a fluorescent screen. When we bombard the electrons with photons the interaction changes the state of the system catastrophically as despite lacking mass, photons do carry momentum.

Mathematically we can show this quite easily if the wave is made of a superposition sum of all the possible states of the particle with constants that represent the probabilities of finding the particle in any of an infinite amount of positions, the probabilities of these possible locations must be 1 as the particle is certain to be somewhere. Therefore if we make the probability of one of these possible states 1 by locating the particle, the other probabilities must be zero! Thus, the wavefunction "collapses" from a superposition to a simple value. I've show this below crudely in a form that describes a "which slit" superposition.

An easy way to understand this physically is by analogy. Imagine me asking you to determine the location of tennis balls I'm firing into a darkened room. The only instrument I'm going to give you to do this is a tennis racquet. There's no way of you doing this without fundamentally changing the state of the ball. You may be able to give me the position of the ball at impact, but you would find it impossible to give me information about the ball after impact. The act of measurement has destroyed the information you had, there is no way you can violently examine that system without changing it fundamentally.

We call any measurable quantity in quantum physics, an observable. Obviously, this is a name that doesn't help the layman distinguish between an "observation" and a measurement". The choice of name seems to suggest that observation is a crucial part of quantum physics, rather than the true meaning of the name: a quantity which can be observed. Other examples of observables are energy, momentum and spin, the above principle applies to these qualities too, any attempt to know one destroys the wavefunction. We often find proponants of quantum woo run versions of the above experiment in which the electrons are fed through spin selectors, therefore collapsing the wavefunction for in the same way as a bombardment of photons does for which way information. We can define this by considering quantum systems to be in extremely delicate balance, with slight perturbations causing collapse.

This is what we find anytime a quantum system interacts with a classically defined object. It's nothing to do with an observer as the following thought experiment should show.

Thought Experiment 1

Of course, the big question is can measurements occur without an observer? The key to considering this idea is to remember that the CHSH inequality has shown there are no hidden variables. Before a measurement is made a quantum system has no determinable observables. In light of this consider this thought experiment.

An isolated nucleus of Uranium 238 exists in the far reaches of space, it has zero momentum. It emits an alpha particle via the process of alpha decay and becomes a thorium 234 nucleus. The conservation of momentum tells us that the total momentum of these two daughter particles must be zero, therefore the momentum in an undefined direction of the alpha particle must be matched by an equal momentum in the negative direction of the thorium 234 nucleus.  Neither direction can be known, until the thorium 234 particle interacts with a particle of dust with a defined location. Suddenly both daughter particles have a definitive directions and thus momentum vectors, they must as there is a physical effect on the space dust.

This interaction can be considered a crude form of measurement, the wave function for both particles has collapsed, no observer necessary.

Finally, let's return to our QC hypothesis, to see how what we've covered strongly implies it is inconsistent with reality.

"Consciousness can exist separately from matter. This consciousness can be shown to have a physical effect in the collapse of the deBroglie wavefunction of a travelling particle. Consciousness is otherwise physically imperceptible. This effect this best shown in Young's double slit experiment." 

Let's  question for a second what we would expect to find if the double-slit experiment was repeated in a world in which the QC hypothesis is true. Surely, an unavoidable consequence of the fact that we can't detect or protect our experiment from incursions and interactions from disembodied consciousness is that we should expect that there would be occasions in which the wavefunction collapses for no discernable reason. It would be as if we'd attempted to gather which way information with the later addition of a photon source and a conscious observer, despite us doing no such thing. If the QC hypothesis were true we would expect to see random wavefunction collapses. This has never been shown to happen. I think that strongly implies that the above hypothesis is incorrect in some way. Either consciousness does not exist separate from matter, or consciousness is not responsible for wavefunction collapse.

 Or Both.

Finally, just for fun.

Thought experiment 2

Plinkett and Nadine are conducting the double slit experiments with the electron gun set to a slow voltage with the particles released at 2 minutes intervals. They do not attempt to collect which way information. As Plinkett observes particle 2 hit the screen at 2:00, Nadine attempts to escape. Plinkett corners her in the living room 3 minutes later. Too exhausted by the struggle to return to his basement lab, he decides to watch the experiment progress on the VHS relay his friends at Lightning Fast VCR set up for him and that he began recording at time 0:00 when the first particle hit the screen. Plinkett tells Nadine when they turn on the VCR they will see particle 3's impression on the screen. Nadine agrees but adds that if they rewind the tape they will see the point appear at 4:00. Plinkett argues that they will not as their was no conscious observer present at this time. He believes the particle will not be present on the tape before 5:00 despite being automatically fired at 4:00. His finger hovers over rewind. 

Who is correct? 

Correct answers get a pizza roll. 

Computer package used: Open University S207, The Physical World: Electron Diffraction.