Multiversa hypothesis incompatible with the double slit

Hugh Everett’s proposition – everything that is possible, happens.

One of the hypotheses that tries to explain the phenomena in quantum physics, especially the quantum collapse that occurs at every measurement – the abrupt end of the quantum state wave and the appearance of the particle – is Hugh Everett’s Multiversa hypothesis. Remember; the state wave is a wave that contains all the possible states of the particle to be measured. In Everett’s proposal, everything that can happen happens physically. Therefore the actual universe, where the measurement takes place, splits into as many physical universes as there are possibilities. In all those split-off universes there exists a copy of the conscious experimenter. Each copy thus perceives one of the results of the experiment. There is then no quantum collapse at all that mysteriously occurs on measurement.

Initially, there were only a few supporters of Everett’s idea. But right now, the idea has quite a lot of support among quantum physicists. Its attractiveness is easy to understand. A non-material consciousness is not needed in his hypothesis, so we can continue to assume that consciousness is a product of the material brain. Which is still the most popular hypothesis in neuroscience today despite a huge amount of excellent forensic and casuistic evidence to the contrary. They apparently wish to remain ignorant of this evidence.

The double-slit as test

Reflecting on the multiversa hypothesis, I thought of Richard Feynman’s statement; “The mysteries of quantum mechanics can be understood from just one experiment. That’s the double slit experiment. The experiment is simple, but the results leave us in awe.” The question then becomes this: can I understand the double slit experiment from the Multiversa hypothesis? Can the double slit experiment serve as a test for this outrageous hypothesis?

The double slit experiment was first performed by Thomas Young in 1805. He let sunlight shine through two slits – two narrow parallel scratches on a sooted glass plate. The result of this looked then and looks still like this:

Interference patterns created by sunlight. (Berdnikov)

Parallel colored bands of light separated by dark bands (fringes). This is called an interference pattern. This pattern is easy to understand with the view of light as a wave. The two slits act as synchronous sources of light waves. The synchronous waves running from the two slits meet and at each location their amplitudes are added together. This is called superposition. The superposition of these two waves creates contiguous fanning lines of maximum vibration (intensity) and between them also contiguous fanning lines of rest (darkness). The colored lines arise because sunlight consists of a whole spectrum of wavelengths, from red to violet, and for each wavelength the locations of its maxima are at different distances from the central maximum.

Explanation by Thomas Young. Flaring lines of maximum deflection arise from the superposition of two synchronous waves.

For more info, I refer you to this excellent YouTube video from Veritasium.

Nevertheless, light is made up of particles

The great problem is that light is not a continuous wave phenomenon, but consists of energy packets, photons, where the energy E of each photon is proportional to the frequency f of the wave. This proportionality constant is Planck’s constant, discovered around 1900. Incidentally, it is difficult to imagine a frequency of the photon itself when it is a particle. What is the frequency of a particle? What does it look like?

E = h.f  h is Planck's constant: 6,626 x 10-34 J.s

Photons and the quantum state wave

Photons are light particles whose behavior is controlled by a quantum state wave, the Schrödinger state wave. (NB: A moving photon has never been directly observed, because the observation means the annihilation of the photon). Each part of that state wave can be described as a vector, an arrow that describes both magnitude and direction of the wave’s deflection. This vector must be described in imaginary dimensions, which is not a problem for the mathematician, but for our imagination it’s a problem. The state wave is not a material wave, which can also be inferred from the fact that this vector is not something existing in our 3-dimensional space. However, the absolute length of the vector squared at a particular location does indicate something useful, the probability of finding the photon at that location when measured. However, a probability is not a material phenomenon. The state wave isn’t either.

The frequency and the wavelength of that non-material state wave are the frequency and wavelength that we seem to measure in our experiments with light, although this apparently consists of photons. When we detect a photon, it is the result of the aforementioned quantum collapse, the abrupt end of the state wave, in which the photon transfers its energy to the detector – for example our retina. The photons that appear as points of light on the detection screen are thus the result of the quantum collapse of the state wave upon arrival at the screen. The cause of the quantum collapse has still not been experimentally determined, although recent experiments seem to indicate that it is caused by the information we can get about the state of the quantum particles. Everett seeks to completely eradicate this enigmatic quantum collapse.

The key – a continuous interference pattern

Back now to the Multiversa hypothesis. We will do an experiment, we will send a single photon through a double slit. According to that hypothesis, our universe splits into as many copies as are necessary to contain all possible photon detections. And these are quite a few. Quantum mechanics predicts a continuous spread of maximum and minimum intensities. So not a limited number of discrete points with nothing between.

The two-slit interference pattern is not one of sharply defined lines, but is gradual and thus continuous. So the block-like pattern on the right is not quite correct.

That means an infinite number of possible outcomes for where the photon can end up on the detection device. Possibly we can adjust that infinity to a countable number of possibilities by taking the Planck length as the smallest possible unit of length. At 10cm wide, it still gives you a huge number of possibilities, somewhere in the neighborhood of 1033. So, just sending one photon through a double slit and detecting it, has to result in about 1033 split off copies of our universe with just as many copies of you and me each observing one of those possibilities in their own universe.

In itself, that outrageously huge number is not sufficient proof that the Multiversa hypothesis is not the ultimate truth. But it seems to me anyhow a strong contraindication and in any case a good reason not to take it as seriously as is done by many physicists. Multiversa is still completely unproven and most likely unprovable.

Measuring at the slit and the multiverse

The Multiversa hypothesis should also be able to provide an explanation for a particularly remarkable, but time and again experimentally confirmed, phenomenon. As soon as we somehow, no matter how, set up the experiment in such a way that we can know through which slit our photon has passed, the interference pattern disappears. The result is a light spot that is strongest in the center and diminishes towards the sides.

As soon as the slits are observed in order to catch passing photons, the interference pattern disappears. There is only one expanding wave left per photon. With many photons, a single light spot is created in the middle behind the slits.

If it can be determined experimentally that the photon passes through the left-hand slit, this means that the state wave must have adapted itself to that information and has changed to a 100% probability of being present in the slit. A 100% probability, in my opinion, is identical to a material presence. In any case, indistinguishable from that. It is then easy to understand that from that location in the slit of 100% probability of presence a single state wave departs and no more wave leaves from the other slit. Which explains the single light spot.

Thus, in the Multiversa hypothesis, the way in which the universe splits into as many universes as there are possibilities, as represented by the state wave, has been significantly altered by our experimental set-up. Now how could my decision to measure or not to measure which slit the photon passed, trigger this massive adjustment in the creation of copies of the universe? A persistent materialist will argue that that decision of mine was already 100% predestined, whereby of course he also expanded the demon of Laplace in his possibilities to fully know and predict all those split-off universes. That is, for example, the – completely unproven – position of Gerard ’t Hooft, Nobel Prize winner.

Is this still plausible?

Is that, this frenzied proliferation of multiversa, wholly predestined in their unimaginable totality, still more acceptable than the hypothesis that the observer’s consciousness creates the manifested reality according to the information at his disposal? That’s my question.

A radical change in perspective

Still, I think Everett noticed something valuable. All it takes to make his hypothesis significantly more plausible, as far as I’m concerned, is a radical change in perspective. His idea was that everything that could happen actually happens. He saw our reality as objectively material. Not only was the reality that we experience material, but all those split-off universes were also material, and so were indistinguishable in the nature of their substance. Now consider that that last phrase, indistinguishable in the nature of their substance, can be disconnected from the idea of materiality. So if we see all those multiversa as non-material probability distributions in the state wave of the universe, then if we’re consistent, we should do the same for the universe we experience. Our daily world of experience is then in fact just as immaterial as all those possible universes that do exist in that state wave.

That is indeed a radical inversion of perspective. The advantage of it is that it offers enormous possibilities for the role of the mind with which we apparently choose and create our experiences from all these possible states. Free will is back, the survival of the spirit after – and before – death is possible again. The near-death experience (NDE) fits completely into this framework and no longer needs to be denied or dismissed as the hallucinations of a dying brain. The latter, by the way, is an idea that does not provide any explanation for an important reported and verified subset of these experiences. These are those NDE experiences where there is no plausible material explanation whatsoever for the content of the experiences. And those are legion. Read “The Self Does Not Die” by Rivas and Dirven. Even if you are an inveterate materialist, then that’s what you honestly should be doing.

Quantum Computers

An Easy Leap Into Quantum Computing ©

There are often interesting reports about quantum computers in the media. The world is on several places busy building quantum computers with very generous budgets, funded by governments and software giants such as Microsoft and Google. They are also working very intensively on this in The Netherlands, Delft – QuTech. Instead of writing blogs on it, spread over different moments, I have devoted a special page on my website to it. It is also made visible in the main menu. This page will – in addition to some information on the subject – contain also actual links to articles on this subject that are interesting to me and – important – readable for laymen.

So you are invited to have a look at Quantum Computers.

Gifts of Unknown Things

Sometimes, in a book actually not really about quantum physics, I unexpectedly come across a text that particularly appeals to me in the context of my idea that quantum physics has an important message for humanity. A message that is still not understood or not been recognized by the majority of scientists today. Lyall Watson however is a scientist who recognizes the message.

A scientist of stature

Malcolm Lyall-Watson is a widely oriented scientist of stature. He is a botanist, zoologist, biologist, anthropologist, paleontologist and ethologist. He was, among other things, director of the Johannesburg Zoo and has produced nature series for the BBC. Watson is an adventurer and also a captivating storyteller. This has resulted in a series of books of which I have only recently read just this one which leaves me wanting more.

I am concerned here with a passage in his book ‘Gifts of Unknown Things’ where he summarizes adequately quantum physics in three pages, in an attempt to explain his experiences on a small Indonesian island where the local population accepts extraordinairy phenomena as an element of everyday life. By the way, I can recommend the entire book to you, if only for its captivating reading pleasure.

An infinite book as a metaphor of the state wave

The text fragment in question: Watson presents in it a very understandable metaphor about quantum physical reality as a book where every set of two pages contains one of the infinite possible states of the universe. Where the book will open is unpredictable, but the book is bound and used in such a way that it does show a preference for certain pages. As long as the book is still closed, everything is possible, all pages – all possibilities – are still there. That is comparable to the situation where the state wave has not yet collapsed. The opening of the book is thus the measurement, the collapse of the state wave by the observation of the reader with only one pair of pages now being readable. But in fact everything is possible, all the pages are still there. Sumo – mentioned in the text – is one of the inhabitants of the island who, because of his belief system, cannot accept what he sees, until a dramatic outcome is needed.

A Modern Physics Problem

“Modern physics has a problem. In Newton's time, concern was directed largely at measuring things, because he believed, as many people still do today, that everything was knowable, and it was just a matter of clear thinking and lots of hard work. It was felt that the collection of information was vital and that when enough was available, the rest could be calculated or inferred. So classical physics for two centuries concerned itself almost entirely with the motion of bodies and the force of fields.

Then Heisenberg showed it was impossible to determine exactly the position and momentum of any body at a single instant in time. This discovery in itself would have been of only academic importance if it had not also shown that changes were necessary in some of the most basic equations of physics. The changes were made, and they resulted in the development of quantum mechanics, and this has begun to bring about a major philosophical revolution.

Physics is concerned with systems. As an example, let's choose a system made up of a number of moving particles that happen to look like the letters of the alphabet. The old physics had its classical equations of motion which were supposed to be able to calculate the complete state of such a system. Let's say that what they had in mind was an arrangement something like this page of this book. A pattern in code which would need deciphering but which could be used, they thought, like the Rosetta Stone, to understand the language and to predict the form of all future states, the pattern on all pages that might precede or follow this one.

The new physics says fine, but there is a problem. There is no such thing as a single state. Each system has an infinite number of possible states, and it exists in all of them simultaneously. Quantum mechanics recognizes not the page, but the whole book as a more valid expression of the pattern of a system at any one moment in time. In fact, it goes a lot further than this thin book can, because it needs an infinite number of pages.

Now, when we try to observe a physical system, when we attempt to make a measurement, we do not find a particle moving at a number of velocities, located in widely different positions. We catch the system in one of its infinite number of states. When we open a book, we see only one of the many different pages. With the book lying closed on the table in front of you, all those pages or states already exist, and any page is possible. The probability is not necessarily equal; there is usually a bias built into the binding which makes the book open more easily at a well-thumbed page. But with the covers closed, the system is open. It is a multiple state and enters a single state only when a reader comes along to take a measurement or make an observation.

In the words of quantum mechanics, an observer collapses the system into one of its component states. He is not part of the system, he is not one of the letters that make up the pattern on the pages, and he cannot be included in the equations. But neither can he be left out, because without him there cannot be any particular pattern. Without an observer, there is no description; but no description can be considered complete unless it takes into account the effects of the observer who made it. There is no such thing as an objective experiment.

This is the measurement problem, and it has left much of the physics community in a state of considerable disquiet. There are inevitably a number of unconvinced Newtonians (like Sumo) who are doing their best to discredit this interpretation, but so far they have had very little success. The uncertainty just won't go away. In fact, it gets more alarming all the time.

When a system is observed, it collapses into one of its states. But what happens when there is more than one observer?

Science refuses to accept as valid any measurement made by only one person. The experiment has to be repeatable and produce the same result. So when two scientists in widely separated laboratories succeed in making the same measurement, when they get the book to open at precisely the same page, there must be some factor which at that moment puts them on common ground. They must be linked. This linkage, which provides them both with the same page number, is a procedure that we call experimental protocol. It has to be followed precisely or the experiment will "fail"—the book will open elsewhere. It is a very strict procedure with a precise set of rules which require that individuality be held as far as possible in abeyance. It suggests that the scientific approach is a ritual, an incantation, a set of magic words and gestures for producing the desired effect.

And what if there are two observers stationed at the same vantage point? Assume that the two scientists involved in this work happened to be together in the laboratory when the experiment was completed successfully for the very first time. They were exploring new territory, so there was no established protocol; they were simply following a hunch. They collapsed the system and exposed one of its states. Both made the same observation. They saw the same page. This could happen only if the observation process itself united them in some way, or if one of them saw the state first and imposed his view of it on the other. Both sides in the quantum-mechanical argument support the theory of relativity which says it is not possible to put either of the observers first. So that leaves us with only one possibility. Observers of the same state at any moment in time are coupled. And if there are more than two, they are grouped. And as joint observers are often too far apart to hold hands or make any normal physical contact during the process of observation, they must be united by some nonphysical factor.

There is only one nonphysical entity that is nevertheless real and sufficiently widespread to be held responsible.

Our consciousness.”

From: Gifts of Unknown Things by Lyall Watson published by Inner Traditions International and Bear & Company, © 1991. All rights reserved.  
Reprinted with permission of publisher.

I totally agree.

It’s not gravity

Gravitons stretch and bend space-time @

Paradoxes as signposts to the truth

I love paradoxes. They provide an opportunity to critically examine your assumptions. That’s what a scientist does if it’s right, not to deny or ignore the paradox, but straight to the point of the problem. In this way, the quantum paradox – the quantum collapse, a particle can be in several places at once but eventually manifests itself in one place when we try to perceive it – was addressed by pinpointing a classical physical cause, namely gravity as the cause of the collaps. Readers of my book already know that my opinion is that the observer does this with his consciousness. But that’s a hypothesis that many physicists don’t like. Even an outstanding thinker and physicist like Carlo Rovelli – read Helgoland – seeks the explanation in a property of matter, namely that matter only exists physically in interaction with other matter. In doing so, he eliminates the consciousness of the observer as the cause of the quantum collapse, but assigns almost telepathic properties to matter, although he wisely does not use that term.

Gravity as the supposed cause of the quantum collapse

The gravitational hypothesis – gravity as the cause of the quantum collapse – is therefore a popular hypothesis. The hypothesis was first proposed by the Hungarian physicist Károlyházy Frigyes in 1960 and later again by Lajos Diosi in 1980. In 1980 this idea was taken up by the well-known physicist Roger Penrose and further developed. It seemed a fruitful idea and put the quantum collapse firmly back into the purely physical realm. Much to the relief of many physicists. Hopefully, the paradox was dealt with. But of course, it must be possible to test it, like any hypothesis, and that was not easy in this case. It didn’t even seem possible.

The idea behind this hypothesis is that the gravitational field is a separate field and not a part of the quantum field. The gravitational field of an object can therefore not be present in several places and that means that the object has to ‘choose’ for a location. I cannot help pointing out here that a field — a state of empty space that exerts forces on the appropriate objects within it — is an abstract concept that, through frequent application, has acquired the status of something physical. We still don’t know what gravity is and I don’t think it’s a good idea to make something we don’t understand the cause of something else we also don’t understand. On top of that, it’s a big problem if you can’t test your hypothesis.

A test of the gravity hypothesis of Penrose in Gran Sasso

But testing the hypothesis – quantum gravity collapse – now seems possible, assuming a physical testable quantum collapse. A charged particle that manifests itself as a result of a physical cause will have to emit a photon when it appears in physical space-time. This is an extremely weak photon, but if this happens with a collection of charged particles at the same time, the effect becomes measurable.

Gravity is unlikely to be the cause of quantum collapse, suggests an underground experiment at Italy’s Gran Sasso National Laboratory. © Tommaso Guicciardini/Science Source

In order to generate this effect, a special detector was built, which is then shielded as much as possible against background radiation. This was done by enclosing this detector in lead and placing it 1.4 km underground in the Gran Sasso National laboratory. The effect that was predicted by Roger Penrose, which should be significantly greater than the ambient radiation in that situation, was not measured. Thus, the gravitational hypothesis has been falsified. For more details, read the full article in Science.

Unfortunate? I think not.

This is of course a disappointment for the materialistic physicists, one favorite hypothesis less. But as far as I’m concerned, one step closer to what I think is the correct interpretation. We create the world by experiencing it. In our consciousness.

An ultra short introduction into quantum physics

Recently I did an online presentation to an audience while I knew I shouldn’t be speaking about electrons, photons and double slit experiments and all that phyicist stuff. Still, I wanted the participants to glean a useful insight into what quantum physics has to say about the world and how it supports the idea of a consciousness that doesn’t depend on our material brain. It worked wonderfully, given the comments and the questions. That is why I am posting this introduction here as well. I’ll start with some basic definitions.


When we talk about particles, what are we actually talking about?

  • A particle is a concept that originates from classical Newtonian physics. That is, it is a model and therefore does not necessarily have to be the true reality. What follows is therefore only the definition of the concept of a particle. However, one that we usually use when we think and talk about reality.
  • A particle is an object where all of its matter exists within its boundaries. It has clear defined boundaries.
  • A particle has an exact location and speed.
  • Material reality consists of particles and their interactions.
  • Particles cannot pass through each other, they collide and usually bounce back or stick together.
  • Particles exist in place and time but are not part of it.


When we talk about waves, what are we actually talking about?

  • A wave is a moving excitation of a coherent medium.
  • A wave has no boundaries. The boundaries are those of the medium. The boundaries of a wave in the ocean are the surrounding coasts.
  • A wave has speed and frequency, but not a precise location.
  • That a wave has no boundaries means that the wave is present everywhere in the medium. Every wave in the ocean exists everywhere in the ocean.
  • A wave is not apart from the medium. It is the medium in a state of excitation.
  • Waves do not collide but pass through each other. Their excitations can be added at any time, creating more complex waves. Even standing waves.

Waves and particles

Waves and particles are thus completely different concepts. To claim that something is a wave and a particle at the same time is therefore confusing, it’s nonsense, a sham. Don’t fall for it.

The quantum wave is a non-material wave

A sound wave is a good example of a material wave with the air acting as the coherent medium. Ditto for a wave in water. The quantum wave and its medium, on the other hand, do appear to be non-material, given the following facts:

  • The mathematical dimensions of the quantum wave’s physical properties do not exist in our 3D reality.
  • The immaterial quantum wave of an object gives us the probability of observing that object as a particle when we focus our attention on a certain location at a certain point in time.
  • The outcome of such a focused attention is called a “measurement” by physicists. Physicists do not agree in this regard to what an exact definition of a measurement is. The result of a measurement is, without exception, something that, independent of the instruments used, an experience in our consciousness.
  • That the quantum wave is a probability wave strongly suggests that the quantum wave is something that is not taking place in material reality but in our mind. Probabilities are not matter. They are numbers.
  • The medium in which a non-material wave propagates must be coherent because a wave can only exist in a coherent medium. A good candidate for a coherent non-material medium is, of course, the mind.
  • Prior to the ‘measurement’ – the observation – the observed particle does not exist. This has been confirmed in many experiments and is therefore a major source of cognitive discomfort for many physicists. That discomfort is in turn the source of interpretations that turn out as inconsistent and/or absurd on critical consideration – such as, for example, the multiverse hypothesis – when these try to explain this phenomenon materialistically.
  • There is no known reason why the manifestation resulting from observation – the quantum collapse – should be limited to atomic dimensions. The fact that we experience the world as a permanent presence is no proof that this is indeed the case. The statistical probability that my desk will be in the same place on the next time I observe it is so close to 100% that I don’t have to worry about that at all. Every time I look it is – it materializes – exactly where I expect it to be. The discontinuities are so small I’ll never be able to observe them.
  • Since the quantum wave itself has no boundaries – that is a basic property of a wave – any object can in principle materialize instantaneously at any location in the universe, although that probability is generally extremely small. This may sound far-fetched, but it is the basis of the so-called quantum tunnel effect, where objects materialize on the other side of an impenetrable barrier without being able to pass through it. This effect has been known since 1927 and is at the root of nuclear fusion, all semiconductor technology and also of the efficiency of the metabolism of animals and plants, something that was discovered at the end of the 20th century. Quantum tunneling can happen even faster than the speed of light.
Quantum Tunnels Show How Particles Can Break the Speed of Light – Quanta Magazine october 2020


An observation (measurement) thus seems to bring the manifestation about of the observed object. This is not necessarily a cause-effect relationship. It is conceivable and even credible that perception and manifestation are identical, that they both do take place in the mind. Hopefully it has become somewhat clear to you how quantum physics does not contradict the idea of a consciousness that exists independently of our brain and can survive death. It even supports it.

For those people who object that it would then be sufficient to simply close their eyes to an oncoming bus or train, for them I have this answer: train and bus are examples of macro objects. It is true that as long as they are not observed, they are a non-material probability wave. The probability of being hit by that bus is 99.999999999999% (or closer to 100%). So, closing your eyes will not help very much, and it should not be forgotten that we have more senses than eyes alone. Finally, the bus driver is also an observer, of course. In philosophy the view of the world as being entirely inside mind is called Idealism.

The above is an extremely concise summary of my view as a physicist on the meaning of quantum physics. If you want to know (much) more I have to refer you to my website or to my book. I invite you not to believe me on my word, but to be curious and to do your own exploration of quantum physics. No mathematics needed.

You can see the presentation ‘Quantum Physics and the Afterlife’ I did here.

The role of consciousness cannot be ignored, Quantum Physics confirms despite opposition

As regular readers of my posts and of my book will know, I am of the opinion that quantum physics does not so much prove the primary role of consciousness, however that it certainly strongly confirms it. This is of course a controversial position. As long as accepted science continues to cling to the materialistic frame of mind, there will be scientists who wholeheartedly try to show this as wrong. They want to maintain their there-is-only-matter vision, although the attractiveness of that idea of reality, in which I am only a casual bystander, escapes me. On top of that, there are also people who take consciousness and its survival after physical death seriously, but they prefer to keep quantum physics out of the whole discussion about consciousness.

Heisenberg’s uncertainty principle explained (?) by classic physics

The same goes for those two Finnish scientists who published a mathematical study in September 2020 in which Heisenberg’s uncertainty relation is a result of statistical fluctuations in space-time, somewhat comparable to the Brownian motion of microscopic particles in a liquid. These Finns, not quantum physicists by the way, would have shown that Heisenberg’s uncertainty relation is not a consequence of the measurement – the observation – of the particle, but is something that takes place entirely in the classical Newtonian world. One of the two authors, Jussi Lindgren, is not a mathematician but is a mathematically very educated person. This he states in his LinkedIn profile:

Part-time doctoral student at Aalto University School of Science, main interests in optimal control theory with applications in macroeconomics, physics and finance. Other academic interests include nuclear engineering and philosophy of science. Quantum physics, relativity and theoretical physics are key interests of mine as well.’

Their publication does indeed contain a impressive piece of complex mathematics. That is not particularly accessible to the layman who, despite his lack of mathematical skills, is interested in the true meaning of quantum physics.

Although my mathematical ability is not what it used to be, I would still like to add a critical note concerning their publication and especially their conclusion. Their conclusion is that the interpretation of quantum physics can be found within the classical Newtonian domain, ie hard objective scientific realism. The Heisenberg uncertainty relation says that there is a fundamental lower limit to the accuracy with which the position and speed of particles can be measured. According to these Finns, the particles in an experiment are permanently objectively present, but are controlled by statistical fluctuations in space-time that make it impossible to measure speed and position with an accuracy greater than Heisenberg’s principle allows. In fact, their approach is an excellently elaborated example of an the ensemble theory in quantum physics. Quantum ensemble theory is only about the statistical behavior of larger ensembles of particles and prefers to ignore the individual particle behavior itself. And therein lies the problem. Ignoring unwelcome facts is not science.

If we hadn’t had the Bell and the delayed choice experiments, I wouldn’t have been able to find good counter-arguments so easily. Their significance cannot be overstated. All Bell experiments have confirmed, with ever increasing confidence and without exception, that two (or more) particles, when they have a common history, are in such a way connected (entangled) that a measurement on one particle immediately makes the other particle exhibit the complementary property, while they did not have that property prior to the measurement. When you assume that those particles exist permanently and objectively, you cannot but assume then that the measured particle communicated faster than light to its entangled partner that it was measured, whereupon the partner ‘decided’ to show the complementary property. A property it did not have before measurement. Such an assumption, as far as I’m concerned, is far beyond what Occam’s Razor recommends us.

And then there are also (fortunately) the delayed choice experiments. These have shown very clearly that the idea of particles that are physically on their way from source to detector, and thus travel materially, cannot be correct, unless you make some rather far-fetched assumptions: about particles that can see into the future, about entangled photons that know that once the position of the other photon has been measured, they should adjust their behavior, showing or not showing interference or not, and, on top of that, retroactively in time. You are of course free to prefer the material view of the world, but then you have to be honest and accept intelligent and instantaneous behavior of elementary particles. Therefore I prefer the idea that it is ultimately the conscious observer who, when he observes an event, also records it for its history as a really happened event. My idea is that it is the conscious observer who is definitely not to be ignored if you really want to be scientific.

An experimental test of non-local realism

Last but not least, I would like to mention here the result of an experiment conducted at the University of Vienna in 2007, one that, in my opinion, has received little attention. In this experiment, the assumption that perception does not affect objective reality was actually tested. By this I do not mean that every measurement always disturbs that which is measured, that was already an accepted fact in classical physics, but that mere observation has an effect on the nature of the observed, although it does not physically touch what is observed. That is what is called a non-local influence.

In this experiment, a complete class of important non-local hidden variable hypotheses has been falsified. These theories presuppose realism. Permanently objectively existing matter. These hidden variable hypotheses propose mechanisms that would explain, for example, the entanglement of photons in Bell-type experiments with effects where they already possessed their polarization all along. They would not manifest it only at the moment of measurement.

The conclusion from this experiment is that we must take the result of a Bell-type experiment and its significance for what being real means, very seriously. We can no longer hope that science can repair the idea of objectively permanent matter of classic physics.

Cause, effect and time

In a previous post, about the book ‘The Idea of the World‘ by Bernardo Kastrup I wrote:

'A universe with only matter offers no explanation whatsoever for the fact that the detection of the slit that was passed, has an effect back in time. That is because the ultimate cause of the disappearance of interference – the manifestation of the photon in one of the slits – must have occurred before the moment of detection of the slit passage.'

A reader stumbled upon this piece of text and rightly so. In my reply to her message I promised to pay extensive attention to retrocausality, cause and effect, as manifested in delayed double-slit experiments. So here’s my attempt to clear things up.

Interference and the double slit

Double slit interference. © Joerg Enderlein

First, let’s look at the common double slit. Whether photons, electrons or buckeyballs of 64 carbon atoms are fired at it, the result is always interference. That’s because these objects pass, in the form of a quantum wave of a certain frequency and wavelength, through the double slit on their way to detection. In both slits, a separate but synchronous wave source is created for each passing object. Those synchronous waves coming out of those two slits will amplify or cancel each other out in certain places.

In Figure 1, the two waves will amplify each other along the dotted lines. The mathematical interpretation of a quantum wave is that those maxima represent the locations of the highest probability that the object will be found there during measurement. On the screen behind the double slits we observe a pattern of light and dark bands. This is not the result of one particle. To get such a pattern, you have to fire at least thousands of particles, where all of them have the same wavelength, at the double slit. This a pattern is the result of interference.

Figure 1 – Origin of the interference pattern behind the double slit.

Observing the slit

The wave therefore always passes through both slits. If we now set up the experiment in such a way that we can observe through which of the two slits each object passes, something remarkable happens. Each particle wave then adapts in such a way that it only appears in one of the two slits. The probability of finding the object in that slit on measurement has become now apparently 100% at the location of that slit. The wave will proceed now beyond the slit. A wave coming out of one slit cannot interfere with itself. Figure 2 show the result when we measure through which slit the object passes. In figure 2 the object passes through the left slit. But the probability of passing through the right slit is of course equal. Only one single wave for each individual object will now leave one of the two slits. The result on the screen is now a spread out spot right behind the middle between the two slits because the individual objects pass the slits alternately. What we see actually is the superposition of two spread out spots of light.

Figure 2 – Observing the slit – no interference. The particle manifests itself in one of the two slits. The pattern on the screen is the summation of the light received from the two slits.

Entangled photon pairs with shared information

Observing the photons at the slit is done by first entangling two photons and then sending one, the signal photon, through the double slit. I describe this experiment in my book in chapter 7 – The delayed choice experiments. Because of this two-photon entanglement, the state wave of the other photon, the idler, has information about the slit through which the signal photon passes. The idler state wave thus possesses information about which slit is being passed. When that information is irretrievably erased the result is interference fringes as in figure 1. If that information is not erased the result is a single spread out spot as in figure 2.

The quantum information eraser

Whether or not information is erased is done by sending the idler photon through a semi-transparent mirror. Passing or reflecting is a fundamentally unpredictable quantum process with a 50/50 probability distribution. When passing, the information is preserved, when reflecting, the information is erased. In the first case, information preservation, the experimental result of a beam of signal photons is indeed a spread out spot, in the second case, information erasure, we see a clear interference pattern.

So far, it’s already an important and hopefully now better understandable quantum experiment. Whether or not information is erased determines the pattern that appears on the screen behind the slits. The real interesting thing now is that we can place the semi-transparent mirror – the information eraser – so far away that the signal photon has already passed through the double slit long and wide, at the moment the idler hits the semi-transparent mirror where randomly is decided to pass (keep information) or reflect (delete information). Even in this set-up, the experimentally measured result is that the interference fringes either do or don’t appear, when the information is respectively either erased or not. This is even true if this random erasure happens in time after the wave of the signal photon has already passed the double slit. The causation of the interference pattern, the manifestation of two synchronous waves or of a single one, happens therefore in time after the slit passage.

Figure 3 – Time line for the two-photon quantum information erasure experiment. Information is erased in time after the moment of having either two waves or a single particle having manifested in the slits. Retrocausality?

Retrocausality? Or an observer effect?

This therefore appears to be an effect with a retroactive effect in time, retrocausality. Study the timeline in Figure 3. Another interpretation, which is the one I prefer, is that the quantum wave of the photons becomes entangled with the measurement setup and that the real quantum collapse, the manifestation of the measured object, only happens when the observer sees the view results. See figure 3 again and consider what it is implicating.

Missed opportunity?

This experiment, Random Delayed-Choice Quantum Eraser via Two-Photon Imaging, was done and published in 2007. The results confirm the apparent retrocausality. However, what I did not find in the description of the experiment is the idea of moving the information-erasing semi-transparent mirror further away so that the signal photon has already been detected as the idler hits the mirror. The event of the photon hitting the detector, conform either the interference pattern or the spread out light spot, would already exist before the idler hitted the mirror. That would confirm even more convincingly that the quantum collapse is ultimately an observer effect and that it is not an effect of the measurement set-up. A missed opportunity.

Cause, effect and time thus become something created by the observer.

I hope this has made the cryptic text at the head of this blog text a lot more understandable. Comments are always welcome, they are the source of clearer texts.

A reaction on a reader comment.

What is information? What is observation?

These is the hard questions in quantum physics: What does it mean to observe? What is information? They seem simple words used and understood by everyone. Apparently they are not.

As far as I’m concerned, everything that enters my consciousness as experience is an observation. Whether I do that directly with my physical senses or whether I use on the other hand a giant instrument like the Large Hadron Collider in Geneva for my measurements, in both cases I receive information about the world. And ultimately always through my physical senses. Only when that information manifests itself in my consciousness can I say that I have been given information and that I understand what it means. In the same process, history is recorded, and time.

In the case of the described experiment above, the information about the result will be stored on a hard drive in a computer. These bits are processed by a computer program so that it can be displayed on a screen. The experimenter observes the result on his screen as little dots of light. Or it can be printed on paper, after which the experimenter views the results. In both cases, only then the information does enter the consciousness of the experimenter and becomes history that can be shared with other observers.

When is information irretrievably lost?

Now what does it mean when we say that the information is lost? If that information has already been observed, then as far as I am concerned, it has not been lost, even when the information has been erased from the hard disk after being observed. In this type of experiment it is a requirement that the information present in the entangled and unmanifested quantum wave is so irretrievably lost that the probablity that it can ever reach an observer somewhere in the future is absolutely zero.

In all the experiments I’ve read about it, the information is lost before the quantum wave will reach the detector. A semi-transparent mirror is very suitable information erasure device. It can be set up in such a way that:

  • only when the quantum wave passes it, the wave will reach the detector.
  • when reflected the information, that was contained in the unmanifested quantum wave, gets lost, erased.

The erased information can then never reach the observer. If, on the other hand, the wave passes the semi-transparent mirror, the information is still contained in the entangled wave. This wave reaches the detector, which in fact also consists of a complex of quantum waves. So, the detector and the quantum wave become entangled. That entanglement then extends to the computer to which the detector is connected and only ends with the observation by the experimenter. Only then will the information contained in the – now with the instruments entangled – quantum wave enter consciousness as an experience of the experiment. This is in fact John van Neumann’s projection postulate that – despite its inherent mind-matter duality – I still find the most plausible explanation for the so-called quantum collapse. Apart from the idealistic interpretation of quantum physics.

If we want to know for sure that it is by the information that eventually reaches the observer that the quantum collapse occurs, irrevocably destroying it can of course also be done by ensuring that it does not end up on the hard disk of the computer. Or immediately and irretrievably deleted. That seems also pretty irrevocable to me. I describe such an experiment in my book Chapter 13, Falsifiability of the Consciousness Model, section ‘Adapted Quantum Eraser’. Or look on this website: ‘A true quantum information eraser‘.

Einstein and the speed limit of the universe

Einstein did not support the fundamental uncertainty of quantum physics. He stubbornly maintained the idea that reality was permanent and objective and that the observer played not a significant role. Yet the observer plays quite an important role in his best-known work, the theory of relativity. Precisely if you assume that the observer makes the observed ‘true’ and thus actually creates reality, his approach to the relativity of space and time offers a surprising outcome.

Special relativity

The special theory of relativity can be followed perfectly by using nothing more complicated than Pythagoras and a dose of high school algebra. But I’m not going to do that here now. There is a lot to be found on the internet doing that. Read for example: Special relativity math2410 from Leeds University.


An extremely important premise for Einstein was that the universe should basically look the same for two observers moving relative to each other. Ultimately, that’s a symmetry argument. Symmetry has been an important criterion in the theories of physics since Emmy Noether introduced it in 1918. He combined this criterion with the insight that the observed speed of light – in a vacuum – must be the same in all circumstances. This followed from Maxwell’s equations for electromagnetic waves and was indirectly confirmed by the experiments of Michelson and Morley who sought to determine the speed at which the Earth traveled through the supposed aether by measuring differences in the speed of light going in different directions with regard to this aether. The outcome was that they could not measure differences in speed, no matter how accurate their experimental set-up was.

To ride with a light wave

In addition, Einstein had realized from an early age that you cannot overtake or even keep up with a light wave. If you could keep up with light, Maxwell’s electromagnetic wave would no longer oscillate from your moving point of view, it would look like a frozen wave. But since the wave’s propagation is both caused and sustained by its ceaselessly oscillating fields, that couldn’t be right. Light must therefore always move at exactly 300,000 km/s for every observer. This follows also undisputedly from Maxwell’s equations because these do not contain any parameter relative to the position of the observer.

Einstein riding the light wave. The wave will seem frozen from his viewpoint. This is not possible. © Paul J. van Leeuwen

Einstein now imagined two observers moving relative to each other but who should both observe the same speed of light. Imagine a light source C standing still for observer Alice. Alice sees the light of C approaching her at c = 300,000 km/s. Observer Bob whizzes at great speed towards ligt source C, say 1/10 of c. Alice now considers that the light coming from C towards Bob must therefore move at 11/10 of the speed of light for Bob. I hope you can follow Alice’s reasoning. Otherwise, try to think of two cars driving towards each other while Alice watches along the roadside. Car with driver Bob drives at 10 km/h and car C drives at 100 km/h towards Bob and Alice. Car C here stands for the light that comes towards Bob and Alice. Alice observes (with radar) that the speed of car C is 100 km/h and that Bob and car C are speeding towards each other at 110 km/h. Now suppose that Bob would also perceive the speed of the oncoming car C relative to him as 100 km/h. That could only be if Bob’s clock ticked at 10/11 the speed of Alice’s watch. And not only Bob’s clock but also Bob’s entire perception of time would have to be slowed down so that Bob actually experiences the speed of car C as 100 km/h. In that case Bob will live a little bit slower. As far as Alice is concerned, Bob is now aging more slowly than Alice.

Time slows down and space shrinks

Now back to the light that is always experienced by every observer at the same constant speed. If Bob moves relative to Alice at 1/10 the speed of light and Bob sees the light move at 300,000 km/s, then that is possible if the time for Bob slows down by 10/11. Bob doesn’t feel that way because he himself is sitting in his delayed time capsule, his car.

This simplified estimate of the slowing of Bob’s time is not 100% correct because something also happens with Bob’s yardsticks, but what matters to me is that you get an understanding of relativity reasoning. If you want to do this completely right, then, as already mentioned, some algebra and Pythagoras are involved and the time dilation, the slowing down of Bob’s time, is described with:

Time dilation T for Bob’s clock moving at speed v relative to Alice’s stationary clock. T0 is the time of Alice’s clock. The closer Bob moves to the speed of light c, the slower his clock ticks as seen from Alice’s viewpoint.

Here v is Bob’s speed, relative to Alice (or Alice’s speed relative to Bob). If you enter here 1/10 of the speed of light c for v, then Bob’s clock turns out to tick 0.5% slower than Alice’s clock. Now we apply the principle of symmetry that Einstein argued. There is no absolute speed, speed is always relative. Bob, who experiences himself as stationary, observes Alice moving away from him at 1/10 the speed of light. So Bob also sees Alice’s clock ticking slower by 0.5%. This seems a paradox, but the theory is correct and has been experimentally confirmed in countless experiments. The solution is that Bob and Alice can’t compare their clocks until they come together and for that at least one of them has to turn around which means speeding up and slowing down. This breaks the symmetry.

You can see from the above time dilation formula that the maximum speed that applies in the universe is 300,000 km/s. The term under the radical becomes negative when v becomes greater than c, which would make the time dilation imaginary. That’s too bad because it makes non-imaginary trips to even the nearest stars impossible for us.

From Alice’s point of view, Bob’s rulers also shorten in the direction of his movement. For completeness, this is the formula for the contraction of fast-moving rulers, the so-called Lorentz contraction:

Lorentz contraction of a ruler L moving with speed v relative to the observer. L0 is the lenght of the ruler when at rest relative to the observer.

It goes without saying that this sparked a lot of discussion in the first half of the 20th century. Einstein took the position that the observers of the clocks and rulers did not play a vital role in relativity effects. According to him, they could just as easily be left out of the equations. Fast-moving clocks would automatically slow down, fast-moving rulers would shorten without the need for an observer. This elasticity of space and time and of the material objects therein was, and is still difficult to grasp but has been confirmed experimentally time and again. We, the physicists, are more or less used to it now, but we do not really understand it. It’s not natural.

Einstein fighting versus the probability interpretation of quantum physics

Einstein seriously put quantum physics on the map with his explanation of the photoelectric effect, for which he received the Nobel Prize. Light consists of particles with an energy per particle according to the Planck formula (f here stands for the frequency):

Planck’s law: the energy of a quantum of radiation energy is propertional to its frequency and is inversely proportional to its wavelength

But after that he argued vigorously against quantum physics and especially its implications, to no avail. Especially against the probability interpretation of Bohr, Heisenberg and Born: that the state wave, the solution of the Schrödinger equation, represents the probability that the particle will be found at a given location and time when measured. That went against Einstein’s gut view of the world as an objectively permanent collection of material objects. Einstein’s objection is understandable if you adhere to the materialistic view of the world, because a probablity is not an objective material object. It is something that exists in our mind. A thought.

And that’s exactly my own idea of how the universe works. Everything we experience takes place in the mind. The perception of the measured particle thus becomes identical to the thought of it. The experience is then the same as its creation. That explains to me very well why the laws of physics behave according to mathematical formulas. That is something that many physicists, including Einstein, have expressed their amazement about. So the observers’ mind plays an indispensable role in the universe, it creates it. Mathematics is something of and in the mind. The mind uses apparantly mathematics in its creation of the universe.

Time and space are concepts of the mind.

That idea suddenly makes things like the slower passing of time, the shrinking yardsticks and the curved space of general relativity, much more palatable. In a dream we would really not notice these things either. There exists no real objective time outside of us that does slow down, there is no objective space outside of us that does shrink, it’s all happening in the mind of every observer.

Science Fiction?

That offers hope for the possibility of exploration of the cosmos. The maximum speed in the universe that we observe – that of light – seems to be something that the mind has imposed on itself. But as soon as we can accept that time and space is happening within the mind, the possibility opens up that we could move through the universe beyond that limitation. Traveling within the mind is not bound by the restrictions of relativity. This, I believe, is also the correct interpretation of entanglement and instantaneous action over long distances, as confirmed by all those Bell tests. Traveling through the universe by means of the mind could even be the way – one that intelligent beings existing elsewhere in this vast universe already have discovered – to travel through the cosmos despite Einstein’s speed limit. And to visit us. Experiments have already been conducted confirming that quantum tunneling shows speeds greater than that of light.

A universe like a slowly fading flare

That the universe is a creation of the mind also offers an alternative for the pending entropy death of the universe that physics has been predicting for a century and a half now. Even if that is a immeasurably distant future away, it remains a bleak prospect contradicting any sense of purpose of the world. What was that fantastic spectacle all for if that is to be the end? But if the universe is the product of the creative mind, then that is by no means an unavoidable end to everything. On the contrary.


What I want to say with this story is that there is a good chance that two apparently incompatible theories – relativity and quantum physics – can be merged together very well when we start to include the all important role of consciousness. The intelligibility of the nature of reality would only increase as a result.

Epicycles and quantum fields

Feynman diagrams

Feynman diagrams are used by physicists to represent the possible interactions between elementary particles.

Wikipedia: The lines in Feynman diagrams represent particles interacting with each other in some fashion. Mathematical expressions correspond to every line and node. The probability of certain interactions occurring can be calculated by drawing the corresponding diagrams and using them to find the correct mathematical expression. The diagrams are basically accounting tools with a simple visual representation of an interaction of particles.

So it is not the case that physicists assume that those particles exist physically during their lifetime and that they follow trajectories. That contradicts the wave aspect that quantum physics assigns to them. They prefer to assume that the particles in some virtual way do ‘try out’ all possible paths, where one is always chosen and becoming physical on measurement. Each Feynman diagram is just a way of visualizing one the possible interactions. But the temptation to view these interactions as objective physical events is strong.

Feynman diagram with two electrons and one single foton for repulsive field interaction

The above figure is one of the simplest Feynman diagrams you can find on the internet. Shown vertically is the time (t), horizontally the position (x). This diagram shows the simplest way two electrons can affect each other. Two electrons fly towards each other, repel each other at time t0 and fly apart again at the same speeds. At the moment t0, when they are at positions x1 and x2, they exchange a photon. A photon carries a certain momentum, transfers it and thus exchanges the momentum of both electrons. After the exchange, the electrons fly apart at the same speeds at which they first approached each other. The question is, of course, how electrons ‘feel’ that there are other electrons nearby so that they have to exchange photons. The exchange, as shown here, is an instantaneous process, the path of the photon is horizontal at t0.

The photon exchanges the electron momenta

Hey, that’s curious, that makes the speed of the photon infinite. That will certainly not be the intent of the diagram. However, there is more that raises questions. The direction of the photon is not indicated. The photon could move from right to left as well as from left to right. The electrons both undergo an momentum change due to the exchange of the photon. Momentum is the amount of movement expressed in mass m times velocity v: p = mv. The left electron undergoes a velocity change Δv1. From this follows a momentum change Δp1= mΔv1, ditto for the right electron: Δp2= mΔv2. The velocity changes Δv1 and Δv2 are of equal magnitude and of opposite direction: Δv1 = -Δv2. This means that the total momentum does not change: Δv1 + Δv2 = 0 so Δp1 + Δp2 = 0. That is 100% according to an important law in physics: The total momentum of a closed system does not change.

The accounting is correct for the momenta

The photon does the transfer of the momentum, because a photon carries a momentum according to De Broglie: p=h/λ. Both electrons undergo an equal and opposite momentum change which is transferred through the photon, whether the photon moves to the left or the right. For example, suppose the photon moves to the right. The left electron undergoes an impulse change Δp1= mΔv1 = h/λ, the right-hand electron Δp2= mΔv2 = – h/λ. This last minus sign is because the photon loses its momentum when interacting with the electron on the right. Since v1 = – Δv2 holds, the total impulse Δp1 +Δp2 is preserved. If the photon travels in the opposite direction, the result is the same. So it doesn’t matter in which direction the photon moves. If the photon has the speed of light, then the impulse changes will be slightly consecutive in time. The emitting electron changes its momentum first in time, the receiving electron a little later. But that’s not a real problem. The accounting of the momenta is correct.

At least two photons are needed.

But what about the energy? A photon also carries an amount energy that is proportional to its frequency f: E=hf. That’s Planck’s law. If the photon moves to the right, the left electron must have lost some amount of kinetic energy because it has transferred it to the flying away photon: ΔE= – hf. As a result the electron on the left has lost some kinetic energy. The receiving right electron then receives this energy as gained kinetic energy. So it has a higher speed. And if the photon were to move to the left, the right electron loses the kinetic energy that the left electron gains. That can’t be right. Both scenarios conflict with the elastic collision of two objects and cause an asymmetry in the course of the interaction. If we want to achieve the same as in an elastic collision we must assume two simultaneous photons, one going from left to right and one from right to left. Both transfer energy and impulse. This way the accounting is correct again. The sum of the transmitted impulses is zero and there is no transmitted kinetic energy. We need two photons for that. In itself, a Feynman diagram can be supplemented in this way. There is no objection to that.

Feynman diagram with two electrons and two photons for complete repulsive quantum field interaction

There should be a simpler story

A correct story with the exchange of photons becomes considerably more difficult with particles that attract each other, such as an electron and a positron. Isn’t it actually simpler to assume a single interaction in which the charged particles exchange their momentum but no energy? In my opinion, a photon is nothing more or less than the observation of an energy exchange that must have occurred. The assumption that it should be a physical particle is the result of the image imposed on us by classical physics. A photon can therefore also be regarded as nothing more than the observation of an impulse exchange. Elsewhere on this website, and also in my book, I argue extensively that the photon does not physically exist and thus does not travel. The photon is, I think, a reified abstraction.

Quantum field theory

In quantum field theory it is assumed that a moving electron, which is a non-physical probability wave as long as it is not measured, is surrounded by a cloud of virtual (!) photons, where two of them become real photons in this case, to take care of the momentum exchange . This representation replaces Maxwell’s electromagnetic field concept. Actually Maxwell wasn’t very happy with his field concept since he had to assign properties to empty space. Quantum field theory now replaces that electromagnetic field by assuming large amounts of virtual photons popping in and out thin air. In this way you avoid the troublesome idea that electrons would have ‘feel’ each other’s proximity and decide ‘in time’ to perform an impulse exchange in order to move away from each other again. In this way the objective electromagnetic field has been replaced by something even more complex and ultimately based on the field concept, a state of empty space, this time chock-full of virtual particles. Admittedly, quantum field theory does provide very precise predictions. But that could also be said about the epicycles of Ptolemy.

A mini Big Bang in a mini universe of billiard balls

Virtual dancing with quantum fields, a dream

Before 1900 we had the rather simple billiard ball model of the universe. Quantum field theory has now taken its place. To get an idea of its message let’s assume that you’ve been worrying deeply about quantum fields and those virtual photons. Exhausted you fall asleep and you start dreaming. You find yourself in a dance outfit on a huge expanse of ultra smooth dance floor where you can’t see the walls. Everywhere people are dancing, it is swarming with them in some places. In quieter places you see someone alone doing a pretty good pirouette. The floor so slippery that there’s no way you can move from your place. How do the others do that? Then you notice that billiard balls are constantly appearing and disappearing everywhere in the air. The heavier the ball, the faster it disappears again. The smaller and lighter ones last a little longer but eventually they disappear too. You understand that those balls are virtual but that they are physical for a short time. Now you understand, you want to dance and you are looking for someone to dance with.

Then you see someone repulsive sliding towards you. You don’t want to dance with this person. So, you grab a large heavy virtual billiard ball, that just appears in the air near you, and you throw it in this person’s direction. The other person catches the ball neatly after which it immediately disappears again into thin air. The result is that you two are sliding apart again. Then you see someone really attractive. You want to dance with that person, but the person is gliding along a trajectory that does not come close to your trajectory. So, you grab another billiard ball, that conveniently pops up at that moment. You throw the ball in the opposite direction and you see to your pleasure that the other person does the same. You move towards each other and begin to dance happily … and then you wake up. End of dream. Regrettable.

But you now suddenly understand the idea of ​​the quantum fields a lot better. It’s just the old billiard balls story again. But now they are ‘virtual’. Virtual is a concept from optics and means that an object exists physically but not physically, it is not tangible. A rainbow is a virtual object. You can’t grab it but materialistic thinking tries to do just that.

Virtual epicycles

When I think about this tortuous explanation with virtual photons, it inadvertently reminds me of the epicycles of Ptolemy that ‘explained’ the movements of the planets in the heavens in a very complex way and that lasted for 1400 years because the idea of the earth at the center was something people preferred rather strongly and, more important, because it was so accurate in its predictions. Take a look at the Ptolemaic animation of the movement of Mars through the heavens below to get an understanding of its utter tortuous complexity. Ptolemy’s epicycles were indeed virtual.

The Ptolemaic model of the solar system. The Earth (blue) right next to the center of the deferent, the great circle. Mars moves around the Earth in epicycles, small circular orbits whose center moves across the deferent in a year. The yellow ball is the sun as it moves through the zodiac in a year.

A particularly persistent misunderstanding

This kind of quotes do keep popping up in reports about quantum phenomena: “Depending on the way in which it is measured, the quantum object manifests itself as a particle or as a wave.” No, no, and again no, that is not the true image of quantum reality in my opinion. In fact it is severely misleading en confusing.

Such statements create the impression of an object that deliberately adapts to the measurement methods used and then decides whether it shows itself as a wave or as a particle. No wonder many people decide that the quantum world is utterly weird and incomprehensible and stop thinking about it.

This false image, this misunderstanding, has its origins in the image of the world that we received from our earliest memories on. An image of a world existing independently of us and in which we fulfill merely the role of spectator, an accidental bystander who might as well not have been there. We are used to imagining something, every physical thing, as something that simply IS and has always been there. We tend to stick to that way of looking at reality even when, depending on the way we look at it, its properties suddenly appear completely different and extremely ambiguous, like the quantum object mentioned above.

Do we actively create our world?

It is rather unusual to think that things are there BECAUSE we perceive them, that they did not exist before our observation and are no longer there after our observation. If we would opt for that way of thought, things would attain properties that we usually attribute to dreams and thoughts and not to ‘real’ things. This way of thinking about reality is not in keeping with the common perception of the permanence of our world. Yet the quantum world teaches us that our idea of an objective permanent world is most likely false.

Looking at the double slit experiment

The double slit experiment is a crucial experiment in quantum physics able to provide a lot of insight. So let’s take a look at it

Electrons fired at a double slit form an interference pattern.

When we fire a large number of particles, photons, electrons or even large molecules, through a double slit, an interference pattern will be created on the screen after the slits. We see a pattern of light and dark bands. That pattern also arises when we fire particle by particle. Even after a long period of firing single particles, certain areas on the screen appear to be hardly hit, which are the light bands in the picture above.

Such an interference pattern is the result of wave behavior. It occurs because waves reinforce or extinguish each other in certain places depending on their synchronous concurrent or opposite motion, respectively. Watch this YouTube video for a very enlightening demonstration of double slit interference.

There is a mathematical relationship between the spacing of the bands of the interference pattern, the spacing between the slits, the distance from the slits to the screen, and the wavelength, but we don’t need to go into that to understand the meaning of this experiment.

Such an interference pattern of dark and light bands only arises when the originating waves have the same frequency and wavelength. It happens when two wave sources vibrate synchronously. The two slits here function as wave sources vibrating in phase. The rather amazing conclusion drawn from this interference pattern is: “Every particle exhibited wave behavior and must therefore also have been a wave.” This also applies to electrons and even to large molecules of more than 800 atoms.

Catching the particle in the slit

When we adjust the experiment in a way so we can determine for each particle which slit it has gone through, the interference pattern disappears and we get a pattern that you can interpret as two single slit patterns that are projected over each other and therefore are actually indistinguishable from a single slit pattern. Each of the two slits now produces a single slit pattern, which is a single light spot with the highest intensity in the center, in much the same location on the screen.

The correct conclusion is that the waves passing through the slits no longer interfere with each other. The relationship between these two waves running from the slits, which let them extinguish or strengthen each other in fixed predictable places, has disappeared. The often drawn conclusion is that we now see particle behavior instead of wave behavior, which actually makes no sense. A single slit pattern is still for 100% the result of wave behavior, only we no longer observe interference such as occurs with two synchronous wave sources. It seems more like as if every wave, connected to each particle, is now originating from only one of the slits and no longer from both. And that’s exactly what’s going on here.

How we see the world as a collection of things

“.. we can determine for each particle which slit it went through …“. Notice how this sentence is formulated. The implicit assumption here is that there is a particle that travels along a path and that shoots through one of the slits. That is an image that stems from the way we got to know the world around us from childhood. And apparently we find it extremely difficult to let that premise go. Ask yourself: Did the fired bullet travel every part of the path to the target? Or didn’t it?

The simple hypothesis: observation manifests the particle

Now, if only for a moment, try to let go of that premise, set it aside. Imagine now that, there is no particle traveling a path, there only is a wave. A wave that appears to be particularly intimately connected to our perception of the particle. (I will postpone here the effort of trying to understand how this connection works.) A wave that will end when we make an observation. An observation thus means that we seem to manifest the particle at that time and in that location. Immediately after our observation has been made, the particle is no longer there, but the wave is there again starting from where we last observed the particle. Now look again, assuming this hypothesis is right, at the version of that double slit experiment where we could determine which slit the particle passed through. Are we now perhaps able to understand this enigmatic disappearing act of the interference bands somewhat better?

Therefore, try to follow the following five logical steps:

  1. According to this hypothesis, it is the observation, in this case through which slit the particle passed, that made the particle to appear in one of the slits.
  2. Its appearance in the slit implicitly means the end of the wave.
  3. Only at the moment the observation information tells you, the particle manifested and existed in the slit.
  4. Immediately afterwards there is no particle and a new wave leaves the slit eventually ending up on the screen behind the slit.
  5. Since the particle did not appear in both slits – at least let’s assume that there is no magical particle multiplying – we now have only one single wave source.
  6. So there is indeed a wave – between the double slit and the screen – but now there is no more interference, because you need two synchronous vibrating wave sources for it to observe.

This hypothesis – observation manifests the particle – gives thus a complete and logical explanation of the disappearance of the interference when we observe the particle at the slit.

Two time-consecutive manifestations of the particle in a single experiment

Where the wave hits the screen, we do observe a bright little spot. In principle, that is also an observation. So when we set up the measurement in such a way that we can observe in which slit the particle appeared, we create a measurement setup with two consecutive locations for observations – and thus, manifestations. One in the slit and the other on the screen behind the slits. That dual observation is the crucial aspect in an experiment where we do observe the particle at the slit.

So it is confusing to say that the observed object behaves like a wave or a particle depending on the way of observing. In both setups, it is consistently true that there is a wave that results in the manifestation of a particle through an observation. In the setup where we look in which slit the particle appeared, we simply make two consecutive observations, whereby a wave manifests itself twice as a particle. The measurement directly influences the measured object and doing two consecutive measurements at two locations within the setup therefore logically should arrive at a result different from a single measurement done only at the screen. As if you gave during billiards the already rolling ball an extra kick and then got surprised that it influenced the outcome. We really don’t have to assume an intelligent ball for that.

Someone has to hit the balls.

Not a particle and wave at the same time, it’s a probability wave

If we look at it that way, then there is no longer a particle that adapts magically in terms of properties to our way of measuring. The whole process is clear and extremely predictable. As long as we don’t measure the object we want to measure it is a wave. As soon as we measure where and when the object was , we will find the object to have been there. The measurement and manifestation of the object thus become identical! This is a very important and deep conclusion.

Now the question of what that wave is and what it consists of becomes an important one. The answer to that question was first proposed by the physicist Max Born in the early 20th century. In his proposal, the quantum wave is a wave that, when interpreted correctly, gives you the probability per location and time, where and when, to find the object during a measurement. Thus, the quantum wave gives us a prediction of reality but not an exact one. It is a statistical prediction, just like when rolling a dice, the probability of exactly getting a six coming up is 1/6 and that the average outcome of a roll is 3.5. Incidentally, Max Born still assumed that the particle was somehow ‘guided’ by the wave which means that the particle traveled a path, albeit unpredictable. That interpretation was later abandoned by most physicists.

Quantum mechanics is statistics

Statistics is the way in which quantum mechanics accurately predicts the results of experiments. With the enormous numbers of particles that play a role in objects larger than a few micrometres, the outcome of a physical event can be predicted with great precision. Just as the average outcome of a hundred billion throws with an ideal die will be exactly 3.5 with a deviation that we will find only after the 8th decimal place. Many quantum physicists do accept the idea that the particle only manifests itself during measurement, but they disagree about how the measurement achieves this, given the large number of different interpretations. Most interpretations attempt to save the objective permanence of the world but until now these fail to do so convincingly. That there is not a winner since more than 100 years could be an indication of wrong underlying and deeply hidden assumptions. In technical applications, quantum physicists simply use the statistical calculation methods – shut up and calculate – and leave the interpretation to the disputing theorists.

The simplest explanation is usually the best

As I wrote at the beginning, assuming that the ‘thing’ aspect of reality only appears because we are looking and that it does not exist physically when we are not observing, means that the reality we perceive has the same quality as thoughts and dreams. If that is the assumption that provides us with the simplest unambiguous explanation of the double slit experiment, the idea that observing manifests reality might now have become not as strange as it probably sounded to you at first. Applying this hypothesis we are able to visualize every part in the double slit experiment without having to try to imagine something that is simultaneously a particle and a wave, which is impossible. This could mean that our belief that the world is permanently out there, regardless of our presence in it, is a very persistent misunderstanding. That is anyhow my deeply felt opinion. The world is there because we create it when observing it. This also applies to something dramatically destructive like the Covid-19 virus in the end. Such a message should raise of course a number of rather hard questions. For some answers on these have a look at another page on this website.