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Routledge eBooks

When efficient causation breaks down… Synchronicity and meaning

Sarah Durston, Ton Baggerman

Published Oct 1, 2025• 0 citations
Publisher

Abstract

In the previous chapter, we saw that rather than thinking about reality as a static state, it may be helpful to think of it as a process, and perhaps even a process in which the observer participates: she has an active role in determining what is observed. This is certainly true in quantum physics, where quantum superposition is not resolved until a measurement is made. Our classical way of viewing the world leads us to interpret it as being much more absolute at the (larger) scale at which we live our lives. But, as we saw in Chapter 4, quantum processes play much more of a role in our daily lives than we typically realise. For example, entanglement, where two quantum systems interact immediately irrespective of their distance, is a central concept in quantum physics. Yet it appears to defy causality, as we are used to defining it (where one event causing another must always precede it). Erik Verlinde said the following about quantum entanglement:

DOI
10.5117/9789462987401_ch05

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The direction of change

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Chapter 4 explored the idea that reality may be an interactive process leading to the stage of time and space rather than set on it, and – perhaps more speculatively – that there may be a role for us as observers in the process of causing reality to unfold. The last chapter investigated synchronicity and noted that there is an apparent overlap between phenomena, such as quantum entanglement and our experience of meaningful coincidences. Now Chapter 6 picks up the thread from Chapter 4 and asks why, if reality is a process, it does not appear random. What is the mechanism by which it appears stable to us, as a continuous stream of events?

Routledge eBooks•Oct 1, 2025•0 citations

Entanglement

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We have seen, in Section 2.5, how the superposition principle leads to the existence of entangled states of two or more quantum systems. Such states are characterized by the existence of correlations between the systems, the form of which cannot be satisfactorily accounted for by any classical theory. These have played a central role in the development of quantum theory since early in its development, starting with the famous paradox or dilemma of Einstein, Podolsky, and Rosen (EPR). No less disturbing than the EPR dilemma is the problem of Schrödinger’s cat, an example of the apparent absurdity of following entanglement into the macroscopic world. It was Schrödinger who gave us the name entanglement; he emphasized its fundamental significance when he wrote, ‘I would call this not one but the characteristic trait of quantum mechanics, the one that enforces the entire departure from classical thought’. The EPR dilemma represents a profound challenge to classical reasoning in that it seems to present a conflict between the ideas of the reality of physical properties and the locality imposed by the finite velocity of light. This challenge and the developments that followed have served to refine the concept of entanglement and will be described in the first section of this chapter. We start by recalling that a state of two quantum systems is entangled if its density operator cannot be written as a product of density operators for the two systems, or as a probability-weighted sum of such products. For pure states, the condition for entanglement can be stated more simply: a pure state of two quantum systems is not entangled only if the state vector can be written as a product of state vectors for the two systems. In the discipline of quantum information, entanglement is viewed as a resource to be exploited. We shall find, both here and in the subsequent chapters, that our subject owes much of its distinctive flavour to the utilization of entanglement.

Oxford University Press eBooks•May 28, 2009•0 citations

Entanglement: quantum information and computation

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In this chapter we shall deal with the most recent and challenging development of quantum theory, and also one of the most important ones for interpretational, foundational, and even technological issues. This field finds its roots in the observation that quantum states can be viewed as bricks of information in a way that is intrinsically different from classical information. As a consequence, the ability to manipulate quantum states translates immediately into a new form of information processing and exchange. What has been discovered during this conceptual passage is that this type of information processing is in many respects much richer than its classical analogue. This has contributed to the understanding of quantum states as an extension of the classical concept of state and not as a defective reality (see also Subsec. 2.3.4 and Sec. 15.5). The impossibility of knowing the value of all observables at the same time that had been seen as a strong limitation in the early days of quantum mechanics, now turns out to be a manifestation of a different – but not necessarily poorer – resource. On the contrary, we have increasingly discovered that superposition and entanglement are additional informational resources. These resources, for instance, allow for certain particular computations that are much faster on a quantum device than on its classical counterpart, and therefore the former is able to solve problems that cannot be practically solved using classical means.

Cambridge University Press eBooks•Apr 16, 2009•0 citations

Pragmatic Information in Quantum Mechanics

Juan G. Roederer

An objective definition of pragmatic information and the consideration of recent results about information processing in the human brain can help overcome some traditional difficulties with the interpretation of quantum mechanics. Rather than attempting to define information ab initio, I introduce the concept of interaction between material bodies as a primary concept. Two distinct categories can be identified: 1) Interactions which can always be reduced to a superposition of physical interactions (forces) between elementary constituents; 2) Interactions between complex bodies which cannot be reduced to a superposition of interactions between parts, and in which patterns and forms (in space and/or time) play the determining role. Pragmatic information is then defined as the correspondence between a given pattern and the ensuing pattern-specific change. I will show that pragmatic information is a biological concept that plays no active role in the purely physical domain; it only does so when a living organism intervenes. The consequences for the foundations of both classical and quantum physics are important and will be discussed in detail. Since by its very definition pragmatic information (the one our brain uses to represent, think about and react to the outside world)cannot operate in the quantum domain, it is advisable to refrain from using it in our mental representation of what is happening 'inside' a quantum system. Although the theoretical framework developed for quantum mechanics handles mathematical entities specifically attributed to a quantum system, the only truly pragmatic information it can provide relates to macroscopic effects on the environment (natural, or artificial as in a measurement instrument) with which the system interacts.

arXiv:1512.05651•Cambridge University Press eBooks•Apr 24, 2017•1 citation

Quantum Measurement

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Cambridge University Press eBooks•Mar 16, 2017•0 citations

Quantum theory and reality

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Abstract In the previous chapter, we have been trying to come to terms with the puzzling Z-mysteries of quantum theory. Although not all of these phenomena have been experimentally tested—such as quantum entanglement over distances of several light years—there is already enough experimental support for effects of this kind to tell us that Z-mysteries are indeed things that we must take seriously as true aspects of the behaviour of the constituents of the world in which we live.

•Aug 22, 1996•7 citations
In the previous chapter, we saw that rather than thinking about reality as a static state, it may be helpful to think of it as a process, and perhaps even a process in which the observer participates: she has an active role in determining what is observed. This is certainly true in quantum physics, where quantum superposition is not resolved until a measurement is made. Our classical way of viewing the world leads us to interpret it as being much more absolute at the (larger) scale at which we live our lives. But, as we saw in Chapter 4, quantum processes play much more of a role in our daily lives than we typically realise. For example, entanglement, where two quantum systems interact immediately irrespective of their distance, is a central concept in quantum physics. Yet it appears to defy causality, as we are used to defining it (where one event causing another must always precede it). Erik Verlinde said the following about quantum entanglement:
Chapter 4 explored the idea that reality may be an interactive process leading to the stage of time and space rather than set on it, and – perhaps more speculatively – that there may be a role for us as observers in the process of causing reality to unfold. The last chapter investigated synchronicity and noted that there is an apparent overlap between phenomena, such as quantum entanglement and our experience of meaningful coincidences. Now Chapter 6 picks up the thread from Chapter 4 and asks why, if reality is a process, it does not appear random. What is the mechanism by which it appears stable to us, as a continuous stream of events?
We have seen, in Section 2.5, how the superposition principle leads to the existence of entangled states of two or more quantum systems. Such states are characterized by the existence of correlations between the systems, the form of which cannot be satisfactorily accounted for by any classical theory. These have played a central role in the development of quantum theory since early in its development, starting with the famous paradox or dilemma of Einstein, Podolsky, and Rosen (EPR). No less disturbing than the EPR dilemma is the problem of Schrödinger’s cat, an example of the apparent absurdity of following entanglement into the macroscopic world. It was Schrödinger who gave us the name entanglement; he emphasized its fundamental significance when he wrote, ‘I would call this not one but the characteristic trait of quantum mechanics, the one that enforces the entire departure from classical thought’. The EPR dilemma represents a profound challenge to classical reasoning in that it seems to present a conflict between the ideas of the reality of physical properties and the locality imposed by the finite velocity of light. This challenge and the developments that followed have served to refine the concept of entanglement and will be described in the first section of this chapter. We start by recalling that a state of two quantum systems is entangled if its density operator cannot be written as a product of density operators for the two systems, or as a probability-weighted sum of such products. For pure states, the condition for entanglement can be stated more simply: a pure state of two quantum systems is not entangled only if the state vector can be written as a product of state vectors for the two systems. In the discipline of quantum information, entanglement is viewed as a resource to be exploited. We shall find, both here and in the subsequent chapters, that our subject owes much of its distinctive flavour to the utilization of entanglement.
In this chapter we shall deal with the most recent and challenging development of quantum theory, and also one of the most important ones for interpretational, foundational, and even technological issues. This field finds its roots in the observation that quantum states can be viewed as bricks of information in a way that is intrinsically different from classical information. As a consequence, the ability to manipulate quantum states translates immediately into a new form of information processing and exchange. What has been discovered during this conceptual passage is that this type of information processing is in many respects much richer than its classical analogue. This has contributed to the understanding of quantum states as an extension of the classical concept of state and not as a defective reality (see also Subsec. 2.3.4 and Sec. 15.5). The impossibility of knowing the value of all observables at the same time that had been seen as a strong limitation in the early days of quantum mechanics, now turns out to be a manifestation of a different – but not necessarily poorer – resource. On the contrary, we have increasingly discovered that superposition and entanglement are additional informational resources. These resources, for instance, allow for certain particular computations that are much faster on a quantum device than on its classical counterpart, and therefore the former is able to solve problems that cannot be practically solved using classical means.
An objective definition of pragmatic information and the consideration of recent results about information processing in the human brain can help overcome some traditional difficulties with the interpretation of quantum mechanics. Rather than attempting to define information ab initio, I introduce the concept of interaction between material bodies as a primary concept. Two distinct categories can be identified: 1) Interactions which can always be reduced to a superposition of physical interactions (forces) between elementary constituents; 2) Interactions between complex bodies which cannot be reduced to a superposition of interactions between parts, and in which patterns and forms (in space and/or time) play the determining role. Pragmatic information is then defined as the correspondence between a given pattern and the ensuing pattern-specific change. I will show that pragmatic information is a biological concept that plays no active role in the purely physical domain; it only does so when a living organism intervenes. The consequences for the foundations of both classical and quantum physics are important and will be discussed in detail. Since by its very definition pragmatic information (the one our brain uses to represent, think about and react to the outside world)cannot operate in the quantum domain, it is advisable to refrain from using it in our mental representation of what is happening 'inside' a quantum system. Although the theoretical framework developed for quantum mechanics handles mathematical entities specifically attributed to a quantum system, the only truly pragmatic information it can provide relates to macroscopic effects on the environment (natural, or artificial as in a measurement instrument) with which the system interacts.
A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it. – Max Planck, 1936 The only way quantum theory allows us to interact with quantum systems is via quantum processes. Thus, the only way we can extract information about the state of a quantum system is to apply some non-deterministic process and observe which of the branches happened. For that reason, many people refer to the act of applying certain quantum processes as measurement and sometimes even as observation . A consequence of this unfortunate terminology is that one of the most touted ‘strange’ features of quantum theory is often misleadingly described as follows: ‘The mere act of observing a quantum state changes it.’ ‘Misleading’, since the concept of measurement described in the previous paragraph is far from the passive concept of observation familiar from our macroscopic world, but is rather a non-trivial process that will almost always drastically affect the quantum state. So, the mysterious aspect of quantum theory is not that ‘observation’ alters the quantum state but, rather, that it is impossible, even in principle, to ‘observe’ a quantum system in the classical sense. Given this fundamental restriction on how we can extract information from a quantum system, what can we learn about that system by means of a quantum process? The answer is, in fact, very little! First, performing a particular measurement could, for the vast majority of quantum states, yield any outcome i with a non-zero probability. In that case, obtaining an outcome i doesn't tell us much about what the state of the system was. Second, we say ‘was’, because the measurement will moreover irreversibly change the state according to the outcome. So rather than revealing the state of a system, a quantum measurement typically erases that state from history! Nonetheless, these quantum measurements are crucial to quantum theory since they constitute the only interface between us, in our classical world, and the quantum world. The great insight of the quantum computing community is that the non-deterministic changes induced by these quantum measurements are not a nuisance, but rather an extremely useful resource.