In a previous article I explained why Heisenberg was wrong about the failure of causality [1].
In this article I am going to comment on the differences between uncertainty, randomness, and causality.
The Observer vs Nature
The first thing to understand when defining uncertainty, randomness, and causality is the difference between the observer and nature.
As I explained in my model of information [2], there are a subjective space and an objective space when dealing with the sources or substrates of information and the meaning [3] of those substrates.
The objective space is nature and its physical phenomena, which have no meaning, therefore are not information.
The subjective space is reserved to the mind, where physical phenomena is captured, processed, and connected to mental objects, turning them into information proper. Therefore, information exists exclusively in the mind.
The mind is the observer of nature.
Heisenberg’s Uncertainty Principle [4] [5] asserts that the observer cannot know the exact position and momentum of a quantum particle at the same time. The same happens to other pairs of conjugate variables [6], such as energy and time.
However, the lack of knowledge by the observer does not mean that the underlying physical processes do not exist. Indeed, all objects and variables continue to exist in the physical space, regardless of the observer’s situation.
On the other hand, the Born Rule [7] says that the states of quantum systems are inherently probabilistic. This is an intrinsic property of nature, regardless of the observer’s situation.
In summary, Heisenberg’s Uncertainty Principle is a limitation to observability, and the Born Rule is an intrinsic property of nature, regardless of the observer’s situation.
It is true that the underlying statistical nature of reality, together with the wave form of quantum objects [8], presents a fundamental limit to observability, and that measurement in itself may affect the state of quantum systems [9], but it is important to note:
1. that physical events continue to occur, whether measured or not, and
2. that what the observer can capture and transform into meaningful information in the mind is distinct from the underlying physical phenomena.
In other words, the events and properties of nature exist and continue whether there is an observer or not to comment, analyze, or predict them.
Uncertainty vs Certainty
Uncertainty means that, starting from initial conditions, the observer cannot learn or predict the next step in physical events, and can measure and know only one of a pair of observable conjugate variables of a quantum system at the same time.
Certainty would mean that, starting from initial conditions, the observer could learn the next step in physical events or know the state of all conjugate variables of a quantum system at the same time.
Again, note that to learn, measure, or know the above is a problem of the observer, but the underlying physical phenomena exist regardless of that problem.
Randomness vs Nonrandomness
As written before, as per the Born Rule, due to the statistical nature of reality, randomness is, indeed, an intrinsic property of quantum systems. The observer has no say in that.
Randomness means that the next step in physical events is probabilistic [10]. This also applies for the creation or genesis of quantum particles [11] [12].
In other words, events in quantum systems have no pattern, are fortuitous, accidental, and due to chance variation.
Nonrandomness would mean that the next step in physical events, and the creation or genesis of particles, would not be probabilistic but due to a pattern, or fixed variation.
Causality vs Spontaneousness
Causality means that the next step in physical events is an effect of, or caused by, the previous step. This happens whether the events are random or nonrandom, observed or not observed.
Random only means that the next state; for example, in position, momentum, energy, time, or direction; will not be the product of a pattern or fixed variation. But, that does not mean that it is not caused by the previous state, or the influence of the previous state in the current state.
The above means that cause and effect are, in fact, not broken at the quantum level. Even if the universe is fundamentally probabilistic, chains of cause and effect, indeed, continue to occur.
Causality means that an event mechanically and logically follows another, as a consequence of it.
On the other hand, spontaneousness means physical events have no previous steps that cause them. This happens, for example, at the quantum vacuum field, where electromagnetic waves and particles are randomly brought into existence, in and out of the quantum field [13].
In this case of the creation or genesis of quantum objects; or their eventual end, absorption, or collapse [14] [15]; causality is not interrupted during their existence.
In other words, after creation, a causal chain of events follows, and only finishes when particles are absorbed, collapse, or end, but that does not mean there was no causality between their beginning and end.
Summary
It is important to distinguish epistemological and cognitive phenomena from physical phenomena in nature.
For example, the universe is not probabilistic because of the Uncertainty Principle, and uncertainty does not mean randomness.
The statistical nature of reality is described by the Born Rule; that is, that quantum states are inherently probabilistic; and, together with the wave form of quantum objects, gives rise to observational uncertainty.
The terminology and concepts explained in this article may seem only a matter of semantics, but that is not the case.
When referring to uncertainty, the statistical interpretation of quantum mechanics, causality, and other important natural properties, many tend to start with the wrong semantics; and, from there, they subsequently build incorrect mental models and constructs about the underlying nature of reality as per our current state of knowledge.
For example, that uncertainty means randomness.
References
[1] Heisenberg Was Wrong About the Failure of Causality – by Donald McIntyre: https://etherplan.com/2020/12/11/heisenberg-was-wrong-about-the-failure-of-causality/14135/
[2] What is Information? – by Donald McIntyre: https://etherplan.com/2020/11/02/what-is-information/13378/
[3] What is Meaning? – by Donald McIntyre: https://etherplan.com/2020/12/08/what-is-meaning/14028/
[4] Uncertainty Principle – by Britannica: https://www.britannica.com/science/uncertainty-principle
[5] The Physical Content of Quantum Kinematics and Mechanics – by Werner Heisenberg (1927): http://etherplan.com/heisenberg-uncertainty.pdf
[6] Conjugate variables – by Wikipedia: https://en.wikipedia.org/wiki/Conjugate_variables
[7] Born rule – by Wikipedia: https://en.wikipedia.org/wiki/Born_rule
[8] Schrödinger equation – by Wikipedia: https://en.wikipedia.org/wiki/Schr%C3%B6dinger_equation
[9] Measurement problem – by Wikipedia: https://en.wikipedia.org/wiki/Measurement_problem
[10] Probability – by Wikipedia: https://en.wikipedia.org/wiki/Probability
[11] Quantum fluctuation – by Wikipedia: https://en.wikipedia.org/wiki/Quantum_fluctuation
[12] Vacuum genesis – by Wikipedia: https://en.wikipedia.org/wiki/Vacuum_genesis
[13] Quantum vacuum state – by Wikipedia: https://en.wikipedia.org/wiki/Quantum_vacuum_state
[14] Continuum, Absorption & Emission Spectra – on New Mexico State University: http://astronomy.nmsu.edu/geas/lectures/lecture19/slide02.html
[15] Wave function collapse – by Wikipedia: https://en.wikipedia.org/wiki/Wave_function_collapse
