Quantum Weirdness

At the smallest scales, particles do not behave like tiny billiard balls with definite properties. Instead, physics describes a world governed by probabilities, uncertainty, and phenomena so strange that even Einstein resisted accepting them.

As the 2 slit experiment shows, electrons do not behave as we would expect and a new way of modelling the world is needed. It turns out to be far stranger and counter-intuitive than anyone expected.

We find that it is not possible to precisely describe properties, such as the position and speed of an electron, in the way we are used to doing in the directly observable world. Instead, all we can do is specify the probability of an electron being in a particular region of space and the probability that it has a velocity in a certain range.

Probability Replaces Certainty

In ordinary life, probability usually reflects incomplete knowledge. A coin toss is unpredictable only because we cannot measure every detail of its motion. In principle, the result is determined.

Quantum mechanics, however, introduced a more radical idea: some events appear fundamentally probabilistic. Even if we knew everything there was to know about an electron, with infinite precision, we still could not predict with certainty what it would do next. A radioactive atom may decay now or a thousand years from now, and physics can predict only the likelihood of each outcome, not the exact moment.

This was deeply unsettling to those who liked the idea of a deterministic Universe, despite its implications. Nature itself no longer seemed fully determined.

Observation Changes the Situation

The famous double slit experiment revealed behaviour unlike anything in ordinary experience. Electrons fired one at a time create an interference pattern associated with waves, as though each electron somehow travels through multiple paths simultaneously.

Yet when scientists attempt to observe which path the electron takes, the interference disappears. The act of measurement changes the result.

In classical physics, observation simply reveals what is already there. In quantum mechanics, observation appears inseparable from the behaviour being observed.

In the early days it was believed that it was a conscious observer which affected the behaviour, leading to redicio ad absurdum thought experiments such as “Schrodinger’s cat” but that was shown to be false. The quantum universe operates just the same in the absence of consciousness and, indeed, before humans even existed.

Nevertheless, a seemingly innocuous question remains to this day: “What is a measurement?”

Nobody knows for certain.

Entanglement

Even stranger is the phenomenon of entanglement. Whenever two particles interact, quantum mechanics can link their properties together so completely that they behave as parts of a single system, even when separated by enormous distances.

Measuring one particle instantly determines the corresponding property of the other. The connection remains regardless of the distance between them.

Einstein famously dismissed this as “spooky action at a distance,” because it seemed to violate the ordinary idea that objects are influenced only by their immediate surroundings.

However, experiments repeatedly confirmed that these correlations are real and cannot be explained by hidden pre-existing instructions carried by the particles.

Again, in the early days, as well in many science fiction stories, this phenomenon was believed to allow faster-than-light communication. And again, this has been shown not to be the case. Nevertheless, it is still true that doing something to one particle of an entangled pair causes an instantaneous change in the properties of the other. Either space is not local as has been assumed and is intuitive or the structure of reality itself is quite different to what we thought.

Nobody knows for certain.

Quantum mechanics is the most successful scientific theory ever created in terms of predictive accuracy. Modern electronics, lasers, and quantum computing all depend on it. Secure encryption and key distribution can make use of quantum entanglement to ensure that no eavesdropper has had access to it.

In Nature, quantum entanglement is an essential part of how photosynthesis works in plants and is believed to be part of the mechanism whereby birds and other species can navigate over huge distances. Well known and used phenomena, such as super-conductivity, rely on quantum entanglement of electrons.

Yet despite its success, the theory resists ordinary intuition. It suggests a universe in which certainty gives way to probability, observation cannot be cleanly separated from reality, and distant particles remain mysteriously connected.

Most physicists and engineers who make use of quantum effects generally do not think about the underlying meaning of the models they are using. Indeed, sometimes, such questions are often discouraged with the response “shut up and calculate!”. Quantum mechanics works extraordinarily well. Understanding what it ultimately says about reality remains another question entirely.

Quantum Mechanics, Mind and Consciousness

Because quantum mechanics contains mysteries and Mind and Conscious also contains mysteries, some workers have been tempted that they must be connected. This is unlikely as will be shown in the next page