Understanding Quantum Mechanics is not difficult

Quantum mechanics (QM) is one of the most successful and powerful theories in the history of physics. It describes the behaviour of very small particles, like photons and electrons. While its predictions have been experimentally validated many times, the interpretations of these results can seem counterintuitive, giving rise to all sorts of weird and "spooky" phenomena.  

An easy way to understand QM is the double slit experiment. Imagine a barrier with two small slits leading to a detection screen. When waves go through these slits, they interfere and create a pattern. But here's the weird part: if you send the photons one at a time through the slits, they also make this interference pattern as if each photon goes through both slits at the same time and interacts with itself. Yet, placing a detector at the slits to determine each photon's path disrupts this pattern, implying the mere act of observation alters outcomes.

Some say the implications of this experiment are profound as it suggests that the act of observation effects the result or the universe splits into “many worlds” or consciousness is playing a role.

However, this quantum phenomenon can be simply explained using wave functions (WF). Rather than describing photons as distinct particles, they are represented by WFs, encompassing all possible states with respective probabilities that sum to one. As time progresses, the WF evolves and expands in a manner akin to a bubble spreading out from its source. This evolution is precisely and mathematically described by the Schrödinger equation.

When the photon interacts with something, termed a "measurement", the WF collapses to a one specific outcome from the many possibilities. This "measurement" can be a deliberate scientific observation or even a simple interaction, like the photon striking a speck of dust. It is as if the measurement bursts the particle’s WF bubble.

Some say that the photon travels a single specific route or perhaps all conceivable routes across parallel universes. However, in the quantum perspective, there isn't a physical photon journeying through space. There's only the wave function until its collapse. Upon collapse, the WF reconfigures, with all probability now focused on the outcome just observed.

If one attempts to determine the photons path by positioning a detector at one slit, the WF of this detector becomes “entangled” with the WF of the photon. This results in the “decoherence” of the WF, leading to the photon either being detected or not. Even if a photon isn't detected, implying it took the alternate route, the entanglement of the WFs still takes place. Without a detector, the screen causes the decoherence, but now it is too late to stop the interference pattern forming.

In essence, quantum mechanics doesn't involve tangible particles but rather wave functions. Particles like electrons and photons only briefly exist when the WF collapses. If we accept this simple interpretation, QM no longer is spooky, weird or difficult to explain.