Is light a particle or a wave?

It is true that the concept of wave function collapse and the idea that particles exist in a superposition of different states before they are measured is a key part of the quantum mechanical description of the world. However, it is not just an "explanation" or a theoretical construct. The existence of wave function collapse and superposition states has been confirmed by a wide variety of experiments, including the double-slit experiment and other experiments that demonstrate the probabilistic nature of quantum systems.

One way to understand the idea of superposition is to consider a simple example: suppose you have a coin that you flip, but instead of just two possible outcomes (heads or tails), the coin can land on any of the points on a continuous scale (e.g. a line). According to quantum mechanics, the coin would exist in a superposition of all possible positions on the scale until you observe it and collapse the wave function.

This may seem strange or counterintuitive, but it is a consequence of the mathematics of quantum mechanics and has been confirmed by many experiments. The uncertainty principle, which states that the more precisely we know the position of a particle, the less precisely we can know its momentum, and vice versa, is another consequence of the wave-like nature of quantum systems and the existence of superposition states.

So while it is true that we cannot know the exact position and momentum of a quantum particle with infinite precision, this does not mean that the particle does not have a definite position and momentum. Rather, it means that the position and momentum of a quantum particle are inherently uncertain and subject to a certain amount of randomness due to the wave-like nature of these systems.