From my understanding, quantum mechanics applies mainly to small microscopic particles. When it comes to macroscopic objects, the wave functions collapse and the quantum mechanical properties are lost.
So in day to day lives, such as for example in our body, do all the chemical reactions that occur happen via quantum mechanics? I mean, is it possible to 100% predict all the chemical reactions that happen in our body?
I think you could accept to possible answer. One is to say that it doesn't play a role in our daily life since no one really needs to understand or care about QM unless you're physicist or something like that and one can have a basic understandment of the world. The fact that people could explain many complicated systems before quantum mechanics may demonstrate how it is not essential in a day-to-day basis. The other option is to realize that QM is essential to the interaction of particles and so it accounts for everything, from how stars work, to how atoms and molecules behave and how things like your computer can allow you to even ask this question in an online forum. QM explains how small things behave and that in turn dictates how everything behaves. I'm not sure if this really answers your question but this is what I interpreted.
Yes, the chemical reactions in your body are explainable in principle by quantum mechanics.
But predicting even a single biochemical reaction from first principles would require enormous computational power. Simulating the trillions of trillions of reactions going on in your body right now is completely impossible.
Someday, quantum computers may make simulations of quantum systems fast and easy, but there are still many technical challenges to get there.
