I’m trying to understand decoherence and the macro/micro distinction in quantum mechanics, and I feel like I’m missing something fundamental
People often explain why macroscopic objects (tables, cats, planets, etc.) don’t display obvious quantum superpositions by saying they constantly interact with the environment, causing decoherence.
But here’s what confuses me:
Don’t microscopic particles also constantly interact with the environment?
For example:
- photons travel through space interacting with fields and matter,
- electrons are affected by electromagnetic interactions,
- atoms are constantly surrounded by radiation, fields, particles, etc.
So why do quantum effects survive there at all?
If interaction with the environment destroys coherence, shouldn’t microscopic systems also decohere almost instantly under ordinary conditions?
Is the distinction really about “small vs large,” or is it more about the degree and complexity of entanglement with the environment?
And if that’s true, then where exactly is the transition from quantum to classical supposed to happen? Is there even a real boundary, or is classical behavior just an emergent approximation due to overwhelming decoherence?
I think I may be misunderstanding what decoherence actually means physically, especially regarding information leakage into the environment.
Would appreciate an explanation from someone who understands the modern view of this better.