silvercats said:
1. Does superposition thing also valid for macroscopic things? (except buckyballs) .
It is valid in principle, yes. There is no boundary between atomic-scale object behavior and macro-scale object behavior. In reality, the effect is essentially zero, as mentioned.*
silvercats said:
2. When we are not looking at the objects, are they really there or not? (if yes,are there proof?)
They are there.
There is no proof in science, only predictive models and evidence.
* here is an analogy, so you understand why I keep saying 'in principle but not in practice':
We are talking about probabilities. There is a non-zero probability that all the air in the room you are currently sitting in in will suddenly but temporarily move to the left, leaving you gasping in vacuum. The laws of thermodynamics do not preclude this happening (temporarily).
However, it is a low probability. One particle can do this easily. A hundred particles all doing it simultaneously is less likely but not improbable. 10
10 particles all doing it simultaneously is
extremely unlikely. Every time you increase the number of atoms you are considering,
the chance that those new atoms will do the same thing is exponentially less. A whole room of atoms contains somewhere around 10
25 .
So, It could happen tomorrow or it could happen in a billion years. The median probability is somewhere upwards of trillions of
trillions of years - longer than the life of the universe.
So I ask you to define for yourself: Can it be said than the air in the room obeys laws that allow it to leap to one side? Is it a non-zero probability that it will happen?Same thing goes for superposition.