Actually, from my understanding of the schrodinger's cat Gedankenexperiment, if you can't see whether it has happened or not then it simultaneously BOTH did and didn't happen until it has been observed by someone.

If the state of possible collision is never observed by anyone then it will remain indefinitely in this state of superposition.

If it the state of possibile collision eventually is observed then the wave function will collapse and it will either have happened or not have happened.

During the state of superposition, it will have some percentage of having happened and some other percentage of having not happened.  Those percentages will be determined by the likelihood of it having happened.