I could completely understand the fact it it was just a limit to our observations but how can it be a property of the microscopic particle itself? Here's how I understand about probabilities: Before a die is thrown, the probability of a certain number coming up is 1/6. But, it's before the die is thrown. But, when the die has been thrown, there is a definite outcome. And, we can't say that the outcome is uncertain or what is happening is uncertain. So, before we observe a microscopic particle, we can calculate the probabilities of where it would be. Before any time instant 't' has happened, we can calculate the probability of where the particle will be at 't' by the wave function but that when 't' happens it has an outcome and the particle has a definite position. So, uncertainties only exist when predicting the future, but the present existence of a particle must have definite position and momentum. Future is uncertain before it happens, but when it happens it must give an outcome. Then, why is it said that microscopic particles posses uncertain positions and momentum?