# Probabilistic, indeterministic and random in QM

## What is random in quantum mechanics?

Logical independence and quantum randomness

Quantum randomness is the statistical manifestation of that indeterminacy, witnessable in results of experiments repeated many times. However, the relationship between quantum indeterminacy and randomness is subtle and can be considered differently.

## Is quantum mechanics deterministic or probabilistic?

Quantum mechanics is deterministic, but it is also probabilistic — i.e. you can deterministically calculate the probability of a random event happening.

## Is the world random or deterministic?

The world is not inherently random, they say, it only appears that way. Their response has been to develop quantum models that are deterministic, and that describe a world that has “objective” properties, whether or not we measure them.

## Is quantum physics probabilistic?

The quantum universe is fundamentally probabilistic, unlike the deterministic universe described by classical physics. Einstein believed that the universe and its laws must be strictly deterministic. He felt that there could be no role for probability or chance, in nature’s foundation.

## What is the difference between probabilistic and deterministic?

In deterministic models, the output of the model is fully determined by the parameter values and the initial values, whereas probabilistic (or stochastic) models incorporate randomness in their approach. Consequently, the same set of parameter values and initial conditions will lead to a group of different outputs.

## Why is quantum mechanics based on probability?

It uses the concept of probability: the outcomes of particle experiments repeated many times are predicted by the QM solutions, an individual experiment having a calculable probability of appearing taken from those solutions.

## What is a quantum probability?

QP theory is a geometric approach to probability where different possibilities (or events or questions) are represented as subspaces, of varying dimensionality, in a multidimensional Hilbert space. Hilbert spaces are like vector spaces, but with some additional properties.

## What is the difference between classical probability and quantum probability?

Classical mechanics is deterministic in that the equations of motion and the initial conditions fully determine a particle’s trajectory. Quantum physics is an inherently probabilistic theory in that only probabilities for measurement outcomes can be determined.