The quantum world is indeterministic because outcomes of quantum measurements cannot be precisely predicted, only the probabilities of different outcomes can be known. This contrasts with classical physics where, under ideal conditions, outcomes can be predicted with certainty if the initial conditions are known.

## Explanation

In quantum mechanics, particles such as electrons or photons are described not just as particles, but as waves spread out over space, represented mathematically by a wave function. This wave function encodes the probabilities of finding the particle in various states or locations when a measurement is made. Prior to measurement, a quantum system can exist simultaneously in multiple states, a principle known as superposition.

The key to quantum indeterminism lies in the act of measurement itself, which affects the system being observed. According to the Copenhagen interpretation [1], one of the foundational conceptual frameworks of quantum mechanics, a system stops being a superposition of states and collapses to a single state only at the moment of measurement. This collapse is fundamentally random; even if you have complete knowledge of the quantum state before measurement, you can only predict the probabilities of the various possible outcomes, not which one will actually occur.

This intrinsic randomness is unlike anything in classical physics and is what makes the quantum world indeterministically. Quantum indeterminism has been experimentally confirmed through phenomena such as the random decay of radioactive atoms and the random outcomes observed in quantum entanglement experiments.

**Therefore, we can say that the quantum world is not deterministic; it is inherently probabilistic, where only outcome probabilities can be predicted.**

## References

[1] Faye, Jan. “Copenhagen interpretation of quantum mechanics.” (2002).