Observations Are Not Gentle In The Quantum World

Principle 1: Merely observing or measuring properties alters quantum entities

Most of the physics you learned until now applies to the macroscopic world.

Your car stays at the same spot where you left it.

You can precisely measure how fast to drive your car and when to brake it to avoid a collision.

You also can measure the speed of other cars around you without causing real damage to them.

Unfortunately, as you move towards the microscopic world in the subatomic realm, things start to differ, and sometimes they make no sense at all.

A particle is no longer a definite particle and can exist in multiple states.

More precisely, it can exist in a combination of multiple states simultaneously. This is called Superposition.

Mathematically, the state of a quantum system is represented by a wave function or ψ (psi).

The quantum state is the probability distribution of all possible states (called Eigenstates) of a quantum system.