However, all observable properties of the state are in fact constant in time. For example, if | Ψ Ψ ( t ) ⟩ ⟩ represents a simple one-dimensional single-particle wavefunction Ψ Ψ ( x , t ) , the probability that the particle is at location x is | Ψ Ψ ( x , t ) | 2 = | e − − i E Ψ Ψ t / ℏ ℏ Ψ Ψ ( x , 0 ) | 2 = | e − − i E Ψ Ψ t / ℏ ℏ | 2 | Ψ Ψ ( x , 0 ) | 2 = | Ψ Ψ ( x , 0 ) | 2 , which is independent of the time t.