# Questions tagged [born-rule]

The Born rule is a rule in Quantum Mechanics that states that the probability density $\rho$ is $|\psi|^2$ where $\psi$ is the probability amplitude.

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### Probability of a quantum particle [duplicate]

Now recently I have started quantum mechanics and I understood the wavefunction but I don't understand why $|Ψ|^2$ gives the probability density of a quantum particle. Is there a reason or perhaps ...
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### How do we expand Bayes theorem to account for probability amplitudes?

The Bayes theorem simply states: $$P(B | A) P(A) = P(A | B) P(B)$$ I wonder if there is something that can be meaningfully said as generalization of this relationship when the probabilities in ...
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### What is the probability of measuring $p$ in the momentum space?

I have a wave function $\Psi (x,t)$. According to the Max Born postulate, $\lvert\Psi (x,t)\rvert ^2$ is the probability density. This quantity specifies the probability, per length of the $x$ axis, ...
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### Why do we describe probability amplitude rather than probability itself in quantum mechanics?

In the quantum mechanics, the dynamics of quantum system are described in terms of probability amplitude. However, we want to calculate the probability in the end which can be measured. Why don't we ...
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### “Probabilities are the ghosts of quantum mechanical amplitudes”

I came across this quote today; [Quantum computers] process information using quantum mechanical amplitudes. And probabilities are sort of the ghosts of amplitudes after they have been degraded to ...
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### Zero Solution in infinite square well?

Consider the well: $$V(x) = \begin{cases} \infty&\text{if }x<0 \\ 0&\text{if }x\in\left(0,L\right) \\ \infty&\text{if }x>L. \end{cases}$$ Solving the time independent ...
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### What is exactly Max Born rule?

I have thought Max Born rule as one of the axiom of quantum mechanics that says norm square of wavefunction gives the probability density. But I also found written somewhere that the rule says that ...
2answers
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### What does a Hilbert space state vector represent in Koopman–von Neumann theory?

I understand what a state vector is in quantum mechanics. I also understand that in KvN theory, both the quantum Hilbert space and the classical Hilbert space are the same (see the answer to this ...
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### Wave Function is case of Space-Time curvature

I have some questions about wave functions and space-time curvature: For what I have understood, Dirac Equation incorporates special relativity in Schrodinger equation, but still there are no ways to ...
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### Normalisation of quantum states: why?

We all learn that quantum states need to be normalized, as they are associated to probabilities which needs to sum up to one. However, I would like to know whether you have other valid reasons to ...