Schrodinger equation from commuation relations

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Discussion Overview

The discussion revolves around the possibility of deriving the Schrödinger equation from the uncertainty principle expressed in commutation relations, specifically the relation between position and momentum operators. Participants explore whether this derivation can serve as an equation of motion for a wave function.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions if the Schrödinger equation can be derived from the commutation relation \([\hat{x},\hat{p}] = i\hbar\) and expresses uncertainty about using this relation as an equation of motion for a wave function.
  • Another participant suggests that the commutator, along with the representation of observables as operators, can lead to the time-independent Schrödinger equation \(H \psi = E \psi\), but notes that the time-dependent equation requires additional considerations.
  • A different participant mentions that while the time-dependent wave equation cannot be directly derived from the commutation relation alone, it can be derived from the commutation relations of the Galilei algebra.
  • Several participants reference Bohm's Quantum Theory, indicating that while it does not directly address the original question, it contains relevant discussions on the connections between the Schrödinger equation and classical mechanics.
  • One participant highlights that Bohm's chapter 9 discusses how the commutator of the Hamiltonian can be related to expected values and classical equations, potentially leading to the Schrödinger equation.

Areas of Agreement / Disagreement

Participants express differing views on the feasibility of deriving the Schrödinger equation from the uncertainty principle. Some propose that it is possible under certain conditions, while others argue that additional relations or frameworks are necessary, indicating that the discussion remains unresolved.

Contextual Notes

Participants note limitations regarding the derivation process, including the need for additional commutation relations and the distinction between operators and classical variables. There is also mention of the dependence on specific interpretations of quantum mechanics.

erkokite
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I was wondering- is it possible to derive an equation of motion for example, the Schrödinger equation from the uncertainty principle (in commutator form)?

i.e. Is it possible to derive the Schrödinger equation from the following:

\left[\hat{x},\hat{p}\right]=ih

I gave it a shot, but of course, all I came out with is ih=ih (which of course is correct), and is the derivation of the uncertainty principle. However, I was actually wondering if I could use the commutation relation as an equation of motion for a wave function. Is this possible?

Thanks.
 
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erkokite said:
I was wondering- is it possible to derive an equation of motion for example, the Schrödinger equation from the uncertainty principle (in commutator form)?

i.e. Is it possible to derive the Schrödinger equation from the following:

\left[\hat{x},\hat{p}\right]=ih

I gave it a shot, but of course, all I came out with is ih=ih (which of course is correct), and is the derivation of the uncertainty principle. However, I was actually wondering if I could use the commutation relation as an equation of motion for a wave function. Is this possible?

Thanks.

You might find chapter 16, sections 19 through 24 (pages 378-383) of Bohm's Quantum Theory interesting. He doesn't do what you ask, but he shows some connections between Schrödinger's equation, the Hamiltonian formulation mechanics and Heisenberg's representation of quantum mechanics that may be relevant to your thinking.
 
That commutator together with the notion that observables are represented with operators is enough to get you the time-independent shrodinger equation H psi = E psi. To get the time-dependent wave equation we also need the commutator [E,t] = i hbar, but then t is not really an operator so no books contain this relation, but it would follow from the classical poisson bracket for those variables along with Dirac's prescription for first quantization.
 
AEM said:
You might find chapter 16, sections 19 through 24 (pages 378-383) of Bohm's Quantum Theory interesting. He doesn't do what you ask,...

Bohm's chapter 9 has something pretty close. He shows how the commutator of the Hamiltonian (which at that point is an operator to be determined designated H) can be found in the expression for the expected value of an operator. He then uses the expected values and correspondence with classical particle equations (Newton's laws) to come up with Schrödinger's equation (ie: coming up with the equations and Erhenfest's theorem in one shot).
 
You can't simply derive

\frac{d\psi (t)}{dt}=\frac{1}{i\hbar}\hat{H} \psi (t) from

[\hat{x},\hat{p}]_{-}=i\hbar \hat{1}

but you can derive both starting with the commutations relations of the Galilei algebra.
 

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