Prove that TDSE is invariant under Galilean Transformation.

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Discussion Overview

The discussion centers on the invariance of the time-dependent Schrödinger equation (TDSE) under Galilean transformations, exploring the conditions and implications of such invariance. Participants are examining theoretical aspects and seeking proofs related to wavefunctions and the foundational principles of quantum mechanics.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants assert that the TDSE is not invariant under Galilean transformations without a phase factor, as noted by one participant who references the need for a mass and time-dependent phase factor to transform solutions correctly.
  • Another participant expresses a desire for a proof of the invariance of the TDSE under Galilean transformations, indicating a need for clarity on the topic.
  • A participant mentions a reference to Ballentine's work, suggesting that it discusses the relationship between the Schrödinger equation and the Galilean principle of relativity, implying that the probabilities of observations are invariant.
  • One participant questions whether the invariance could be deduced from the canonical commutation relation remaining unchanged under specific transformations, proposing a connection to the transformation of position and momentum operators.
  • There is acknowledgment of the complexity of the issue, with one participant noting that while they initially believed the TDSE was invariant, the introduction of the phase change complicates the matter.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the invariance of the TDSE under Galilean transformations. There are competing views regarding the necessity of a phase factor and the implications of the canonical commutation relations.

Contextual Notes

The discussion highlights the dependence on specific definitions and the subtleties involved in the transformation of wavefunctions. The role of phase factors and the implications of canonical commutation relations are noted as areas requiring further exploration.

Viraj Daniel Dsouza
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I want the proof for a general wavefunction Ψ(x,t).
 
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The Schrödinger equation isn't invariant under Galilean transformations. It's invariant under a central extension of the universal cover of the Galilean group. Specifically, this means that you cannot just apply a Galilean transformation to the wave-function, but you need to add a (mass and time dependent) phase factor in order to transform a solution into another solution. In contrast to the Lorentz group, the phase factor cannot be made to vanish in case of the Galilean group.
 
Viraj Daniel Dsouza said:
I want the proof for a general wavefunction Ψ(x,t).

A proof of what?
 
PeterDonis said:
A proof of what?

I want to prove that the time dependent Schrödinger equation is invariant under Galilean transformation.
 
Viraj Daniel Dsouza said:
I want to prove that the time dependent Schrödinger equation is invariant under Galilean transformation.

See chapter 3 Ballentine - QM - A Modern Development - he does the converse - proves the Schrödinger equation from the Galilean principle of relativity. Specifically he assumes the probabilities of an observation are invariant.

BTW I think Rubi is right although I haven't gone deep into it.

Added Later:
Had a quick scan through Ballentine and Rubi is correct. Here is a paper I found on it - note the phase change mentioned by Rubi.
http://www.ijqf.org/wps/wp-content/uploads/2015/07/IJQF-2486.pdf

It says it is invariant - but with that phase change things are a bit murkier. Interesting question - before going into it I would have said yes it is - however its a bit more subtle.

Thanks
Bill
 
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Could this be somehow deduced from the fact that the canonical commutation relation ##[\hat{x},\hat{p}]=i\hbar## doesn't change in the transformation

##\hat{x} \rightarrow \hat{x}+vt##,
##\hat{p} \rightarrow \hat{p} + mv##

with ##m## and ##v## real numbers and ##t## the time?

On the other hand, the commutator at any time ##t## will also remain the same if the ##vt## is replaced by ##\beta t^2## or something else that is nonlinear in ##t##.
 

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