Schrodinger equation/Madelung equation phase transformation

  • Context: Graduate 
  • Thread starter Thread starter binbagsss
  • Start date Start date
  • Tags Tags
    Phase Transformation
Click For Summary

Discussion Overview

The discussion revolves around the phase transformation of the Schrödinger equation and its implications, particularly focusing on the Madelung transformation. Participants explore the conditions under which the transformation is valid, the assumptions regarding the wave function, and the implications of polar decomposition in the context of the Proca action.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant questions whether the phase transformation requires the same asymptotic behavior at infinity and at specific points, suggesting that this is often overlooked.
  • Another participant asserts that if the functions are equal for all inputs, their limits must also be the same, thus negating the need to mention asymptotic behavior explicitly.
  • Concerns are raised about the assumption that the amplitude function \( R(\vec{x},t) \) is non-negative, with implications that this may restrict the wave function's descriptive power.
  • Some participants discuss the validity of performing a similar phase transformation on the Proca action, indicating that each component of the field can also be expressed in terms of magnitude and phase.
  • There is a debate about whether it is valid to write the polar decomposition of complex fields using different phase angles for \( B \) and \( B^* \), with some suggesting that this introduces unnecessary complexity.
  • Participants explore the nature of the phase angles \( \phi \) and \( \phi_1 \), questioning whether they should be treated as real or complex quantities.
  • One participant emphasizes that any complex number can be expressed in terms of real components, while also noting the limitations of equating different forms of decomposition.

Areas of Agreement / Disagreement

Participants express differing views on the assumptions and implications of the phase transformation and polar decomposition, indicating that multiple competing perspectives remain unresolved.

Contextual Notes

Limitations include the dependence on specific definitions of the wave function and the assumptions regarding the nature of the phase angles in the polar decomposition. The discussion also highlights the complexity of treating \( B \) and \( B^* \) independently in the context of the Proca action.

  • #31
binbagsss said:
to which I said I understand it may seem illogical as you would then be introducing two more real quantities.
You did mention in post #8 that it would introduce more fields. However, once again, a number of other posts you have made in this thread made me wonder exactly what you understood.
 
Physics news on Phys.org
  • #32
PeterDonis said:
No, I said the opposite, that the amplitudes must be the same. Go read that post again.
i said, with that, as in with theta being the same, the amps must be the same. whereas i asked about differing theta. so basically if i did a polar decomposition using different amplitudes and phases for both B and B*, then I would end up with two more equations when varying the action. Ignoring the fact that that I would now have four independent variables, if I were to write ##B=B_1 e^{i\phi} ## and ##B*=B_2 e^{i\phi_2}## , then, from them being complex conjugates of each other, I would obtain constraints, such as ##B_1 \exp^{-i\theta}=B_2 \exp^{i\phi_2} ##, and ##B_1 \exp^{i\theta}=B_2 \exp^{-i\phi_2} ##but because of the differing amplitudes/arguments, neither the amplitudes or arguments in the exponents need to be the same?
 
  • #33
binbagsss said:
Ignoring the fact that that I would now have four independent variables
In other words, ignoring the fact that in the case you were asking about, the Proca equation, you don't. You only have two. Or more precisely, two for each 4-vector component (since the Proca equation is for a spin-1 vector field instead of a spin-0 scalar field); but all that means is that you stick a 4-vector index ##\mu## on ##B##.

You need to make up your mind what you are asking about. Are you asking about the actual Proca equation? Or are you asking about some other case, which AFAIK has no physical relevance and is not discussed in the literature, where you somehow have four independent variables instead of two? You said before that you were asking about the Proca equation. Are you now changing the discussion to be about something else?
 
  • Like
Likes   Reactions: renormalize

Similar threads

  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 12 ·
Replies
12
Views
5K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 0 ·
Replies
0
Views
1K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K