Wave Function in Lorent tranform

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Discussion Overview

The discussion centers on transforming a wave function from one inertial frame to another using Lorentz transformations. Participants explore the implications of this transformation within the context of both classical and quantum mechanics, addressing the mathematical steps involved and the conceptual understanding of wave functions in different frames.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant requests a detailed calculus approach to transform the wave function using Lorentz transformations, questioning the applicability of this transformation across inertial frames.
  • Another participant suggests that the wave function can be understood in the context of relativistic quantum field theory, but questions if this aligns with the original inquiry.
  • A different participant argues that the term 'wave function' may not be used in a quantum mechanical sense, indicating that the original equation resembles a classical wave equation.
  • One participant provides a starting point for the transformation using the chain rule of differential calculus, indicating a method to derive the relationship between derivatives in different frames.
  • Another participant outlines the Lorentz transformation equations and suggests a method for calculating derivatives with respect to the transformed coordinates.
  • A participant expresses gratitude for the responses and indicates they can perform the transformation, offering to share their findings later.
  • References to a specific text on relativity are made, suggesting a resource for further exploration of the topic.

Areas of Agreement / Disagreement

Participants exhibit a mix of agreement and disagreement regarding the interpretation of the wave function and its transformation. Some propose that the wave function can be treated classically, while others argue for a quantum field theoretical perspective. The discussion remains unresolved on the exact nature of the wave function in this context.

Contextual Notes

There are limitations in the discussion, including assumptions about the definitions of wave functions and the applicability of the Lorentz transformation in different contexts. The mathematical steps for the transformation are not fully resolved, and there are varying interpretations of the wave function's role in classical versus quantum mechanics.

Leo_nic
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how to tranform wave function(x,t) to same coordinate wave function(x',t')
with Lorentz Tranformation (please show all the calculus).

and why we know the Lorentz tranform can do this function to use in every inertial frames.
 

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It does seem to be possible to make sense of [itex]\psi(x,t)=\psi'(x',t')[/itex] using some relativistic quantum field theory, but is that really what you're looking for?

The equation you posted looks like an attempt to find a relativistic version of the Schrödinger equation by making the substitutions

[tex]E\rightarrow i\hbar\frac d{dt}, p\rightarrow -i\hbar\frac d{dx}[/itex]<br /> <br /> in the relativistic formula [itex]E^2=p^2c^2+m^2c^4[/itex] (with m=0) instead of in the non-relativistic formula [itex]E=p^2/2m[/itex]. If you do it in the non-relativistic equation, the result is the Schrödinger eqauation. It might seem plausible that you'd get a relativistic wave equation if you start with the relativistic expression for the energy instead.<br /> <br /> However, this doesn't work. The "psi" isn't going to be a wave function. It's a classical field, which needs to be "quantized" to a quantum field before we can do anything with it.<br /> <br /> Here's how I would make sense of [itex]\psi(x)=\psi'(x')[/itex] (where x now represents all the coordinates including time), if we assume that the "wave function" represents a one-particle state in the quantum field theory of a (not necessarily massless) non-interacting scalar field:<br /> <br /> [tex]\psi(x)=\langle 0|\phi(x)|\psi\rangle=\langle 0|U(\Lambda)^\dagger U(\Lambda)\phi(x)U(\Lambda)^\dagger U(\Lambda)|\psi\rangle=\langle 0|\phi(\Lambda x)|\psi'\rangle=\psi'(x')[/tex][/tex]
 
I don't think the OP is using the term 'wave function' in a quantum mechanical sense, since the attached thumbnail is the classical wave equation.

The definition of the lorentz transformation is such that psi(x,t) = psi(x',t') i.e. events occurring at x,t are seen as occurring at x',t' in the other inertial frame.
 
D'oh. Well, at least it would have been a good answer in the quantum mechanics forum. :smile:
 
thank you for answer

My mean is how to tranform change the function(x,t) to function(x',t')
My teacher tell me it can do by calculus
He sample a start is use chain rule differential calculus

dU/dx' = (dU/dx)(dx/dx') + (dU/dt)(dt/dx')

and I no idea
why in the end ddU/dx'x' = (1/c^2)(ddU/dt't')

please show me if it true.
 

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Start with the Lorentz transformation

[tex]x' = \gamma x - \beta\gamma t[/tex]
[tex]t' = \gamma t - \beta\gamma x[/tex]

now calculate

[tex]\frac{dx}{dx'} , \frac{dt}{dt'}[/tex]

and apply

[tex]\frac{d\Psi}{dx'} = \frac{d\Psi}{dx}\frac{dx}{dx'} + \frac{d\Psi}{dt}\frac{dt}{dx'}[/tex]

then differentiate again. Repeat for t'. I think that ought to work, but I haven't time to do the whole calculation.
 
Last edited:
Thank you for answer

Now I can do it ,thank you for all thinking

if you want see answer i can post but you will wait a many time.

if you want see please tell me.
 
wave function and LT

Leo_nic said:
Thank you for answer

Now I can do it ,thank you for all thinking

if you want see answer i can post but you will wait a many time.

if you want see please tell me.
You can see a transparent approach in
C.Moller
The Theory of Relativity
Clarendon Press 1952 p.56 Ch.23
 

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