Fourier Transforms: Proving Proportionality

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Homework Help Overview

The discussion revolves around proving the proportionality of a wave packet expressed through a Fourier transform, specifically focusing on the Gaussian form of the integral involved. The subject area includes Fourier transforms and wave packet analysis in physics.

Discussion Character

  • Exploratory, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to show the proportionality of a wave packet to a specific exponential form using Fourier transforms. They express difficulty in achieving the desired result with their initial approach. Other participants inquire about the integral for the wave packet in momentum space.

Discussion Status

Some participants have reported solving the initial problem but have moved on to a new integral involving a different parameterization. There is an ongoing exploration of methods to graph the resulting function.

Contextual Notes

Participants are working under the constraints of homework rules, which may limit the extent of guidance provided. The discussion includes specific parameters and forms that are critical to the problems being addressed.

smallgirl
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1. We consider the on shell wave packet:
\varphi(t,x)=\int\frac{dk}{2\pi}exp(-\frac{(k-k_{0})^{2}}{\Delta k^{2}}+ik(t-x))dk<br />

I need to show it is proportional to:
exp(ik_{0}(t-x)-\frac{\triangle k^{2}}{4}(t-x)^{2})dk
through a Fourier transform of the gaussian


3. I used a Fourier transform of the form e^(ikx) but this doesn't seem to give me the right answer as I end up with something proportional to exp(-\frac{(k-k_{0})^{2}}{\triangle k^{2}}+ikt)dk before integrating
 
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Show us what you think the integral for ##\varphi(t,k)## is.
 
Solved it! :-)...

However I now need to solve this:

\int\frac{dk}{2\pi}exp(-\frac{(k-k_{o})^{2}}{\triangle k^{2}}+ik(pt-x)


where p=1-\frac{h_{00}}{2}-h_{01}-\frac{h_{11}}{2}

by using Fourier transforms
 
Solved this one too now :-)

Not sure how to graph it though...
 

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