Why Do 3D Shapes Appear as Ripples on a Pond?

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Discussion Overview

The discussion revolves around the visual representation of electrons and their behavior, particularly why they appear as ripples on a pond rather than as three-dimensional objects. It touches on concepts from quantum field theory (QFT) and quantum mechanics (QM), exploring the nature of particles and their intrinsic properties.

Discussion Character

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

Main Points Raised

  • Some participants propose that electrons do not conform to traditional three-dimensional object definitions, suggesting a different understanding of their nature.
  • One participant notes that the video in question is misrepresented, emphasizing that it depicts laser light interacting with an electron rather than showing the electron itself.
  • A reference to momentum distribution and interference fringes is made, indicating that these phenomena depend on ionization times and the phase of the IR field.
  • There is agreement among some participants that the electron lacks intrinsic geometry, aligning with the views of nugatory.
  • One participant expresses uncertainty about the concept of particles after studying QFT, indicating a shift in understanding.
  • A clarification is made that particle counting is not done directly through QFT but rather through particle detectors, which measure probabilistic outcomes.

Areas of Agreement / Disagreement

Participants generally agree on the non-traditional nature of electrons and the challenges in defining particles within QFT. However, there remains uncertainty and differing interpretations regarding the implications of these concepts and the visual representations involved.

Contextual Notes

The discussion includes assumptions about the nature of particles and the interpretation of visual data, which may not be universally accepted. There are also unresolved questions regarding the definitions and properties of particles in the context of quantum mechanics and quantum field theory.

Danyon
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Why does it look like a ripple on a pond instead of a three dimensional object?
 
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It doesn't look like a three-dimensional object because an electron is not a three-dimensional object, at least not as we usually understand the term.

The video was made back in 2008, and has been seriously misrepresented by some pop-sci sources. It's not a picture of an electron, it's an image of laser light pulses that have interacted with an electron that cannot be seen in the video but is presumed to be in the moving dark area at the center of the video.
 
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From the article : "the resulting momentum distribution will be smeared out and show interference fringes that depend on the different ionization times".

"Four stroboscopic images taken at different XUV-IR delays (t0) are presented in Fig. 1(c) (a complete movie spanning one full optical cycle is available in Ref. [27]). The clear up or down asymmetry in the momentum distributions confirms that each image corresponds to ionization at one particular phase of the IR field so that the momentum distribution is shifted up or down in the direction of polarization of the IR field."
 
I agree with nugatory, the electron is not a particle in the sense we are accustomed so it lacks intrinsic geometry. See this for discussion .
 
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Chronos said:
I agree with nugatory, the electron is not a particle in the sense we are accustomed so it lacks intrinsic geometry.

Glad to see others like Rodney Brooks approach.

Its a bit different, but has the advantage of being true.

I really do believe an intuitive understanding of QFT is a good place to start in understanding QM.

Thanks
Bill
 
After reading an intro QFT text, I don't even know what a particle is anymore, much less how we can count them.
 
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You don't count particles using QFT but a particle detector ;-). QFT describes the probabilistic counting rates, no more no less.
 

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