What do Electromagnetic waves actually look like in space?

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Discussion Overview

The discussion centers on the visual representation of electromagnetic (EM) waves in space, exploring how they are depicted and what their actual physical characteristics might be. Participants consider the nature of EM waves compared to other types of waves, such as sound waves, and the implications of their oscillatory behavior.

Discussion Character

  • Exploratory, Conceptual clarification, Debate/contested

Main Points Raised

  • Some participants question whether EM waves physically oscillate in the same manner as sine waves, suggesting that the graphical representations may not accurately depict their behavior.
  • One participant proposes that EM waves do not have a specific shape and that a single wavefront can be approximated as a spherical pulse radiating outward, transitioning to a plane wave at large distances.
  • Another participant seeks clarification on the meaning of oscillation in time and whether spherical pulses propagate in a spherical direction from the source.
  • It is noted that the sinusoidal representation of EM waves reflects the strength and polarization of the EM field rather than physical displacement, contrasting with acoustic waves.
  • A participant emphasizes that the 'wiggly line' representation of EM waves serves as a graphical tool to illustrate the amplitude and direction of electric and magnetic fields, rather than a literal depiction of their appearance in space.

Areas of Agreement / Disagreement

Participants express differing views on the physical representation of EM waves, with some agreeing on the nature of their oscillation while others challenge the adequacy of graphical representations. The discussion remains unresolved regarding the exact visual characteristics of EM waves in space.

Contextual Notes

Limitations include the dependence on definitions of wave behavior, the interpretation of graphical representations, and the unresolved nature of how EM waves physically manifest in space.

jaydnul
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I know they're represented as sine waves but what would they actually look like in space. they wouldn't actually physically go up and down and side to side like a sine wave would they? I have seen representations of sound waves, which i assume is a longitudinal wave, but not a EM wave.
 
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Well they don't really have a specific shape because they oscillate in time. But a single wavefront is just a spherical pulse that radiates outward, and at large distance from the source can be approximated as a plane wave.
 
What do you mean they oscillate in time? and do these spherical pulses propagate in a spherical direction from the source?
 
lundyjb said:
they wouldn't actually physically go up and down and side to side like a sine wave would they?

Correct, the sinusoidal component of an EM represents the strength and polarisation of the EM field, not physical displacement as in the case of an acoustic wave.

Claude.
 
The 'wiggly line' you see in representations of EM waves is not a picture of how something 'looks'. It's just a graphical representation of the amplitude and direction (vector) of the Electric and Magnetic Fields.
A similar thing can be done when plotting sound waves - which are longitudinal, of course. You can represent the instantaneous pressure at a point in space on an axis at right angles to the movement and this will also look like a wiggly line. It is not a picture of what happens but it is is a lot better way of showing what goes on than trying to draw dots and lines of different spacing, which is very difficult to do, for a start!
 

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