Are light waves/ EM waves damped?

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Discussion Overview

The discussion centers around the nature of light waves and electromagnetic (EM) waves, specifically addressing whether these waves are damped as they travel through space and the implications for visibility of distant objects. Participants explore concepts related to amplitude, intensity, and the behavior of light over distances.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • One participant suggests that light waves dampen as they travel, leading to a decrease in amplitude that makes distant objects difficult to see.
  • Another participant argues that light does not lose strength in empty space but rather spreads out, which results in a smaller amplitude when it reaches the observer's eyes.
  • A later reply emphasizes that the energy of light spreads over a larger area as distance increases, which affects visibility, rather than intrinsic damping of the waves themselves.
  • It is noted that collimated light sources, like lasers, can maintain intensity over longer distances, suggesting a lack of intrinsic damping.
  • One participant provides a mathematical perspective on how to calculate the fraction of light from a star that reaches the observer's eye, highlighting the geometric considerations involved.

Areas of Agreement / Disagreement

Participants express differing views on whether light waves are damped. While some argue against intrinsic damping, others propose that the perceived decrease in visibility is due to spreading rather than damping. The discussion remains unresolved with multiple competing views present.

Contextual Notes

Participants reference concepts such as amplitude, intensity, and photon distribution, but there are no settled definitions or consensus on the mechanisms at play. The discussion includes assumptions about the behavior of light in different contexts, such as collimated versus non-collimated sources.

Who May Find This Useful

This discussion may be of interest to those exploring the properties of light and electromagnetic waves, including students and enthusiasts in physics and optics.

Arup Biswas
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We can't see objects from objects far away from us. Why? I think light waves damps! When it reaches our eyes it's amplitude is too small to be visualised! Is this true? If indeed EM waves are damped then why? If not please give a suitable definition for the mentioned phenomena too !
 
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Light traveling through empty space does not lose strength (although it does spread out). The wikipedia article on "tired light" is a good start.
 
Last edited:
Arup Biswas said:
We can't see objects from objects far away from us. Why? I think light waves damps! When it reaches our eyes it's amplitude is too small to be visualised! Is this true? If indeed EM waves are damped then why? If not please give a suitable definition for the mentioned phenomena too !

It is not damped. It is because the energy gets spread out over a wider area that the amplitude becomes small (in QM terms, the number of photons per unit area becomes smaller) as it goes further from the source. Why do you think a light bulb is harder to look at with your eyes when you are an inch away, versus when you are 100 meters away?

If you have a plane wave, collimated light source, such as a laser, then the intensity or brightness can be preserved over longer distances, and it will be as bright 1 inch away as well as 100 meters away. This, this is easily an indication that there is no intrinsic damping.

Zz.
 
Thanks ZZ I got your point [emoji5][emoji5] At least for now this much will help me to progress [emoji5]
 
Last edited by a moderator:
You can work out what fraction of the light from a star reaches your eye. It's the area of your pupil divided by the area of a sphere with a radius equal to the distance to the star. It's a wonder any photons make it.
 

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