Is There a Connection Between Rainbows and Holograms?

  • Context: Undergrad 
  • Thread starter Thread starter skynelson
  • Start date Start date
  • Tags Tags
    Rainbows
Click For Summary

Discussion Overview

The discussion explores the potential connections between rainbows and holograms, focusing on their properties, underlying physics, and mathematical comparisons. Participants examine the nature of light, coherence, interference, and diffraction in both phenomena, considering theoretical implications and practical observations.

Discussion Character

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

Main Points Raised

  • One participant suggests that rainbows share similarities with holograms, noting that both involve coherent light and wavefront emergence, despite differences in their underlying physics.
  • Another participant references an article discussing rainbows, asserting that they are not 3D objects and do not cast reflections, which contrasts with holographic properties.
  • A participant argues that rainbow light is not coherent and questions the validity of describing it as a hologram, emphasizing that holograms are fundamentally based on interference patterns.
  • Another viewpoint states that rainbows result from dispersion and internal reflection rather than interference, suggesting that the phenomena are fundamentally different.
  • One participant proposes that the lack of literature comparing holography and rainbows may indicate that the two phenomena are not related, cautioning against premature conclusions without thorough exploration.
  • Discussion includes the concept of supernumerary bands in rainbows, which some participants relate to diffraction effects, while others emphasize the broad nature of the diffraction pattern due to the small size of raindrops.
  • One participant raises the question of spatial coherence in sunlight, suggesting that it may not be entirely accurate to label rainbow light as spatially incoherent, citing research on coherence properties.
  • Another participant discusses the nature of interference in relation to holograms, noting that interference can occur without diffraction, and raises the idea that the fundamental aspect of holography may not solely rely on diffraction.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between rainbows and holograms, with no consensus reached. Some argue for similarities while others emphasize fundamental differences, particularly regarding coherence and the role of interference.

Contextual Notes

Participants note limitations in the discussion, including the complexity of coherence in sunlight, the definitions of interference and diffraction, and the need for further exploration of the mathematical relationships between the two phenomena.

  • #31
hutchphd said:
I believe these are sun dogs
I think what is shown is a halo. These are associated with sun dogs, which, afaiaa, are more describable as distinct images of the Sun. It's all the same sort of phenomenon and, because ice crystals have specific angles between faces, they tend to be seen at particular angles as the crystals mostly orientate in the same plane (floating down with the side face horizontal - like falling leaves), which localises the image. Perhaps the halo is due to very small crystals that do no orientate horizontally. The order of the colours seems to be that red is in the inner band - moving out to blue but there is a clear cyan band beyond. Cyan can be described as 'minus red' (i.e. green plus blue). That seems to imply that there is a much bigger range of dispersion than what spherical water drops produce.

Edit later - this is probably rubbish: I misinterpreted the video - but the video is still interesting. This Nasa link is interesting and can account for a lot of claimed UFO sightings. The sun dog seems to be zapping across the sky at amazing speed. Just what the enthusiast want to see!
 
Science news on Phys.org
  • #32
hutchphd said:
I believe these are sun dogs
There are no sun dogs in that photo from Tom
 
  • Like
Likes   Reactions: Tom.G
  • #33
davenn said:
There are no sun dogs in that photo from Tom
True. It's a 'candidate situation' for sun dogs but the ice crystals are not aligned anywhere so all you get is a halo, from reflections at all angles in all places. To get a distinct image, a large proportion of the crystals need to be aligned (as I have read - horizontal like falling leaves) and that will produce a sharp reflection image.

Where I live in the UK I never see sun dogs, despite looking at the sky a fair bit. That's a shame but, with the prevailing winds from the West (Atlantic) , we do get some interesting clouds and cracking sunsets. Flat country and massive skys have their own charm.
 
Last edited:
  • Like
Likes   Reactions: hutchphd

Similar threads

MATLAB How Do You Create a Hologram Using Matlab?
  • · Replies 1 ·
Replies
1
Views
10K
Graduate Rayleigh criterion when light phase is known
  • · Replies 4 ·
Replies
4
Views
4K
Graduate Birefringence and Automotive Window Tinting
  • · Replies 9 ·
Replies
9
Views
8K
Undergrad Overview of General Fresnel Equations + Complex IORs
  • · Replies 6 ·
Replies
6
Views
4K
Graduate The holometer - experimentally testing the holographic principle?
  • · Replies 8 ·
Replies
8
Views
8K
Alternator torque when connected to a phase-shifted AC source
  • · Replies 3 ·
Replies
3
Views
2K
Graduate Interference of a bunch of incident electromagnetic waves
  • · Replies 1 ·
Replies
1
Views
2K
Graduate Twistors and celestial holography
  • · Replies 21 ·
Replies
21
Views
6K
Undergrad Non-locality by memory (Jung, 2020) applied to stochastic mechanics
  • · Replies 5 ·
Replies
5
Views
2K
Medical The Human Mind and Predicting Behavior
  • · Replies 3 ·
Replies
3
Views
7K