Infrared Remote Controls & Red Light: How Fast Does It Need To Go?

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Discussion Overview

The discussion revolves around the effects of Doppler shift on infrared light emitted from a remote control when it is moving towards an observer at high speeds. Participants explore the conditions under which infrared light might shift into the visible spectrum, particularly focusing on the speed required for such a shift to occur.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant questions whether the frequency of electromagnetic waves emitted by an infrared remote control would increase if it were moving quickly towards the eye.
  • Another participant humorously suggests that the emotional state of the person throwing the remote control could influence the situation, but acknowledges that the Doppler shift from a human throw would be insufficient to make infrared light visible.
  • A later reply reiterates that a typical throw would not generate enough Doppler shift to make infrared light visible, suggesting that a mechanized device would be necessary to achieve such speeds.
  • One participant proposes the idea of a "Doppler roller-coaster" where humans could experience color changes due to speed, while also noting that sound is a more straightforward application of Doppler effects compared to light.

Areas of Agreement / Disagreement

Participants generally agree that a human throw would not produce sufficient Doppler shift to make infrared light visible, but there is a playful debate about the implications of speed and emotional context. The discussion remains unresolved regarding the feasibility of achieving visible light through Doppler effects in practical scenarios.

Contextual Notes

Participants mention limitations related to current technology and the need for mechanized launching devices to achieve the necessary speeds for significant Doppler shifts in light.

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What happens if an infrared remote control is pointing and coming at your eye really fast while transmitting... would the frequency of the em waves increase? If so, how fast would it need to be traveling in order to appear red?
 
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How angry is the boyfriend/girlfriend that is hurling the remote control at your face?
 
Seriously though, the angriest of all angriest boyfiends/girlfriends could not cause enough Doppler shift to cause the infrared light to appear visible simply by hurling it at your face, without some sort of mechanized launching apparatus such as a highly sophisticated rail-gun or some such, which is beyond our present technology. On the other hand, a very angry boyfiend/girlfriend, might be able to hurl a well aimed remote control at your head such that you see red after the fact.
 
collinsmark said:
Seriously though, the angriest of all angriest boyfiends/girlfriends could not cause enough Doppler shift to cause the infrared light to appear visible simply by hurling it at your face, without some sort of mechanized launching apparatus such as a highly sophisticated rail-gun or some such, which is beyond our present technology.
Hey! I wanted to make a Doppler roller-coaster, with humans having enough speed to see the same colors through all the trip while the light itself did change.

Anyway, the easiest way to use Doppler's is for sound, not light. If you research enough the topic of light you could end up getting a Nobel or banned from PF :smile:
 
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