What Causes the Pixelated Snow in Night Vision?

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  • Thread starter Thread starter Loren Booda
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Discussion Overview

The discussion centers around the phenomenon of pixelated "snow" observed in night vision, exploring potential causes such as retinal cell activity, lingering images, and cosmic rays. The scope includes conceptual understanding and speculative reasoning about visual perception in low-light conditions.

Discussion Character

  • Exploratory, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant suggests that the "snow" is caused by the random firing of retinal cells, particularly noticeable against a dark background.
  • Another participant questions the role of cosmic rays in causing scintillation, asking how often they might trigger such events.
  • A further response provides a rough estimate of the frequency of low-energy cosmic rays at sea level, noting uncertainty about their impact on retinal events and suggesting they are likely too rare to be significant.

Areas of Agreement / Disagreement

Participants express differing views on the causes of the pixelated snow, with some attributing it to retinal activity while others introduce the possibility of cosmic rays, indicating that the discussion remains unresolved.

Contextual Notes

There are limitations regarding the assumptions about the frequency and impact of cosmic rays on retinal perception, as well as the definitions of terms like "scintillation." The discussion does not resolve these uncertainties.

Loren Booda
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After an hour in the dark of my bedroom, I still see points of light, like "snow" on a TV. Are these caused by present photons, the random firing of retinal cells, or lingering images?
 
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They are random firing of the cells,.
You see more of them against the dark background, unless there are enough of them to see in normal lighting it's nothing to worry about.
 
How often do you think cosmic rays would cause a scintillation to occur?
 
Lowest energy cosmic rays (still 10^9ev) are about 1 /m^2/s at sea level
I don't know what fraction would trigger an event on your retina but they are going to be rare enough (because of the area) that I don't think you would notice them
 

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