What is the longest wavelength ever seen by the human eye?

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In summary, the human eye's sensitivity to long wavelengths drops off significantly, with only a very low sensitivity to 800+ nm light. The longest wavelength that humans have been able to see is 852 nm, which can be barely perceived as a faint red. This is due to the fact that humans have multiple alleles for cone pigments, allowing for slight extensions of the visible spectrum. Some women may also have tetrachromatic color vision due to these rare alleles, while color blindness is caused by a lack of these alleles. However, the pigments in rod cells do not absorb longer wavelengths and therefore do not contribute to extended vision in this direction. Additionally, there is an optical problem with extending the range of visible wavelengths, as the
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Grebulous
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I've gotten curious about how the human eye's sensitivity to long wavelengths drops off. What's the longest wavelength anybody has ever seen? I know there is nonzero (but very low) sensitivity to 800+ nm light, but does anybody know the extreme long wavelength limit of human vision?
 
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My mouse has a 852 nm laser and I can just barely see a faint red when I stare into it.
 
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See this article:
http://www.iscc.org/jubilee2006/abstracts/JakabAbstract.pdf [Broken]

Humans have a lot of alleles for the cone (color) pigments, some rare ones extend the visible spectrum slightly. This also results in a very few women having tetrachromatic color vision, and it is also the root cause of color blindness. Rod cell pigments do not absorb longer wavelengths - google for the Purkinje effect - so they probably do not extend vision in the direction you are interested in.

Note: there is an optical problem with extending the range of visible wavelengths - an image that is correctly focused on the fovea (cone cells) for 500nm light willl not be focused well at 1000nm, assuming humans could see 1000nm light which they cannot, AFAIK.

See this for the 'five site rule' on the origins and evolution of color vision in mammals
http://mbe.oxfordjournals.org/cgi/content/abstract/15/5/560
 
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1. What is the longest wavelength ever seen?

The longest wavelength ever seen is approximately 10^25 meters, which corresponds to a frequency of about 10^-25 Hz. This wavelength was observed in 1997 and is associated with the cosmic microwave background radiation.

2. How was the longest wavelength ever seen measured?

The longest wavelength was measured using a specialized instrument called the Cosmic Background Explorer (COBE). It was designed to detect and measure the cosmic microwave background radiation, which is the leftover radiation from the Big Bang.

3. Why is the longest wavelength ever seen significant?

The longest wavelength ever seen is significant because it provides evidence for the Big Bang theory. The cosmic microwave background radiation, which has a wavelength of about 10^25 meters, is considered to be the earliest remnant of the universe and supports the idea that the universe began in a hot, dense state.

4. Can the longest wavelength ever seen be observed by the human eye?

No, the longest wavelength ever seen is far beyond the range of wavelengths that can be detected by the human eye. Our eyes are only sensitive to wavelengths between 400-700 nanometers, which is a much smaller range compared to the 10^25 meters of the longest wavelength.

5. Is it possible for a longer wavelength to be observed in the future?

It is possible that a longer wavelength may be observed in the future with advancements in technology. However, it is also possible that the current longest wavelength of 10^25 meters may remain the longest wavelength ever seen, as it is believed to be the wavelength corresponding to the beginning of the universe.

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