Is Infrared Light Invisible to Humans Due to Eye Limitations?

[gehrenfeld]

I am 74yo and love Physics.
If my basic knowledge of physics is correct, light is a photon.

My question is:
1. Is the reason we cannot see infrared light because the spectrum travels at a wave link our eyes cannot see?
2. Does the light from the sun have all the different waves combined, and we only see one frequency, or are all the waves separate?

I hope my question made sense.

 

[PeroK]

My question is:
1. Is the reason we cannot see infrared light because the spectrum travels at a wave link our eyes cannot see?

Yes. See, for example:

https://en.wikipedia.org/wiki/Visible_spectrum

2. Does the light from the sun have all the different waves combined, and we only see one frequency, or are all the waves separate?

https://en.wikipedia.org/wiki/Sunlight#Composition_and_power

 

[gehrenfeld]

Thank you.
I learned a great deal from those articles.

 

[DaveC426913]

More specifically, the reason we can't see infrared is because our retinas have cone cells with proteins that are sensitive to a small range of the spectrum, and they are not stimulated by light in the IR range. (off the right side of the graph - wavelengths > 750nm):

https://en.wikipedia.org/wiki/Color_vision

This explains why some animals can see in other parts of the spectrum - they have different proteins.