We don’t see light until it’s reflected off something and depending on what the thing is, it absorbs some wavelengths and not others and that’s how we perceive colours. But why? How come we just don’t see all light all the time (when exposed to it)?
In: Physics
You don’t see the individual colors of the sunlight because they’re bundled.
As soon as the light hits an object, a part of it is absorbed and a part of it is reflected.
If you have LED lights at home, ones where you can set them to any color you want, you can try to make plants look black by setting the LED’s to red. Basically, take a color wheel and set your lights to the opposite color you want to black out.
By emitting only red photons, you can only perceive those reflected red photons.
If you turn your lights on and set one of them to blue, another one to red and the other one to green, you’ll see that you begin to see colors similarly to sunlight.
So, sunlight comes with all wavelengths or colors of the spectrum bundled together. From red to violet. A lens or prism makes those visible because each wavelength behaves differently. That’s why you perceive sunlight as neutral white.
What? This question doesn’t make any sense. How would you see light that doesn’t enter your eyes? We see things with light. In order to see something, light that’s bounced off it has to reach our eyes? Essentially what you’re asking is “why can’t we see light with other light” which, again, doesn’t make sense.
>We don’t see light until it’s reflected off something
Not really. We can see the light of a lightbulb (or the Sun, for that matter, although I don’t recommend it) directly by looking at it.
Basically, it’s due to how we see. Our vision works by perceiving the light that enters our eyes. Therefore, it logically follows that what we can see is limited to what enters our eyes. Most of sunlight doesn’t enter our eyes, so we don’t perceive it.
Sunlight shines down on us, so if we’re, say, looking straight forward at noontime, the light rays from the sun are (in general) passing perpendicularly past our eyes, not entering them. But those light rays strike objects around us and then get bounced in all directions, including toward our eyes, allowing us to perceive those objects.
**ELI5:** Imagine you have a cup with a sensor on the inside bottom that detects water. The cup represents your eye and the sensor represents the receptors in your eye. If you turn on a faucet and hold the cup sideways in the water, pretty much no water enters the cup because the opening is sideways, so the sensor detects no water. This is like all the light that goes past our eyes without being perceived/’seen’ because it doesn’t actually enter our eyes. Now put a spoon under the faucet to splash water everywhere. Some of it will get inside the cup and trigger the sensor. This is the light from objects around us, being reflected into our eyes.
Obviously we can only see the light that is reflected into our eyes, but as far as your premise goes, I don’t know if it’s true that we don’t perceive light that’s “not reflected”. Think about how we see brightness and darkness of colors based on what we perceive to be in shadows or not, doesn’t that dispel your idea?
Look at the sun… you’re seeing sunlight.
You can’t see rays from the side because how could you… the photos aren’t heading toward your eyes. They’re heading away from your eyes. What would you be seeing?
You can see them when they hit something because then some of the light bounces in the direction of your eyes.
We see sunlight when it hits our eyes. You can definitely see direct sunlight, ie when it doesn’t reflect off of something – when you look directly at the sun.
We don’t see random rays of light all the time because most of them don’t reach our eyes.
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