Haven’t studied physics in years, just wondering.
Also does the same concept work for animal skin, skin being the surface?
Edit: reflects*?
Haven’t studied physics in years, just wondering.
Also does the same concept work for animal skin, skin being the surface?
Edit: reflects*?
Comments
No, because that’s simply what it means to be that color. Being able to reflect a wavelength means you are that wavelength.
A blue flower is blue because it emits relatively more blue light than other colors in the visible spectrum. It’s really that simple. Details and confusion about how absorption and reflection work don’t change the simple fact that a blue flower is blue because there’s a lot of blue light coming from it.
No. A blue flower absorbs everything but blue. That means it “is blue”, because that’s how we describe things that reflect or emit blue light.
No, the definition of “being blue” is reflecting mainly blue light.
So a blue flower is blue because of the definition of being blue.
The flower isn’t anything. When it is exposed to certain energies it will absorb some and reflect others. This doesn’t mean it has any colour properties itself; the light is doing all the work.
In the absence of light it has no colour.
That’s kind of like saying a flower is everything except a flower. Something is blue because it reflects (or emits) blue light.
Well matter doesn’t have an intrinsic color so no. Just because the petals absorbed all the red and green doesn’t make them combination red and green.
The flower is blue, because that’s what you have decided to call the color of the light that hits your retinas after reflecting off of it.
Quite the other way around. It is blue because it reflects blue light. What color something is is not defined by which wavelengths it absorbs, but rather which ones it doesn’t.
In simpler terms, it is blue because we see it being blue. That’s really all there is.
Objects that emit blue light also absorb blue light. For example, a blue LED
Objects that only reflect blue light look blue under an external white light. For example, blue paint.
We call something blue when the light reaching our eyes from that object is mostly blue, regardless of how that is happening. For example, we say the sky is blue, but that’s mostly because it scatters blue light in a different direction than other colors, rather than because of how much is absorbed/reflected. The longer wavelengths don’t get scattered as much, which you notice a lot at sunrise/sunset.
There’s a variety of ways why something can appear a certain color. You are right in some senses although the comments about “it is what being blue is” are not wrong either.
Take chlorophyll as an interesting example. It absorbs blue, reflects green and (mostly) transmits red. So leaves appear green by the light that they reflect, but have a reddish appearance when you shine the light through them (this can be made more visible by mashing them in water). And to make it even more complicated, if you irradiate chlorophyll by UV light, it will emit red light.
Besides there are some plants and fungi who have color not because of pigments (molecules with a color) but because of how lights interacts with the structure in the surface layers. E.g. the marble berry. There’s nothing “blue” in the marble berry and you wouldn’t get any blue color if you mashed it.
> Physics tell us that a surface emits the colors that it cannot absorb
Not really. Even if we take reflection instead of emission. The spectra of absorption and reflection are usually different but they can overlap, it’s not like things must 100% either reflect or absorb a certain wavelength.
But when we talk about about emission, there are substances that emit exactly the wavelength that it absorbs. Like sodium does.
there’s a lot that goes into color perception. and we have to realize that humans see only a fraction of light. what we call the visible spectrum. The range of wavelengths perceived by other animals is different. some insects perceive more blue/ultraviolet. if we use cameras that can detect those wavelengths, there may be additional patterns hidden to our naked eye, but visible to other species.
there’s many reasons why it would be a bad idea to describe something as “everything but the color you’re seeing”. and like i said, we can’t even see all wavelengths to properly describe things in this way.
should you then list out every wavelength range that was absorbed? Also, a blue led is not reflecting a blue wavelength, so now we have to differentiate between these scenarios. and then there are colors that we perceive because multiple wavelengths are exciting molecules in our eyes, that send signals to our brain. for example, pink, magenta, white.
also fun fact, blue pigments, a chemical that absorbs lower energy light but reflects higher energy light, are very rare in nature. what we tend to see as blue is usually not just a direct reflection, but some other neat physics going on.
Why is the color blue so rare in nature? | Live Science