Mister Qwerty
kiwifarms.net
- Joined
- Apr 11, 2018
If a tree falls in a forest and no one is around to hear it, does it make a sound? It depends on your definition of the word "sound". In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid. But it is also defined as vibrations that travel through the air or another medium and can be heard when they reach a person's or animal's ear. There are also sound waves that are not audible to humans (ultrasound and infrasound).
If a tree falls in a forest and no one is around to hear it, is the tree trunk and branches brown? That's more difficult to answer. You need 3 things in order to see colour: light, an object, and an observer.
Colour in not in the object. Colour only exists with (observed) light. Without light there is no colour (if you're in an enclosed room with no lamp or windows a red ball is black, along with everything else in that room). An object absorbs all other colours of the spectrum other than what it reflects back (white reflects almost all the light it falls on it, black absorbs almost all the light that falls on it). But these colours are not seen unless there is an observer with eyes to recognize it as colour.
Light goes into the eye through the optic nerve to the visual cortex which is located all the way back to the rear of the brain (you would think it's located behind or near the eyes but it's not).
If a tree falls in a forest and no one is around to hear it, is the tree trunk and branches brown? That's more difficult to answer. You need 3 things in order to see colour: light, an object, and an observer.
Colour in not in the object. Colour only exists with (observed) light. Without light there is no colour (if you're in an enclosed room with no lamp or windows a red ball is black, along with everything else in that room). An object absorbs all other colours of the spectrum other than what it reflects back (white reflects almost all the light it falls on it, black absorbs almost all the light that falls on it). But these colours are not seen unless there is an observer with eyes to recognize it as colour.
Light goes into the eye through the optic nerve to the visual cortex which is located all the way back to the rear of the brain (you would think it's located behind or near the eyes but it's not).