But Poster He or I said that the colour of light is frequency, not speed, and then, Scott, the admin went on supporting what Poster He or I have said.
And because of your words, I have asked myself this question many times; what is colour? Is colour frequency or is colour the speed of light? Or is it both?
This question may not be simple, because I feel one difficulty may be that light is too fast for us to see, so when I write about light, I am writing about something that is I cannot see, so it may not be easy.
But then, another person asked: “If you cannot see it, then what are you writing about?”
Well, I used the observation of sun; tomorrow have not yet happened, but it is because from past observation, you have seen the sun rises again and again, so you feel it is possible that the sun will rise again the tomorrow, even though tomorrow have not yet happened.
So as light, we cannot see the speed of light because it is too fast, but I feel I can use my past observation to write about the possibility of how light can behave, which may not be easy.
Let me begin with the question: What is frequency? Frequency is how frequent or how many times it appears, right? So if light travels as a wave when it is subjected to external force, the light wave is just like the wave you see in a river or in an ocean.
When you look at a sea, there are many waves. Each wave is like a mountain. And a stream of waves is made up of many mountains. So when there are many waves forming a stream, it is just many mountains. The image I am describing now is perhaps like a picture for you to see what is a light wave.
Now, back to the question: What is frequency? I have said that light travels like a wave in ocean if it is subjected to external force. The frequency of the light wave is dependent on how many waves there are in a fixed distance. So if there are more waves in a fixed distance, then, there is more frequency. If there are less waves in a fixed distance, then, less frequency.
So now, from my descriptions, you have a better picture of waves, frequency and how light travels.
Now, it may be true that if there is a light that hits certain object, the speed of light will change because of the external force. But the question is: If the speed of light changes when it hits an object, will the frequency change?
Yes, it is possible that the frequency may change if light hits an object. Maybe the wavelength may change.
But the thing is: When light hits an object, maybe there is little change to the wavelength, but the speed of light may change much more than the wavelength. And now, if you look at the waves in ocean, if the wavelength is the same, the faster the waves, then, the more frequency, if the wavelength does not change.
So this is why when a light hits an object, maybe there is little change in wavelength, however, the speed of light may change much more than the wavelength, and so there is also more change in the frequency than the wavelength.
But why is it that the wavelength will change a little?
Using the image you see in ocean, you will feel that no matter how fast ocean waves travel, there is always just little change in wavelength, or at least, the proportion of the speed that ocean waves accelerate will always be much larger than the change of wavelength.
Now, if light wave is just like the wave in ocean, so, this is why when light hits an object, there may be little change in the wavelength, but there may be more changes in the speed of light and frequency.
So now, if you have the picture of what I am talking about, you will feel that colour has to do with the speed of light. But is colour the speed of light or is it frequency?
Maybe colour is frequency or density. Why? Because what is colour?
Colour is the characteristic of light, and it can be red, purple, blue, yellow and so on.
So colour is just a characteristic of light. Now, what is the characteristic of light?
The characteristic of light is density, how compressed light is.
So density is how compressed a thing is, and because the characteristic of a thing is how compressed it is, such as the characteristic of gas is less compressed than the characteristic of a solid.
So colour is density, and density is the same as frequency if light travels.
Because if the speed of light does not change, then, the more density, the more frequency.
So colour itself is density, and the colour of light wave can be determined by its frequency.
And because there is little change in wavelength if light changes its speed; if light changes its speed more, then, the more frequency will change.
So even if the speed of light is not colour itself, but, the changes in the speed of light may change the colour of light if it hits an object.
Do you agree?
Secondly, I want to say here, that even though light travels like a wave when it is subjected to external force, light is still a particle, where light waves are made up of particle, so to me, light is still a particle when it travels like a wave. But if light is not subjected to external force; light that is moving in a straight line will move on forever in a straight line if it is not subjected to external force, because of inertia.
Do you agree?