Post by StuartG on May 6, 2011 21:24:36 GMT 1
Lets start with my 'frivolous' comment. The devil is in the detail, or lack of it. It doesn't state what sort of light. We perhaps infer 'white' light, but this 'light' is a fraud, it consists of all the colours of the visible spectrum [roygbiv]. These 7 colours are not neatly divided as by a line between them, but one wavelength progressively changes into the next. What Newton did with His prism was to show this 'fraud' in its true colours. These colours are given names and an arbitrary wavelength/frequency is allocated to them within the range of each. So on entering the prism the 'white' light is really all the 7 colours, now in the references it said "However, light travels slower through any given material, or medium, that is not vacuum." Ah, so there is our one bit of 'Small print' from my previous 'frivolous' statement, that's why it stated 'in a vacuum', because its velocity is slowed immediately it tried to proceed through anything of substance. The prism is substantial enough to cause a noticeable difference in its behaviour, it causes the 'white' light to be broken down to its constituent colours, which are now left to fend for themselves in this new environment. Here's an animation...
upload.wikimedia.org/wikipedia/commons/f/f5/Light_dispersion_conceptual_waves.gif
en.wikipedia.org/wiki/Prism_%28optics%29#How_prisms_work
see how the 'red-end' is bent [refracted] less than the 'blue-end'. So Newton 'nailed this fraud' now that the white light is split and the colours are affected differently dependent on their wavelength/frequency. As done on Earth, the light is in a medium of air/atmosphere before entering the prism so the velocity of light will be c divided by the refractive index of the medium [atmosphere]. So when the colours emerge back into the atmosphere they will be travelling at c divided by their refractive index of the atmosphere which is now colour dependent.
en.wikipedia.org/wiki/Optical_fiber#Index_of_refraction "The larger the index of refraction, the slower light travels in that medium."
en.wikipedia.org/wiki/Refractive_index
"Refractive index of materials varies with the frequency of radiated light. This results in a slightly different refractive index for each color."
Cheers,
StuartG
Here's some 'small print' en.wikipedia.org/wiki/Vacuum
"Physicists often discuss ideal test results that would occur in a perfect vacuum, which they simply call "vacuum" or "free space", and use the term partial vacuum to refer to real vacuum. The Latin term in vacuo is also used to describe an object as being in what would otherwise be a vacuum."
Outer space is an even higher-quality vacuum, with the equivalent of just a few hydrogen atoms per cubic meter on average.[4] However, even if every single atom and particle could be removed from a volume, it would still not be "empty" due to vacuum fluctuations, dark energy, and other phenomena in quantum physics.
Think about 'space' there are some huge clouds of gases and particles the 'light' or any em for that matter will not be travelling at 'c' and will be bumping around in the 'busier' locations.
If the prism we have spoken of were to have a twin and it was placed upside down to the other, base to base, would form a diamond shape, round off the corners, and that's called a 'lens', so that's how that works.
upload.wikimedia.org/wikipedia/commons/f/f5/Light_dispersion_conceptual_waves.gif
en.wikipedia.org/wiki/Prism_%28optics%29#How_prisms_work
see how the 'red-end' is bent [refracted] less than the 'blue-end'. So Newton 'nailed this fraud' now that the white light is split and the colours are affected differently dependent on their wavelength/frequency. As done on Earth, the light is in a medium of air/atmosphere before entering the prism so the velocity of light will be c divided by the refractive index of the medium [atmosphere]. So when the colours emerge back into the atmosphere they will be travelling at c divided by their refractive index of the atmosphere which is now colour dependent.
en.wikipedia.org/wiki/Optical_fiber#Index_of_refraction "The larger the index of refraction, the slower light travels in that medium."
en.wikipedia.org/wiki/Refractive_index
"Refractive index of materials varies with the frequency of radiated light. This results in a slightly different refractive index for each color."
Cheers,
StuartG
Here's some 'small print' en.wikipedia.org/wiki/Vacuum
"Physicists often discuss ideal test results that would occur in a perfect vacuum, which they simply call "vacuum" or "free space", and use the term partial vacuum to refer to real vacuum. The Latin term in vacuo is also used to describe an object as being in what would otherwise be a vacuum."
Outer space is an even higher-quality vacuum, with the equivalent of just a few hydrogen atoms per cubic meter on average.[4] However, even if every single atom and particle could be removed from a volume, it would still not be "empty" due to vacuum fluctuations, dark energy, and other phenomena in quantum physics.
Think about 'space' there are some huge clouds of gases and particles the 'light' or any em for that matter will not be travelling at 'c' and will be bumping around in the 'busier' locations.
If the prism we have spoken of were to have a twin and it was placed upside down to the other, base to base, would form a diamond shape, round off the corners, and that's called a 'lens', so that's how that works.