Wednesday, 28 January 2009
Diamonds Are Forever
The speed of light in a vacuum is 186,000 miles per second. But when light travels through a diamond it can be slowed to speeds of 80, 000 miles per second. If you look closely at a faceted diamond (fat chance I get) you can see that it soaks up white light and breaks it apart like a prism, dispersing it into a rainbow of colours. Prisms made of glass work on the same principle. We are taught that as light enters the prism it slows down, and then re-emerges at its previous speed, but now it is made-up of all the different colours of the spectrum. The components of white light get refracted by different angles and follow different paths within the prism. The phenomenon due to which white light splits into component colours is called dispersion.
The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye. A typical human eye will respond to wavelengths in air from about 380 to 750 nanometers. A nanometer (nm) is one billionth of a meter. The wavelength is defined by the distance travelled by the speed of light in one second. The visible spectrum begins with the shorter wavelengths of violet at 400 nm. So we are saying that violet light travels 400 billionths of a meter, about 400 million million times a second (400 terahertz). From this relationship one can conclude that the wavelength of light is inversely proportional to frequency.
We are taught that upon entering a new medium (such as glass or water from air) the speed and wavelength of light is reduced, although the frequency remains unaltered. The speed of light travelling through window glass is around 120,000 miles per second, and I shall use this same speed for the light passing through the prism. 120,000 miles per second is two thirds the speed of light in a vacuum. If the frequency remains at 400 terahertz, then the slower moving violet light shall form wavelengths which are one third shorter - that's something like 266 nm; but this is the size of shortwave UV light and it's outside the visible spectrum! The angles of refraction impose that the light which appears as violet inside the prism, is the exact same which emerges once again into the medium of the air. The violet light, once outside the prism, is restored to its normal speed (around 180,000 miles per second) - but with no obvious change in its wavelength or frequency. If the wavelength and frequency of the light has remained the same, then it is the velocity at which the wave propagates that has changed.
Science dictates that the mechanism by which a light wave is transported through a medium occurs in a manner which is similar to the way that any other wave is transported - by particle -to -particle interaction. In a vacuum the light can travel at its top speed because there are no particles to slow it down. The speed of light is supposedly slowed down by the optical density of a medium. The optical density of a material relates to the sluggish tendency of the atoms of a material to maintain the absorbed energy of an electromagnetic wave in the form of vibrating electrons before re-emitting it as a new electromagnetic disturbance. The more optically dense a material is, the longer it stalls light moving through the material (one indicator of the optical density is the index of refraction value of the material).
I struggle with this current theory. Light travels just fine through a vacuum without being passed from atom to atom. Is it possible that light is actually propagating through a medium that is inside the vacuum : the aether field? If light travels through the aether, why would it choose to switch travel plans in a medium (such as glass or water), and instead travel from atom to vibrating atom? The speed of light must remain the same inside the prism because the wavelengths, and frequencies throughout the spectrum are consistent with those outside the prism. What illusion is taking place that makes it appear as if light is slowing down inside the prism? One possible explanation is that if the speed of light does not change inside the prism, then it is the aether field which is being stretched.
There is one more question which arises out of a simple curiousity - why is it that as the light exits the prism, it is always pointing down?