Luminosity is the amount of light that is radiated from a star. White light is the composition of all colors. In elements, the energy discharge can be displayed as light. Just by looking at the colors that are discharged, one may precisely identify the element. In understanding the universe, the Doppler effect is one of the most important tools. The Doppler effect is a shift in frequency due to a moving source. Skipping a rock on water would be an example of this effect. The circles would be off center because the rock is a moving source. The wavelength is shorter when the rock is coming toward an individual. Also, the frequency will increase and the wave crests will shorten. When the source is moving away from an individual, the wavelength increases and the frequency decreases. This principle is identical with light. In a rainbow, the longest wavelength is the red portion and the shortest wavelength is the violet portion. If a body is emitting light and it is approaching someone, we would say the radiation is blue shifted. A red shift, on the other hand, ocurs when the emitting object is receding, or when a spectrum is shifted to longer wavelengths. Hubble measured that the farther the distance of a galaxy is from us, the greater the red shift, which is Hubble's law. In fact, galaxies possibly could be receding from us as fast as the speed of light. The greater the distance of a galaxy, the greater its velocity. The universe is constantly expanding in all directions. There is a raisin cake model to explicate this, considering the raisins to be the galaxies and the cake being the space between. The raisins are uniformly distributed throughout the cake, just as the galaxies are throughout the universe. If we bake the cake, as it rises the raisins will spread farther apart from one another. The neighboring raisins, closest perhaps to the one in the center, would not move as fast as ones farther away because there...
