Intensity (Headlight) Effects

The effect of angular compression tends to concentrate incoming photons in front of a moving observer. This causes objects in the forward direction to look brighter, and objects behind an observer to be dimmed. This effect is compounded by time dilation, since the shutter of a moving camera will be open longer and thus collect more light. These combined effects produce a significant brightening in the direction of motion, which is called the headlight effect.

In this animation, the camera is accelerating to near light speed in a starfield. Angular compression makes the stars appear to shrink inwards to the centre of the screen, and the increasing concentration of light coming from this direction makes them brighter and brighter. As we travel faster, this effect increases until the intensity is so great that the entire view is overcome by the whitewash of light.

In many of our animations we turn intensity effects off, in order to allow other interesting effects to be seen. This means the apparent brightness of objects is the same as if there were no relativistic effects. You might think of this as what you would see if you were looking through a computer corrected video camera which compensated for variation in brightness at different angles.