Division by Zero (Part II)

To understand how the error occurred, we first have to understand the changes on the path of which light travels when the speed varies. Below shows a frame.

        

Frame A

In the frame, the red path shows the path of which the light beam travels when the device moves at the speed v. When the speed increases to v', instead of travelling through the red path, it travels through the orange path. The angle between the path and the ground reduces when the speed increases. So, if the device travels at 99% the speed of light, the angle between the path and the ground will be very close to zero, similar to the frame below.

When the speed reaches the speed of light, the angle will become 0 degree. The light beam could never meet A'. The light beam will take time to travel A to A'. In other words, to an observer travelling along with the device at the speed of light, time stops. This proves that 

is correct.