|MadSci Network: Physics|
Hi Jose, I will try to explain the complex theory behind wave dynamics in simple terms: A photon can be imagined as a packet of waves. Imagine it like people travelling together in a bus. The bus speed is the group velocity and determines when the packet reaches its target. For photons, this velocity is always the speed of light. Just like people in a bus, waves can move within the packet and thus temporarily be faster or slower than the packet speed. Does the bus reach the target faster because of this? No. Unlike a bus, the length of a photon is not fixed. During its travel, it generally expands. Thus the front is faster than the back. Does an expanding bus reach its target faster? Again the answer is No. Although the front and wave velocities might exceed the speed of light, no signal can be carried by these, because we can detect only entire photons and thus have to wait until "the bus arrives" to now that we got a signal. Greetings from Indonesia, Frank Berauer
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