What’s the SD with this guy? I have looked up his faster than the speed of light on the internet but came up with a lot of technical talk.
Can anyone sort it out in simple language for me?
Q.E.D
July 14, 2003, 8:38pm
2
In a nutshell: the arrival of a photon at their detector (from aalso has tails to both earlier and
From here. It’s about as simple an explanation as you’re going to find.
Gunter Nimtz was on about ‘quantum tunneling’ where objects (such as photons) can traverse a distance without passing through the intervening space.
Interesting as that stuff is it does not net you faster than light travel. There are many things that exhibit faster than light movement (such as a shadow given the right circumstances) but the real trick is if you can send information faster than light and quantum tunnelling doesn’t get you that. Indeed, it appears that quantum tunneling exhibits a sort of optical illusion of FTL travel that doesn’t pan out upon closer inspection (this is mentioned in my quote below…follow the link for other ‘problems’ with supposing FTL travel in this manner).
To understand what is happening, we need to go back to the wave packet description of photons. The wave packet represents a probability distribution where the peak corresponds to the most likely position of detecting the particle. However, because such wave packets are spread out, there is a chance of detecting the particles in other places which means some photons will appear to arrive early and some will arrive late. Now when a photon approaches a barrier such as the optical filter, what happens is that the first part of the wave passes through the barrier relatively easily compared with the rest of the wave packet. The result is that the photon wave packet gets reshaped, so that its peak is shifted closer to the front. When raced against another photon travelling though air (or a vacuum) the leading edge of both wave packets arrive at the same time. However, because of reshaping the tunnelling photons appear on average to arrive earlier than their non-tunnelling partners. This gives the impression that they have travelled faster than light. The reason the first part of the wave packet passes through the barrier more easily than the rest of it is that it takes a little time for the optical filter to block transmission. The filter works by building up coherent multiple reflections between its different layers. These reflections produce interference patterns which block transmission. But when the wave packet first arrives it takes a while to establish these patterns. In other words, preferential treatment of the leading edge of the wavepacket creates a sort of “optical illusion shifting”, the transmitted peak earlier in time (see Diagram). This is another reason why it wouldn’t be possible to send a signal faster than light. "To send a signal a you need to open a shutter or do something to make a sharp break in the wave packet, says Chiao. “No matter how much reshaping a barrier produces, the wave peak can never overtake the front of the wavepacket.” So it is this that really determines how quickly you can send a signal. No amount of wave reshaping will make the front of the wave packet arrive earlier than expected.
SOURCE: http://www.socorro.demon.co.uk/gunter.htm