Bob Klahn ---> MALTE SCHMIDT AM 31.01.06
BETREFF: *Days of Future Past*

Hi Bob!

BK>>>  is moving at the speed of light, and, as it is detected, it is
BK>>>  one light second from science station y, and two light seconds
BK>>>  from science station x.
MS>> Not that it matters, but how would they detect it? You
BK>  Govt surplus sensors from the first Enterprise when they
BK>  scrapped it. Remember, these are space stations.

ah, yeah. Subspace, I forgot about that. Got me there...



BK>>>   second between crossing y and crossing x. That is, the wave
BK>>>   front covers the 10 light seconds between y and x in one
BK>>>   second, yielding a speed of 10 times the speed of light.
MS>> That scenario is as if you take two trains. One starting in
MS>> A and going to C, while the other train starts in B and is
MS>> going to Station D. If those two trains (=photons) arrived
MS>> at the same time at station C and D respectively, that
MS>> still wouldn't mean that trains can go infinitely fast. You
MS>> are not talking about the same photon(s) that have been
MS>> measured at both stations.
BK>  No, but the trains also cannot close the distance between C and
BK>  D while traveling between A and C in one case, and B and D in
BK>  the other.

What I wanted to tell you with the analogon is, that the trains have as  
much in common as do the photons. The name "wave front" is a human term,  
how shall the photons know that you want them to be one structure.
At least at low intensities the photons do not interact. So you have more  
or less a swarm of qm-particles not knowing of each other. So there isn't  
really anything travelling from C to D or between those two space  
stations.


MS>> With all the probability wave junk from quantum physics you
MS>> can create much more difficult problems to solve.
BK>  Except that this is a real world situation.

Well, those problems are real also. Otherwise it wouldn't make much sense  
discussion them.


[..]
BK>  If you want to break the wave down into 'quanta', while it isn't
BK>  the same 'quanta' traveling between x and y, there is no way you
BK>  can tell them apart. So, effectively, for purposes of microwave
BK>  communication, it is as if the wave covered those two points at
BK>  10 times the speed of light.

I disagree or do not quite understand what you want to tell me.:-)
Maybe it is even just a picture they want to give you and their intention  
was not to show that something can go faster than the speed of light?

But about the not being able to tell them apart. That is of course  
correct. I don't know which photon has been measured. But I do know, that  
it wasn't the same twice, that should be sufficient.

Maybe you are talking about the collapse of the wave function of the  
photons? That is theoretically indeed an instantaneous process. But that  
does not mean, that a photon can travel infinitely fast. The photon is not  
really at one moment at space station y (when we measure one of his fellow  
photons) and one sexond later at space station x, when we measure it.

Bye,
Malte!
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