Q:

Conceptual accuracy of analogy of special relativity

I was trying to explain how objects can’t travel faster then the speed of light to myself the other night. I then remembered that Richard Feynman has stated that information, not objects, can’t travel faster than the speed of light. I finally found a way to explain it to myself and was wondering if it was fundamentally accuracy.
Say a particle travels distance D in 1 second. By traveling this distance in 1 second, the particle goes faster than the speed of light. Of course, one would not be able to know this, because information can not go faster than light. 
Now, Alice suspects that the particle has traveled distance D to Bob. However, the fastest she can communicate her concern is by using light or radio waves. She uses one of these methods. Bob confirms that the particle has traveled distance D. However, in the time that Alice has taken to gather the information, enough time has passed that the particle would have possibly traveled less than the speed of light. 
Even though a particle may travel faster than the speed of light, the only way to measure this is by using a method that travels less than the speed of light. Because of this, it is impossible to know for sure that it went the speed of light. It is equally likely that it went at the speed of light. 
Even though the particle may have traveled faster than light, the information could not have. Because the information can not travel faster than light, there is no way to know if the particle went faster than the speed of light. The possibility can not be ruled out, however.
Is this analogy conceptually correct? I am not worried about whether it is fully correct. I am asking if it demonstrates why information can not travel faster than the speed of light.

A:

In principle, there would be no problem in measuring the speed of something  that travels faster than the speed of light. You can have two clocks at different distances and a person on each clock stops the watch when the object passes next to him. 
There is a problem with this because it would obviously allow to transfer information at faster the speed of light. It can be shown that, If you could transfer information faster than light, then you could send information to the past, causing lots of paradoxes. One of the possible ways out of this paradox is that tachyons cannot interact with normal matter in any way, which in the example above means you cannot measure its speed because you cannot even see it or detect it. I believe this is the standard view today, but not everybody agrees with it.

