TT speed

 I am still thinking tracking error, but the aspect of speed throws me off that idea. 

OP, Though I couldn't get what you were describing, it finally came clear when larryi posted. Whether it matters or not, it still is something that I had never considered before. A new thought for me. I very much appreciate discussing or learning about these sorts of topics. 

It still twists my mind, but I enjoy the talk. Thanks. It is almost like an original thought for me that now will be a challenge to analyze.

 I see different perspectives here that don't jive. One aspect can be true from a certain perspective, but to change the perspective may be not to disprove the first, as it may seem. The second perspective may not be in line with the subject as was first supposed.

 Then there are of course those who chime in with what seems to be relevant but is not.

  Just thinking out loud here. Appreciate the thread.

 I know, it is a small number, but just the thought made my brain explode. I doubt that I will understand it. This course of logic doesn't come easily to me, and so that may be the reason it fascinates me. 

 The things that we may never understand (speaking for myself really) don't defy observation of occurrence, just maybe the ability to understand.

It bears repeating. This was very cool discussion to me. It begs the observation of even daily life. We see what we see, but do we?

  Thanks so much for keeping civil a topic that was entertaining and informative.

   Cheers, Greg >>>>>>>> P.S. Don't forget to think.