"every measuring instrument introduces additional noise and possible distortion into the signal." #readingToday
It's clear from Shannon's model that every time we introduce a new message channel, there is the possibility of more noise and distortion of the message, leading to greater uncertainty about what to do with the information. Noise is a transmutation of one symbol into another. Thus every measuring instrument introduces additional noise and possible distortion into the signal. There is even a case to be made for saying that the transducer is an intended distortion to the standard scale: a helpful distorting translation that we hope is performed reliably. In using distortion as a tool, we now have a distinction between intended and unintended transitions.
The Search for Certainty, Mark Burgess, 2013