Observations represent the truth, models…

In the last year during a larger meeting I had made a comment, which let a lot of attendees shake their head and others just smile. The statement was:

“Observations represent the truth, models the state of our understanding.”

Like I have said before, on the first sight it is of cause rubbish that observations have anything to do with the truth. Indeed, truth is a great word with many different meanings and implications. In the context above “truth” (which anyhow should always set between quotation marks) describes the possible best estimation of the real world by the current available technology in real case situations. When I personally write things up, I usually use a measurement operator to make this clear that observations are never able to describe the full reality. How much effort observers might put at it (and they usually do an amazing job), the real physical state of a physical system can only be approximated. Continue reading