The concept of "observer" always bother me. It seems that a light meter, or a thermometer, are equally observers as a brain/body is an observer. WHich then boil

The concept of "observer" always bother me. It seems that a light meter, or a thermometer, are equally observers as a brain/body is an observer. WHich then boils down to something like "to interact." Time goes one way because particles/fields interact. Is this right?