While measuring, you can deal with here and now or then and there, but it is impossible to deal with there and now.
There are many quantities we try to measure, which are equally entangled (energy, mind, brain etc). Such mundane measurement as knowledge is also lost nowadays. We cannot analyze our dinner and eat it. We cannot dissect the mathematics underlying Mozart and at the same time fill the emotional impact.
In accordance with quantum mechanics your choice determines and influences your measurements., You can imagine a spinning coin to prove that. To measure whether it is head or tail you must stop it (force the coin to choose one side).
Those things, which are integrated in groups make measurements difficult and even deceptive. In this case it is possible to measure only average meaning, not concrete information. And averages can’t represent an individual.
All measurements go with an error bar-a graphic that helps to determine a probable error you are dealing with. If an error bar is larger than the measurement itself, it means that the measurement can’t be taken very seriously. Still, there are many scientific works, which have huge error bars. Usually scientists ignore this fact and don’t make necessary amendments in their conclusions. The most common example is an intelligence test (IQ test), where the score has an error plus or minus 3