Zettelkasten can't replace experiments

 The main purpose of note taking is to memorize information from the past. Everything what is written in books can be converted into note cards. The ability to add new cards and retrieve existing content makes it easier to remember content read in the past. This provides to the researcher a perfect external memory of all the read information.

In spite all the advantages, note taking with the Zettelkasten principle has one major drawback: it can't replace the experiment. Experiments are used in science to gather new information not written down in the existing literature. There are physical experiments, e.g. measuring the voltage in a circuit, mathematical experiments e.g. a number crunching problem, and even musical experiments in which a new song gets composed. All these experiments are by definition not available yet so they can't be found in the existing notes. If a zettelkasten is a look back into time, an experiments looks forward into the future.

The main problem with the zettelkasten notetaking principle is that encourages the researcher to look only in the past. Creating lot of notes and read them multiple times is equal to stay within existing knowledge. This is equal to a very conservative philosophy and rejects novelty. The untold bias is that everything important was written in the past, either by the researcher itself or by other authors who have published books about the subject. And everything what is not written down in the past, doesn't exists.

In contrast, an experiment driven research project is working with the opposite principle of a Zettelkasten. The question is not what was written about a subject already, and the question is not what sort of notes are avaiable, but the question is how to investigate something from scratch without pre-knowledge. The idea is heat up water and measure at which degree the maximum is reached, the goal is to program a prototype in python and think about the difficulties. So we can say, that the limitation of the Zettelkasten has to do with the difference between past and future.