The Copenhagen Interpretation of quantum mechanics warns that the theory is valid if and only if its application is limited to viable real experimental arrangements. But this warning begs the question: What type of experimental arrangement is in fact viable to observe, for example, the value of momentum? Accepted quantum mechanics gives no answer. To find an answer, we cannot help using some theory that existed before quantum mechanics (although we are often not conscious of this). This difficulty is not easy to resolve. I therefore cannot give a perfect alternative theory in the present paper; instead, I give a discussion of the issues involved. This paper amounts to a public question to many physicists and mathematicians: could a possibility exist, by working together, to perfectly understand quantum phenomena by using a new suggestion given here?
