You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Materialism

Context:
With the advent of quantum physics, some scientists believed the concept of matter had merely changed, while others believed the conventional position could no longer be maintained. For instance Werner Heisenberg said "The ontology of materialism rested upon the illusion that the kind of existence, the direct 'actuality' of the world around us, can be extrapolated into the atomic range. This extrapolation, however, is impossible... atoms are not things." Likewise, some philosophers[which?] feel that these dichotomies necessitate a switch from materialism to physicalism. Others use the terms "materialism" and "physicalism" interchangeably.

Question:
Werner Heisenberg suggested that atoms are not what?

things