What is a thing?

“From the range of the basic questions of metaphysics
we shall here ask this one question: “What is a thing?”
The question is quite old. What remains ever new about it
is merely that it must be asked again and again"


                                                         Martin Heidegger

"Therefore, the transition from the `possible' to the `actual' takes place
during the act of observation. If we want to describe what happens in an
atomic event, we have to realize that the word `happens' can apply only to
the observation, not to the state of affairs between two observations. It
applies to the physical not the psychical act of observation, and we may say
that the transition from `possible' to `actual' takes place as soon as the
interaction of the object with the measuring device, and thereby with the rest
of the world, has come into play; it is not connected with the act of
registration of the result in the mind of the observer. The discontinuous
change in the probability function, however, takes place with the act of
registration, because it is the discontinuous change of our knowledge in the
instant of registration that has its image in the discontinuous change of the
probability function."

                                                                                      Werner Heisenberg