Lets suppose we have an object, could be a quark or proton or a chair. Is there some physics description's that we can say, If these conditions satisfy, the particle will exist. This question may seems metaphysical but I am asking in physics perspective. It seems like to me that things are exist when we observe them or we can feel their intereaction due to other things. I found this "This means that we can no longer assume that the properties we measure necessarily reflect or represent the properties of the particles as they really are. These properties are like secondary qualities – they exist only in relation to our measuring devices. This does not mean that quantum particles are not real. What it does mean is that we can ascribe to them only an empirical reality, a reality that depends on our method of questioning. Without a measuring device to record it, there is a sense in which the recognisable properties of quantum particles such as electrons do not exist" (https://blog.oup.com/2011/02/quantum/) So I believe that our observations makes things real ? .