Physical Reality in Motion: Space and Time as Co-Present Attributes of Matter

Contemporary debates classify spacetime as substance, relation, structure, field, or functional role. This article develops an open materialist reconstruction that distinguishes the ontological subject of physical existence, its necessary mode of existence, and its essential attributes. Matter is the ontological subject; motion is its necessary mode of existence; space and time are objective, essential attributes co-present in matter’s existence in motion. Determinate material existents concretely bear and manifest these attributes. Five coordinated propositions articulate this structure without causal or deductive ordering. Dialogues with relativity and quantum gravity test its scope while preserving the distinction between physical reality and theoretical representation. This is a preprint version and has not yet undergone journal peer review.