My understanding is, if you want to do proper science you should start with a certain WorldView about the Universe.
The purpose is to start with a set of definitions which we all agree about, however they can be adapted.
Starting point is that there exists a universe in time, which exists of objects (stars) which each, at any moment in time have a certain position.
Everything in the universe outside the objects is called space. Space is not empty but consists of gas and dust.
Each of these positions at each moment is called an event. This can also be described that the existance of any object in time, can be considered as a sequence of events. This can also be seen that the positions of all the objects, at a certain moment, can be considered as the state of the universe.
All the events, at a certain moment, throughout the whole of the universe are happening simultaneous.
Specific related to this document it is important that events at this moment are happening now. Compared to these events, other events have happened in the past and different events will happen in the future. It is important that the occurence of these events (In general) have nothing to do with any human activity.