Different type of Universe

Imagine an environment inside a fluid, that send messages using phonons, pressure waves. Each movement of parts of some matter lumped together, say marbles immersed in water. Suppose two marbles, freely moving image the water  strike together. Moving marbles will emit phonons. Suppose there is an observer immersed in the water. Imagine how this observer will preserve the environment around it. It will know that by phonons that strikes it what ours happening around it. When two marbles strike and start to move in different directions, the observer  who is in a different location, other than the location of collusion, will have knowledge of the collusion by sensing the pleasure waves. The observer will have knowledge of what is happening around it from pressure waves. Like a subm arine know it's environment by the pings reflected.
Imagine how the size of an object is measured here. How relationship of two events are perceived here. Which happens before and which after.
Simaltanity do not exist here. But the observer will get an idea of all what is happening around it. It will have a crude idea of before and after. But nothing will be definite. To know about before and after submarine's clock need to be used. This is very similar to the brains clock inside it. Events will be happening around us, but we need our brains clock to organise these events. Each observer will organise it differently. There will be no universal structure of the happenings around us. There is no before and after. No larger and smaller. No far and near. The brain using the messages it get to organise what happen around us.
Therefore we can definitely say that things happen around us, but we cannot compare these without message carriers like photons. Therefore the world we see using these comparisons is not definite. Not fixed, it is fluid. Our comparison of two astronomical events, say big bang and the present, is observer dependent.

What would be like teaching geometry to a dolphin?

If you receive two pings there are two objects. Number of objects depends on the number of pings.