Much has happened in the last one hundred years to shape the way we think about heaven and the cosmos and what lies beyond:
In 1916 Einstein published his theory of general relativity: a description of how gravity is actually a geometric property of space/time. It was actually his original theory (before he modified it) that showed that the universe would expand and coalesce over time. (He did not like that implication since he believed that the universe was static and did not have an origin. So he amended his formula, only to have to change it again when it was proved that the universe was expanding) The universe as proposed by the Einstein is that space is finite and unbounded (much like the surface of a sphere, which has a finite area but no edges).
In 1927, the Catholic priest Georges Lemaître proposed that the universe began with the sudden explosion of a “primeval atom.” In 1929, Edwin Hubble gave proof of Lemaître’s theory by showing that the universe was expanding.
But it was the discovery of the cosmic microwave background in 1965 that finally pushed strong support for the Big Bang model. Cosmic Microwave Background is thermal radiation filling the observable universe almost uniformly. It was predicted to be there as a leftover of the Big Bang event. And with that being found, it left little doubt in scientists minds that the universe began with a Single event, is expanding, is finite, but unbounded.
So given our understanding of the universe and how it functions, we tend to see heaven as a plane of existence that is outside of space/time. Since it does not operate by our laws, the realm of heaven works independently from us. Heaven can interact with our world, but we may not be able to detect it. Here is a quick depiction of how we might view heaven and the universe today:
For More on our view of heaven, past and present, visit this page: Heaven