I always ask those that claim the cosmos is FINITE to explain what is beyond "The Barrier". No matter what they answer - heaven, another universe etc, I always answer by asking is THAT finite too? Of course they usually look at you blankly like kangaroos in spotlights right before the bullet...
A vast emptiness that created something out of nothing (where did the atoms come from to start with?), and now we are swimming in this sea of matter and anti-matter, energy and dark energy perpetually ad naueum ad infinitum.
I like the idea some have posited before of what if we are the cells of another life-form, and we are simply looking out into inter-cellular/peri-plasmic space... just as a virus would when inside the much larger microscopic cells (look up images of viruses and be amazed how geometric they are, as well as there functional capabilities). And then that larger life-form is inside another life-form and so on for infinity
I used to be kept awake at night trying to comprehend the Cosmos (and of course, failing) as a kid - it is what got me interested in astronomy.
And when you think of the complexity of the idea, and try to ponder ALTERNATIVES, you realise that any alternative is just as bewildering and infinite.