Darkness on the Edge of the Universe

"A hundred billion years from now, any galaxy that’s not resident in our neighborhood will have been swept away by swelling space for so long that it will be racing from us at faster than the speed of light. (Although nothing can move through space faster than the speed of light, there’s no limit on how fast space itself can expand.)

Light emitted by such galaxies will therefore fight a losing battle to traverse the rapidly widening gulf that separates us. The light will never reach Earth and so the galaxies will slip permanently beyond our capacity to see, regardless of how powerful our telescopes may become.

Because of this, when future astronomers look to the sky, they will no longer witness the past. The past will have drifted beyond the cliffs of space. Observations will reveal nothing but an endless stretch of inky black stillness.

If astronomers in the far future have records handed down from our era, attesting to an expanding cosmos filled with galaxies, they will face a peculiar choice: Should they believe 'primitive' knowledge that speaks of a cosmos very much at odds with what anyone has seen for billions and billions of years? Or should they focus on their own observations and valiantly seek explanations for an island universe containing a small cluster of galaxies floating within an unchanging sea of darkness — a conception of the cosmos that we know definitively to be wrong.

And what if future astronomers have no such records, perhaps because on their planet scientific acumen developed long after the deep night sky faded to black? For them, the notion of an expanding universe teeming with galaxies would be a wholly theoretical construct, bereft of empirical evidence."

We’ve grown accustomed to the idea that with sufficient hard work and dedication, there’s no barrier to how fully we can both grasp reality and confirm our understanding. But by gazing far into space we’ve captured a handful of starkly informative photons, a cosmic telegram billions of years in transit. And the message, echoing across the ages, is clear. Sometimes nature guards her secrets with the unbreakable grip of physical law. Sometimes the true nature of reality beckons from just beyond the horizon."
- posted by cjb @ 3:04 PM