In a mountain hike, there's a moment when the horizon freezes: that's the summit of the pass. Something similar happened to our universe about five billion years ago. Its expansion was accelerating, but for several billion years the pace changed smoothly, then suddenly jumped to a sharper regime. New calculations show: it's all due to the future event horizon — the boundary beyond which light will never reach. At that very moment, its radius reached its maximum size and briefly stopped growing.

This is where the holographic principle comes into play: everything that happens inside a cosmic volume is encoded on its boundary, like on a shell. Dark energy, which pushes galaxies apart, depends on the amount of information (entropy) on that shell. At the critical moment, the slope of this entropy determined where the universe would go: if the horizon is slightly "rough," it plunges into a phantom energy state — acceleration becomes unstoppable, and in the distant future it will tear apart all matter.

Now astronomers can test this picture by observing supernovae and other distant objects. If the data confirm that the expansion rate changed exactly this way, we won't just learn about the past: we'll peer into the very 'granularity' of spacetime. So the pass left behind will tell us what lies ahead.