The universe is constantly expanding, but it seems to be shrinking from our human viewpoint. This isn't a metaphor; it's a cosmic reality. Welcome to the concept of the "affectable universe" - the portion of the universe we can touch, send signals to, and influence, which is steadily getting smaller.
The shrinking of the affectable universe is due to a simple reason: the universe expands faster than the speed of light, which is the fastest speed we know of. This means stars over a certain distance, around 16.5 billion light-years away, are impossible for us to reach. And as the universe expands, more and more stars and planets will cross this unreachable line.
However, this doesn't mean we can't see those planets. There's another concept called the "observable universe,” which is part of the universe we can observe from Earth. As time passes, light from increasingly distant regions can reach us. So, each second, our observable universe grows, allowing us to discover stars and galaxies previously unknown to us because their light hadn't reached our planet.
The universe is vast and difficult for any single human to grasp. The contrast between the affectable and observable universe provides yet another humbling reminder of our small yet incredibly fascinating place in the universe.
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