On cosmic scales, humans are extremely fragile. Made of mostly water, our bodies are soft meat bags with surprisingly malleable minds, both of which are easily damaged in ways most difficult to heal.
And we don't live long.
Among other things, this means even our most advanced means of propulsion are incapable of transporting humans to other stars in a single lifetime. This is because even the closest stars (like Proxima Centauri) are unconscionably far away — so far that to reach them, we'd need colossal amounts of energy, and a ship capable of supporting human life for thousands of years as generations are born, live, and die in endless succession, like a master's thesis on existentialism.
However, there's a way around the pitfalls of human frailties, and the abyssal depths of time and space. For example, the idea of wormholes offers a theoretical gateway connecting any two points in space and time with one another, like a cosmic bridge.
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