For generations, when we looked out at the distant stars, we could only wonder whether there were planets and the conditions for life-as-we-know-it around them. The past 25 years have brought forth a revolution in planet-finding, with thousands of known, confirmed planets, including many of potentially habitable, Earth-like worlds. But could we ever get there? Reader C. Vidal wants to know:

Do you think interstellar travel is possible (by any civilization). It seems to me that all possible solutions are one way trips.

When it comes to interstellar travel, I definitely do think it’s possible. But there definitely are constraints, dependent on how we’re willing to do it.

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