Some scientific questions aren’t just unanswered, but may even be unanswerable. We can never gather evidence from before the big bang, for instance, or the era when the first spark of life on Earth ignited. We may never know how long the human lifespan can be extended, or what consciousness is. Nevertheless, researchers will keep searching. Join Scientific American editors Seth Fletcher, Allison Parshall and Clara Moskowitz for a discussion of these mysteries, which are at the center of our October issue’s special package: Impossible Questions.

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