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I'd still prefer he answers :)

Posted using Partiko Android

Hehe. You want to hear directly from the mouth of an expert. Cool 😎

In @greenrun's message, it could be "visible" in the sense of "visible in a detector". Similarly to the fact that one needs an appropriate apparatus to detect non visible electromagnetic waves.

Oh!! That definitely was the case.
But I also think @greenrun is trying to be nonfictional and factual just as he always does, for things he may have read or seen somewhere :) Great though!!