"Impossible" and "Unpossible": we confuse these two ideas all the time, and it doesn't serve us.
Something that is "impossible" cannot ever possibly happen, according to all known laws of science.
Something that is "unpossible" cannot happen according to reality as we know it.
There's a difference.
Most of what we call "impossible" is actually "unpossible." Something I want may be impossible to me, right now, this month, with my current circumstances. That means it's not impossible, it's merely unpossible.
Really, instead of saying "that's impossible" we should be saying "that's unpossible." Or "that's impossible, according to how I have defined this other term." Or, if we really want to be honest about it, we could say "that's not possible for me, yet."
Even something "impossible" should have an asterisk next to it, because our scientific understanding of the laws of nature is always expanding. New discoveries can and will change our understanding of what's possible. That's what science does, and it works.
The word that changes everything: "yet." But I'll take an asterisk as a shorthand for 'yet'.
Faster than light travel: impossible*.
Next time you find yourself writing that something is "impossible," try writing it as "impossible*" instead.