Resolve has different meanings depending on the context, but in this case, I think the best meaning for "resolve into" is: "To become separated or reduced to constituents" -An impossibility that nature will quickly reduce to (into) death- In the context of The Big Bang Theory dialogue, means that the natural solution to what Sheldon is saying is death for both of them. Impossibility refers to "occupy the same spacea as that Buick in front"... so if Penny doesn't slow down, they will crash the car in front and die in this accident... Resolve into here has the meaning of "find a solution to" but you know Sheldon's dialogues are always overblown.

Like become, but more like, "inevitably become" Think about this word "solve" -- when nature "resolves" into death, it is something that happens because of rules, like a math problem which is solved.

Give us the whole sentence, please. We’re travelling forward at, good Lord, 51 miles an hour. Now let’s assume that your brakes are new and the callipers are aligned, still, by the time we come to a stop, we’ll be occupying the same space as that Buick in front of us, an impossibility that nature will quickly resolve into death, mutilation and… oh look, they built a new put-put course. This is Sheldon going off at Penny. You know, if you say the context it makes it a lot easier for us all. Anyway, this is humour, and unless you get the joke, it won't be of use to explain.

At present this sentence does not make sense.

If Penny doesn't slow down, they will crash the car in front and die in this accident... Resolve into here has the meaning of "find a solution to" but you know Sheldon's dialogues are always overblown.