A classic and award-winning Science Fiction story by Murray Leinster
The gist of the story is that scientists on a deep-space expedition unexpectedly run into (not literally) an alien ship doing the exact same thing. They work out a way of communicating with each other, but the problem is that while the aliens say
they want to be friends and don't have notions of conquest in mind, blind faith that they're telling the truth risks not only the ship and the lives of the crew, but potentially the lives of the entire human race. The story primarily focuses on the human assigned as the radio operator who communicates with the aliens and his conversations with the rest of the crew.
As the human captain sees it, the primary objectives of his ship are to find out everything they can about the aliens and get that information back to Earth, subordinate only to preventing the aliens from finding out anything about the location of Earth and getting that
information back to their home planet. The aliens feel the exact same way. The alien communicator at one point sends a message to the effect "You guys are nice. It's too bad we'll probably end up having to kill each other."
The story provides examples of:
- Aliens Are Bastards - Maybe. We're not sure, and nobody's going home until we are sure, or the aliens are dead. Which would make humans the "alien bastards".
- An Offer You Can't Refuse - The human captain hatches a plan to make one of these to the aliens. Immediately after his ultimatum, several of the aliens collapse in convulsions; it's revealed they're laughing because the alien captain was just about to make the exact same offer.
- First Contact - Obviously.
- Fool's Map - The humans want to discuss astronomy with the aliens, and to aid this they send the aliens some mockups of star maps, realizing that a real star map would give away too much information about Earth's location. When they get some maps back from the aliens, their astronomers briefly drive themselves nuts trying to figure out from what point in the galaxy star maps might look like that ... until they realize the aliens just sent back the same maps distorted slightly.
- "Hell Yes" Moment - The humans find out that the aliens see by infrared light, meaning that they probably evolved in a red dwarf system, giving the humans a leg up on knowing where the alien homeworld is.
- Higher-Tech Species - Neither race knows if the other is this or not, and neither wants to gamble on it by starting a fight and finding the other has better weapons, or by turning and running and finding out the other ship is faster or has better tracking capabilities.
- Oh, Crap - Shortly after the humans deduce the alien star is probably a red dwarf, they realize that the same logic can be used by the aliens to determine that humans probably evolved in a yellow dwarf system. The story doesn't specifically mention it, but this is a significantly worse than even exchange, since there are a lot more red dwarfs than yellow ones.
- Properly Paranoid - The story ends before we find out for sure whether the aliens are potential allies and trading partners or bloodthirsty conquerors, but given the stakes, the initial paranoia is certainly justified.