Leo Birnam, the secretary of scientific affairs [sic], spends most of the story convincing Colonial Commissioner Nicholas Orloff of how serious the Jovian threat is to humanity. The square footage of Jupiter's surface means that the Jovians have fifty times the resources as Earth's empire.
Once Orloff is convinced of the danger, head scientist Prosser describes the difficulty in getting force fields strong enough to hold an atmosphere against the vacuum of space. This is the one bit of technology that they know will be possessed by the Jovians when they launch their war of extermination.
"Not Final!" has been reprinted several times; Possible Worlds Of Science Fiction (1951), Asleep In Armageddon (1962), Time Probe The Sciences In Science Fiction (1966), Toward Infinity Nine Science Fiction Tales (1968), First Contact (1971), The Early Asimov (1972), Encounters (1988), and The Complete Stories, Volume 2 (1992).
"Not Final!" provides examples of:
- Artificial Gravity: Ganymede has underground bases with fields of artificial gravity to keep the inhabited areas at Earth-normal. Orloff and Birnam have to cross two miles of Ganymede-normal to reach Ether Station.
- Artistic License Astronomy: According to this story, Jupiter has a surface. While that may have been a plausible theory in the 1940s, most scientists knew that such a surface couldn't be solid. At best there would be layers of gas compressed to liquid form.
- Deflector Shields: These force fields are created by "interatomic bonds" (also known as the Strong Nuclear Force). Prosser, the scientist in charge of Ether Station, is proudly proclaiming that a force field capable of holding a Jovian atmosphere against the vacuum of space is impossible. Meanwhile, Hal Tuttle, an engineer, is on his way to Ganymede in a spaceship he designed with a force field for a hull. He estimates that these fields are capable of containing much more pressure than just Jovian atmosphere.
- Dramatic Irony: After Prosser has reassured Nicholas Orloff that the Jovians cannot escape Jupiter because making force fields strong enough to hold an atmosphere against the vacuum of space is impossible, two other characters are talking about how happy Orloff will be to be the first passenger in a spaceship with a force field instead of a steel hull.
- Everybody Smokes: Because this was published in 1941, two of the main characters begin smoking in an artificial environment, in the private office of a third character that they're waiting for. The ubiquitous expectation of smoking means the problems of eliminating second-hand smoke residue on Ganymede isn't addressed.
- Feeling Oppressed by Their Existence: The Jovians believe that they are the only intelligent form of life. Once they realize that they have been communicating with non-Jovian life (that is, humans), they are offended and announce that they are the natural masters of the universe and the vermin will be eliminated.
- Finale Title Drop: This story is about Prosser, a scientist working on creating force fields capable of holding an atmosphere against the vacuum of space. He declares that it is scientifically impossible, and repeats "That's final!" several times. This story subverts the trope by having an epilogue where another character has managed to do exactly that, showing how wrong Prosser is, and making the title a response to Prosser's claim.
- Final Solution: The Jovians believe that they are the only intelligent form of life. Once they realize that they have been communicating with non-Jovian life (that is, humans), they are offended and announce that they are the natural masters of the universe and the vermin will be eliminated.
- First Contact Math: Birnam describes how first contact with Jovians involved a lot of back-and-forth on math, such as adding, square roots, and factorials. This went on for over five years, as human scientists on Ganymede communicated by radio clicks to the surface of Jupiter.
- Foil: This story contrasts scientists and technicians. Prosser, a scientist, pays attention to current theory. He remarks several times that scientists are careful and follow/test theories before trying to put them into action, while technicians try to do things without understanding them. A technician trying to create force fields would blow themselves up due to being less careful and never realize that it was "impossible". Hal Tuttle, designer of the Translucent, is exactly the sort of technician that Prosser despises. After losing an arm and an eye when space buckled under the pressure, he kept trying to make force fields work, finally succeeding.
- High-Class Glass: Nicholas Orloff went to Oxford University and maintains upper-class attitudes, such as a monocle affectation, to show off how much more highly educated he is compared to the average person.
- One World Order: Earthmen have united under a single government, one that has begun colonizing additional parts of the Solar System, including Ganymede.