The scientist decides to use the ray to shrink himself to the size of an ant to infiltrate a secure facility. Because oxygen molecules are now too large to cross his alveolar membranes, he asphyxiates in seconds.
The alien assassin alters its cellular structure to disguise itself as a house cat. Strictly bound by the conservation of mass, the 90-kilogram cat immediately collapses through the floorboards.
A scientist opens a portal to a parallel dimension. The other dimension has a slightly lower vacuum energy state. Our entire universe collapses into the portal at the speed of light.
The spy activates his cloaking suit, bending all light around his body. Because no light reaches his retinas, he is perfectly invisible and completely blind.
A street samurai gets a massive, superhumanly strong robotic arm installed. The first time he tries to punch a hole in a concrete wall, the recoil shatters his entirely normal human collarbone and spine.
A hero pilots a spaceship as fast as he can to find a cure for a plague ravaging Earth. He returns a week later, subjective time, to find the cure works perfectly, but humanity has been extinct for 4,000 years.
A medical team shrinks their submarine to microscopic size to repair the President's damaged heart. At that scale, Brownian motion causes the surrounding water molecules to violently batter the vessel to pieces instantly.
An assassin travels exactly 80 years into the past to alter history. Because the solar system is moving at 230 kilometers per second around the galactic center, he materializes in the hard vacuum of deep space and dies.
A highly advanced alien armada enters the solar system to conquer Earth and strip-mine its oceans for water. They realize the Oort cloud is full of easily accessible ice comets completely free of Earth's steep gravity well, so they mine those instead and never even say hello.
Genetic engineers create a superhuman with a metabolism ten times faster than normal, granting him incredible speed and reflexes. He spends 22 hours a day eating mayonnaise straight from the jar just to avoid starving to death.
Hotshot space fighter pilots engage an enemy armada, firing their continuous-beam megawatt lasers. Because the vacuum of space is an excellent insulator, the ships are unable to shed the resulting waste heat and the pilots are forced to stop firing on risk of boilng alive.
Humanity builds a massive, 50-meter-tall bipedal mech to fight an impending alien threat. Upon taking its first step, its joints instantly shatter under its own immense mass as dictated by the square-cube law.
Pioneers land on a lush, Earth-like exoplanet. The gravity is 1.0g, the atmosphere is breathable, and there is water. However, the native biosphere uses a slightly different chirality for its amino acids. The colonists slowly starve to death while eating full meals every day.
@NASA A futuristic space agency sends people to a celestial body after a wrong break. They don't find anything new, but their photos are slightly better quality than before.
Gritty blue-collar workers set out to mine a near-Earth asteroid made of solid platinum. They successfully capture the asteroid and bring the platinum back to Earth. The sudden influx of precious metal completely crashes the global commodities market.
Humanity receives an incredibly complex radio transmission from the TRAPPIST-1 system. A team of the world’s most brilliant linguists and mathematicians spend 30 years decoding it. They fail because the transmission was encrypted.
A plucky crew of rebels attempts to ambush a massive battleship. Because there is no stealth in space, the battleship detects their thermal emissions from 40 million kilometers away.