From Alfred Speer's 10 mph vision in 1871 to modern failures in Paris, the moving walkway has failed as mass transit because of the fundamental physics problem of safely onboarding people onto a platform already moving at high speed, leading to trips and falls.

Unlike on Earth, where atmospheric drag makes electromagnetic launchers (mass drivers) impractical, the Moon's vacuum environment makes them highly efficient. This technology could turn the Moon into a "train station" for the solar system, launching raw materials and goods to Mars at a fraction of the energy cost.

The moving walkway’s popular debut at World's Fairs typecast it as an amusement ride, creating a "magnificently impractical" reputation that prevented government officials from taking it seriously for major urban infrastructure projects like the Brooklyn Bridge.

The NFL's potential European expansion via supersonic jets mirrors baseball's history. The Dodgers and Giants only moved from New York to California once commercial air travel made cross-country trips practical. This reveals a recurring pattern where transportation breakthroughs are the critical catalyst for unlocking bi-coastal or intercontinental sports markets.

Against investor advice and industry trends favoring VTOL (vertical takeoff and landing) drones, Zipline opted for a fixed-wing airplane design. They realized their customers valued range above all else, and a simple airplane could fly 10-30x farther, solving the core problem more effectively.

Unlike most technologies that become cheaper over time, developing a new jet engine has grown more expensive, even on an inflation-adjusted basis, with new programs costing over $10 billion. This is because engines constantly push the frontiers of material science and engineering, keeping R&D costs and barriers to entry extraordinarily high.

SpaceX previously pitched using rockets for ultra-fast intercontinental travel (e.g., NYC to Tokyo in 30 minutes). While not a current focus, this concept reveals a core strategy: framing its technology as a replacement for massive existing markets, like the entire commercial airline industry. This justifies enormous valuations and ambitious long-term goals.

Simply replacing jet engines with electric motors on current aircraft designs is ineffective. The extreme weight of batteries demands a complete redesign from the ground up, optimizing the entire airframe to accommodate a fundamentally different and heavier energy source.

Fusion reactors on Earth require massive, expensive vacuum chambers. Zephyr Fusion's core insight is to build its reactor in space, leveraging the perfect vacuum that already exists for free. This first-principles approach sidesteps a primary engineering and cost hurdle, potentially making fusion a more commercially viable energy source.