Unsolved: Engineering¶
| Problem | Status | Difficulty |
|---|---|---|
| Space elevator | Unsolved | Very hard |
| Practical flying cars | Active progress | Medium |
| Hyperloop at scale | Early research | Hard |
| Much better batteries | Active progress | Hard |
| Wireless power | Early research | Hard |
| Cheap green hydrogen | Active progress | Hard |
| Self-healing materials | Active progress | Medium |
| Earthquake-proof cities | Active progress | Hard |
| Carbon-negative buildings | Early research | Hard |
| Autonomous construction | Active progress | Medium |
Space elevator¶
Status: Unsolved · Difficulty: Very hard
A cable running from the ground up to orbit would let cargo ride into space for a tiny fraction of what rockets cost. It would be the single biggest change to space access there is.
Current approaches: mostly theory for now, plus research into ultra-strong tethers like carbon nanotubes and graphene. Some people suggest building a lunar elevator first, which is possible with materials we already have.
Why it's still open: no material we can make is anywhere near strong enough and light enough for an Earth cable about 36,000 km long. Space debris and weather make it harder still.
Timeline: the Earth version is not happening this generation. A lunar one is plausible around mid-century.
Related: self-healing materials, asteroid mining.
Much better batteries¶
Status: Active progress · Difficulty: Hard
Batteries are the bottleneck for electric cars, for storing renewable power, and for portable everything. Better ones unlock the whole clean-energy shift.
Current approaches: solid-state batteries, which are safer and denser and which Toyota and QuantumScape are racing to build, sodium-ion, which is cheap and needs no scarce lithium, lithium-sulfur, and large flow batteries for the grid.
Why it's still open: energy density, cost, safety and lifespan pull against each other, so improving one usually hurts another.
Latest: solid-state cells hit lab milestones between 2023 and 2025, with the first cars expected late this decade.
Self-healing materials¶
Status: Active progress · Difficulty: Medium
Infrastructure that repairs its own cracks would cut maintenance costs and prevent sudden failures in bridges, pipes and planes.
Latest: self-healing concrete, using bacteria that seal cracks with limestone, and self-healing polymers are already in early real-world use.