McMullen, Sean. "A Greater Vision"
Divergence: c 40,000 BCE
What if: Aborigines in Australia progressed much much faster, developing steam engines by 22000 BCE, atomic power by 10000 BCE and rockets by 800 BCE.
Summary: Worried by Europe's increasingly speedy and warlike technological progress, aborigines decide to stop Columbus's expedition.
Published: In Analog, October 1992.