Driving from Rome to Tuscany in a rental car, we were at the mercy of the satellite navigation system. The first crisis was when it indicated we were on the exit ramp but we knew we were still on the freeway. So we ignored it. After a few hundred metres, it nonchalantly showed us we were back on the freeway.
Human judgment saved the day. But what if this had been a self-driving car? The problem is that the civilian satellite navigation system as implemented in most cars has wiggle room; it’s only accurate to about 10 metres.
Fortunately, a state-of-the-art technology upgrade is on its way. Surprisingly, delivery of more accurate mapping will also depend on the ancient science of geodesy, born in ancient Greece from the struggle to decide between Homer’s view that the world was flat and Pythagoras’s view that it was spherical.
Today we know that Pythagoras was right, but our planet is far from being a perfect sphere. And it has another quirk that bodes poorly for the twenty-first century’s needs for precision satellite navigation. The continents don’t stay put.