When Mark’s sleds hit the ground, they would be traveling at about 65 miles per hour. That’s a snail’s pace by bobsled standards. Olympic bobsled tracks are typically about twice as high as the Tower of Pisa, so the sleds reach much higher speeds, sometimes approaching 100 miles per hour. Because air resistance increases at higher speeds, and because the long and winding course gives it more time to accumulate, its effect becomes significant in elite competition — which is why every pound matters.

In a sense, Galileo’s experiment doesn’t work, at least not on this planet. Two differently-weighted bowling balls — or bobsleds — do fall at slightly different speeds, thanks to air resistance.

If both objects are extremely heavy, the difference in their falling speed becomes vanishingly small. If you had a pair of bobsleds made of solid lead, each weighing several tons, put an extra 10-pound weight on one of them, and dropped them from the tower, they would land so close together that the tiny difference between them could only be seen with a microscope.

However, you would be wise to not try that particular experiment in Pisa.