Could humans run on water?

With the 2024 Paris Olympics just days away, sports fans are braced to see who will run, jump, row, fight and dance themselves into the history books. One of the most exciting moments will be the 100 m sprint finals, when athletes compete to become the fastest man or woman on Earth.

Over the years we have seen jaw-dropping performances from the likes of Usain Bolt and Florence Griffith-Joyner. Scientists have been captivated by top sprinters – trying to understand how physique, technique and nutritional intake can help athletes push the limits of human ability. In this episode of the Physics World Stories podcast, we tackle the more speculative question: could an Olympic-level athlete ever run on water?

Grappling with this question is our guest Nicole Sharp, engineer and science communicator specializing in fluid dynamics. She runs the fluid dynamics blog FYFD and authored the recent Physics World feature “Could athletes mimic basilisk lizards and turn water-running into an Olympic sport?“. Basilisk lizards are famed for their ability to skitter across water surfaces, usually to escape predators.

It won’t surprise you to know that scientists have already grappled with this question. For instance, a team in Italy studied whether it was possible in reduced gravity conditions equivalent to the Moon. Sadly, a water race on the Moon is unlikely due to the absence of pools of liquid on the lunar surface.

One place that could provide the setting for a liquid sprint are the ethane and methane lakes on Saturn’s moon Titan. These are the only large stable bodies of surface liquid in our solar system found outside Earth. If such an event were to happen tomorrow, perhaps the gold medal favourite would be US sprinter Sha’Carri Richardson – the current 100 m world champion who weighs just 45 kg.

Listen to the podcast to discover whether Richardson would sprint or sink at the inaugural Titan Olympics.