There's a week left of a big vote to decide which is the biggest scientific problem facing mankind today.
The UK public is choosing one of six global problems is the most important for scientists to solve - for the chance to win £10 million.
The competition is called the Longitude Prize, and commemorates 300 years since the first Longitude Prize was set.
Jenny looks at the problem of paralysis, which is when someone loses the ability to move one or more muscles. How can we restore movement to those with paralysis?