Remember these are physicists so this solution only came after they spent hours trying to throw string across (you may neglect air resistance) float string across (you may neglect the mass of the string) and jump across (assume a spherical physicist in a vacuum).
The mathematicians came up with the string solution, but only after a few days of attempting to drop the ball of string from the bottom to the top because they had a different convention about coordinate systems.
I'd have expected the physicists to be first with the string theory. The mathematicians should have spent at least one week discussing knot topologies.
Disclaimer: I have a Physics degree.