Original: If a closed string splits and its two parts later reconnect , its worldsheet will look like a single pipe splitting to two and then reconnecting , which also looks like a torus connected to two pipes ( one representing the ingoing string , and the other -- the outgoing one ) .
Simplified: For example , if a closed string splits , its worldsheet will look like a single pipe splitting ( or connected ) to two pipes ( often referred to as a pair of pants -- see drawing at right ) .