Who is the most popular musician? And how do musicians form collaborations? We will explore these questions by using mathematics and network science, and find out how Harry Potter and Wikipedia can explain why some songs are more popular than others. Discover the power of math! Dr. Clara Stegehuis (UT) investigates problems inspired by applications in network science, physics and computer science. This lecture takes place in the context of the exhibition IMAGINARY - Beauty and Power of Mathematics.