Guest Stars Avi Loeb as Himself (Astrophysicist) Grant Tremblay as Himself (Astrophysicist) Alex Filippenko as Himself (Astrophysicist) Max Tegmark as Himself (Theoretical Physicist) Sean Carroll as Himself (Theoretical Physicist) Lewis Dartnell as Himself (Astrobiologist) Katherine Freese as Herself (Cosmologist) Alessandra Abe Pacini as Herself (Physicist) Samuel Levin as Himself (Evolutionary Biologist)