“Originally, the burden of proof was on physicists to prove that time travel was possible. Now the burden of proof is on physicists to prove there must be a law forbidding time travel.”

American theoretical physicist, science communicator, futurologist, and writer of popular science

Michio Kaku is an American theoretical physicist, science communicator, futurologist, and popular science writer. He is a professor of theoretical physics at the City College of New York and the CUNY Graduate Center. He has written several books on physics and related subjects, and he is a familiar presence in radio, television, and film. He also writes regularly for his own blog and for other popular media outlets. In 2021, he received the Sir Arthur Clarke Lifetime Achievement Award for work that helped connect science and science fiction.