“When you look at the calculation, it's amazing that every time you try to prove or disprove time travel, you've pushed Einstein's theory to the very limits where quantum effects must dominate. That's telling us that you really need a theory of everything to resolve this question. And the only candidate is string theory.”

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.