“It would take a civilization far more advanced than ours, unbelievably advanced, to begin to manipulate negative energy to create gateways to the past. But if you could obtain large quantities of negative energy—and that's a big “IF”—then you could create a time machine that apparently obeys Einstein's equation and perhaps the laws of quantum 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.