Can time travel survive a theory of everything?
It’s complicated. But studying ways to visit the past could help us understand the cosmos
![Doctor Who](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2019/09/091719_ts_time-travel_feat.jpg?fit=1028%2C579&ssl=1)
The TARDIS and other fictional time machines make time travel look relatively easy (Peter Capaldi and Jenna Coleman are shown promoting the BBC’s Doctor Who). But just because it’s permitted by the laws of physics, doesn’t mean it’s practical.
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