^TagTime travel (possibility)

Of the four dimensions, only time is mysterious. We can play games with the other three, the spatial dimensions — imagining, for example, 2- or even 1-dimensional universes, as in Flatland (1884). But in the end, they follow the rules. Time goes in one direction only and time travel — moving time in the other direction is easy to imagine in principle but full of nearly impossible conundrums in practice. Astrophysicists struggle to figure it out. Our brains are adapted to keeping track of the present (the experience of “now”) and the past (memory). But that only tells us how we come to be aware of time. It doesn’t tell us what time is. We get a bit closer, says Read More ›