The curious minds at What If examine overwriting Einstein’s theory of relativity with time travel, imagining paradoxes, causality, and cosmic consequences.

Like stretch marks left on skin that expanded too quickly or cracks embedded in freezing ice, cosmic strings are artifacts of ...

Contents -- Acknowledgments -- Preface -- Dreaming of time travel -- Time travel to the future -- Time travel to the past -- Time travel and the beginning of the Universe -- Report from the future -- ...