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Daryl Janzen / The Conversation

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More from Daryl Janzen / The Conversation

A long-exposure photograph of a night sky, showing the circular motion of stars as white streaks of light. The star trails radiate out from a central point, with some appearing thicker and brighter. In the lower part of the frame, the dark silhouette of a forest of evergreen trees is visible against the night sky.

What, exactly, is space-time?

By Daryl Janzen / The Conversation

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