“Catch a glimpse of a relatively nearby star and you see it as it existed when, perhaps, Lincoln was president (if it’s 150 light-years away). … Stranger still, the sky we see at any moment defines not a single past but multiple overlapping pasts of different depths. The star’s image from 100 years ago and the [distant] galaxy image from 100 million years ago reach us at the same time.” And this principle holds true for much more than just the night sky.