When the James Webb telescope peers into space, it sees not just far away but far back in time: its images catch galaxies as they were just a few hundred million years after the Big Bang, more than 13 billion years ago

When the James Webb telescope peers into space, it sees not just far away but far back in time: its images catch galaxies as they were just a few hundred million years after the Big Bang, more than 13 billion years ago

Most of us first learn to think of a telescope as a magnifier, pulling the far-off close so a smudge becomes a planet. That works fine for the Moon. It breaks down once you point a big enough mirror at the edge of the observable universe. At that scale the instrument is not really a magnifier at all. It is closer to a time machine, and the farther it looks, the deeper into the past it reaches. That is not a poetic flourish. It comes straight out…