Light from space always reaches us after a delay. For example, the light from our nearest star system, Alpha Centauri, takes four years to reach Earth, so when we look at Alpha Centauri, we see it as it was four years ago.
The James Webb Space Telescope (JWST) will take this idea to the extreme, studying objects so distant that the telescope will essentially be looking back 13.5 billion years — close to the start of the universe.
