ASTRONOMERS have a great advantage over archaeologists: they can see the past. The finite speed of light means that the further away a cosmic object is, the longer its light takes to reach us. An image recorded by our telescopes today tells us how that object looked long ago when its light was emitted.
Using our most powerful telescopes on Earth and in space, we can now trace the universe’s story back to a time when it was just 500 million years into its 13.7-billion-year life. Meanwhile, a single flash that bathed the cosmos in light 400,000 years after the big bang provides us with an isolated exposure of the universe in this infancy.
This infant universe is, like a newborn baby, almost featureless, yet to assume the characteristics that will mark it out in later life. When our telescopic cameras pick up its story again, however, it is recognisably its adult self – stars, galaxies and clusters of galaxies already populate its reaches.
When our telescopes pick up the universe’s story again, it is already recognisably its adult self
What happened in between, during the universe’s turbulent, formative adolescent years? That has long been a matter of conjecture. Now, thanks to a combination of new instruments and refined observational techniques, the missing reel of the universe’s story is about to be slotted in – presented in the crackle and hiss of giant radio waves.
We already have a rough storyboard for the universe’s missing adolescence. Clues are encoded in the cosmic microwave background, that radiation suddenly liberated 400,000 years into the universe’s life. …