The observable universe is about 93 billion light-years across
It is only 13.8 billion years old, yet we can see things now sitting far beyond a 13.8-billion-light-year reach.
Here is a puzzle that trips up almost everyone: if the universe is 13.8 billion years old, and nothing travels faster than light, how can the observable universe be roughly 93 billion light-years wide? The answer is that space itself has been stretching the whole time.
Light that set out shortly after the Big Bang has been traveling toward us for billions of years, but the patch of space that emitted it has been carried much farther away by cosmic expansion as the light made its journey. So an object whose ancient light is only now reaching us sits, today, about 46 billion light-years away. Double that for the view in every direction and you get a diameter near 93 billion light-years.
This is just the observable portion — the sphere from which light has had time to reach us; the universe as a whole may be far larger, possibly infinite.
We simply cannot see past the horizon set by the speed of light and the universe’s age.
Sources & references
2 referencesWell-established. Corroborated by 2 independent sources.
