Ask Ethan: How can we see so far away in such a young Universe?
46 billion light years in all directions in just 13.8 billion years? Here’s how it’s done!
“They say the universe is expanding. That should help with the traffic.”
-Steven Wright
There are a few fundamental facts about the Universe — it’s origin, it’s history, and what it is today — that are awfully hard to wrap your head around. One of them is the Big Bang, or the idea that the Universe began a certain time ago: 13.8 billion years ago to be precise. That’s the first moment we can describe the Universe as we know it to be today: full of matter and radiation, and the ingredients that would eventually grow into stars, galaxies, planets and human beings. So how far away can we see? You might think, in a Universe limited by the speed of light, that would be 13.8 billion light years. But it’s not, and Mark Hertzberg wants to know why:
How can we look at a segment of space 92 Billion miles across when light from each edge only had 13.7 billion years to travel? Even assuming you mean those points would have moved away farther during the travel time and we are calculating where they would be rather than what we see, and include that at that distance space can be expanding faster than c, the numbers still seem high.
