Astronomically Large Numbers

There’s something that’s blowing my mind these days. When we look out into deep space and wonder about the existence of intelligent life (or life at all) in other galaxies, the distances are so big that what we’re looking at is an image of what those celestial bodies were incredibly long ago. We’re literally looking back in time.

For example, our nearest neighbor, the Andromeda galaxy, is 2.5 million light years away. That means that it takes light 2.5 million years to reach us from that galaxy, which means that the image of the Andromeda galaxy that we’re seeing right now is an image of what that galaxy looked like 2.5 million years ago.

And now the mind blowing part, that means that any intelligent beings on another distant planet in the Andromeda galaxy who are looking out into space at this moment and seeing our planet are seeing it as it was 2.5 million years ago. That means that if they had the ability to really zoom in, they’d be seeing our planet during the early part of the Stone Age when we just came out of an Ice Age. They’d be seeing that right now at this very point in time 2.5 million years after it happened.

It’s realizations like this that make me realize how impossibly difficult the concept of travel over these vast distances is, especially given the fact that what we seeing is limited by the speed of light. If we were to figure out a way to travel the speed of light, it would take us 2.5 million years to reach the Andromeda galaxy. That sink in for a bit. If we started the journey back at the beginning of the Stone Age, we would just now get there but we wouldn’t see our travelers via our telescopes on Earth for another 2.5 million years.

And the real mind blowing thing is that this is the closest galaxy to ours which means that these numbers only get bigger as we look out at other galaxies.