How Do Objects Appear 14 Billion Light-Years Away in the Universe?

[slafferty]

Oops: Just discovered the Cosmology forum. Sorry for posting in the wrong area. (Can edit but don't see a way to move and delete.)

I hope this isn't a really dumb question and that it is appropriate for this forum. Here goes:

We look out in the night sky and see objects which are roughly 14B light-years away. The light is said to have left them 14B years ago. Since they and our planet came from a single place about 14B years ago, how did they get that far away, 14B years ago?

Thanks for your help and please hold the laughter down :)

Steve

 

[Valerie Park]

The answer to your question is a bit complicated. The universe is constantly expanding, and so galaxies and other objects are getting further away from each other all the time. This means that the distances between objects that we observe now were much smaller 14 billion years ago. Furthermore, the light that we see from distant objects today was emitted much earlier than 14 billion years ago - it has just been travelling for so long that it takes that amount of time for it to reach us. On top of this, there is also something called the "cosmological redshift" which causes light from distant objects to be shifted to longer wavelengths, making them appear redder (hence the name). This phenomenon is due to the expansion of space itself, and means that light from even further away will be shifted to even longer wavelengths, allowing us to see objects that are even more distant than 14 billion light-years away.Hope this helps!