How can something be 12 billion light years away in a 14 billion year old universe?
Upon first glance, it would seem that the light has been traveling for 12 billion years from something that started off 12 billion light years away in a 14 billion year old universe. That would leave only two billion years for the object to separate 12 billion light years from us, which means it would have to travel 6 times faster than the speed of light (on average), which is against the “law” of relativity. This seems to be a paradox. The answer is that space itself expands. This can be explained using a two-dimensional analogy to try to explain the effect (which actually occurs in three dimensional space). This analogy just illustrates the point – it is not to meant to be taken literally. Picture a balloon that is deflated. Now, draw two dots 2 centimeters apart on the surface of the balloon. Now, pretend light travels at a speed of 1 centimeter per second on this balloon. Let’s say at some time, a signal gets emitted from one of the “dots”. (This is analogous to the source emitting
Related Questions
- The most distant objects are reported to be about 13 billion light years away, and the universe is said to be 14 billion light years away. What stops us seeing further?
- If the Universe is only 10 billion years old, why isn the most distant object we can see 5 billion light years away?
- How can something be 12 billion light years away in a 14 billion year old universe?
