Why do human beings can detect the light, which is 49 billion light-year away in distance, even the universe is only 13 billion years old?

By Guangyao Q

Human beings can detect light, which is 49 billion-year away in distance, but universe is only 13 billion years old. How is it possible? Since light speed is the limitation of speed, where does the extra light-year or distance come from?

Comic microwave background radiation

The light we can see is the comic microwave background radiation, which was created about 13 billion years ago. It is the earliest light. In macro-scope world, light speed is the limitation, and anything can not be faster than light. 

The light, which is 49 billion-year away in distance, does exist because of the metric expansion of universe. Universe expands constantly. The claim is needed to be made that the distance, which is discussing about, is between two subjects at the same moment. For instant, we detected the light, which is 49 billion-year away in distance. At the moment of the star emitted the light, the start could be just 10 billion-yar away in distance. The metric expansion of universe gave the light extra distance to travel. Now, the light we detect is actual the same light, which was emitted 13 billion years ago, but the distance between earth and the star is 49 billion-year away.

People always think about faster-than-light but often do not distinguish the difference between time and distance. It is a common mistake among society. Scientists have not discovered anything, which is faster that light, so far. For any macro-scope thing, it is impossible to travel faster-than-light because of the required infinity energy.

Thanks for reading.

Reference:
https://en.wikipedia.org/wiki/Observable_universe#Size
https://en.wikipedia.org/wiki/Metric_expansion_of_space
https://en.wikipedia.org/wiki/Comoving_distance#Comoving_coordinates
http://www.astro.ucla.edu/~wright/Dltt_is_Dumb.html