An eternity. https://phys.org/news/2014-05-does-light-experience-time.html https://phys.org/news/2014-05-does-light-experience-time.htm... : photons don't expe

An eternity. https://phys.org/news/2014-05-does-light-experience-time.html https://phys.org/news/2014-05-does-light-experience-time.htm... : photons don't experience any time at all. Edit: I think it's appropriate as the lyrics start "in my memory you are moonlight, starlight". Postulating that the subject of the song is light makes the "waited for a light year" more of an "I would walk 500 miles" type of song lyric.