This question already has an answer here:
Einstein famously made a thought experiment: what would he see if he sat on a beam of light? His answer was -- it's impossible. Owing to him being a body with mass, he can never ever reach light speed unless fueled by an infinite amount of energy.
My question is a little different but sort of the same. At the instance of the photon's creation, it experiences no distance and no time. Then it hits something, is absorbed, and that's it. The photon "stopped."
To the photon, that took no time at all. How? From its perspective, did it simultaneously exist and not exist?
Also, I know the world line of a photon is 45 degrees on the spacetime diagram. But I only know this as a fan of science, not because I'm a physicist. So what does the complete world line of a single photon look like? Is it a line segment, with a well defined beginning and ending?