Question 28087 talks about the expansion of the universe. But it is not clear to me what happens to the light: does it also travel a greater distance or not, because of its mass 0?
Asker: Marine, 60 years old
Answer
It’s very simple. Light travels at the speed of light, 300,000 km per second.
But the distance that light traveled in a year long ago has now increased due to its expansion. Today, the distant source from which we now receive light is actually farther than the time it took light to get here times the speed of light. For the big bang itself (13.7 billion years ago) there is already a factor of about three: it is therefore 41 billion light years away.
Answered by
prof. Christopher Waelkens
Astronomy
Catholic University of Leuven
Old Market 13 3000 Leuven
https://www.kuleuven.be/
Old Market 13 3000 Leuven
https://www.kuleuven.be/
.