Questions answered in this episode:

"What is preventing light from going faster than 300 000 km/s?"-mmbn6fan

"If photon has rest mass = 0 , then why does black hole pull it in?" - Karan Karnik
"When black holes absorb matter, the matter's velocity accelerates into the black hole because of stronger and stronger gravity. But how about light? The speed of light is the limit, so what happens then? :-)" - Robert Kongshaug

Submit your questions for the next round of Ask the Experts by clicking here and posting in the YouTube comments (Google account required). And while you're there be sure to subscribe to our Spacelab channel for weekly videos on space and astronomy. 

The question with the most "likes" will be answered in the next video by a new guest expert. Previous episodes have featured astronomer Caleb Scharf, astrophysicist Neil deGrasse Tyson and Scientific American's own editor in chief, Mariette DiChristina.