Why Hasn't the Whole Universe Collapsed into an Enormous Black Hole? [Video]

Eric R. Olson

Questions answered in this episode:

"Let's say I'm an alien on a ship 65 million or more light-years away. Using a telescope, I look at Earth and I see dinosaurs living their daily lives. If my ship started travelling towards earth near the speed of light. Would I see the dinosaurs moving faster--fast-forwarded?"—sl270703

"If all movement is relative, how can there be a speed limit? In order to measure speed, you have to measure it against something. So...what is the speed limit measured against?"—lordv27


"If a black hole's event horizon gets bigger every time its density gets bigger, i.e., it "absorbs" mass, why hasn't the whole universe collapsed into an enormous black hole yet? Shouldn't this kind of expanding black hole be getting bigger exponentially? And will this be the end of our universe and possibly the birth of a new one (or where ours began—a big bang)?"—Shaido666

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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.

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