Questions About the Big Bang

[Alex K]

I just have to complain about one thing that is conceptually wrong, but creeps into every popular explanation - the expansion being " faster than the speed of light" is not a good description of what happens.

Why?

Because cosmic expansion, in the language of Einstein's relativity, is not objects moving * through space * at ever greater speeds, but rather space expanding. All distances get multiplied by a factor increasing with time, the so called scale factor. Since nothing really moves through space in cosmic expansion, it only makes limited sense to assign the increase in distance over time to a velocity. If the universe is big enough, even moderate expansion rates will give you effective distance increases per time that would correspond to faster than light velocities. Casting it in that language makes it appear as if there was a contradiction with the cosmic speed limit when there isn't.

I give you an analogy: imagine two snails on a rubber band sitting 2 feet apart. They can only crawl one foot per minute max. Now you pull the rubber apart such that its length doubles in 10 seconds. The snails will now suddenly be 4 feet apart. Did they magically crawl 1 foot in ten seconds each, thus beating their own speed limit? No, the distance between them increases because the rubber stretches, and theirn distance has increased at 2 feet per 10 sec, but at no point did they exceed their max crawl speed on the rubber!