How the balloon analogy for an expanding universe is almost perfect

MOST people have probably heard that the universe is expanding. Certainly New Scientist readers have, because I keep writing about it in this column. It is perhaps easy to accept the statement that the universe is expanding without thinking too deeply about it. It is just some weird physics indicating that, as time goes on, galaxies get further away from each other. Or maybe you have heard the old race car analogy, that galaxies moving apart are like two cars racing away from each other.

I personally detest the race car analogy and prefer the balloon with slightly magical…