Why is the sky dark at night?

One thing educators like to say is that there are no stupid questions. I disagree, mildly: unasked questions might fit that category. Still and all, even basic questions are worth asking, and sometimes can lead to profound insight.

For example, one of my favorite questions is also one of the simplest: "Why is the sky dark at night?" The wonderful folks at Minute Physics took this query on, and show you why this question is so very important.

See? Just by asking why the sky is dark, you can figure out that the Universe is neither infinite in space nor in time. It had a beginning! It doesn't get much more profound than that.

And another thing I like about this video is that it answers this question in a very similar way to how I do. It's something I've been meaning to write about here on the blog, but I suppose I waited too long. Now I don't have to.

Funny, too. I have a BAFact I was going to post on this very topic on October 7, just a week from now! Why? Well, that's not a stupid question at all, and I'll answer it... in a few days.