A Fresh Look at the Expansion Theory

When I first heard of the Expansion Theory years ago, I don't think I ever really considered taking it seriously.  It struck me as the sort of cornball idea that's only good for shaking up your preconceptions and possibly motivating you to consider different perspectives, the typical sort of thing that inevitably comes up in conversations about "thinking outside the box", something akin to my "microcosm" idea mentioned a few months back.  But yet, the theory has stuck with me, nagging at my mind from time to time, and tucked away on some back shelf where I didn't really bother talking about it.  Today, however, it somehow came up in a conversation I was having with my daughter, and this leisurely day of leftovers and laying around watching TV provided me with an occasion to dust it off, bring it down from the shelf, and reconsider it.  After some brief hunting around on the internet, I found some people who actually take the idea seriously, as well as some interesting arguments for and against.  Some of the advocates of the theory seem a bit...crackpot-ish, even a little too...Flat Earth, but some of them seemed to make a fairly sober and compelling case.  I won't say that I'm completely sold on the idea.  Far from it.  But I'm no longer so quick to dismiss it either.

For those of you who've never heard of it, the Expansion Theory is basically the idea that all the matter in the universe is in a constant state of expansion, and this expansion is fairly uniform.  Since (under this theory) we're expanding along with everything else, this expansion is nearly imperceptible.  If fact, it only manifests itself in one obvious way: gravity.  Confused yet?  Don't worry, my daughter didn't know what the heck I was talking about either.  Let me see if I can't find a way to make it clearer.

If I hold a ball in my hand, and I let it go, it appears to fall to the ground as though pulled there by a force of attraction.  What the Expansion Theory is saying is that the ball doesn't fall at all; it doesn't actually even move.  The Expansion Theory says that the Earth and the ball come to meet each other as they expand, filling the space between them.  Because I'm growing, and the room is growing, and...well, everything is growing, then I don't see that the ball gets any bigger.  I just see the ball and the Earth rapidly colliding.  You see, as long as I'm holding the ball in my hand, and I'm standing solidly on the ground, then the ball and I are both being pushed outward through space by the expanding surface of the Earth.  But the second I let go of the ball, it stays at that same point in space until the surface of the Earth expands to meet it.  To our eyes, it appears to fall.  (See figure below.)

I know, it sounds crazy, right?  The idea that you, your computer, and the room you're sitting in have all doubled in size while you've been reading this seems absolutely ludicrous.  But is it really any more ludicrous that attributing gravity to a curvature of space that you can't see?  Anyway, like I said, I'm far from completely sold on the idea.  It has a few obvious problems, and a few not-so-obvious problems.  For one thing, you have the fact that gravity gets weaker with distance.  At first glance this seems to definitely contradict the theory, but I've come across some intriguing proposals for tackling that problem.  Again, I haven't gone off the deep-end completely.  It's just something interesting to pursue on a lazy day while I lounge around the house digesting my turkey, a little worthwhile time spend outside the box.  I'll keep you posted.