The Atomic Universe

Some people see this similarity and wonder if it goes even farther. The Earth has a lone moon orbiting it, and an atom of hydrogen has a lone electron going around it. Maybe the whole Universe is nothing more than a giant atom!

I see this analogy on the internet sometimes, and while poetic, it's flawed. First, electrons do not really orbit the nucleus of an atom. That is an old-fashioned way of saying it, and does not include what we call quantum mechanics. The Universe, on a very small scale, does not behave in ways that make much sense to us. Details are very difficult to explain here, but the way it works out, electrons can only be at very specific distances from the nucleus, called "preferred energy levels". A planet, on the other hand, can be at any distance from its star.

Worse, gravity and electromagnetism have a fundamental difference: while you can have positive and negative electricity (and north and south magnetic poles), gravity only has positive mass. Electromagnetism can either attract or repel, but gravity can only attract. Finally, electromagnetism is tremendously stronger than gravity; it is about 10⁴⁰ times stronger! That's a 1 followed by 40 zeros, or a ten thousand trillion trillion trillion times stronger, if I didn't drop a zero somewhere. Think of it this way: a tiny magnet can attract an iron needle off a table, even though the entire mass of the Earth is pulling it the other way using gravity!

So it would be nice to be able to make an Atomic Universe analogy, but as usual, Nature is more subtle than we can easily know.