I've been talking about dark matter a lot, and yet there's still so much to explain about it. For example, dark matter and normal matter (protons, neutrons, and electrons) have a few things in common:
- They both have mass.
- They both feel the effects of gravity.
- They both cause their own gravity.
But that's where the similarities end. I can make a long list of the ways that dark matter and gravity are different from one another, but I prefer to give you an example. Imagine the following scenario: you stand up from your seat, walk towards the wall, and smack right into it. You might wind up looking like this.
On the other hand, what if you were made of dark matter? Well, you'd try to stand up, but that wouldn't work. You see, protons are charged particles, electrons are charged particles, and even neutrons (which are neutral) are made up of charged particles. This means that when they get close to one another, the electromagnetic force keeps them from passing through each other. Dark matter doesn't feel the electromagnetic force, and so as you pushed down on the floor, the floor wouldn't push back, and you'd pass right through it. How much stronger is the electromagnetic force than gravity? 1038 times stronger. The odds of gravity acting as strong as the electromagnetic force, even for an instant, are the same as picking the winning numbers to the New York lotto jackpot six times in a row.
In fact, if you were made of dark matter the center of the Earth would pull you towards it, just as it would for regular matter. But without the electromagnetic force to stop you, you would simply fall through the Earth towards the center. In fact, without the electromagnetic force, there would be nothing to hold your body together, and if you managed to raise your hand, there would be nothing to keep your hand attached to your body; it would simply fly off into the air, bound to the Earth by nothing more than gravity. Here's something weird: since there's no electromagnetic interaction on dark matter, it wouldn't get trapped at the center of the Earth; you would pass through the center, come out the other side (presumably in Indonesia or something for where I am), and then fall back through the center of the Earth, and wind up back where you started, and you would do this for eternity.
Maybe this gives you a little handle on what would happen to you if you were made of dark matter, and just how different this stuff is from everything we're used to.