To review a little, all matter in our universe is made up of empty space, occasionally interspersed with atoms, which themselves are made up of mostly empty spaces, except for a bunch of even smaller stuff called quarks. To use an example that a layman can understand, when you hit yourself on the head with a rock, even though it feels kind of owie, it could be much worse, because both your head and the rock are composed mostly of empty space. Especially your head, if you have this habit.
All these quarks are just random electric charges that pile together until they form matter, or as it is popularly called, "stuff." The behavior of quarks is best explained by quantum mechanics, which no one understands. If you lick the top of a nine-volt battery, and think of what happens to your tongue as a quantum, you understand it nearly as well as most Nobel prize-winners.
Physicists discovered quantum by shooting electrons around and losing some of them. Consider that electrons are very small—there are nearly 100 quiptillion ones in the period at the end of this sentence—and you would think misplacing a few would be no big deal. But it is, and some scientists think that proves that other universes exist, and that's where the missing electrons are.
Naturally these other universes are better than ours. Instead of being made of mostly empty space, like our cheap-o realm of existence, they are made of real stuff, stuff like purple Jell-o, or tofu. In fact, there could be a tofu universe and a purple Jell-o universe. And they could be at war, so that their tofu and purple Jell-o parts could be mixed together. Try not to think about that. The lesson here is never study physics while you are eating lunch.
These better universes influence ours, because they can. Stuff from them could even poke through into ours. In a more scientifically aware future, when your wife discovers a pair of strange panties on the bench seat in your minivan, the explanation "It must have come from another universe, honey," will be acceptable, so it's not all bad news.
Better quality universes may also imply that our universe is not real at all, but a hologram or a picture show put on for the amusement of other universes. The question is, if our universe is a hologram, who is watching? And what kind of hyper 3-D glasses are they wearing? And what are their favorite shows? These are questions that are only beginning to be answered. First off, it's obvious they have patience. Thirteen billion years is a long time to sit in a theater, even if you have brought a tub containing a whole hot buttered popcorn universe. It is doubtful, however, that they are watching us. Our universe is more like a fireworks show than a TV channel. Here on Earth, we welcome the occasional asteroid smash, but by and large the spectacular stuff—supernovas, neutron stars, galaxies colliding—happens on a much larger scale and far away.
The sad fact is that we can enjoy all the world wars and random murders we want, but it's doubtful other universe audiences care. What they are really looking forward to is our Milky Way getting t-boned by the next galaxy over about four billion years from now. It should be quite a show, and other universe people that don't have the time to watch it live certainly have their DVR's set for it.
So there you have it. We're made of nothing, and exist as sort of a IMAX theater for vastly superior mulitversal beings. Science marches on, and if you don't like where it's heading, here's a nine-volt battery to lick. And a rock. You know what to do with it.