What is the Universe Expanding Into?

What is the universe expanding into? Well that's a good, yet slightly mislead question. Often when we learn about the expansion of the universe we are told to envision it as a balloon that’s being blown up. Dots on the balloon represent galaxies, and as the balloon is blown up, the space between galaxies increases, representing the expansion of the universe. This is a somewhat poor analogy, as it makes us think of the universe as an object that expands into a surround space (the air in the room). This is not true. Instead of thinking about the universe as an object that expands into another space, think about it as a sheet of rubber. The universe contains any imaginable space, and can be stretched like a rubber band. Don't think of universe expansion as galaxies hurtling outwards pushing the edges of the universe farther and farther out. Imagine instead that the galaxies are stationary, and that the space between them is stretching, causing the universe to expand.

This helps answer the question: what is the universe expanding into? Well, since the universe is all space, it's not expanding into anything. Rather, the entire universe is stretching and becoming larger.

It's ok if your still a bit confused…. So are astronomers! There are various theories about the structure of the universe and how it moves. Until we can come up with some observational evidence proving one of these theories correct, we will all sit here puzzled about the "edge of the universe" and what might be "beyond" it.

Rocket Fuel

This post was prompted by my recent endeavor to  create a safe, yet effective way for high school age kids to launch home made bottle rockets….

Ever wonder what fuels the space shuttles? The solid rocket boosters contain the propellant that initially gets the rocket off the ground. The main propellant is ammonium perchlorate, a white granular chemical that, believe it or not, is not terribly toxic. The rest of the fuel consists of aluminum, iron oxide, epoxy, and  some sort of polymer (a molecule that helps hold all the fuel parts together). The solid rocket boosters sit underneath the external tank are ignited electronically, often from the ground. These monstrous tanks of fuel weigh 1.3 million pounds when full, and produce 2.8 million pounds of force(that's a lot of force!)

So if your kids decide they want to do a rocket launch experiment for their science fair project, here's my advice: buy a rocket launch kit with a solid fuel component. I've spent a good deal of time trying to get fuel like Alka-Seltzer and water, vinegar and baking soda, and compressed air to work as good propellants. And despite the numerous you-tube videos showing nice rockets, liquid and air propellant just doesn't work. Trust me, it's safer for them to get an Estes electronic rocket launcher. Happy rocket launching!