The Expanding Universe

Measuring Expansion The universe is expanding. We know that because of the red shift in the spectrums of distant galaxies. Often, this is expansion is described as being similar to what happens to the raisins in a loaf of raisin bread as it rises (But seriously, who eats raisin bread?). The dough (or space) gets bigger, but the raisins (galaxies like ours) stay the same size and simply move apart. Take a moment to read about this here.

Our online textbook also includes a short demonstration that you can try if you have a balloon at home. You can read about it and try it out by clicking here. If you don't have a balloon, Below is a video that can help you understand. It even shows the balloon model as a demonstration. Please watch this short, but cool NASA video:

ESCI A.S1.O1.A5 The Center of the Universe VID

Redshift

It seems like we don't get a whole lot from space. A few rocks here and there and some light. As limited as this may seem we actually can know a lot about space form these sources, especially from light. The light from stars can work sort of like a bar code. Each star gives off it's own unique light. From this light we can tell what the star is made of and how the star is moving.

Remember ROY G. BIV? This acronym helps us remember the colors of the rainbow, but it is also part of the spectrum of light. Electromagnetic waves exist in different forms, such as visible light, depending on wavelength. One of the most important thigns we have seen with this light is that it has a redshift, or is father down the spectrum towards the red side than it shoudl be. Why is this? Watch this video to see why this happens and what we learn from it.

ESCI A.S1.O1.A5 Stephen Hawking-The Expanding Universe VID

So what we see is that every galaxy in the universe is redshifted. This means that they are all moving away from each other, or in other wards, the universe is expanding. But expanding from what? Where and when did it begin and what was it like? If everything int he universe was together at one point what kind of energy would it take to get it all to start flying away from one another? A large explosion? Like a big bang perhaps? But don't get in your head that there was a fiery explosion with an unflinching action star slowly walking away. It was really more like an inflation, much like our balloon example. Like the latex of the balloon, space is expanding and taking everything with it.

Questions to consider:

How can we tell that the universe is expanding?
What exactly is it that is getting bigger?
What will the universe be like in the future?
What can we assume about its past?