Dark Energy and Dark Matter

In 1998, researchers analyzing light from a special kind of supernova, or exploding star, found evidence that the expansion of the universe is actually accelerating!b At first, the scientists were skeptical, but evidence soon mounted. Naturally, they wanted to know what form of energy was causing the accelerating expansion. For one thing, it seemed to be working in opposition to gravity; and for another, it was not predicted by present theories. Appropriately, this mysterious form of energy has been named dark energy, and it may make up nearly 75 percent of the universe!

[Diagram on page 18]

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74% dark energy