Relativity and Time

What does E=MC² tell us about the universe?
Answered by Science Channel
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    Science Channel

  1. The ramifications of Albert Einstein's relativity equation are vast, but it ultimately breaks down to this: Mass and energy are interchangeable, and there's only a set amount of matter/energy in the universe. Energy only comes into being at the expense of matter, and matter only comes into being at the expense of energy. This premise underlies numerous technological advances involving nuclear energy and gives us a framework with which to understand distant stars.

    In observing the expansion of the universe, astronomers discovered that it holds a lot more than just the matter and energy we can observe. Dark energy and dark matter may be impossible to see, but they have huge consequences on our universe. Dark energy, an invisible energy that speeds up expansion, makes up 73 percent of the universe. Dark matter -- invisible material that may cause the universe to collapse in on itself -- makes up 23 percent of our universe. The remaining 4 percent is matter we can see.

    Using Einstein's basic equation can help astronomers better understand how the universe began -- the big bang theory -- along with events that happen now and might occur in the future. For example, Einstein didn't stop at E=MC2 but expanded the equation to help explain what happens to energy in motion. Most of us who don't study math, science and physics find it much easier to recall the shorter, catchier equation. When it's expanded to include "p" for momentum, however, it adds understanding about transfer and transformation of light and energy [source: PBS]. In outer space, the energy can be massive -- as when millions of stars orbit within a black hole. A black hole is a gigantic -- albeit distant and mysterious -- example of how resting mass converts to energy.

    Scientists say that E=MC² forms the basis for fusion, which explains not only how energy transfers to light from the sun, but also how nuclear fusion could one day create energy for nuclear power [source: University New South Wales]. And that's just one of many practical and, well, universal applications of Einstein's equation. Because it's a mathematical equation, most of us need reminding from time to time that everything has energy and Einstein's work continues to open doors to exploration of our world here on Earth and beyond. Even the radiation pressure that propels spacecraft to study our distant universe is made possible by Einstein's E=MC2 because atomic nuclei transform mass into energy.

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