Energy to burn: conserved, consumed, or converted, it's the engine that drives every event.(UNIVERSE)

Publication: Natural History

Publication Date: 01-OCT-05

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COPYRIGHT 2005 Natural History Magazine, Inc.

The word "energy" pops up everywhere nowadays. Did you have enough energy to get out of bed on time this morning? Does that vitamin-charged, candy-colored sports drink deliver the energy promised in the ads? How much energy do you spend chasing your kids? Are your energy costs going up this winter? Will new sources of renewable energy alleviate the new energy crisis?

Words that get used in many different ways tend to invoke elusive or imprecise concepts. In spite of some abuses within the New Age movement, "energy" is not that kind of word. What it describes is real and measurable. Energy drives everything that has ever happened in the universe. Without it, nothing would move, no tasks would ever be started or finished, and no events would ever take place.

Across the cosmos, energy takes on multiple identities and spans a staggering range of strengths. At the lowest end, though not quite at zero, is the so-called quantum vacuum, also known as the zero-point field. It's the closest possible approximation of total lethargy offered by the universe. (Paradoxically, the zero-point field of the entire cosmic vacuum may account for the mysterious acceleration of the universe.)

Individual electrons are a few steps up the energy scale. They whirl around the protons and neutrons of the atomic nucleus at assorted energy levels that trace concentric clouds. Once every 10 million years or so, the lone electron in any given hydrogen atom in interstellar space does a stately "spin flip," which shifts it to a slightly lower energy and releases a radio wave--a big event in the life of that atom, but nothing you'd write home about.

Take a big leap up the scale, and you get to the destructive potential of the thousand-foot-wide asteroid 99942 Apophis, which has Earth in its path and enough impact energy to wipe a major city clean of all its structures and inhabitants. Unlike friendly asteroids, with friendly names like 445 Edna or 1060 Magnolia or even 13123 Tyson, asteroid Apophis bears the Greek name of the Egyptian god of chaos, darkness, destruction, and evil.

Stronger still is the raging furnace in the Sun's core, which generates enough nuclear energy in one second to supply the needs of every person on Earth for a trillion years. Up near the high end is the omnipresent cosmic microwave background; although weak and harmless locally, in its entirety it holds some ninety powers often more energy...

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