How Goldilocks Moved to Space and the World of Economists

How Goldilocks Moved to Space and the World of Economists

The story is ‘just right’ for astronomers judging the habitability of other planets.

BEN ZIMMER

Nov. 15, 2013 7:29 p.m. ET

When astronomers announced earlier this month that there could be billions of Earthlike planets in the Milky Way, a fairy-tale character made a familiar return to the headlines: Goldilocks. For planets to support life as Earth does, they must be not too big and not too small, not too hot and not too cold. In other words, they must be “just right,” like the porridge, chair and bed Goldilocks finds in the Three Bears’ house.The Goldilocks story is “just right” for scientists explaining their findings of potentially life-sustaining worlds beyond our own, and the allusion has proved to be handy in other fields where some sort of “Goldilocks principle” is necessary to navigate between two extremes.

While “goldilocks” has been used since the 16th century to describe someone with flaxen hair, the fairy-tale character is of much newer vintage. When Robert Southey first published the story in 1837, the interloper was a meddling old woman. In later versions she became a young girl, dubbed Silver-Hair, Silver-Locks and eventually Goldilocks in the early 20th century.

The figure of Goldilocks made its way into extraterrestrial speculations as early as 1935. That year, the Los Angeles Times reported that astronomers at Mount Wilson Observatory had “turned Goldilocks” to determine how many planets might be habitable. “With identical curiosity and startlingly similar conclusions, the astronomer now is sampling the stars for conditions to support life.”

The “Goldilocks problem,” as it would come to be known, considers why Mars, Venus and Earth, while formed at the same time and from similar raw materials, have such different climates—with only Earth being “just right.”

To support life, a “Goldilocks planet” must be in the habitable “Goldilocks zone” around its sun. The latest study, led by astronomy professor Geoffrey Marcy of the University of California, Berkeley, estimates as many as 40 billion Goldilocks planets.

Outside of astronomy, Goldilocks pops up in engineering, political science and especially economics. In December 1966, The Wall Street Journal quoted a Johnson-administration official as saying, “We’re getting very close to a ‘Goldilocks’ economy right now—not too hot, not too cold, but just right.” President Johnson’s Council of Economic Advisers tried to fine-tune the economy, but critics mocked its “Goldilocks theory.”

Still, many in today’s financial world seek a “Goldilocks market”: not too bearish or bullish. Even if outer space has billions of just-right planets, here on Earth that magical balancing act can be difficult to pull off.