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Art Molella, Jerome and Dorothy Lemelson Director
Chromolithograph, about 1893, of Christopher Columbus bidding farewell to the queen of Spain on his departure for the New World, August 3, 1492. Courtesy Library of Congress

With the rising cost of fuel and the impossible demands on our time these days, we are constantly looking for shortcuts. That puts us in the company of history's most famous seeker of shortcuts, Christopher Columbus, who sailed west to reap the bounties of Asia. Key to his audacious plan to reach the "Indies" was the spherical shape of Earth, which, contrary to insidious schoolbook myth, almost everyone at the time accepted. [1] Had Columbus not seriously underestimated Earth's size, he might have made it to his true destination. [2] Instead, his accidental landfall on the present San Salvador Island (now part of the Bahamas) introduced his fellow Old Worlders to the wonders of what they called the New World. The Genoese explorer's serendipitous encounter fed an ever-growing fad for discovery--and an ever-growing need to know where you were headed.

This astrolabe dating from about 1450 has twenty-five star pointers shaped like heads of dogs. The grid of lines below the star map is for setting star positions. It is designed for an observer standing at the latitude of London. Gift of Lessing J. Rosenwald. Division of Medicine and Science, National Museum of American History

Though Columbus had only a limited acquaintance with celestial navigation, celestial is what it's all about in the modern age of space exploration, the newest and most outrageous frontier. I am as concerned as any of my fellow earthlings about where we go post-Apollo and after the impending demise of the space shuttle. Though there is talk of traveling to Mars and even the moon again, I have yet to hear a definitive plan from NASA or anyone else.

In the meantime, why think so small? Far more exotic worlds beckon: new planets, star systems, galaxies, and even parallel universes. And it's not just science fiction writers who are thinking this way. Intergalactic space and time travel has also become a fashionable topic among some very respectable scientific thinkers, including Stephen Hawking, Brian Greene, and Michio Kaku. They admit this is the ultimate scientific and engineering challenge to navigation. Without shortcuts, you can't even think of trying "to boldly go where no man has gone before," as Star Trek intoned. Even allowing for the discovery of a revolutionary form of rocket propulsion, there is the absolute ban on exceeding the velocity of light--a speed limit policed by none other than Albert Einstein with his theory of relativity--which one must do to traverse cosmic distances in anything less than a ridiculous amount of time.

This hypothetical spacecraft with a “negative energy” induction ring was inspired by recent theories describing how space could be warped with negative energy to produce hyperfast transport to reach distant star systems. Digital art by Les Bossinas (Cortez III Service Corp.), 1998. Courtesy NASA

Yet it was Einstein who also suggested some theoretical loopholes--what are now called wormholes, those tunnels between two points in space-time (also made popular by Star Trek)--based on the curvature of space-time posited in his general theory of relativity. In 1935, with his student Nathan Rosen, he explored warps in the fabric of space-time that offered possible shortcuts. The Einstein-Rosen bridge shortcut involves black holes. As Kaku explains it, "At the center of a black hole, there is a 'throat' that connects space-time to another universe or another point in our universe." [3] That's the magical shortcut. But, how do you navigate a wormhole? According to Einstein and Rosen, you can't, because it closes fatally before you and your spaceship can squeeze through.

There the matter stood for quite a while, until in 1988 physicist Kip Thorne and colleagues at CalTech found a solution to Einstein's equations that kept the portal open long enough to allow safe passage. Ordinary matter and energy, according to relativity theory, give space a positive curvature, like the surface of a sphere. While that was a useful shape for Columbus, it is a problem for navigating wormholes, posing an impenetrable "singularity" (a point where space-time curvature becomes infinite). Thorne and his team introduced the idea of an extremely rare form of matter with "negative energy density," which they theorized curved space in the opposite direction and thus kept the wormhole open for traversing not only our universe, but between ours and other universes. [4] "Negative energy" seems to exist theoretically, although it is exceptionally hard to obtain, even in the minutest quantities.

Long a skeptic of such things, Stephen Hawking has lately come around to giving the concept of navigating wormholes his tentative blessing, though he still insists that time travel can only go in one direction, toward the future and not the past. More precisely, his position is that it is "theoretically possible," which of course is not at all the same as saying you can actually do it. [5]

I confess to being utterly fascinated by the fascination that physicists like Hawking and Thorne have with cosmic and intercosmic travel. But what does it all mean? The imagination should soar; yet at the same time I appreciate the dose of reality in Kaku's statement that "While Thorne's time machine seems theoretically possible, [it is] exceedingly difficult to build from an engineering viewpoint." [6] A magnificent understatement, to say the least. Then again, if Columbus didn't have a dream (or had had his global dimensions right), would he ever have dared to venture forth?

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Notes

[1] Some 350 years after Columbus, belief in a flat Earth began to resurface with the publication of Samuel Birley Rowbotham's Zetetic Astronomy: Earth Not a Globe, first published as a pamphlet in 1849 and later as a book in 1865. Followers of Rowbotham (aka "Parallax") founded the United Zetetic Society in 1884, antecedent of today's Flat Earth Society.

[2] See Samuel Eliot Morison, Admiral of the Ocean Sea: A Life of Christopher Columbus (Boston: Northeastern University Press, 1983), p. 65.

[3] Michio Kaku, Parallel Worlds: A Journey through Creation, Higher Dimensions, and the Future of the Cosmos (New York: Doubleday, 2005), p. 119.

[4] Kip S. Thorne, Black Holes and Time Warps: Einstein's Outrageous Legacy (New York: W. W. Norton, 1994).

[5] Stephen Hawking and Leonard Mlodinow, A Briefer History of Time (New York: Bantam Books, 2005), pp. 110-114.

[6] Kaku, Parallel Worlds, p. 135.

From Prototype, June 2011

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