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Mark Subbarao, University of Chicago, Sloan Digital Sky Survey   
By Ron Cowen

A new breed of scientists leads a cosmic revolution in thinking how the universe came to be.

Get a taste of what awaits you in print from this compelling excerpt.

Imagine a universe with no stars, no galaxies, and no light: just a black brew of
primordial gases immersed in a sea of invisible matter. Beginning a few hundred thousand years after the blinding flash of the big bang, the universe plunged into a darkness that lasted almost a half billion years. Then something happened that changed it all, something that led to the creation not just of stars and galaxies, but also of planets, people, begonias, and lizards. What could that something have been?

New clues to this puzzle—one of the most fundamental in cosmology—are pouring in from many directions. Theorists using supercomputer simulations have retraced the steps that produced the first stars and galaxies. Astronomers peering through giant new telescopes have journeyed back in time in search of the first galaxies. Researchers studying images from the Hubble Space Telescope have discovered the breathtaking diversity of the galaxies that surround us today—from giant pinwheels blazing with the blue light of newborn stars, to misshapen footballs glowing with the ruddy hue of stars born billions of years ago, to tattered galaxies trailing long streamers of stars torn out by collisions with intruder galaxies.

Less than a century ago astronomers knew only about our own galaxy, the Milky Way, which they believed held about 100 million stars. Then observers discovered that some of the fuzzy blobs in the sky weren't in our own galaxy, but were galaxies in their own right—collections of stars, gas, and dust bound together by gravity. Today we know that the Milky Way contains more than 100 billion stars and that there are some 100 billion galaxies in the universe, each harboring an enormous number of stars.

Our view of the universe is changing completely, says cosmologist Carlos Frenk of the University of Durham in England, and it's largely because of our new understanding of galaxy formation: "It's no exaggeration to say that we're going through a period of change analogous to the Copernican revolution."

Get the whole story in the pages of National Geographic magazine.

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Take a virtual adventure through space and explore digital images of the first stars, colliding galaxies, and a scan of the universe.


There are some 100 billion galaxies in the universe. Do you think life exists elsewhere in ours and in neighboring galaxies?


From the Milky Way to creatures of the deep, this month's desktop decorations offer universal appeal.

More to Explore

In More to Explore the National Geographic magazine team shares some of its best sources and other information. Special thanks to the Research Division.

Did You Know?
The Future Universe

Once upon a time, dark matter was the strangest, hardest to fathom material in the universe. What was all that stuff that we could not see that was responsible for the structure of the cosmos—and could be the controlling factor in its fate? Dark matter, along with the inherent force of gravity, could eventually slow the expansion of the universe, scientists said. It could cause the universe to crunch back on itself or, if not a crunch, the universe might drift ever more diffusely through infinity.

Now, meet dark energy. Albert Einstein proposed it in 1917 to balance an equation he was working on, but later called this "cosmological constant" his "biggest blunder." Theories about an energy that could counteract gravity have bounced around since then, but have usually faded out. Then, in 1998, astrophysicists were confronted with evidence they could not ignore. Something was opposing the incessant pull of gravity and seemed in fact to be accelerating the speed at which galaxies were flying apart from one another. It looked like an antigravity force—but didn't we learn that nothing could overpower the force of gravity? This arresting new force was dubbed dark energy, and it may have the upper hand in the fate of the universe.

Some cosmologists look 50 or 100 billion years down the road and theorize that whatever the dark energy is, it will cause our cosmic horizon to shrink so extremely that we will see only a handful of galaxies in our sky, and even they will fade from view. They envision a universe so stretched by cosmic expansion that it will become a lonely, dark "vapor." (Not to worry—the Earth will be long gone by then.) In the interim scientists will grapple with the effect that dark energy has on the expansion of space-time and strive to understand how unseeable cosmic forces, now dark energy as well as dark matter, shape our universe.

—Barbara W. McConnell

For one cosmologist's view of the fate of the universe, see

Did You Know?

Related Links
Harvard-Smithsonian Center for Astrophysics
Links to background information on many topics, including the basis of cosmology, observational astronomy, and theoretical astrophysics.

Space Telescope Science Institute
Contains images made by Hubble Space Telescope and educational links for the whole family.

NASA Space Science
Information on all NASA missions past, present, and future, yielding an understanding of the value of space-based research, can be found here.

European Space Agency
Here are missions led by a consortium of European countries and links to space science topics.

American Universities
Find links to individual universities in the United States. A few clicks will reveal current research and science tutorials. Some suggested links include: California Institute of Technology; University of California, Berkeley; University of Chicago; University of Arizona; Pennsylvania State University.

Worldwide Universities
Links to research programs in universities outside the United States. Suggested links include: University of Durham (UK); University of Cambridge (UK); University of Toronto (Canada).


Abel, Tom, Greg L. Bryan, and Michael L. Norman. "The Formation of the First Star in the Universe." Science (January 4, 2002), 93-8.

Ferris, Timothy. The Whole Shebang. Simon and Schuster, 1997.

Gribben, John. Companion to the Cosmos. Little, Brown and Company, 1996.

Kauffmann, Guinevere, and Frank van den Bosch. "The Life Cycle of Galaxies," Scientific American (June 2002), 46-58.

Keel, William C. The Road to Galaxy Formation. Springer, 2002.

Larson, Richard B., and Volker Brom. "The First Stars in the Universe," Scientific American (December 2001), 664-71.

Rees, Martin. Our Cosmic Habitat. Princeton University Press, 2001.

Steidel, Charles C. "Observing the Epoch of Galaxy Formation," Proceedings of the National Academy of Sciences, vol. 96 (April 1999), 4232-5.


NGS Resources
DeVorkin, David. "Beyond Earth: Mapping the Universe." National Geographic Books, 2002.

Klesius, Michael. "Super X-Ray Vision," National Geographic (December 2002), 42-53.

Zimmer, Carl. "How Old Is It? Solving the Riddle of Ages," National Geographic (September 2001), 78-101.

Achenbach, Joel. "Life Beyond Earth," National Geographic (January 2000), 24-51.

Sawyer, Kathy. "Unveiling the Universe," National Geographic (October 1999), 8-41.

"The Universe" Map supplement, National Geographic (October 1999).

Daily, Laura. "What an Eye-Opener!" National Geographic World (April 1998), 28-32.

Smith, Bradford A. "New Eyes on the Universe," National Geographic (January 1994), 2-41.

Gore, Rick. "The Once and Future Universe ," National Geographic (June 1983), 704-49.

Weaver, Kenneth F. "The Incredible Universe," National Geographic (May 1974), 589-625.

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