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AS THE SORROWFUL investigation continued last week into the disintegration of a space shuttle, astronomers gathered in Washington, D.C., for an unrelated, euphoric announcement: An unmanned, distant satellite had sent back remarkable pictures of the universe in its infancy.
The data established its age, what it is made of, and how fast it is expanding, all with much greater precision than earlier probes. And the first stars were shown to have formed much earlier than thought, just 200 million years after the Big Bang that started the cosmos.
The scientists were jubilant, as well they should have been. John Bahcall, a distinguished astrophysicist at the Institute for Advanced Study in Princeton, said the data marked a rite of passage for cosmology, from philosophical uncertainty to increasing precision.
What began not long ago as speculation about enormous quantities of unidentified "dark matter" and "dark energy" in the universe has been confirmed. We know now that only 4 percent of the cosmos consists of atoms, the building blocks of bananas, battleships, and babies. Another 23 percent is dark matter, presumably particles left over from the Big Bang. The remainder, 73 percent, is dark energy. Just what dark energy is remains to be proved, but scientists are hot on...